THE COMPARISON OF ENERGY CONSUMPTION BETWEEN CENTRAL AND SPLIT TYPE AIR CONDITIONING SYSTEM IN DORMITORY BUILDINGS: SHINAWATRA UNIVERSITY

Transcription

1 THE COMPARISON OF ENERGY CONSUMPTION BETWEEN CENTRAL AND SPLIT TYPE AIR CONDITIONING SYSTEM IN DORMITORY BUILDINGS: SHINAWATRA UNIVERSITY By Ronnachai Vutthivithayarak SIU THE: SOT-MESE

2 THE COMPARISON OF ENERGY CONSUMPTION BETWEEN CENTRAL AND SPLIT TYPE AIR CONDITIONING SYSTEM IN DORMITORY BUILDINGS: SHINAWATRA UNIVERSITY A Thesis Presented By Ronnachai Vutthivithayarak Master of Engineering in Systems Engineering School of Technology Shinawatra University June 2007 Copyright of Shinawatra University

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4 Acknowledgments The author wishes to express his sincerest gratitude to his adviser, Asst.Prof. Dr. Apichat Praditsmanont, for his guidance, advice, discussions, suggestions and encouragement throughout the period of study. Sincere thanks are due to Prof.Dr. Preeda Wibulswas for his willingness to act as a member of the thesis committee. Thanks are due to Dr.Pruitipong Thaicham for acting as co-adviser of the committee. Thanks are also due to Assoc. Prof. Dr. Suppachart Chungpaibulpatana for consenting to be external examiner. The author really appreciates the invaluable guidance, kindly advice and continuous encouragement given by his dear friend, Ms. Manwad Chokesuwattanaskul. Appreciation is also due to her parents, Dr. Suwat and A. Malinee Chokesuwattanaskul for their kindness and encouragement. Their help was priceless and will never be forgotten. Also, the author would like to express his gratitude to his senior, Mr. Thikhumporn Daorote, for his help in testing on site and data collection, suggestions and kindness. My sincere thanks are due to Mr. Yossapong Ketbang and all staff at the technical section at Shinawatra University (SIU). The author also acknowledges the warm welcome and kind help by all SIU s instructors and staff especially Assoc.Prof. Dr. Suravuth, Asst.Pof.Dr.Chuthatip, A.Elizabeth, Ms.Keeratikorn, Ms.Poorida, Graduate school, Dormitory section, Building and Ground section. Very special thanks to SIU for providing the author with a scholarship to undertake the Master s Degree. The author appreciates the support of the Air Technical Division, Directorate of Aeronautical Engineering, Royal Thai Air Force for allowing the author to undertake the course study and other invaluable support. Finally, profound gratitude is due to my parents whose inspiration helped me in steering me through life. Heartfelt thanks are due to my sister who has borne the responsibility of my family alone during my absence from home. This work is dedicated to all of them. i

5 Abstract Almost thirty five percent of the electrical energy consumption of Shinawatra University (SIU), is utilized by the central air conditioning system for service the dormitory buildings. The energy consumption of this part in 2006 is nearly 910,000 kwh. According to almost energy consumption of SIU is from the air conditioning system and the dormitory buildings are the biggest energy user of this system, energy conservation program should be performed at this point. This study focuses on the energy consumption of split type and central air conditioning system and the possibility to install split type air conditioning system instead of the central air conditioning system. By operating the split type air conditioning system, huge quantity of energy may be saved. Not only saving the energy consumption in dormitory buildings but changing to use split type air conditioning system also make the possibility to shut down the chiller after office hours. This alternative operation can save around 384,444 kwh or 1,253,320 baht. However, SIU must pay additional cost to maintain split type air conditioning system about 141,600 baht per year. The total net profit is around 1,111,720 baht per year. When comparing between the investment cost, which around 4.3 million baht, and the total net profit, this investment can be recovered the cost within five years and two months (at 10% interest rate). On the other hand, selecting the air conditioning system for general apartment or dormitory is also analyzed. It does not only consume less energy but the cost of split type system is also cheaper than the central system around 500,000 baht. The split type air conditioning system is recommended again. According to the reasons about the energy conservation and the investment cost. So, the suitable air conditioning system of apartment or dormitory buildings which has the energy pattern similarly with SIU s dormitory buildings is the split type air conditioning system. Keywords: Energy conservation Energy consumption Central air conditioning system Split type air conditioning system Dormitory or apartment buildings Shinawatra University ii

6 Table of Contents Title Page Acknowledgement Abstract Table of Contents List of Figures List of Tables i ii iii vi viii Chapter 1 Introduction 1.1 General Significant Objectives Scopes 3 Chapter 2 Literature Review 2.1 History of Air Conditioning System Air Conditioning System Basics and Theories Refrigeration cycle Humidity Refrigerants Types of Air Conditioning System Central air conditioning system Direct expansion system Air Conditioning System at Shinawatra University Water cooled chiller Pond cooling system Fresh air system Dormitory Building at Shinawatra University General profile Electricity fee 23 iii

7 Chapter 3 Methodology 3.1 Study Related Reviews Data Measurement and Data Collection Calculate the Data Analyze the Air Conditioning System Conclusion 27 Chapter 4 Result and Discussion 4.1 Existing Air Conditioning System Energy consumption of existing air conditioning system Seasonal Energy Efficiency Ratio (SEER value) Split Type Air Conditioning System Energy Efficiency Ratio (EER value) Energy consumption of split type air conditioning system Appropriate Size of Central Air Conditioning System 52 Chapter 5 Analysis and Comparison 5.1 General Comparison between Central Air Conditioning System 56 and Split Type Air Conditioning System 5.2 Comparison of the Energy Consumption of Existing and Split Type 57 Air Conditioning System at SIU s Dormitory Buildings Energy consumption of the air conditioning system in the 57 dormitory buildings Energy consumption of the air conditioning system in the 59 other buildings 5.3 Analysis on Financial Issues Dormitory buildings at SIU New dormitory and apartment buildings Analysis on Qualitative Issues 71 iv

8 Chapter 6 Conclusions, Implications and Recommendations 6.1 Conclusions Implications Assumptions Limitations Suggestions and Recommendations for Further Studies 84 References 87 Appendices Appendix A BAS Data of Cooling Load Distribution 89 Appendix B Questionnaire about the Existing Air Conditioning System 122 in the Dormitory Buildings at SIU Appendix C Surveyed Data about the Existing Air Conditioning System 124 Appendix D Size and Operation Hours of AHUs and FCUs 127 Appendix E Suitable Capacity (BTU/hour) of Air Conditioning System 134 in Different Size and Characteristic of the Rooms Biography 135 v

9 List of Figures Title Page Figure 1 Comparison between the Chiller s Actual Operation Level 2 and the Minimum Suitable Operation Level Figure 2.1 Diagram of the Refrigeration Cycle 4 Figure 2.2 Several Types of All Air Air Conditioning Systems 8 Figure 2.3 Air and Water Air Conditioning Systems 10 Figure 2.4 All Water Air Conditioning Systems 12 Figure 2.5 Air-Cooled Package Air Conditioning Systems 14 Figure 2.6 Air Conditioning System s Workload during Daytime 17 Figure 2.7 Air Conditioning System s Workload during Nighttime 17 Figure 2.8 Comparison between the Chiller s Cooling Load for MHB 18 and Dormitory Buildings. Figure 2.9 Chiller s Working Process Diagram 18 Figure 2.10 SIU s Air Conditioning System Diagram 19 Figure 2.11 Pond Cooling System at SIU 20 Figure 2.12 Fresh Air System in MHB 21 Figure 2.13 Heat Recovery Wheel 21 Figure 2.14 Heat Pipe Dehumidification Process 22 Figure 4.1 Break down the Energy Consumption of Existing Air Conditioning 29 System in Dormitory Building at SIU Figure 4.2 SEER Value of 375-ton Chiller during a Day in March Figure 4.3 SEER Value of 190-ton Chiller during a Day in March Figure 4.4 SEER Value of 375-ton Chiller during a Day in August Figure 4.5 SEER Value of 190-ton Chiller during a Day in August Figure 4.6 SEER Value of 375-ton Chiller during a Day in March Figure 4.7 SEER Value of 190-ton Chiller during a Day in March Figure 4.8 Average SEER Value of 190 and 375 tons Chiller in a Different 39 Period of Time Figure 4.9 Comparison between SEER Values of 375-ton Chiller at Different 40 Capacities vi

10 Figure 4.10 Comparison between SEER Values of 190-ton Chiller at different 40 Capacities Figure 4.11 Using Time of Air Conditioning System at Dormitory Buildings 43 on Normal Day and Weekend Figure 4.12 Average Demanded Cooling Load on Normal Day and Weekend 49 in Summer Semester (March 06) Figure 4.13 Average Demanded Cooling Load on Normal Day and Weekend 50 in Regular Semester (August 06) Figure 4.14 Average Demanded Cooling Load on Normal Day and Weekend 50 in Summer Break (March 07) Figure 5.1 Unsatisfied Issues of Residents in the Dormitory Buildings about 72 the Existing Air Conditioning System Figure 5.2 Percentage of the Residents Who are Willing to Reduce the Energy 76 Consumption by the Air Conditioning System vii

11 List of Tables Title Page Table 2 Comparison between Advantages and Disadvantages in 15 Different Type of Air Conditioning Systems Table 4.1 Energy Consumption of Chiller Plants in March Table 4.2 Energy Consumption of Chiller Plants in August Table 4.3 Energy Consumption of Chiller Plants in March Table 4.4 Energy Consumption of Water Pump that Supplies 31 Dormitory Buildings Table 4.5 Monthly Energy Consumption of AHUs and FCUs 32 in Dormitory 1 Table 4.6 Monthly Energy Consumption of AHUs and FCUs 33 in Dormitory 2 Table 4.7 Comparison between Load Capacity and Power Input of Motor 34 with VSD Table 4.8 Energy Consumption of Fresh Air and Exhaust System 35 at Different Motor s Capacities Table 4.9 EER Value of each Label Number of Air Conditioning System 42 Table 4.10 Comparison of Cooling Load and EER Value in Different Brands 42 and Series (Market Price in April 2006) Table 4.11 Size of Rooms, Air Conditioners Capacity and Using Time Pattern 45 of SIU Dormitories in Regular Semester Table 4.12 Size of Rooms, Air Conditioners Capacity and Using Time Pattern 48 of SIU Dormitories in Summer and Winter Break Table 4.13 Cooling Load Demand of Chiller Plants Supplied to Dormitory 51 Buildings Table 4.14 Dormitory s Cooling Load Demand in Summer Semester 52 (March 2006) Table 4.15 Dormitory s Cooling Load Demand in Regular Semester 52 (August 2006) viii

12 Table 4.16 Dormitory s Cooling Load Demand in Summer Break 52 (March 2007) Table 4.17 Summary of the Daily Average Cooling Load Demand at 53 Dormitory Building Table 4.18 Cooling Load Demand at SIU in Summer Semester (March 2006) 54 Table 4.19 Cooling Load Demand at SIU in Regular Semester (August 2006) 54 Table 4.20 Cooling Load Demand at SIU in Summer Break (March 2007) 55 Table 5.1 Summary of Monthly Average Energy Consumption of 58 Air Conditioning Systems in the Dormitory Buildings at SIU Table 5.2 Average Energy Consumption of the Existing Air Conditioning 60 System in the other Buildings from 6.00 p.m a.m. Table 5.3 Monthly Energy Consumption of Split Type Air Conditioning 61 System in the other Buildings during the off-office Hours Table 5.4 Overall Energy used which can collect from the Dormitory Buildings 63 Table 5.5 Overall Energy used Based on the Electricity Charges from PEA 63 Table 5.6 Details of Monthly Dormitories Staff Salaries 64 Table 5.7 Annual Dormitory Maintenance Cost 65 Table 5.8 Comparison between Incomes and Expenses of the Dormitory 65 Buildings Table 5.9 Investment Cost of a Split Type Air Conditioning System at SIU 67 Table 5.10 Pay Back Periods for Installation of Split Type Air Conditioning 68 System Table 5.11 Calculation for Installation Cost of a Central Air Conditioning System 70 Table 5.12 Comparison on the Qualitative Issues of Central and Split Type 77 Air Conditioning System Table 6 Data used to Calculate the Energy Consumption of the Split Type 84 Air Conditioning System ix

13 Chapter 1 Introduction 1.1 General Air conditioning systems consume huge amounts of energy, especially in tropical climate zones. Nowadays it is important to consider energy consumption because energy, fuel and natural gas, is continuously depleted and will be used up in the near future if everyone uses it wastefully. As technology has developed, so too has the range of air conditioning systems. Current air conditioning systems are more efficient, more convenient, and consume less energy. Constructors or engineers have more choices about what type of air conditioning system to select and install. Many factors need to be considered, including initial costs, installation costs, energy consumption, appropriateness, maintenance costs etc. Determining the type of air conditioning systems to be installed in a dormitory building is no easy matter a decision should only be reached by analyzing all the elements and comparing the advantages and disadvantages. Shinawatra University (SIU) uses a central air conditioning system which consists of a combination of 4 chillers. The energy consumption of the University can be divided into 2 main areas, the Main Hall Building and the Dormitory Buildings. In both cases, the largest cause of energy consumption is the air conditioning system. For this reason it is an interesting topic to study and, hopefully, as a result of this thesis, practical suggestions for reductions in energy consumption may be forthcoming. 1.2 Significant Due to the high price of electricity at present, SIU spends a lot of money (around 700,000 baht) monthly on electricity. The majority of energy consumed in SIU is in the dormitory buildings. Because the dormitory buildings include more than 200 air-conditioned rooms (approximately more than 10,000 m 2 of air conditioned areas), the air conditioning system consumes the highest amount of energy when compared to other systems. In SIU the air conditioning system, especially the chiller plants, consume around 60 percent of the total energy consumed by SIU. 1

14 SIU has an important policy about energy conservation and pays a lot of attention to the reduction of energy consumption as all buildings in the university were designed with energy conservation in mind. The architects who planned the SIU buildings were concerned about energy conservation and the best technology or the best systems were selected and installed in order to achieve the energy conservation goal. Unfortunately, students and staff at the present time only number about 20 percent of the estimated amount. The installed systems seem to be oversized. In particular, the air conditioning system was designed to supply 4 dormitory buildings. The capacity of a chiller that can deal with more than 1,000 persons is too large because nowadays SIU has only 2 dormitory buildings with students and staff. The chillers should be run between percentage of capacity to achieve their best performance. However, the load demanded is too low at around percentages of capacity, as shown in the figure below. The inappropriate supply of air conditioning makes SIU consume energy extravagantly. The oversized air conditioning system does not only make the electricity costs higher but also makes the maintenance costs higher too. The unsuitable operating level of the chiller plant makes the life span of the equipment shorter. The solution to these problems is to select a suitable size or system which is appropriate for the actual energy use. Operation level of chiller plant on 31 July - 4 Aug 2006 % Capacity a.m p.m a.m p.m a.m p.m a.m p.m a.m p.m. Actual operation level Minimum operation level Time Figure 1 Comparison between the Chiller s Actual Operation Level and the Minimum Suitable Operation Level 2

15 1.3 Objectives Part I is a study of comparisons between the general characteristics of central and split-type air conditioning systems to establish the advantages and disadvantages of each type, using the pattern of energy usage of the dormitory buildings at Shinawatra University. Part II is a study to investigate the possibility of replacing the existing system with a split-type air conditioning system, if it is found to be cost effective. 1.4 Scopes This research focused on the energy consumption, the efficiency, the effectiveness and the system s performances of the air conditioning system in the dormitory buildings at SIU. This research specifically focuses on the comparison between central and split type air conditioning system by considering the advantages and disadvantages of each type of system, which does not include the other types of air conditioning systems. This research is a study to investigate the possibility of replacing the existing air conditioning system at SIU with a split-type air conditioning system. The study in this research is based on the pattern of energy usage in the dormitory buildings at SIU. Suggestions from this research will be made in order to find the most suitable air conditioning system but will not include the development of the system, the dormitory structure or energy patterns. 3

16 Chapter 2 Literature Review 2.1 History of Air Conditioning System According to the modern principles of air conditioning systems, the heat is moved out from the space by using the refrigerant as the heat carrier. In fact, this principle has been known since the time of the ancient Romans. They invented a basic air conditioning system by circulating aqueduct water through the walls of certain houses to cool them off, thus cooling the interior air. As this sort of water usage was expensive, generally only the wealthy could afford such a luxury. At the beginning of 19 th century, the scientists invented and developed many theories and equipment to create air conditioning systems with the high efficiency and effectiveness resulting in the discovery of new technologies throughout these past 2 centuries. 2.2 Air Conditioning System Basics and Theories Refrigeration cycle. 2 LOW PRESSURE 3 EXPANSION VALVE CONDENSER 1 COMPRESSOR 4 EVAPORATOR HIGH PRESSURE LIQUID VAPOR Figure 2.1 Diagram of the Refrigeration Cycle Source: Department of Alternative Energy Development and Efficiency [DEDE] (2005) 4

17 An air conditioner works in a similar way to a refrigerator. A heat pump transfers heat from a lower temperature heat source into a higher temperature heat sink. Heat would naturally flow in the opposite direction due to the second law of thermodynamics (Clausius (2007) introduced the second law of thermodynamics: Heat cannot of itself pass from a colder to a hotter body in 1850). A refrigerator works in much the same way, as it pumps the heat out of the interior into the room in which it stands.the refrigerant flows through the system, and changes in state or condition. There are four processes in the refrigeration cycle as follow. 1) The compressor which pumps the refrigerant around the system, it is the heart of the air conditioner. Before the compressor, the refrigerant is a gas at low pressure. Because of the compressor, the gas becomes high pressure, gets heated and flows towards the condenser. 2) At the condenser, the high temperature, high pressure gas releases its heat to the outdoor air and becomes sub cooled high pressure liquid. 3) The high pressure liquid goes through the expansion valve, which reduces the pressure, and thus temperature goes below the temperature of the refrigerated space. This results in cold, low pressure refrigerant liquid. 4) The low pressure refrigerant flows to the evaporator where it absorbs heat from the indoor air through evaporation and becomes low pressure gas. The gas flows back to the compressor where the cycle starts all over again. (Daikin Europe N.V., n.d.) This cycle takes advantage of the ideal gas law PV = nrt, where P is pressure, V is volume, R is the universal gas constant, T is temperature, and n is the number of moles of gas (1 mole = molecules). The most common refrigeration cycle uses an electric motor to drive a compressor. Since the evaporation occurs when heat is absorbed and the condensation occurs when heat is released, air conditioners are designed to use a compressor to cause pressure changes between two compartments, and actively pump a refrigerant around. A refrigerant is pumped into the low pressure compartment (the evaporator coil). The low temperature and pressure in the compartment of evaporator coil causes the refrigerant to evaporate into a vapor, taking heat with it. In the another compartment (the condenser), the refrigerant vapor is compressed and forced through another heat exchange coil, condensing into a liquid, rejecting the heat previously absorbed from the cooled space. The heat exchanger in the condenser section (the heat sink mentioned above) is cooled most 5

18 often by a fan blowing outside air through it, but in some cases can be cooled by other means such as water. ( Air Conditioning, 2006) Humidity. Humidity in the air has an important role to the air conditioning system. The efficiency of cooling process is affected directly by the moist air. Refrigeration air conditioning equipment usually reduces the humidity of the air processed by the system. The relatively cold (below the dewpoint) evaporator coil condenses water vapor from the processed air, (much like an ice cold drink will condense water on the outside of a glass), sending the water to a drain and removing water vapor from the cooled space and lowering the relative humidity. Since humans perspire to provide natural cooling by the evaporation of perspiration from the skin, drier air (up to a point) improves the comfort provided. The comfort air conditioner is designed to create a 40% to 60% relative humidity in the occupied space. In food retailing establishments large open chiller cabinets act as highly effective air dehumidifying units. ( Air Conditioning, 2006) Refrigerants. A refrigerant is a compound used in a heat cycle that undergoes a phase change from a gas to a liquid and back. The two main uses of refrigerants are refrigerators/freezers and air conditioners. Until concerns about depletion of the ozone layer arose in the 1980s, the most widely used refrigerants were the halomethanes R-12 and R-22, with R-12 being more common in automotive air conditioning and small refrigerators, and R-22 being used for residential and light commercial air conditioning, refrigerators, and freezers. Some very early systems used R-11 because its low boiling point allows low-pressure systems to be constructed, reducing the mechanical strength required for components. New production of R-12 ceased in the United States in 1995, and R-22 is to be phased out in R-134a and certain blends are now replacing chlorinated compounds. One popular 50/50 blend of R-32 and R-125 now being increasingly substituted for R- 22 is marketed under the trade name Puron. While the R-22, R-12 and other ozone depleting refrigerants are being phased out. The ideal refrigerant has good thermodynamic properties, which are noncorrosive, and safe. The desired thermodynamic properties are a boiling point 6

19 somewhat below the target temperature, a high heat of vaporization, a moderate density in liquid form, and a relatively high density in gaseous form. Since boiling point and gas density are affected by pressure, refrigerants may be made more suitable for a particular application by choice of operating pressure. Corrosion properties are a matter of materials compatibility with the components used for the compressor, piping, evaporator, and condenser. Safety considerations include toxicity and flammability. ( Air Conditioning, 2006) 2.3 Types of Air Conditioning System Air conditioning systems can be categorized according to the means by which controllable cooling is accomplished in the conditioned space. They are further segregated to accomplish specific purposes by the special arrangement of the equipment. There are two basic system categories: Central air conditioning systems and Direct expansion systems. Each category has a different working process, advantages, disadvantages etc. In selecting a suitable air conditioning system for a particular application, consideration should also be given to the following: System constraints: cooling load, zoning requirements, heating and ventilation Architectural constraints: size and appearance of terminal devices, acceptable noise level, space available to house equipment and its location relative to the conditioned space, acceptability of components obtruding into the conditioned space Financial constraints: capital cost, operating cost, maintenance cost (Department of Architecture, The University of Hong Kong [DA HKU], 2001) Central air conditioning systems. The central air conditioning system can be divided in many subcategories and each type have specific characteristic. A different of advantages and disadvantages is an important thing that must be realized. 1) All air systems An all air system provides complete sensible and latent cooling capacity in the chilled air supplied by the system. Heating can be accomplished by the same air 7

20 stream, either in the central system or at a particular zone. All-air systems can be classified into 4 categories: (a) Single duct systems (b) Dual duct systems (c) Multi zone systems (d) Reheat systems (a) Single Duct Systems (b) Dual Duct Systems (c) Multi Zone Systems (d) Reheat Systems Figure 2.2 Several Types of All Air Air Conditioning Systems Source: Air Conditioning System (n.d.) 8

21 System advantages - The central plant is located in unoccupied areas, hence facilitating operating and maintenance, noise control and choice of suitable equipment. - No piping, electrical wiring and filters are located inside the conditioned space. - Allows the use of the greatest numbers of potential cooling seasons house with outside air in place of mechanical refrigeration. - Seasonal changeover is simple and readily adaptable to climatic control. - Gives a wide choice of zonability, flexibility, and humidity control under all operating conditions. - Heat recovery system may be readily incorporated. - Allows good design flexibility for optimum air distribution, draft control, and local requirements. - Well suited to applications requiring unusual exhaust makeup. - Infringes least on perimeter floor space. - Adapts to winter humidification. System disadvantages - Requires additional duct clearance which can reduce the usable floor space. - Air-balancing is difficult and requires great care. - Accessibility to terminals demands close cooperation between architectural, mechanical and structural engineers. (DA HKU, 2001) For these reasons, these air systems are suitable for buildings which have the same cooling load requirement in each section, e.g. the place or office building where the air conditioning system is turned on and off in every room at the same time and the required temperature is pre-set. The operation times and the temperature are controlled by central unit. 9

22 2) Air and water systems An air-and-water system is one in which both air and water (cooled or heated in a central plant room) are distributed to room terminals to perform cooling or heating functions. The air side is comprised of central air conditioning equipment, a duct distribution system, and a room terminal. The supply air, called primary air, usually has a constant volume which is determined by: - The ventilation requirement. - The required sensible cooling capacity at maximum cooling load. - The maximum sensible cooling capacity following changeover to the winter cycle when chilled water is no longer circulated to the room terminal. The water side consists of a pump and piping to convey water to heat transfer surfaces within each conditioned space. The water is commonly cooled by the introduction of chilled water from the primary cooling system and is refereed to as the secondary water loop. Individual room temperature control is by regulation of either the water flow through it or the air flow over it. Figure 2.3 Air and Water Air Conditioning Systems Source: Air Conditioning System (n.d.) 10

23 System advantages - Individual room temperature control. - Separate sources of heating and cooling for each space available as needed to satisfy a wide range of load variations. - Low distribution system space required as a result of reducing the air supply by use of secondary water for cooling and high velocity air design. - Reduced size of central air handling equipment. - Dehumidification & filtration performed in a central plant room remote from conditioned space. - Outdoor air supply is positive. - Maintenance required for individual induction units which have no moving parts, i.e. no fans. - Air duct dimensions are smaller than VAV systems or CAV systems - Zoning of central equipment is not required. - No fan comes together with the coil, making the conditioned space quiet. System disadvantages - Limited to perimeter space. - The primary air supply is usually constant with no provision for shutoff. - Not applicable to spaces with high exhaust requirement. - Higher energy consumption due to increased power required by the primary pressure drop in the terminal units. - Controls tend to be more complex than for all-air systems. - A low chilled water temperature is needed to control space humidity adequately. - Seasonal changeover is necessary. - Initial cost is usually higher (DA HKU, 2001). The advantages and disadvantages above show that air and water systems are suitable for buildings which have different cooling loads and using schedules, a high ratio of relative humidity in each section. These different operating conditions need separate control units, e.g. hotels, apartment or places where every room has a different air conditioning system usage style (operating time, temperature). High 11

24 investment required for these system in terms of installation, operation and maintenance costs. 3) All water systems All water systems are those with fan-coil, unit ventilator, or valance type room terminals with unconditioned ventilation air supplied by an opening through the wall or by infiltration. Cooling and dehumidification is provided by circulating chilled water through a finned coil in the unit. Heating is provided by supplying hot water through the same or a separate coil. Figure 2.4 All Water Air Conditioning Systems Source: Air Conditioning System (n.d.) System Advantages - Flexible and readily adaptable to many building module requirements. - Provides individual room control. System Disadvantages - No positive ventilation is provided unless wall openings are used. - No humidification is provided. - Maintenance and service work has to be done in the occupied areas. - Seasonal change over is required (DA HKU, 2001). 12

25 The advantages and disadvantages of all water air conditioning systems are shown above. This type of system is appropriate for buildings which have a different cooling load and use schedule in each section. These different operating conditions need to be supported by a separate control units. Furthermore, this system not only needs less usage area and creates less noise but it also consumes less energy than the air and water system. However, the humidification process is less efficient, e.g. hotels, apartments or place where every room has a different air conditioning system usage style (operating time, temperature) and also has limitations in terms of the usage area and energy consumption Direct expansion systems. Direct expansion of refrigerant, without the chilled water cooling medium is the significant of this air-conditioning type. In a split-system central air conditioner, an outdoor metal cabinet contains the condenser and compressor, and an indoor cabinet contains the evaporator. In many split-system air conditioners, this indoor cabinet also contains a furnace or the indoor part of a heat pump. The air conditioner's evaporator coil is installed in the cabinet or main supply duct of this furnace or heat pump. If your home already has a furnace but no air conditioner, a split-system is the most economical central air conditioner to be installed. In a packaged central air conditioner, the evaporator, condenser, and compressor are all located in one cabinet, which usually is placed on a roof or on a concrete slab next to the house's foundation. This type of air conditioner also is used in small commercial buildings. Air supply and return ducts come from indoors through the home's exterior wall or roof to connect with the packaged air conditioner, which is usually located outdoors. Packaged air conditioners often include electric heating coils or a natural gas furnace. This combination of air conditioner and central heater eliminates the need for a separate furnace indoors. (DA HKU, 2001; The Institute of Industrial Energy [IIE], 2004) 13

26 Figure 2.5 Air-Cooled Package Air Conditioning Systems Source: Air Conditioning System (n.d.) System Advantages - Convenient to install in a typical room. - Provides individual room temperature control. - Having a capability to cool the separated area. - Dehumidification & filtration are performed. - Capital cost of this system is cheaper than other systems because it provides a smaller amount of cooling load. - Maintenance required for individual units and the process is not complicated. System Disadvantages - The efficiency of this system is worse than other systems because the ratio between cooling load and energy consumption is low. - Required additional amount of air conditioner when cooling the large area. - The evaporator in the cooling area can make noise. (DA HKU, 2001) Due to the above reasons, the direct expansion system is suitable for buildings which have a small cooling load and the cooling load in each section is different. Furthermore, the direct expansion system is appropriate for buildings that have a requirement to separate the air conditioning system into individual parts to divide the responsibility for controlling the energy usage and maintaining the air conditioner, e.g. small office buildings, condominiums, residential. 14

27 Table 2 Comparison between Advantages and Disadvantages in Different Type of Air Conditioning Systems System Advantages Disadvantages Appropriation All air systems The central plant is located in unoccupied areas, hence facilitating operating and maintenance, noise control and choice of suitable equipment. Difficult to control the temperature and humidity in the different sections or rooms. Air-balancing is difficult and requires great care. A building which has the same cooling load requirement in each section, e.g. The office building. Heat recovery and humidity control system may be readily incorporated. Requires more using area because air duct is larger than water pipe. Air and water systems Individual room temperature control. Dehumidification & filtration performed in a central plant Reduced size of central air handling equipment because Higher energy consumption due to increased power required by the primary pressure drop in the terminal units. Controls tend to be more complex than for all-air A building which has the different relative humidity and cooling load in each section, e.g. The hotel, apartment and etc. water pipe is smaller than air duct and using less power in sending the fluid along the pipeline. systems. Initial cost is usually higher All water systems Flexible and readily adaptable to many building module requirements. Provides individual room control. No humidification is provided. Maintenance and service work has to be done in the occupied areas. Less energy consumption than air and water systems. A building which has the different cooling load in each section, But the total cooling load should be constant e.g. The office building, department store and etc. Direct expansion systems Convenient to install in a typical room. Provides individual room temperature control. Dehumidification & filtration are performed. Maintenance required for individual units and the process is not complicated. The efficiency of this system is worse than other systems because the ratio between cooling load and energy consumption is low. The evaporator in the cooling area can make noise. A building which has small cooling load or extremely different cooling load in each section, e.g. The office building, department store and etc. 15

28 2.4 Air Conditioning System at Shinawatra University The air conditioning system at Shinawatra University (SIU) is designed as the central system that operated by four main water cooled chillers, this system supplies cool water to many parts in SIU (Main Hall Building, Dormitory Buildings, Laboratory Building and Sky Link). In this thesis we will pay a lot of attention to Dormitory parts because these buildings consume energy nearly that of the Main Hall Building Water cooled chiller. There are four water cooled chillers in the Shinawatra University building system including two centrifugal chillers and two screw chillers with capacities of 375 and 190 tons, respectively. Both types of water cooled chiller will run individually at the different time. The Centrifugal Chiller is operated at the regular load requirement (day time 9.00am -5.00pm), whereas, the Screw Chiller is used at the part load requirement (night time 5.00 pm-9.00pm). In the winter season (Oct- Feb) as the weather is normally cool, there is less load requirement for generating the chilled water. Therefore, the screw chiller is sufficient to satisfy the load requirement. Appropriate selection of chiller: Practically, the appropriate size of chiller may be selected by considering the temperature of chilled water. If the temperature of water leaving from the chiller is greater than 45 F and the temperature of returning water is gradually higher, thus, there is a requirement for switching the chiller to the higher capacity one (centrifugal chiller) or running two or more chillers at the same time. Air conditioning schedule: As SIU is mainly used although a day. Therefore, the majority of work load on air conditioning system during day time is at Main Hall Building. Because MHB is extremely used during office hours. After office hours, air conditioning system is seldom used in MHB, the work load of MHB is immediately decreased similar to any other office buildings. Consequently, the majority of work load on air conditioning system during nighttime mostly comes from the dormitory; however, the work load of dormitory building does not increase too much. Due to the closeness between dormitory buildings and MHB make the residents can go back to their room conveniently during a day. The dormitory s cooling load demand during daytime is quite high nearly the work load during night 16

29 time. The day time and nighttime chiller s cooling load was shown in the figure below. (Bunyathikarn, 2002; Chokesuwattanaskul, 2006) Figure 2.6 Air Conditioning System s Workload during Daytime Source: Bunyathikarn (2002) Figure 2.7 Air Conditioning System s Workload during Nighttime Source: Bunyathikarn (2002) 17

30 Day time & night time of the chiller's cooling load 31 July - 4 Aug Tons MHB Dorm a.m p.m a.m p.m a.m p.m a.m p.m a.m p.m. Time Figure 2.8 Comparison between the Chiller s Cooling Load for MHB and Dormitory Buildings. Working processes: The air conditioning system was installed with water cooled chiller type (90% of the main campus uses the central chilled water system). Water Tank Water Chiller Cooled Water with 4-7ºc Water Pumping AHUs Fan Coil Units Water with 16 c Figure 2.9 Chiller s Working Process Diagram 18

31 Figure 2.10 SIU s Air Conditioning System Diagram Water from the tank is directly transferred to the water chiller. The chiller will normally cool the water down to 4-7ºc and let the chilled water flow out to the water pumps. Then, the water pumps will feed the chilled water to the Air Handling Units (AHUs) and fan coil units. After that the water will come out from the AHUs and fan coils units with the temperature around 16ºc and flow back to the water cooled chiller. (Bunyathikarn, 2002; Chokesuwattanaskul, 2006) Pond cooling system. With the design of large pools and different elevation (3 meters) of the pools around campus, the pond cooling system creates the benefits for the energy conservation. As the water from pools is used as a source of heat sink for the water cooled chiller system, the heat can be released by natural evaporation during the flowing time from the higher level part of pool (Pool 1) to the lower part (Pool 6). That means there is no electricity use. Comparing to the cooling tower, the pond cooling system seems to be better in terms of environmental impacts as it dose not cause higher temperature and humidity to the environment. (Bunyathikarn, 2002; Chokesuwattanaskul, 2006) 19

32 Figure 2.11 Pond Cooling System at SIU Source: Bunyathikarn (2002) Fresh air system. The fresh air system of SIU has been designed to work separately from the air conditioning system. The separation of fresh air system brings the better efficiency in fresh air volume control. The fresh air from outdoor is treated by the Outdoor Air Treatment Unit (OAT) before delivering to building. The OAT will reduce the temperature and humidity level of fresh air, and also supply a variable volume of fresh air (depending on the fresh air requirement of the space). As a result of the OAT capability, the cooling load will decrease. (Bunyathikarn, 2002; Chokesuwattanaskul, 2006) 20

33 Figure 2.12 Fresh Air System in MHB Source: Bunyathikarn (2002) 1) Heat recovery wheel The heat recovery wheel works as a heat exchanger to recover the discarded cooling air from the system. The exhausted cooling air will be used to cool down the new incoming fresh air of the OAT. The energy can be saved by precooling ventilation air using the cooler air exhausted from the building. Recovery of heat energy from exhaust air is accomplished through the use of rotating wheel shown in figure below. The systems are effective in recovering energy but require that intake and exhaust to the building be at the same location. This system may also be effective during the cooling season, when they function to cool and perhaps dehumidify the warm incoming fresh air.. (Bunyathikarn, 2002; Chokesuwattanaskul, 2006) Figure 2.13 Heat Recovery Wheel Source: Bunyathikarn (2002) 21

34 2) Heat pipe The heat pipe is a close system capillary, which is made from copper. It can quickly transfer heat from one point to another. It is often referred to as the "superconductors" of heat as they possess an extra ordinary heat transfer capacity and rate with almost no heat loss. A heat pipe has an ability to transport heat against gravity by an evaporation-condensation cycle with the help of porous capillaries that form the wick. The inner side of wicking capillary contains the refrigerant such as Freon, ammonia, oxygen, methane, and water. The refrigerant will receive the heat, and consequently evaporate. The vapor from evaporation will move up to another side tip, meanwhile the vapor will evolve the heat out and condense to be fluid at the surface inside the pipe. Then, it will continuously flow back to the lower heated tip (Shankara N. K. R., n.d.) Figure 2.14 Heat Pipe Dehumidification Process Source: Hancock & Reeves (1999) In the air conditioning system, the use of heat pipe can directly save the energy. Two sets of heat pipe are installed in front of and behind the cooling coil. The benefits of the heat pipe in the front are to precool the air temperature and remove the moisture out from the air. The out going air from the cooling coil mostly is overcooled, which contains high moisture with low temperature. That means it requires the high energy to reheat and get the moisture out of the air. The heat pipe in the back of the cooling coil is utilized for reheating air without using the additional energy. (Chokesuwattanaskul, 2006) 22

35 2.5 Dormitory Building at Shinawatra University General profile. There are two 5-story-dormitory buildings for students and staff at SIU that are located next to the Laboratory building. The first building, which was built in 2002, is currently a male student dormitory. Its usable area is about 5,882 sq-m. This building has 113 rooms (104 are for residential purposes). There are 100 typical rooms with 36 sq-m. of floor area for 3 persons, and 4 deluxe rooms of 56 sq-m. for 4 persons, in this building. There are another 9 rooms, including the manager s room, offices, service rooms (conference, kitchen, TV, and etc.). Every room is airconditioned, completely furnished with a bathroom (supplied with hot water). The second building was finished last year. The usable area is about 5,868 sq-m. This building has 117 rooms for female residents (97 are for residential purposes). There are 75 typical rooms with 46 sq-m. of floor area for 3 persons, 16 special rooms of 46 sq-m. for 2 persons, and 6 suite rooms of 92 sq-m. for senior staff, in this building. There are another 20 rooms including a lounge, lobby, common room, internet, reading, laundry, salon, medical room, advisor room, and etc. Every room is airconditioned, completely furnished with a bathroom (supplied with hot water), like the first building Electricity fee. An electricity fee for the dormitory building at SIU is collected every month from students and staff. The students in normal rooms can use the first 100 units of electricity for free and the first 150 units for deluxe room. If the users use additional electricity, they are charged 5 baht per unit. Staff and visitors must pay for electricity at a fee of 5 baht per unit from the first unit. The electricity meters of each room are in the control rooms (beside the elevator on each floor). The authorities of SIU have to record amount of energy monthly to calculate the electricity cost. This electricity meter measures all electricity is used in each room except the energy which is consumed to produce chill water supply each room. 23

36 Chapter 3 Methodology There are 5 steps of methodology in this thesis, study related reviews, data measurement, calculate the data, analyze the data and conclusion. 3.1 Study Related Reviews Study related reviews or related topics about air conditioning systems especially central and split type air conditioning systems. Study various types of air conditioning systems. Study related literature or articles about central and split type air conditioning systems. Study the advantages and disadvantages of split-type air conditioning systems. Study the advantages and disadvantages of existing air conditioning systems. 3.2 Data Measurement and Data Collection Collect data relating to existing air conditioning systems in terms of energy consumption and characteristics of the dormitory buildings at Shinawatra University. Collect data from the data base that was recorded by BAS for information about the capacity of the chiller, the actual operation of chillers, the temperature of the chilled water, the operation of water pump etc. Survey the use of air-conditioning in each room to discover the energy usage pattern of Dormitory buildings. Survey the use of air-conditioning in each room to reveal unsatisfied or disappointed issues that occur with the air conditioning system of the dormitory buildings. Collect information about the chiller s energy consumption, cooling load distribution, and the chiller s electricity meter recorded by mechanics who are responsible for controlling the air conditioning system. This data is collected in 3 different periods of time for represent summer semester, regular semester and summer or winter break. 24

37 Collect monthly electricity meter data for all the rooms in the dormitory buildings. Collect general data of the dormitories e.g. amounts of using room, rental rate, electricity fee rate, etc. Collect financial data relating to the dormitories e.g. incomes and expenses, maintenance cost, staff salaries, etc. Collect information regarding the total energy consumption of some parts of the air conditioning system by using a CT scanner. Collect other necessary data about the existing system regarding the basic details of air conditioning system such as the architectural information about the air conditioning system, the capacity of the AHUs and FCus, etc. Collect the split type air conditioning system data such as average EER value, average actual price and etc. Collect the data about the general water cooled chiller regarding the capacity, SEER value, price and also with its components. 3.3 Calculate the Data 1) Existing system s data Calculate the energy consumption of the air conditioning system in the dormitory buildings for all the regular semester, summer semester and summer break by collecting data as described in 3.2 (total energy consumption and cooling load distribution from BAS) by finding the ratio between the cooling load distribution for every hour and comparing this with the total energy consumption. Break down each part of the energy consumption of the air-conditioning system in the dormitory buildings at SIU (a combination of the chiller s cooling load, AHUs & FCUs and the fresh air & exhaust system). Calculate the standard value of the air-conditioning system (SEER value). 2) Split type air conditioning system data Calculate the average operation hours of the air conditioning system in all rooms in the dormitory buildings from the survey results. 25

38 Calculate the energy consumption of the split type air conditioning system. - Calculate from average operation hours of each room. - Calculate from the existing cooling load demand. 3.4 Analyze the Data Analyze the air conditioning system to discover the method to achieve the energy conservation goal. 1) Analyze the characteristics of energy use in order to find the most appropriate air-conditioning type and size To install a split type A/C system to the new dormitory or apartment building. - Analyze in terms of energy consumption and electricity costs. - Analyze the financial implications in terms of all costs and its effectiveness. - Analyze qualitatively, in terms of advantages and disadvantages the other factors alongside energy consumption and financial issues e.g. maintenance and convenience. To install a split type A/C system to the dormitory buildings at SIU, where a central A/C system is already installed. - Analyze in terms of energy consumption and electricity costs. - Analyze financial factors in terms of all costs and the pay-back period. - Analyze qualitatively, in terms of advantages and disadvantages, factors other than energy consumption and financial issues e.g. maintenance and convenience. To install the appropriate chiller size to the new dormitory or apartment building. - Analyze in terms of energy consumption and electricity costs. - Analyze financial factors in terms of all costs and the effectiveness. - Analyze qualitatively, in terms of advantages and disadvantages, factors other than energy consumption and financial issues e.g. maintenance and convenience. 26

39 To install the appropriate chiller size to the dormitory buildings at SIU that currently have a central A/C system. - Analyze in terms of the appropriate chiller s capacity and the possibility to be installed and operated. - Analyze financial factors in terms of all costs and the pay-back period. - Analyze qualitatively, in terms of advantages and disadvantages, factors other than energy consumption and financial issues e.g. maintenance and convenience. 2) Comparison between the existing and the split-type air conditioning system Focusing on the air conditioning system at dormitory buildings as an independent system and focusing on the air conditioning system at dormitory building system at dormitory buildings as an integrated system in term of energy consumption and energy saved, financial and qualitative issues. 3.5 Conclusion Conclusion the best method to support the energy conservation policy. Make the suggestions on how to use the existing air conditioning system in the dormitory buildings at SIU more efficiently and more effectively. Make the suggestions on how to introduce a new type of air conditioning system e.g. a split-type air conditioning system and a smaller chiller size instead of using the existing air conditioning system in the dormitory buildings at SIU. Make suggestions to anyone who wants to build apartments or dormitories for the most efficient and effective air conditioning system. 27

40 Chapter 4 Result and Discussion In this chapter, the energy consumptions of central and split type air conditioning systems are determined. The efficiency of each system is a factor that cannot be neglected because it affects the energy consumption directly. The efficiencies of the central and split type air conditioning systems are represented by SEER and EER values. Furthermore, it is also necessary to estimate the appropriate size and proper operating schedule for each system. 4.1 Existing Air Conditioning System Energy consumption of existing air conditioning system. The energy consumption of the existing air conditioning system at SIU can be estimated by combining the energy usage of the Chiller s plant, Air Handling Units (AHUs) & Fan Coil Units (FCUs) and Fresh air & Exhaust systems. Chilled water is produced by chiller plant. It is supplied through the chilled water pipes by the water pumps to AHUs & FCUs located inside the building. The AHUs & FCUs generate the cool air for the conditioned spaces by blowing air through the chilled water pipes. The supplied cool air reduces the temperature inside the conditioned spaces to make the room cooler. The fresh air and exhaust systems operate separately from the air conditioning system in order to control the amount of incoming fresh air suitable for the occupants needs. In this process, the chiller s plant consumed the majority of the total energy use which is about 75 percent. The AHUs & FCUs and fresh air & exhaust system consumed the energy about 22 and 3 percent respectively. The overall energy consumption of the existing air conditioning system is equal to 75,704 kwh. 28

41 Energy consumption of existing air conditioning system in dormitory building at SIU Fresh air and Exhaust, 2,300 kwh, 3% AHUs&FCUs, 16,956 kwh, 22% Chiller's Plant AHUs&FCUs Fresh air and Exhaust Chiller's Plant, 56,448 kwh, 75% Figure 4.1 Break down the Energy Consumption of Existing Air Conditioning System in Dormitory Building at SIU Chiller s Plant: The existing air conditioning system at SIU is a central system. The chiller produces chilled water and the water pump supplies the chilled water to the conditioned area. Thus, the energy used by the chiller plant is a combination between the energy use of the chillers and pumps. This system supplies the chilled water to two dormitory buildings and the other buildings at SIU. To investigate only the energy consumption of the dormitory buildings, cooling load distribution data from the Building Automation System (BAS) have to be used. This data shows the cooling load demand in each building which can be used to calculate a ratio of cooling load demand of each building and the total demand. By comparing the ratio of cooling load demand for dormitory buildings with the total amount of electricity used by the chiller plant, the energy consumption of chiller plants that supplied to dormitory buildings can be estimated. Tables below show the monthly energy consumption of the chiller plants used for dormitory buildings. Table 4.1 is the energy consumption in March 2006 which represents the summer semester, Table 4.2 is the energy consumption in July-August 2006 which represents the regular semester and Table 4.3 is the energy consumption in February-March 2007 which represents the summer break and the holiday in winter season when the system was operating only the 190-ton chiller. 29

42 Table 4.1 Energy Consumption of Chiller Plants in March 2006 MHB (kwh) Dorm (kwh) Lab+Skylink (kwh) Total (kwh) Average Sat-Sun 444 1, ,717 Average Mon 1,369 1,251 1,367 3,986 Average Tue-Thu 1,583 1,340 1,252 4,176 Mar ,101 41,203 36, ,019 Table 4.2 Energy Consumption of Chiller Plants in August 2006 MHB (kwh) Dorm (kwh) Lab+Skylink (kwh) Total (kwh) Average Sun 230 1, ,700 Average Mon 1,756 2, ,,839 Average Tue 1,635 1, ,346 Average Wed 1,801 1, ,250 Average Thu 1,611 1, ,332 Average Fri 1,555 1, ,438 Average Sat 558 1, ,359 Aug ,629 58,032 21, ,588 Table 4.3 Energy Consumption of Chiller Plants in March 2007 MHB (kwh) Dorm (kwh) Lab+Skylink (kwh) Total (kwh) Average Sun 525 1, ,395 Average Mon 1,224 1, ,921 Average Tue 1, ,483 Average Wed 1,163 1, ,023 Average Thu 1,459 1, ,058 Average Fri 1,288 1, ,933 Average Sat 459 1, ,461 Mar ,157 34,789 24,204 93,149 Based on the summaries of the dormitory s energy consumption in these 3 months (41,203 kwh, 58,032 kwh and 34,789 kwh), the annual energy used by the chiller plant for the dormitory buildings can be calculated by specifying a 2-month period for summer semester, 8-month period for regular semester and 2-month period for summer & winter break. The annual energy consumed by the air conditioning system at dormitory buildings is about 616,240 kwh. Other equipment necessary for the chiller plant system are chilled water pumps which supply the chilled water to the buildings in SIU. To estimate the energy 30

43 consumption of the water pump for dormitory buildings, the percent of energy used by the water pumps for the dormitory buildings is assumed to be the same ratio as the energy used by the chillers (from Appendix A). Table 4.4 shows the energy consumption of the water pumps. Table 4.4 Energy Consumption of Water Pump that Supplies Dormitory Buildings Duration Percent of energy used by chillers that supplies Monthly total energy consumption of pump Energy consumption of pump which service dorm to dormitory buildings (kwh) (kwh) Summer semester 35% 10,610 3,736 Regular semester 48% 11,755 5,611 Summer & Winter break 37% 11,755 4,390 The monthly total energy consumption of the chiller plant including both chillers and chilled water pumps (from Table 4.4) will equal 44,939 kwh in summer semester, 63,643 kwh in regular semester and 39,179 kwh, in summer or winter break. By specifying a 2-month period for summer semester, 8-month period for regular semester and 2-month period for summer & winter break, the annual energy used by the chiller plant for the dormitory buildings can be calculated, and its value is about 677,380 kwh or equal to 56,448 kwh per month. AHUs and FCUs: Basic components of AHUs and FCUs consist of coils, damper, filter fan and motor drive. The AHUs and FCUs can only be used for cooling, heating or in combination. The part in the AHUs and FCUs which consumes the most energy is the motor drive. When AHUs and FCUs are operated, the motor drives require constant power input. For this reason, the energy of AHUs and FCUs depends on the operation time and the power input of motors or blowers. To calculate the energy consumption of AHUs and FCUs at dormitory buildings, the operational hours must be obtained from the surveyed data (in Appendix B) which shows that most residential rooms use the air conditioning system about hours per day. The power input depends on the size of each motor. When multiplying the energy consumption per hour and the operating hours, the monthly energy consumption is obtained. 31

44 Table 4.5 Monthly Energy Consumption of AHUs and FCUs in Dormitory 1 AHU & FCU Room Power input Operation hours Energy Real use Total (kw) normal day weekend (kw) (room) (kw) 1A-01 LOBBY ,414 1A-02 FITNESS F-01(DO1) SR F-02(DO1) SR F-03(DO1) OFFICE F-04(DO1) OFFICE F [DO1] RESIDENTIAL F-07[DO1] 214[TV] F [DO1] RESIDENTIAL F [DO1] RESIDENTIAL F-07[DO1] 214[TV] F [DO1] RESIDENTIAL F-13 [DO1] F [DO1] RESIDENTIAL F [DO1] RESIDENTIAL F-07[DO1] 214[TV] F [DO1] RESIDENTIAL F-13 [DO1] F [DO1] RESIDENTIAL F [DO1] RESIDENTIAL F-07[DO1] 214[TV] F [DO1] RESIDENTIAL F-13 [DO1] F-14,16,18,20,22,24,26 [DO1] RESIDENTIAL F-15,17,19,21,23,25,27 [DO1] RESIDENTIAL RF-01[DO1] ELEVATOR Total Dorm 1 11,559 32

45 Table 4.6 Monthly Energy Consumption of AHUs and FCUs in Dormitory 2 AHU & FCU Room Power input Operation hours Energy Real use Total (kw) normal day Weekend (kw) (room) (kwh) GF-03[DO2] ENTERTAINMENT GF-05[DO2] MEETING ROOM MF-03[DO2] CLASS ROOM MF-07[DO2] NURSE ROOM MF-08[DO2] NURSE ROOM MF-11[DO2] NURSE ROOM F [DO2] RESIDENTIAL F-07[DO2] 213[TV] F [DO2] RESIDENTIAL ,223 3F [DO2] RESIDENTIAL F-07[DO2] 313[TV] F [DO2] RESIDENTIAL ,174 RF-01[DO2] ELEVATOR Total Dorm 2 5,397 The overall energy consumption of this system is 16,956 kwh per month which includes 11,559 kwh from dormitory 1 and 5,397 kwh from dormitory 2. The power input of motor and the operational hours are shown in Tables Only the AHUs and FCUs which are regularly used; they are shown in the table above and the operational time of residential rooms are the average values. The complete information of all AHUs and FCUs can be found in Appendix C. Fresh air and exhaust system: Air conditioning systems cools and condition the air. The fresh air and exhaust system support the air conditioning system in this conditioning process to make the indoor air most suitable and comfortable for users. Normally, this system may include partial air treatment, such as heating, humidity control, filtering or purification, etc. More complete treatment of the air is generally called air conditioning. Not only does circulate fresh air and exhaust stale air, this system also reduces the humidity, and improves the indoor air quality. 33

46 However, the regular fresh air and exhaust system is different from the system at SIU, which has been designed to work separately from the air conditioning system. The separation of fresh air system provides better efficiency in fresh air volume control (Bunyathikarn, 2002; Chokesuwattanaskul, 2006). This fresh air and exhaust system works independently; thus, the energy consumption of the system must be calculated separately from the chiller plant. The energy consumption of this system is low because this system consists of 8 blowers (each building has 4 blowers, 2 of fresh air and 2 of exhaust) with the Variable Speed Drive (VSD) to ensure precise control of torque and speed of induction motor drive. To minimize the energy consumed by these blowers, VSD always control torque and speed of motors appropriated to the demand of fresh air volume in dormitory buildings at anytime (Daorote, 2006) Reducing the motor speed also decreases the energy consumption of the motor. The relation of the speed of motor and the energy consumption is a power 3 equation. (Electricity Generating Authority of Thailand [EGAT], n.d.), which is shown in the Table 4.7 below. Table 4.7 Comparison between Load Capacity and Power Input of Motor with VSD Flow rate (n) Motor's capacity (n) Power input (n 3 ) 0% 0% 0.0% 10% 10% 0.1% 20% 20% 0.8% 30% 30% 2.7% 40% 40% 6.4% 50% 50% 12.5% 60% 60% 21.6% 70% 70% 34.3% 80% 80% 51.2% 90% 90% 72.9% 100% 100% 100% Source: EGAT (n.d.) From Table 4.7, the reduction of energy consumption of the fresh air and exhaust system with VSD are more than the reduction of motor s speed. For example, when the motor works at a full capacity load, the energy is consumed at 100%. When the motor works at a speed of 80%, the energy consumption is only about 50% of the 34

47 energy consumption at full capacity. This means that reducing a speed of motor only by 20%, energy consumption can be saved by 50%. Assuming the actual performance of the AUHs and FCUs motors is similar to this specification in Table 4.7, the existing fresh air and exhaust system which is controlled by VSD should consume energy at acceptable level. The energy consumption of fresh air and exhaust system depends on a speed of motor that varies by time. Thus, the exact value can be quite difficult to calculate. Table 4.8 shows a comparison of the energy consumption of this system from 50% to 100% capacity of the motor. The result of this calculation is about 842-6,732 kwh. However, the average load should be approximately around 70-80% and the system will consume the energy about 2,300-3,450 kwh. For the best estimation, the lower limit of the average energy consumption of this system at 2,300 kwh will be used. Table 4.8 Energy Consumption of Fresh Air and Exhaust System at Different Motor s Capacities Hours Power Energy consumption in different motor s capacity (kwh) (daily) input(kw) 100% 90% 80% 70% 60% 50% FRESH AIR NO:1 Dorm NO:2 Dorm NO:1 Dorm , NO:2 Dorm EXHAUST NO:1 Dorm NO:2 Dorm NO:1 Dorm NO:2 Dorm Total 6,732 4,908 3,447 2,309 1, Seasonal Energy Efficiency Ratio (SEER value). The SEER value represents the ratio between the produced cooling load and the energy consumption in a unit of BTU/h/W. For an air conditioning system, the SEER value can be calculated from the produced cooling load data and the energy consumption from Appendix A. The hourly SEER value on each day was shown in Figures

48 SEER of 375-ton Chiller (March06) SEER(BTU/h/W) Mon20 Wed22 Mon27 Wed29 Standard a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m. Time Figure 4.2 SEER Value of 375-ton Chiller during a Day in March 2006 SEER of 190-ton Chiller (March06) SEER(BTU/h/W) Sat18 Mon20 Wed22 Sat25 Mon27 Wed29 Standard p.m p.m p.m p.m p.m. p.m. p.m. a.m a.m a.m a.m a.m a.m a.m. Time Figure 4.3 SEER Value of 190-ton Chiller during a Day in March

49 SEER of 375-ton Chiller (Aug06) SEER(BTU/h/W) Mon31 Tue1 Wed2 Thu3 Fri4 Standard 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m. Time Figure 4.4 SEER Value of 375-ton Chiller during a Day in August 2006 SEER of 190-ton Chiller (Aug06) SEER(BTU/h/W) p.m p.m p.m p.m p.m p.m p.m a.m a.m. Time 3.00 a.m a.m a.m a.m a.m. Figure 4.5 SEER Value of 190-ton Chiller during a Day in August 2006 Mon31 Tue1 Wed2 Thu3 Fri4 Sat5 Sun6 Standard 37

50 SEER of 375-ton Chiller (March07) 20 SEER (BTU/h/W) a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m. Wed28 Thu1 Fri2 Mon5 Tue6 Wed7 Thu8 Fri9 Mon12 Tue13 Standard Time Figure 4.6 SEER Value of 375-ton Chiller during a Day in March 2007 SEER (BTU/h/W) SEER of 190-ton Chiller (March07) 6.00 p.m p.m p.m p.m p.m p.m p.m a.m. Time 2.00 a.m a.m a.m a.m a.m a.m. Figure 4.7 SEER Value of 190-ton Chiller during a Day in March 2007 Wed28 Thu1 Fri2 Sat3 Sun4 Mon5 Tue6 Wed7 Thu8 Fri9 Sat10 Sun11 Mon12 Tue13 Standard 38

51 Average SEER Value in a different period of time SEER Value (BTU/h/W) ton-chiller in summer semester 190-ton-chiller in regular semester 190-ton-chiller in summer break 375-ton-chiller in summer semester 0 Sunday Monday Tuesday Wednesday Day Thursday Friday Saturday 375-ton-chiller in regular semester 375-ton-chiller in summer break Figure 4.8 Average SEER Value of 190 and 375 tons Chiller in a Different Period of Time Figure 4.8 shows in the daily average SEER values. When average the daily SEER value in this figure the average SEER value of 375-ton chiller in March 2006 is BTU/h/W and 190-tons chiller is BTU/h/W. The summary of SEER value of 375-ton chiller in July-August 2006 and March 2007 are 9.84 BTU/h/W and 9.25 BTU/h/W. The SEER values of 190-ton chiller are BTU/h/W and 6.5 BTU/h/W respectively. The standard of SEER value according to Energy Policy Act of 2002 (EPA) is 13.0 BTU/h/W. The SEER value of the existing system is too low, which indicates that the system may have some problems. In addition to the low efficiency of the air conditioning system the performance of the chiller should be concerned because different amount of energy was consumed at the different chiller s capacity. According to a designed SEER value shown in Figures 4.9 and 4.10, the highest SEER value which occurs at % chiller s capacity is about BTU/h/W for 375-ton chiller and for 190-ton chiller, the highest SEER value is about BTU/h/W. Reducing chiller s capacity will also reduce the SEER value. The reduction of SEER value at different level of chiller s capacity was shown in Figures The design value should be compared with the real SEER value of 375 and 190 tons chillers when running at different chiller s capacity (Appendix A). The 39

52 calculated SEER value at different chiller s capacity was plotted together with the designed SEER value in Figure for comparison. SEER Value of the existing 375-ton Chiller SEER Value (BTU/h/W) % 90% 80% 70% 60% 50% 40% 30% 20% Capacity Designed SEER Value Actual SEER Value in March 06 Actual SEER Value in August 06 Actual SEER Value in March 07 Figure 4.9 Comparison between SEER Values of 375-ton Chiller at Different Capacities SEER Value of the existing 190-ton Chiller SEER Value (BTU/h/W) % 90% 80% 70% 60% 50% 40% 30% 20% Capacity Designed SEER Value Actual SEER Value in March 06 Actual SEER Value in August 06 Actual SEER Value in March 07 Figure 4.10 Comparison between SEER Values of 190-ton Chiller at Different Capacities 40

53 When comparing between the designed and actual SEER value, the trends are similar. The SEER values are higher when operated in a high chiller s capacity and falls down when operated in a lower chiller s capacity. The difference between the designed and actual SEER value in a same chiller s capacity shows that the actual efficiency is extremely lower than designed value in every percentage of chiller s capacity. It is suggested that this problem should be solved immediately and the maintenance and improvement of the system may need to be carried out. From Figures , the efficiency of each level of chiller s capacity in the different period of time is determined. The best efficiency of these chillers occurs when operating at the full load. Running at low chiller s capacity make the efficiency decreased. Generally, any chillers must be operated about % of full capacity to reach a high efficiency (Little, 2002). In this optimum range the average SEER value of 375-ton and 190-ton chiller is between BTU/h/W and BTU/h/W respectively. However, the chiller always operates about percent of its capacity. The actual SEER value in this range is between BTU/h/W. This range of SEER value is unacceptable. This is an important reason why the existing central air conditioning system consumes energy more than it normally does. 4.2 Split Type Air Conditioning System Energy Efficiency Ratio (EER value). The EER value is an index that shows the produced cooling load (BTU/h) when the system consumes 1 Watt of electrical power. According to the Electricity Generating Authority of Thailand (EGAT), the energy consumption of air conditioning system is represented by number 1-5 rating. No.1 rating air conditioner can produce less than 7.6 BTU/h of cooling load by consuming 1 Watt of electrical power. No.2 is better than no.1 in cooling load about BTU/h/W. No.3 and 4 have better efficiency in cooling load about and respectively (EGAT, 2006). No. 5 air conditioner has the best rating in saving energy. To achieve No. 5 rating, the air conditioner must have EER value more than

54 Table 4.9 EER Value of each Label Number of Air Conditioning System Rating Energy Efficiency Ratio (EER) Label No.5 Upper than 10.6 Label No Label No Label No Label No.1 Lower than 7.6 Most of split-type air conditioning system in Thailand receives No.5 rating with EER value about The details of many popular split-type air conditioners in Thailand which have a capacity about 15,000-23,000 BTU are listed in Table 4.10 below. Although the average EER value in this table is about 11.2, in this thesis, the average EER value of 11.0 is used. Table 4.10 Comparison of Cooling Load and EER Value in Different Brands and Series (Market Price in April 2006) Brand Series BTU EER Carrier 42TAR Carrier 42TAR Central Air CFW-TF Central Air (Neo-tech) CFH-NE Daikin AT18GV2S Daikin FTKD24BVMS Fujitsu AWM18A Fujitsu AWM24A Hitachi RAS-T18CE LG A18LCRN33B,R,M LG S18LCN Mitsubishi Heavy duty SRK19CES Mitsubishi Electric MSPB18VC Mitsubishi Electric MS-SB24VC Panasonic CS-S15GKT Panasonic CS-C18GKT Samsung AS18FAN Toshiba RAS-18NKPX-T

55 4.2.2 Energy consumption of split type air conditioning system. In order to investigate the possibility of installing split type air conditioning system, the energy consumption of split-type air conditioning system has to be calculated. To calculate the energy consumption, the energy pattern of the building (the usage time of air conditioning system in every room) from the survey shown in Figure 4.11 and the energy efficiency ratio (EER value) must be used. 70 Using time of Air conditioning system at dormitory buildings on normal day and weekend Rooms Normal day Weekend :00 12:00 13:00 14:00 15:00 16: :00 18:00 19:00 20:00 21:00 22:00 23:00 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 8:00 9:00 10:00 Time Figure 4.11 Using Time of Air Conditioning System at Dormitory Buildings on Normal Day and Weekend The energy consumption of the split type air conditioning system for the dormitory buildings can be calculated by 2 proposed methods which are the calculation from average operation hours of each room, and the calculation from the existing cooling load demand. 43

56 1) Calculation from average operation hours of each room This method calculates the energy consumption of split type air conditioning system by multiplying the operation hours of each room with the proposed capacity of the split type air conditioner. This amount is a cooling demand of each room. When adding them together, the result is the total cooling demand of the buildings. Dividing this total cooling demand by the EER value (assumed to be 11), the energy consumption of split type air conditioning system can finally be calculated. 44

57 Table 4.11 Size of Rooms, Air Conditioners Capacity and Using Time Pattern of SIU Dormitories in Regular Semester Room No: Room's size Size of air conditioner Average hour Cooling load in Cooling load (sq-m) (BTU/h) per day 1 day per room (BTU) in 1 day (BTU) Dorm 1 Hall , ,000 Office , ,000 Sr ,000 90,000 Sr ,000 60,000 Fitness , , ,206,207,209,211, ,786 1,398, ,223 TV Room , , ,306,307,309,316, ,786 2,397, ,320,321,323,324, 325, , ,571 TV Room , , ,404,405,406,407, ,786 2,797, ,409,410,411,412, 413,416,421, , ,571 TV Room , , ,502,503,506,507, ,786 3,795, ,509,510,511,512, 513,515,516,517,518, 519,521,524, , ,571 TV Room , ,000 Elevator ,000 60,000 Dorm 2 Nurse ,320,000 1,320,000 Study ,000 64,000 Study ,000 64,000 Entertainment , , ,203,205,207, ,105 1,704, ,212,214 TV Room , , ,303,304,305,306, ,105 4,262, ,309,310,311,312, 315,316,317,318,319, 321,322,324,325,326 TV Room , ,000 Elevator ,000 60,000 TOTAL ,401,067 21,531,505 45

58 The energy pattern from the surveyed data in Figure 4.11 above is used to find the average usage hours of every residential room. The calculation shows that the average usage time of air conditioning system at dormitory buildings is hours per day. However the compressor of the air conditioner is not fully operated for the whole period. The compressor s operating period is related to the many factors such as an indoor air temperature, an outdoor air temperature, the thermostat setting temperature, etc. The maximum energy consumption occurred when a compressor works at full capacity throughout the operating time. In this calculation, the maximum value of energy consumption will be used when compared with the other system. If this maximum energy consumption is still less than those of other systems, it is certain that this split type air conditioning system consumes energy less than other systems. The cooling demand can be calculated by multiplying this average operating hour by the capacity of split type air conditioner which depends on size of each room (The relation between the capacity of split type air conditioner and the room s size has shown in the Appendix D). In Table 4.11 above, the total cooling load is calculated from size of room and average operating hours. The daily cooling load is equal 21,531,505 BTU or tons. When dividing this value by the EER value, the monthly energy consumption of the split type air conditioning system in dormitory building can be found. The monthly energy consumption calculated by this method equals to 58,722 kwh (in a month of 30 days). From Figure 4.11, the graphs show the surveyed data of the air conditioning usage pattern during regular semester. Due to the time limitation for data collection, the air conditioner usage time of each room was collected in regular semester. Although the characteristics of usage time pattern of regular and summer semesters may not be exactly the same. The usage time pattern for regular semester will also be used in summer semester. In fact, the amounts of occupied rooms in dormitory buildings in summer semester are less than those in regular semester. Thus, the air conditioning system is used less than during the regular time. However, the use of the peak energy consumption has an advantage. If this high energy consumption is still lower when compared with those of other system, this system will definitely consume less energy. 46

59 During the summer and winter breaks, the usage pattern of air conditioning system is considerably decreased. Only staff and some foreign students live in dormitory buildings. The pattern in using an air conditioner is analyzed in Table In this period, most of students go back home except some foreign students live on the university campus. The number of students who live in the dormitory is less than during the normal semester. Thus, the energy consumption of dormitory buildings is reduced. However in Table 4.12, the calculation is assumed that some university staff and all foreign students still remain in dormitory buildings and use the air conditioners similar to the weekend usage pattern. This assumption may lead to an over estimation of both the amount of people in dormitory buildings and the energy consumption. When compared with the energy consumption from the other system, if the energy consumption of split type air conditioning system still lower, the system is able to save more energy than others. 47

60 Dorm 1 Table 4.12 Size of Rooms, Air Conditioners Capacity and Using Time Pattern of SIU Dormitories in Summer and Winter Break Room No: Room's size Size of air conditioner Average hour Cooling load in Cooling load (sq-m) (BTU/h) per day 1 day per room (BTU) in 1 day (BTU) Hall , ,000 Office , ,000 Fitness , , ,206,207,209,211, , , ,223 TV Room , , ,316,324, , , , ,000 TV Room , , ,404,406,408,409, ,000 2,160, ,416,421,422, TV Room , , ,502,506,508,512, ,000 2,640, ,517,518,519,521, 525 TV Room , ,000 Dorm 2 Elevator ,000 60,000 Nurse ,320,000 1,320,000 Entertainment , , ,203,205,207, ,000 2,048, ,212,214 TV Room , , ,309,310,311,312, ,000 2,816, ,317,318,319,321, 326 TV Room , ,000 Elevator ,000 60,000 TOTAL ,256,000 14,648,000 48

61 From Table 4.12, the daily cooling demand is about 14,648,000 BTU or 1,221 tons. The monthly produced cooling demand is about 36,620 tons. The energy consumption in summer and winter break can be found by dividing this amount with EER value. The energy consumption of the air conditioning system in summer and winter break is about 39,949 kwh per month. The annual energy consumption is the sum of energy use during 10 months of regular semester and 2 months of summer or winter break, which is equal 667,121 kwh. By dividing the yearly energy consumption by 12, the average monthly energy consumption is about 55,593 kwh. 2) Calculation from the existing cooling load demand The concept of this method is to find the cooling load demand of the system then divide by the EER value. The energy consumption is calculated. This method uses the dormitory s cooling load demand from BAS shown in Figures and combines this daily cooling load demand to find monthly cooling load demand. Cooling load (tons) Average demanded cooling load in summer semester (March 06) 8.00 a.m a.m a.m p.m p.m p.m p.m p.m p.m a.m a.m a.m. Time Normal day Weekend Figure 4.12 Average Demanded Cooling Load on Normal Day and Weekend in Summer Semester (March 06) 49

62 Cooling load (tons) Average demanded cooling load in regular semester (August 06) 8.00 a.m a.m a.m p.m p.m p.m p.m p.m. Time p.m a.m a.m a.m. Normal day Weekend Figure 4.13 Average Demanded Cooling Load on Normal Day and Weekend in Regular Semester (August 06) Cooling load (tons) Average demanded cooling load in summer break (March 07) 8.00 a.m a.m a.m p.m p.m p.m p.m p.m p.m a.m a.m a.m. Time Normal day Weekend Figure 4.14 Average Demanded Cooling Load on Normal Day and Weekend in Summer Break (March 07) Table 4.13 shows the daily average cooling load demand in each day and combine into monthly cooling load demand to find the annual cooling load demand. The monthly cooling load demand in summer semester is 35,844 tons, in regular semester is 46,642 tons and in summer break is 19,459 tons. 50

63 Table 4.13 Cooling Load Demand of Chiller Plants Supplied to Dormitory Buildings Summer semester (tons) Regular semester (tons) Summer break (tons) Average Sun 941 1, Average Mon 1,229 1, Average Tue 1,232 1, Average Wed 1,232 1, Average Thu 1,232 1, Average Fri 1,232 1, Average Sat 941 1, Monthly Total 35,844 46,642 19,459 The yearly cooling load demand can be calculated by combining 8-month of cooling load demand during the regular semester and 2-month of cooling load demand during summer semester and 2-month of cooling load demand during summer & winter break. From the data of the monthly cooling load demand in Table 4.16, the annual cooling load demand is about 483,742 tons. Dividing this cooling load demand by EER value of 11, the annual energy consumptions is 527,699 kwh. The monthly average energy consumption is 43,975 kwh. Comparison of these two calculation methods shows that the monthly average energy consumption of the first and second methods is 55,593 kwh and 43,975 kwh, respectively. The difference is about 11,618 kwh or 21% due to various simplified assumptions made in the calculation method. For example in the calculating for energy consumption of split type air conditioning system from average operation hours of each room assumes the compressor working at full capacity all the time while the air conditioning system are switch on, the estimation of usage time pattern in summer semester and summer break is too high and etc. The higher value of monthly energy consumption of split type air conditioning system (55,593 kwh) is selected to compare with the energy consumption of other system. If this amount is still lower than those of other systems, it can be confidentially concluded that this split type air conditioning system can saves more energy than others. Therefore, if dormitory buildings install this split type air conditioning system, the estimated overall energy consumption will equal to 55,593 kwh per month. 51

64 4.3 Appropriate Size of Central Air Conditioning System The appropriate size of central air conditioning system can be calculated from the cooling load demand of air conditioning system in dormitory buildings. The chiller s cooling load demand in Appendix A, shows that the maximum cooling load demand is 97 tons, and the minimum cooling load demand is about 7 tons. The summary of the cooling load demand at dormitory buildings in each semester is shown in Table Table 4.14 Dormitory s Cooling Load Demand in Summer Semester (March 2006) Minimum (tons) Maximum (tons) Average (tons) Sat-Sun Mon Tue-Thu March Table 4.15 Dormitory s Cooling Load Demand in Regular Semester (August 2006) Minimum (tons) Maximum (tons) Average (tons) Sun Mon Tue Wed Thu Fri Sat August Table 4.16 Dormitory s Cooling Load Demand in Summer Break (March 2007) Minimum (tons) Maximum (tons) Average (tons) Sun Mon Tue Wed Thu Fri Sat March The results from Table illustrate the maximum, minimum and average cooling load demand during different periods. (summer semester, regular semester and summer break), thus the daily maximum, minimum, and average values of cooling load demand in one year can be found in Table

65 Table 4.17 Summary of the Daily Average Cooling Load Demand at Dormitory Building Minimum (tons) Maximum (tons) Average (tons) Sun Mon Tue Wed Thu Fri Sat All month Table 4.17 clearly shows that the maximum and minimum cooling load demands differ greatly. The maximum cooling load demand is about 97 tons and the minimum cooling load demand is about 7 tons. The minimum value is only 7 percent of the maximum value. To deal with the maximum value, chiller has to have a capacity nearly 100 tons. When selecting 100-ton-chiller to service a building, the chiller will operate at less than 50% of its capacity at the average or minimum cooling load demands, which may be inappropriate. One way to solve this problem is breaking down 100-ton chiller into 2 of 50- ton chiller. To deal with the maximum capacity or the cooling load demand more than 50 tons, 2 chillers will be operated and only 1 chiller is operated when the cooling load demand is lower than 50 tons. However, in the early morning when the cooling load demand goes to minimum point about tons, the chiller will run at its low chiller capacity and low efficiency. At this time, size of the new chiller cannot be reduced anymore because 50 tons is the smallest capacity of water cooled chiller for the central air conditioning system. Another problem happens in scheduling the turn-on and turn-off time of the chillers. The duration time to operate 1 or 2 chillers is varied depending on the cooling load demand, and it is difficult to identify and set the operating time for reach the optimum point. By sharing the cooling load demand between two chillers, the individual cooling load will fall down to tons when the total cooling load demand is about tons. The efficiency of both chillers will be lower than the appropriate level. 53

66 The size of chiller which is smaller than 50 tons is available in an air cooled chiller type. The air cooled chiller has a capacity from tons. However, main problem to select the capacity of chiller is the range between minimum and maximum cooling load demand. Varied cooling load demand is a constraint in sizing the chiller. The water cooled chiller, in general, has better efficiency and more EER value than air cooled chiller in the same capacity. Fortunately, the existing air conditioning system of the dormitory buildings at SIU is not a stand alone system. This system serves 4 main buildings on the SIU campus. The problem of the low cooling load demand can be relieved. The new chiller may be installed to improve and solve the existing problem about the low cooling load demand. The appropriate size of the new chiller can be analyzed from the existing cooling load demand. Table 4.18 Cooling Load Demand at SIU in Summer Semester (March 2006) Minimum (tons) Maximum (tons) Average (tons) Sat-Sun Mon Tue-Thu March Table 4.19 Cooling Load Demand at SIU in Regular Semester (August 2006) Minimum (tons) Maximum (tons) Average (tons) Sun Mon Tue Wed Thu Fri Sat August

67 Table 4.20 Cooling Load Demand at SIU in Summer Break (March 2007) Minimum (tons) Maximum (tons) Average (tons) Sun Mon Tue Wed Thu Fri Sat March From Table , although the minimum cooling load demand increases but the range between maximum and minimum cooling load demand is still wide. Based on the cooling load demand of the whole air conditioning system, possible solution to install the new chiller can be suggested. Solving the problem of the low cooling load is to find an appropriate size and schedule for operate the central air conditioning system. However, the selection of the new chiller to install in the existing system cannot be concluded only from this information. Further studies are required to analyze its possibility of reducing the energy consumption in more details, and the data in this thesis should be useful for these further studies. 55

68 Chapter 5 Analysis and Comparison From the results in Chapter 4, energy consumptions of the central and split type air conditioning systems are calculated. The energy consumption of these systems are analyzed and compared to determine which air conditioning system is suitable. In this chapter, the central and split type air conditioning systems are analyzed and their energy consumptions compared. The results of these comparisons, shown in sections 5.1 and 5.2, can be used to assess each type of air conditioning system. Selecting an appropriate air conditioning system should include not only the issues related to energy consumption, but also other issues, such as financial and qualitative issues for apartment or dormitory and in SIU s dormitory buildings. The analysis of these issues are mentioned in section 5.3 and General Comparison between Central Air Conditioning System and Split Type Air Conditioning System Before comparing the energy consumption of central and split type air conditioning systems, the appropriate size of each system must be determined. The size of a split type air conditioner depends on the size or special volume of each room. The size of a central air conditioner is more difficult to determine because it depends on the peak cooling load demand of the building. It is critical to determine the minimum, maximum and average cooling load demand of the building. The results in section 4.3 illustrate the maximum, minimum and average cooling load demand during different periods. Table 4.17 shows that the maximum and minimum cooling load demands differ greatly. The minimum value is 7 percent of the maximum value. The problem of low cooling load demand frequently occurs. Furthermore, the constraints of sizing the chiller and scheduling operating times have an important relationship with the energy consumption. The cooling load demand varies greatly, operational scheduling is hard to manage. The selection of a central air conditioning system is directly affected by this constraint. 56

69 The pattern of energy consumption in dormitory buildings at SIU is different from general apartment or dormitory buildings. SIU dormitory buildings are located on campus and close to the Main Hall Building. The dormitory residents are able to come back to their rooms quite often. In contrast, residents of general apartment or dormitory buildings off campus only come back to their rooms when they finished their daily work. In addition, most residents in dormitory buildings at SIU go back home during the weekend. However those in general apartment or dormitory buildings do not. Considering the scope of this thesis, the energy consumption pattern of general apartment building is assumed to be consistent with that of the dormitory buildings at SIU. Considering the current energy consumption pattern of dormitory buildings at SIU, it may not be feasible to use a central air conditioning system in the dormitory or apartment buildings. With a higher SEER value, central air conditioning system will consume energy efficiently when it is operated at % of its capacity. Apartment occupancy schedule is uncertain. Occupants turn on the air conditioner at different times. Central air conditioning system is appropriate for a building with certain operating hours such as a department store, and office buildings where most rooms turn on and turn off the air conditioner at a set schedule. 5.2 Comparison of the Energy Consumption of Existing and Split Type Air Conditioning System at SIU s Dormitory Buildings The energy consumption of each type of air conditioning system plays an important role in selecting an appropriate system. In this section, the energy consumption of each system is analyzed. After that, the energy consumption of central and split type air conditioning systems either in the dormitory s buildings or other buildings are compared Energy consumption of the air conditioning system in the dormitory buildings. At present, SIU uses central air conditioning system. Chilled water from the chiller plant is supplied to the dormitory buildings as well as other buildings on campus. The energy consumption for the dormitory buildings only is difficult to estimate. Thus, the energy consumed by central and split type air conditioning 57

70 systems in the dormitory buildings must be estimated by using measurements and calculated data. The results are summarized in Table 5.1 below. Table 5.1 Summary of Monthly Average Energy Consumption of Air Conditioning Systems in the Dormitory Buildings at SIU Energy consumption Average price Total Price (kwh) (Baht/kWh) (Baht) Existing Air conditioning system 75, ,795 Split type Air conditioning system 55, ,233 Difference 20, ,562 Percent of difference 26.57% 0% 26.57% The energy consumption which is shown in Table 5.1 comes from the monthly average energy consumption of each type of air conditioning system. The energy consumption of the existing system is calculated in and the energy consumption of split type air conditioning system is calculated in The average price per unit of electricity for the existing air conditioning system is acquired from the study of Chokesuwattanaskul (2006). This average price per unit of electricity comes from the average electricity price per unit for every month in In sum, the comparison between the energy consumption of the existing and split type air conditioning systems shows the possibility of saving energy at a rate of around 20,111 kwh per month or 65,562 Baht per month (786,742 Baht per year) in electricity costs Energy consumption of the air conditioning system in the other buildings. The existing air conditioning system of dormitory buildings at SIU is not a stand alone system. This chiller plant also services other buildings on the SIU campus. Taking the dormitory s air conditioning system out of the central system will affect the whole system. It is possible to shut down the central air conditioning system during the night time (while most of the normally cooling load demand come from dormitory buildings). In addition, this assumption may have repercussions for energy conservation in other buildings in the system. 58

71 If the dormitory s air conditioning system was shut off from the central air conditioning system, the existing cooling load demand after office hours (between 6.00 p.m a.m.) would be very low. Except for dormitory buildings, there are only few places in SIU that still uses the air conditioning system during this period. The Main Hall Building (MHB), the library and computer laboratories use the air conditioner until 9.30 p.m.; PABX (control room) and UPS room use the air conditioner 24 hours a day. In the laboratory building, the cafeteria uses the air conditioner until 9.00 p.m. and the control room uses the air conditioner 24 hours a day. In the sky link during this period, when the outside temperature is not too high, it may be possible to ventilate naturally without using the air conditioning system (Chokesuwattanaskul, 2006). The air conditioning system in these rooms i.e. library, computer lab, PABX, UPS room, cafeteria and control room, could be operated by a split type system. During this period, the cooling load demand on the chiller plant is non-existent, and the chiller can be shut down during this time period. The energy consumption should be reduced because the chillers always run less efficiently during these periods. However, while the chiller is shut down, the rooms which rely on chilled water from the chiller cannot be used anymore. Only the rooms in which the split type air conditioners were installed can be used. Under these conditions, it can be assumed that dormitory buildings should be installed with its own split type air conditioning system, whereas a central air conditioning system will be operated for other buildings (MHB, Laboratories and Sky Link) between 8.00 a.m. to 6.00 p.m. For any rooms which still need to be air conditioned after office hours, a split type air conditioning system may be installed and operated until the central air conditioner is turned on the next day. Shutting the chiller down 14 hours a day and using a split type air conditioner in its place will change the total energy consumption. Considering the current operation of the existing air conditioning system, the energy consumption in other buildings after office hours for different time periods is shown in Table

72 Table 5.2 Average Energy Consumption of the Existing Air Conditioning System in the other Buildings from 6.00 p.m a.m. Summer semester (kwh) Regular semester (kwh) Summer & Winter break (kwh) Average Sun 1,375 1,009 1,282 Average Mon Average Tue Average Wed Average Thu Average Fri Average Sat 1, ,020 Monthly Average Total 27,488 20,668 25,243 The information in Table 5.2 can be used to calculate the annual energy consumption. This value is around 270,802 kwh per year (calculated by combining 8- month of energy consumption during the regular semester and 2-month of energy consumption during summer semester and 2-month of energy consumption during summer & winter break). The monthly average energy consumption of air conditioning system in other buildings, except the dormitory buildings is 22,567 kwh. If the chiller plant is shut down between 6.00 p.m. to 8.00 a.m. of a normal day and 24 hours in Saturday and Sunday, the split type air conditioning system must be installed. The capacity, operating hours and energy consumption of the split type air conditioner in other buildings are shown in the Table 5.4, and the overall energy consumption of split type air conditioning system in other buildings during the after office hour is equal to 10,640 kwh. 60

73 Table 5.3 Monthly Energy Consumption of Split Type Air Conditioning System in the other Buildings during the off-office Hours Operating hours (hours per day) Capacity Efficiency Energy Consumption Energy consumption (kwh per month) Room normal days weekends (BTU/h) (EER value) per hour (kw ) normal days weekends Library , , Com lab , PABX , Ups , Technician , , Control , , Cafeteria , Total 6,800 3,840 Total Energy consumption in 1 month 10,640 According to Tables 5.2 and 5.3, the energy consumptions of the existing and split type air conditioning systems during the after office hour can be compared. The comparison shows the energy consumption of existing system is about 22,567 kwh. After installing the split type air conditioner, the energy consumption of these parts at SIU will decrease to 10,640 kwh. Thus, the split type system can save 11,927 kwh of electricity monthly. This energy saving must be added to 20,111 kwh of energy saving from the dormitory buildings. The overall energy saving when operating split type air conditioning system at dormitory buildings compared to existing central air conditioning system is equal to 32,037 kwh per month. SIU can save about 104,443 baht monthly or 1,253,320 baht per year. One possibility in saving energy consumption of air conditioning system when separating dormitory buildings out of the central system is to operate only 190 tons chiller during the office hours. However, additional reductions on the overall cooling load demand are required. If SIU can operate a small chiller, the chiller may run at full capacity, and the efficiency of the air conditioning system will be improved. The energy consumption will be decreased. In this case, more information to confirm the exact details of the operation may be needed. The possibility of reducing energy consumption should be analyzed in further studies and the data in this thesis may be useful for future research. 61

74 5.3 Analysis on Financial Issues One of the main considerations for installing the new system or improving the existing system is budget. The analysis of financial issues consists of 2 parts. The first part is the analysis on present financial details of dormitory buildings at SIU, and, the cost for changing central air conditioning system to split type air conditioning system, as well as the pay back period of this change. The second part is an analysis on suitable air conditioning system for general apartment or dormitory buildings Dormitory buildings at SIU. 1) Financial details of dormitory buildings at SIU This financial analysis is based on the present financial situation of dormitory buildings at SIU, which includes the monthly income and expenses. The income include the residential room rent, store rental fee and electricity fee and the expenses including staff salaries (manager, office staff, technicians, house keepers, gardeners and security guards), electricity charges from PEA (Provincial Electricity Authority), maintenance cost, depreciation, etc. The main income of the dormitory comes from rents. The monthly rental rate for students is 9,000 baht per room and staff rate is 3,000 baht per room. During the academic year , there are 68 rooms occupied by students and 5 rooms for staff. The dormitory receives a total rental income about 627,000 baht every month. The rent is collected during the 3 semesters. Thus, in a year, the dormitory can collect the rental fee for only 10 months or around 6,270,000 baht. According to this reason, the average rental fee that can collect from students and staff is about 522,500 baht per month. Another income of dormitory buildings comes from the electricity fee. The occupant who uses the electricity more than the permitted limit (100 units for the 2, 3- person room and 150 units for the 4-person room) must pay the electricity fee. The excess electricity usage is charged at 5 baht per unit. Staff is also charged at 5 baht from the first unit. 62

75 Table 5.4 Overall Energy used which can collect from the Dormitory Buildings Summer Regular Summer Annual Average Excess electricity Semester Semester Break Excess energy use by students and staff (kwh) 2,052 4,315 2,852 44,329 3,694 Electricity fee charge (baht) at 5 baht per unit 10,260 21,575 14, ,645 18,470 Table 5.4 shows the excess energy use of all rental rooms. The monthly average energy use for which the fee can be collected is around 3,694 kwh, which is equal to 18,470 baht when charging the electricity rate of 5 baht per unit. Including rents and electricity fees, the total income of dormitory buildings is about 540,970 baht per month. The monthly expenses of dormitory buildings consists of the electricity charges from PEA, staff salaries, and maintenance costs. The monthly average electricity charge is calculated from the monthly average energy used. It is shown in Table 5.5. Table 5.5 Overall Energy used based on the Electricity Charges from PEA Summer Regular Summer Annual Monthly Sources of energy used semester semester Break average (kwh) (kwh) (kwh) (kwh) (kwh) 1.Total energy use of dormitory buildings (electricity meter) 19,645 28,535 21, ,342 25, Energy use of dormitory building 1 (electricity meter) 14,131 19,560 15, ,411 18, Energy use of dormitory building 2 (electricity meter) 5,514 8,975 5,554 93,931 7,828 2.Energy use from chiller plant supply to dormitory buildings 64,195 82,899 58, ,452 75,704 Overall energy used 83, ,134 79,524 1,215, ,266 In Table 5.5, the overall energy used is calculated from two main sources of energy consumption. The first source comes from electricity meter of dormitories 1 and 2; another source comes from the energy consumption of chiller for dormitory buildings. This data comes from the collected data of dormitory office and the calculated result in Chapter 4, respectively. The data collected in summer semester, regular semester and summer break can be used to calculate the annual energy consumption. It is assumed that a year is a combination of 8 months during the regular semester and 2 months during the summer semester and 2 months during the 63

76 summer & winter break. When dividing this annual energy consumption by 12 months, the result is the monthly average energy consumption of dormitory buildings. This number is about 101,266 kwh. The average electricity cost per unit from PEA is about 3.26 baht (average the electricity cost from every month in 2006). At this electricity rate, SIU has to pay for the electricity at dormitory buildings around 330,128 baht per month. Another expense of dormitory buildings is staff salaries. There are many staff with different duties at dormitory buildings. Some staff, such as technicians, housekeepers and gardeners, are hired to work on the whole campus. In this calculation, it is estimated that 4 technicians and 6 housekeepers and gardeners have direct responsibilities in dormitory buildings. Staff salaries are also estimated values depending on the position. Details of dormitory staff salaries are shown in Table 5.6. Table 5.6 Details of Monthly Dormitories Staff Salaries Staff at dormitory Salary Amounts Total Manager 30, ,000 Office staff 15, ,000 Technicians 15, ,000 House keepers & Gardeners 8, ,000 Security guards 8, ,500 Total 8,500-30, ,500 Maintenance cost is one of important expenses of dormitory buildings. An annual budget for the dormitory maintenance was set for the dormitory buildings, surrounding areas and facility systems. From B&G service s data, in the academic year 2006, these budgets were 170,000 baht for the building maintenance, 100,000 baht for equipment maintenance, and 300,000 baht for air conditioning services and maintenance by York (excluded of spare parts). However, the budget of building maintenance and equipment is for 2 of dormitory buildings and the gymnasium. The air conditioning maintenance budget is for the chiller plant which services many buildings in SIU. The calculation to identify dormitory maintenance cost is shown in Table

77 Table 5.7 Annual Dormitory Maintenance Cost Budget Approximately percent of dormitory used Overall Budget (baht) Dormitory's budget (baht) Maintenance building 67% 170, ,333 Maintenance equipment 67% 100,000 66,667 Maintenance chiller 48% 300, ,000 Total ,000 From Table 5.7, the approximate percentage of building and equipment maintenance budget for dormitories is 67% of total budget which is intended for 3 buildings (two dormitory buildings and gymnasium). For dormitory buildings part, it is equal to two third or 67% of total budget. The budget for chiller maintenance comes from a percent of energy used by chiller for dormitory buildings in regular semester from Table 4.4. The annual dormitory maintenance cost is equal to 324,000 baht or 27,000 baht per month. The other expenses of dormitory buildings are depreciation cost, construction cost and etc. These expenses should be added to the total expenses. However, the depreciation and construction costs, etc. are difficult to identify the exact cost. For this reason, the total expenditure will not include these other expenses. The comparison between incomes and expenses of dormitory buildings is shown in Table 5.8. Table 5.8 Comparison between Incomes and Expenses of the Dormitory Buildings Sources of incomes Baht/month Sources of expenses Baht/month Overall rental fee 540,970 Staff salaries 277,500 Exceed electricity fee 20,554 PEA electricity charge 330,128 Maintenance cost 27,000 Total income 561,524 Total expenses 634,628 Regularly, SIU is not allowed to gain any profits from university owned dormitories. The intention is to sustain the operational cost. However, the comparison in Table 5.8 shows the net monthly income is lower than the net monthly expenses by 73,104 baht. It means the dormitory still needs to be subsidized by SIU. According to this comparison, the present financial details of the dormitory buildings are not in an appropriate condition. Income is less than expense. The profit in each month is not sufficient to reach the break-even point or even sustain its 65

78 operation. Nevertheless, the dormitory at SIU is intended to provide residential services to students rather than aiming to make profits. Major expenses of the dormitory buildings are staff salaries, electricity charge and maintenance cost. There are many methods to reduce these expenses, such as managing the staff to work efficiently, hiring of staff suitable for the number of students, reducing energy consumption and etc. These solutions need further studies to find the most appropriate way to operate the dormitory. The main objective of this thesis is to explore the possibility of installing the split type air conditioning system, for energy conservation purpose. Switching to the split type air conditioning system may reduce expenses. The main energy use in dormitory buildings comes from the chiller plant (about 75%). The energy consumption in this part cannot be precisely included into an electricity fee of each room. Therefore, the higher electricity rate is charged to cover the cost of producing chilled water. When operating the split type air conditioning system, the actual energy used can be read directly from the electricity meter. Each occupant must pay according to its own energy usage. Residents will be well aware of the money paid for electricity cost and will adjust his/her energy consumption accordingly. 2) Investment cost of split type air conditioning system Investment cost is one of important factors affecting the decision to change the air conditioning system at dormitory buildings for energy saving purpose. This section analyzes the cost of split type air conditioners if it is installed in every room at dormitory buildings. The capacity and amount of air conditioners is provided in Table The cost of these air conditioners is the average price of many popular split-type air conditioners in Thailand. These data is used to calculate the investment cost of split type air conditioning system plus the installation which is shown in Table

79 Table 5.9 Investment Cost of a Split Type Air Conditioning System at SIU Dormitory Buildings Capacity of air conditioner (BTU/h) Range of price (baht) Average price (baht) Number Total (baht) 10,000 15,000-25,000 20, ,000 15,000 25,000-35,000 30, ,620,000 16,000 25,000-35,000 30, ,000 18,000 30,000-42,000 35, ,000 20,000 32,000-42,000 37, ,000 25,000 40,000-45,000 42, ,500 30,000 55,000-60,000 57, ,500 40,000 60,000-70,000 65, ,000 55,000 80,000-90,000 85, ,000 60,000 90, , , ,000 Total 3,270,000 Other place Capacity of air conditioner (BTU/h) Range of price (baht) Average price (baht) Number Total (baht) 15,000 25,000-35,000 30, ,000 30,000 55,000-60,000 57, ,500 45,000 65,000-75,000 70, ,000 50,000 70,000-85,000 77, ,500 Total 1,040,000 Overall system 4,310,000 3) Maintenance cost of split type air conditioning system The maintenance of air conditioning system is necessary to maintain the air conditioners in good condition. It improves the performance, extends life-time, saves the energy consumption, etc. of air conditioners. The maintenance cost is one of the important factors affecting the decision to change the air conditioning system at the dormitory buildings. The annual maintenance cost in Bangkok and surrounding areas (in 2006) is about 1,000 1,500 baht per unit. According to several air conditioner service centers, the average maintenance cost is around 1,200 baht per year. This cost is spent for the service from service provider. In this service, the air conditioners are cleaned every six months, checked every 2 months, and repaired when the air conditioners are out of 67

80 order. This cost does not include spare parts. To replacing the existing air conditioning system, approximately 118 units of split type air conditioning system are needed. The total maintenance cost in one year is about 141,600 baht. 4) Pay back period Before investing in each project, finding its pay back period is very important. The pay back period is the time required to accumulate the net profit to equal the initial investment. It helps analyze whether or not the project is worth the investment. In this case, the net profit for replacing the existing air conditioning system comes from the saving from operating cost of the split-type system (about 1,253,320 baht per year) minus the maintenance cost (about 141,600 baht per year). The annual net profit is about 1,111,720 baht (92,643 baht per month), and the pay back period can be calculated from the net profit, investment cost and Discount Factors (DF). Pay back periods of different DF values are shown in Table 5.10 below. Table 5.10 Pay Back Periods for Installation of the Split Type Air Conditioning System DF = 0% DF = 10% End of year Net profit Cumulative Net profit Cumulative 0-4,300,000-4,300,000-4,300,000-4,300, ,111,720-3,188,280 1,010,655-3,289, ,111,720-2,076, ,777-2,370, ,111, , ,252-1,535, ,111, , , , ,111, ,291-85, ,111, , ,830 Pay back period about 3 years 11 months about 5 years 2 months The value of energy savings in Table 5.10 come from the section 5.2 comparison on energy consumption between existing air conditioning system and split type air conditioning system at SIU s dormitory buildings. The monthly energy savings from split type air conditioning system is about 32,037 kwh which is about 104,443 baht per month or 1,253,320 baht per year. Subtracting the maintenance cost about 141,600 baht per year, the result is 1,111,720 baht. This amount is considered 68

81 as an annual net profit. However, the net profit normally covers other costs such as depreciation cost, life-cycle cost and etc. In this thesis, the calculation of the net profit is simplified by using only operating and maintenance costs of central and split type air conditioning system. From Table 5.10, the pay back period for the installation of split type air conditioning system is calculated in 2 cases. When the investment has no loan s interest, DF is assumed to be zero. It takes 4 years and 11 months to reach the breakeven point. Another case is when DF is equal to 10%. It takes 5 years and 2 months to reach the break-even point. 5) Investment cost of additional chillers The installation of split type air conditioning system is mainly proposed as the main solution to reduce energy consumption at dormitory buildings. From the result and analysis in Chapter 4 and 5, the split type air conditioning system seems to perform better than the existing system in energy savings. However, the choice of installing additional chillers still cannot be neglected until it is studied further. According to the information from Johnson Controls International (Thailand) Co.,Ltd., the price of York water cooled chiller which has capacity of 50 to 100 tons are about 1,000,000 and 1,400,000 baht respectively. The investment cost of additional chiller is lower than that of split type air conditioning system. It would cost 3,000,000 baht (around 75% of installing split type air conditioning system) to install an additional chiller. Considering whether or not this investment is worth, the return profit must be calculated. The profit, in this case means the savings on electricity charges. The estimated amounts of energy savings need further information on the optimum capacity of new chiller and the proper operational schedule New dormitory and apartment buildings. 1) Investment cost of split type air conditioning system Assuming similar energy consumption pattern of the dormitory building at SIU, the investment cost of split type air conditioning system in the new dormitory or apartment buildings will remain the same, about 4,310,000 baht. 69

82 2) Investment cost of central air conditioning system To install the central air conditioning system in a new building, the investment cost is different from that cost of adding chillers to the existing system. The existing system already has all components of a central air conditioning system except the new chiller. The new system, on the other hand, needs the installation of all components e.g. cooling tower, water pump, AHUs & FCUs, chilled water pipe, fresh air and exhaust system, etc. In central air conditioning system, operating with one chiller seems difficult. The chiller cannot continuously operate without stopping. Most apartment or dormitory buildings require 24-hour operation and the air conditioning system must operate at all time. Consequently, the alternate chiller must be installed, which means there must be two chillers, each take turn to operate as the other undergoes maintenance. The cost of chiller with a capacity between tons is between 1,000,000-1,400,000 baht. The total cost of 2 chillers is between 2,000,000-3,000,000 baht. When including the cost of other parts e.g. cooling towers, water pumps, AHUs & FCUs, chilled water pipe, fresh air and exhaust system, etc. which is about 2,000,000 baht for chillers cost, the total investment cost of central air conditioning system is approximately 4.8 million baht. Table 5.11 Calculation for Installation Cost of a Central Air Conditioning System Equipments, Parts Capacity Range of price (baht) Average price (baht) Amounts Total (baht) Chillers RT 1,000,000-1,400,000 1,250, ,500,000 Cooling tower RT 80, , , ,000 AHUs & FCUs BTU 9,713-27,213 12, ,325,000 Pumps kw 40,000-60,000 50, ,000 Control flow switch - 1,800-2,500 2, ,000 Other parts e.g. pipelines, electric cable and etc ,000 Total 4,787,000 Table 5.11 shows important components which will be used to calculate the total investment of the central system. The price of each component comes from the manufacturer. The chiller s price is from Johnson Controls International (Thailand), 70

83 the cooling tower s price comes from A.M.P. Industrial product and K.S. Engineering, AHUs & FCUs prices come from Carrier s International company (Thailand), pumps, control switch and other equipments come from the conclusion of central air conditioning equipments price which shown at Thai HVAC (n.d.). The cost to install a central air conditioning system in a new dormitory or apartment buildings is approximately 4,787,000 baht. 3) Comparing investment cost of split type and central air conditioning system From the calculations on the investment costs of both air conditioning systems, the investment cost of central air conditioning system is higher than the investment cost of split type air conditioning system by 0.5 million baht. However, this calculation is based on the assumption of general apartment or dormitory buildings have the same characteristic with the dormitory buildings at SIU. The installation cost is only one of many factors that should be considered in selecting the air conditioning system. Maintenance and life-cycle costs should also be used in the selection of an air conditioning system. Generally, chillers can be used for years (Piper, 2006) but the split type air conditioners can be used for 15 years (Foreman, 2006). The machine life depends on the use pattern, using condition, maintenance and etc. The comparison between cost of these two systems need further information to confirm whether the overall costs of split type air conditioning system is lower than central air conditioning system. 5.4 Analysis on Qualitative Issues Although the main focus of this thesis is on the energy consumption of air conditioning system in dormitory buildings at SIU, qualitative issues cannot be ignored. The quality of air conditioner is one of many factors to consider. The advantage and disadvantage of each system are analyzed. Furthermore, this issue directly relates to the usage of air conditioning system. The analysis of qualitative issues uses the data from the survey on the air conditioning system at dormitory buildings in January, The questionnaire in this survey asks 60 dormitory occupants about the pattern of their air conditioner usage, unsatisfied or disappointed issues, suggestions, etc. The questionnaire and surveyed data is shown in Appendix B. 71

84 Percentage of rooms Unsatisfied issues of the residents Temp. Using time Humidity Maintenance Noise Payment Type of disappointed issues Figure 5.1 Unsatisfied Issues of Residents in the Dormitory Buildings about the Existing Air Conditioning System In the survey, the qualitative issues to be considered can be categorized in 6 topics which relate room s temperature, using time of cooling, humidity and fungus, system maintenance, noise and energy cost and payment. Considering these six issues, 56.67% of residents feel unsatisfied with the electricity cost and 45% of residents feel unsatisfied with the maintenance of the system include cleaning and repairing. The noise of air conditioner becomes problematic for 31.67% of the residents, and only 26.67% are unsatisfied with the room s temperature, the using time for cooling and high humidity, respectively. Electricity cost: The electricity cost is the main source of unsatisfaction at dormitory buildings and it can be a key to reduce energy consumption. At present, electricity fee is charged according to the meter reading. Each room pays the electricity bill from the usage of all electrical equipment in the room e.g. lights, computers, televisions, FCUs, etc. The electricity used by chiller s plant which supplies chilled water to the room cannot be explicitly measured. According to this condition, the dormitory cannot collect the directly used by the chiller from residents directly. Thus, higher electricity fee rate is charged to cover the cost of producing the chilled water. Energy conservation in air conditioning system does not truly reflect the reduction of electricity fees. It seems unfair for the people who always turn off the air conditioning system to pay higher electricity bills. 72

85 The solution is to add the amount of electricity used in air conditioning system into the electricity fee of each room. Then every room will pay for the actual energy usage in air conditioning system and other electrical equipments. However, in the central air conditioning system, it is quite hard to identify the amount of energy consumed by chiller in producing chilled water to supply for each room. Using the split type air conditioning system may eliminate this problem. The split type air conditioning system is easier to identify the energy consumption of each room, and helps eliminate any suspicion in electricity fees. Maintenance: The maintenance includes cleaning, repairing and maintaining. Air conditioners have to be maintained every 3-6 months (Expat Web Site Association [EWSA], n.d.). The central air conditioning system, in which the chiller plant has to be operated 24 hours a day, needs the reserved chiller for switching operation. The chiller can be maintained only when it is shut down. The maintenance of the chiller is not generally as simple as maintenance of a split type air conditioning system. It required more equipment or more skills. The maintenance of the central air conditioning system must also include the chiller plant, chilled water pipes and AHUs and FCUs. For the split type air conditioning system, the maintenance process is not as complicated as that of the central air conditioning system. However, large amounts of split type air conditioners installed in the building increase the maintenance works and needs longer time to complete. Changing air conditioning system cannot solve the problem due to the lack maintenance. In order to eliminate this problem is to clean, repair and maintain the air conditioning system regularly. Noise: The air conditioning system must have some components that generate the air flow for cooling a room. These components such as AHUs, FCUs, and cooling coil unit, have a motor or blower which have movable parts. The vibration of these components is hard to avoid and it always makes noise. The best way to solve this problem is to have good maintenance. When compare these two systems in on noise level, central air conditioning system seems to have less noise than split type air conditioning system. Central air conditioning system has only air handling or fan coil unit and chilled water pipe in the conditioned area. The split type air conditioning system, on the other hand, with most 73

86 parts in the conditioned area, although some parts of it are outside nearby the conditioned area, these parts can create noise that may come into a room. Room temperature: Reducing the room s temperature is a main purpose of using an air conditioning system. In the cooling process, heat is transferred outside the room until the temperature inside reaches the preset temperature. The existing air conditioning system has a problem of maintaining room s temperature at the preset temperature. In the central air conditioning system, the temperature of chilled water from chiller plant is directly applied to the room s temperature. For example, when the temperature of leaving chilled water from chiller plant is set at 45 F, the room s temperature can reach C. However when increasing the temperature of leaving chilled water to 48 F, the lowest temperature can be achieved in each room is only around C (Chokesuwattanaskul, 2006). In this situation, although the users in each room set the temperature lower than 22 C, the room s temperature can reach only 22 C. The problem of controlling the room s temperature in the central air conditioning system may come from setting the leaving temperature of chilled water too high. On the contrary, the split type air conditioning system can cool the room s temperature independently from the leaving temperature of chilled water. If the capacity of the split type air conditioner is sufficient and appropriate for the size of the room, the problem of controlling the rooms temperature will not occur. The limitation of central air conditioning system may be an advantage in conserving energy. Some rooms where the residents often set the thermostat temperature too low, there will be an increase the cooling load demand of the chiller. Setting a proper temperature of leaving chilled water can eliminate the excessive cooling load demand. Setting the temperature of leaving chilled water from chiller plant at 48 F is intended to save more energy. The indoor temperature ranging between C should be acceptable for comfort. The appropriate indoor condition in Thailand proposed by Khedari, Yamtraipat and Hirunlabh (2001) varies between C. Using time for cooling: The ability of the air conditioner to dissipate the heat from the conditioned spaces in the shortest time is one of the important performances of the system. The usage time to cool the room depends on many 74

87 factors, such as the temperature inside and outside, size of the room and the performance of air conditioner. Type of the air conditioning system is not as important as the size of air conditioning system. Installation of suitable size and acquire suitable maintenance are a keys eliminate this problem. Humidity: Reducing the air temperature and the humidity in the air make the conditioned room more comfortable. The cooling process blows dried and cooled air into the conditioned space. The exhaust system blows stale air outside. Both central and split type air conditioning systems must have a suitable dehumidify process in order to create comfort air in the conditioned space. The exhaust and fresh air system in dormitory buildings at SIU is operated between 9.00 a.m. to 9.00 p.m. in the winter and summer seasons. In a rainy season, this system is operated 24 hours a day. Although the exhaust and fresh air systems are operated regularly, some rooms in the dormitory buildings still have fungus on the wall. This indicates that the humidity problem still exists and needs further studies on appropriate operating time and size of the air conditioning, exhaust and fresh air systems. User s behavior: The questionnaire appeared in Appendix B asks residents about their willingness to reduce energy consumption of the air conditioning system. The result shows that only 45 rooms or 75% agrees with the energy conservation campaign. Other 15 rooms or 25 percent do not pay any attentions to the energy saving issue. 75

88 Students and staff who are willing to follow energy conservation program 25% Not willing Willing 75% Figure 5.2 Percentage of the Residents who are Willing to Reduce Energy Consumption by the Air Conditioning System Figure 5.2 shows that 75% of the residents are willing to help save energy. Most residents are concerned about electricity fees and the excessive energy consumption. This group has an important role in helping SIU save energy in either the existing or split type air conditioning system. The remaining 25% don t pay any attention to the energy saving matter. Some of them ignore the energy conservation campaigns. Some of them misunderstood electricity charges and the benefits from the energy conservation. Clear explanation about the billing system and the benefits from this campaign may make them willing to save energy. Installing the split type system will make electricity fees of every room more consistent with the real energy usage, and eliminate the residents suspicion on the electricity fees. Thus, more residents may agree to join in energy conservation campaign. Other limitations: The qualitative issues between the existing and split type air conditioning systems are compared. In fact, qualitative issues which should be considered are more than topics covered by this thesis. Details about other issues 76

89 are collected in section type of air conditioning system. Advantages and disadvantages of qualitative issues are summarized in Table Table 5.12 Comparison on the Qualitative Issues of Central and Split Type Air Conditioning System Qualitative issue Central air conditioning system Split type air conditioning system Electricity cost Difficult to identify the exact amount of Measure the energy consumption of each room energy used in each room. by the electricity meter. Maintenance Chillers are installed at the same place convenient to maintenance but the system is more complicated. Split type air conditioning system is more simple to maintain than chiller plant but the individual unit make the maintenance inconvenient. Noise Annoying noise can come from any part of the Noise comes from fan coil unit and chilled air conditioner which is installed inside or water. nearby the conditioned area. Room s temperature Limit of the lowest temperature setting depends Temperature can be reduced until reaching the on the leaving temperature of chilled water. maximum capacity of the air conditioner. Depending on the capacity of air Depending on the capacity of air conditioner Using time for conditioner either central and split type air either central and split type air conditioning cooling the room conditioning system. system. Humidity Either supplying dried air from the air conditioner or blow out stale air is important in dehumidify process. Either supplying dried air from the air conditioner or blow out stale air is important in dehumidify process. User s behavior Difficult to identify exact amount of energy used in each room. It will make the users ignore the energy conservation. Electricity measurement of every room is based on the real used of energy. More users will agree to join in energy conservation campaign. Other limitation Using more area to install chiller and its Most users familiar with this type of air equipment as a cooling tower, etc. conditioning system. It makes a convenient use. 77

90 Chapter 6 Conclusions, Implications and Recommendations 6.1 Conclusions The air conditioning system at the SIU campus consumes the largest amount of energy (about 75%), and around a half of this amount is consumed by the dormitory buildings. Due to the small amount of occupants on SIU campus at present, the cooling load demand is quite low compared to the capacity of the existing air conditioning system. It is only approximately percent, which results in low efficiency, although the appropriate cooling load demand should be up to percent of the capacity. This cooling load demand is recorded by the Building Automation System (BAS) which shows the distribution of the cooling load demand in each building. This data is used to identify the energy consumption of the dormitory s air conditioning system. The energy consumption of the split type system is calculated using the actual pattern of air conditioning usage at the dormitories. In this thesis, the usage time of the air conditioners was obtained from a survey of most dormitory residents. In addition, this survey also explored various qualitative issues related to the use of the air conditioning system. By replacing the existing central air conditioning system with a split type air conditioning system, the efficiency of the cooling operation would improve, despite previous studies that claim that the central air conditioning system normally consumes less energy than the split type air conditioning system, especially in water cooled types like the existing system. However, operating the air conditioning system at low efficiency makes this system consume substantially more energy than the manufacturer s designed value. In this thesis, the conclusion is presented in 4 sections based on the results of the analysis in Chapter 5. 1) Conclusions resulting from a general comparison between central and split type air conditioning systems Currently, the maximum and minimum cooling load demands of the dormitory buildings differ greatly. The minimum value is only 7 percent of the maximum value, 78

91 and the problem of a low cooling load demand frequently occurs. Because the cooling load demand varies greatly, scheduling operation times is difficult to manage. The selection of a central air conditioning system is directly affected by this constraint. Considering the current energy pattern of the dormitory buildings at SIU, it may not be possible to use a central air conditioning system in the dormitory or apartment buildings. The characteristic of most apartment buildings is the uncertainty of the schedule. This type of air conditioning system is appropriate for a building with a certain operating hours such as department stores and office buildings where most rooms turn on and turn off the air conditioner during the same period. 2) Conclusion resulting from a comparison of the energy consumption of the existing air conditioning system at the SIU dormitory buildings and split type air conditioning systems When operating a split type air conditioning system, significant amounts of energy could be saved. The comparison between the energy consumption of the existing and split type air conditioning systems in the dormitory buildings reveals a possibility of saving the energy of around 20,111 kwh per month and saving electricity costs of around 65,562 Baht per month (786,742 Baht per year). In addition, changing to the split type air conditioning system also allows the possibility of shutting down the chiller out of office hours. The operation of the split type system in the dormitory buildings instead of the existing central air conditioning system could save a total of around 32,037 kwh of energy per month, which is around 104,443 baht per month or 1,253,320 baht per year. However, replacing the existing air conditioning system with the split type air conditioning system adds the maintenance cost around 141,600 baht per year. Finally, the annual net profit after operating an split type air conditioning system is around 1,111,720 baht. 3) Conclusions resulting from the analysis of financial issues To install a split type air conditioning system, the investment cost is around 4.3 million baht. When compared to the amount of energy conserved (around 100 thousand baht per month), this investment cost can be recovered within 5 years and 2 months (at 10% interest rate). The investment cost, net profit and pay back period of 79

92 the split type system shows an attractive result. Considering its average life time of 15 years, the split type air conditioning system seems to be worth the investment. On the other hand, the installation of the additional chillers will cost around 3 million baht for the existing system at SIU and around 5 million baht for the new dormitory or apartment building. This investment seems to be high and not worth the investment because of the higher operating cost when compared to the split type air conditioning system. Furthermore, the appropriate type of air conditioning system for general apartments or dormitory buildings is analyzed by assuming the same energy pattern as that of the dormitory buildings at SIU. The use of the split type air conditioning system is more applicable due to the air conditioning usage pattern in the dormitories. In addition, the investment cost of the central air conditioning system is more expensive than the split type air conditioning system by around 500,000 baht. Therefore, the split type air conditioning system is recommended for general apartment or dormitory buildings. 4) Conclusions based on the analysis of qualitative issues In addition to the energy consumption and financial issues, qualitative issues should also be considered when selecting the air conditioning system because this issue directly relates to the usage of air conditioning system. The existing central air conditioning system has the difficulty of collecting a monthly electricity fee from the dormitory residents. SIU did not install any sensors to measure the volume of the chilled water supplied to each room. Thus, the electricity fee cannot be charged directly based on real usage. A higher electricity rate is charged to cover the cost of producing the chilled water. However, this problem can be solved with the installation of the split type air conditioning system. 5) Conclusions based on the objectives of thesis From these conclusions based on the analysis of general comparisons, energy consumption, financial issues and qualitative issues, the split type air conditioning system is recommended for the dormitory buildings both at SIU s dormitories and off campus. Split type air conditioning systems are more suitable for apartment buildings than central air conditioning systems because each room has a different cooling load demand at different periods of time and the total cooling load varies greatly. 80

93 Replacing the existing central air conditioning system in the dormitory buildings at SIU with the split type air conditioning system would cost around 4.3 million baht. When comparing the net profit which will be gained, at least 92 thousand baht per month, the split type air conditioning system seems to be worth the investment because this investment cost can be recovered within 5 years. Furthermore, an awareness of energy conservation by the residents may be raised by operating the split type air conditioning system since the electricity fee can be charged directly based on real air conditioning usage. 6.2 Implications The study of this thesis claims that split-type air conditioning systems are more appropriate for dormitory or apartment buildings than central air conditioning systems. The selection of the recommended system will have advantages in terms of energy consumption, financial issues and qualitative issues. However, the assumptions and limitations of this study are significant and should be considered seriously before making a decision to install this system in such buildings Assumptions. In order to achieve the objectives, many assumptions were made which will have directly affected the results and outcomes of this study. These assumptions are presented as follows: 1) Pattern of energy usage in the dormitory buildings Generally, every apartment building has its own energy pattern which is always significant and different from other apartment buildings. In this study, knowledge of the energy pattern was necessary when calculating the energy consumption. Different energy patterns will give different results. To simplify the calculation, the energy pattern in the dormitory building at SIU was selected to represent the energy pattern of general apartment buildings although it may be different from the actual energy pattern of general apartments or other dormitory buildings. 81

94 2) Cooling load demand from BAS In this study, a lot of data and information was measured and collected for the analysis and calculations. The reliability of the results depends on the accuracy of the measured and collected data. At present, the distribution of the cooling load demand can only obtained from the BAS. This collected data relies totally on measuring instruments or sensors which have not been calibrated and may not have been maintained. However, the cooling load demand from the BAS is assumed to be reliable in this study. 3) Monthly net profit in operating split type air conditioning system Normally, the monthly net profit when operating a split type air conditioning system must be calculated from all the costs of this system e.g. the operating cost, maintenance cost, life-cycle cost, depreciation cost, etc. However, in this thesis it is assumed that only the operating and maintenance costs, which are the main costs when operating a split type air conditioning system, will be compared with the investment cost in order to find the pay-back period Limitations. Due to the limitations of measuring instruments, some data can not be measured directly, thus an estimation from the normal operation is used to solve this problem. Using the estimated data for the analysis and calculation is a limitation of this thesis that directly affects the result of this thesis. Furthermore, some data in this thesis is very difficult and complicated to estimate. To simplify this study, it does not cover this types of data. The limitations of this thesis are listed as follows: 1) Proposed schemes in this thesis According to the scope of this thesis, the suggestions from this research will be proposed in order to find the most appropriate system between central and split type air conditioning systems without considering other air conditioning systems or the development of other issues e.g. the system s efficiency, machines or equipment, energy patterns, etc. This is an important basic limitation of the study which directly affects the results. 82

95 2) Calculation of the energy consumption of the central air conditioning system With the existing air conditioning system, the data of fresh air & exhaust system can not be directly measured. The average motor s capacity in this calculation comes from an estimation of the normal operation which is around 70-80%. The motor s capacity is estimated at 70% of its capacity. This estimation will make the calculated energy consumption lower than the real energy used. The total energy consumption at 75,704 kwh seems to be at the lower limit of this system. However, this thesis uses the lower limit of the estimated energy consumption of the existing air conditioning system. As a comparison, if the energy consumption of this system is still higher than that of the other system, it can be concluded that the existing air conditioning system definitely consumes more energy than the split type air conditioning system. 3) Calculation of the energy consumption of split type air conditioning system In the calculation of the energy consumption of the split type air conditioning system, some data was not available and estimated values were used to calculate the upper limit of the energy consumption of the split type air conditioning system. The underlying reason is that if this higher value is still lower than the energy consumption of the existing system, the split type air conditioning system definitely consumes less energy than the existing air conditioning system The data used in the estimation of the energy consumption of the split type air conditioning system is shown in Table 6.1 below. 83

96 Table 6 Data used to Calculate the Energy Consumption of the Split Type Air Conditioning System Variable data Used data Actual or normal data Compressor s operating period Fully operational for the whole period Operating up to a workload in each period EER Value Energy pattern during the summer semester Equal to energy pattern during a regular semester Less than the energy pattern during regular semester People who live in dormitory during the summer break All foreign students and staff who live in dormitory buildings Some foreign students and staff live in the dormitory buildings Method for calculating energy consumption of split type system Calculating from average operating hours for each room (higher value) In the range between the results of these 2 methods Residents concern about the electricity fee and reduction of energy consumption when they Not included Must be affected are charged directly for usage. Occasions to operate the 190-ton chiller in other buildings Not included Must be affected 6.3 Suggestions and Recommendations for Further Studies From the analysis and comparison, it may be concluded that considerable opportunities for energy conservation in the SIU air conditioning system exist. These opportunities exceed the scope of this thesis but some opportunities that need further study can be identified from this study. These suggestions aim to help improve future studies so that they will be more general, reliable and useful. 1) Pattern of energy usage in the dormitory buildings The energy pattern in this thesis refers to the energy pattern of the SIU dormitory buildings. Using this thesis result for other buildings is possible.. If the energy pattern of other buildings is different from SIU, the energy consumption results will also be different. If the energy pattern is too different, recalculating with the new energy pattern should help to acquire more consistent results. 84

97 2) Cooling load demand from BAS Although the measuring instruments and sensors of the BAS may lack calibration and maintenance, data from the BAS is still the most reliable data that SIU has at present because SIU has no other equipment which can measure the distributed cooling load demand of each building. Calibrating these instruments will make data collection more reliable. To reach the most consistent result, the measuring instruments and sensors must be maintained regularly. 3) Monthly net profit in operating a split type air conditioning system Although the monthly net profit when operating a split type air conditioning system should include the operating cost, maintenance cost, life-cycle cost, depreciation cost etc., this thesis used only the operating and maintenance costs to represent the monthly net profit. However, the other costs are also important to the investment. Consequently, the information relating to the financial analysis in this study should only be considered as a decision guideline. In future studies, the other costs should be analyzed to make the result more accurate and it can be used in decision making. 4) Proposed schemes in this thesis The amount of energy that can be saved from the results of this thesis is excluded when considering other types of air conditioning systems or the development of other issues e.g. improving system s efficiency by maintenance, operating suitably sized chillers, promoting an energy conservation campaign etc. To acquire more energy conservation, these issues should be analyzed in more detail and combined with the split type air conditioning system in further studies. The information from this thesis such as the cooling load s demand, the actual performance of the chiller, dissatisfaction about the electricity charges etc., will be useful and will make the study more reliable and cover more detail. 85

98 5) Calculation of the energy consumption of air conditioning system Due to the limitations in this thesis, a further study to identify the accuracy and reliability of the data can help confirm the results of this thesis. The estimated values, which were used to calculate the energy consumption of either a central air conditioning system or a split type air conditioning system, could be replaced by real data. Improving the accuracy of the data will help estimate the energy consumption more accurately. The results of that thesis will be more reliable. 6) Qualitative issues of air conditioning system The surveyed data explored some qualitative issues raised by the dormitory residents regarding the existing air conditioning system. According to this collected data, further study is needed to improve the existing system. The main issue is the high energy usage of the air conditioning system because the surveyed results show that most residents did not pay any attention to energy conservation. Other problems include the performance of the air conditioner, humidity and fungus, maintenance etc., therefore further study is needed to find the causes and solutions to these problems. 86

99 Appendix A BAS Data of Cooling Load Distribution Saturday 18th March, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

100 Monday 20th March, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

101 Wednesday 22nd March, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

102 Saturday 25th March, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

103 Monday 27th March, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

104 Wednesday 29th March, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

105 Wednesday 26th July, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

106 Thursday 27th July, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

107 Friday 28th July, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

108 Saturday 29th July, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

109 Sunday 30th July, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

110 Monday 31st July, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

111 Tuesday 1st August, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

112 Wednesday 2nd August, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

113 Thursday 3rd August, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

114 Friday 4th August, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

115 Saturday 5th August, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

116 Sunday 6th August, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

117 Monday 7th August, 2006 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

118 Wednesday 28th February, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

119 Thursday 1st March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

120 Friday 2nd March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

121 Saturday 3rd March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

122 Sunday 4th March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

123 Monday 5th March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

124 Tuesday 6th March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

125 Wednesday 7th March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

126 Thursday 8th March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

127 Friday 9th March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

128 Saturday 10th March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

129 Sunday 11th March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

130 Monday 12th March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

131 Tuesday 13th March, 2007 Time table Size of chiller (tons) Total % of cooling tons Efficiency Meter 375 or 190 tons Cooling tons MHB Lab Building Dormitory Skylink of chiller (kwh) 8.00 a.m a.m a.m a.m a.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m p.m a.m a.m a.m a.m a.m a.m a.m

132 Appendix B Questionnaire about the Existing Air Conditioning System in the Dormitory Buildings at SIU ระบบปร บอากาศของหอพ ก มหาว ทยาล ยช นว ตร แบบสอบถามน ม จ ดประสงค เพ อพ ฒนาระบบปร บอากาศท ใช อย ในมหาว ทยาล ยช นว ตร ให ม ประส ทธ ภาพมากข น เพ อลดปร มาณการใช ไฟฟ าและแก ไขป ญหาท เก ดข นในป จจ บ น ข อม ลท ได ร บจะถ กเก บร กษาเป นอย างด และไม ม ผลใดๆต อการพ กอาศ ยหร อการจ ดเก บค าไฟฟ าในขณะน ทางผ จ ดท าหว งว าจะได ร บความร วมม อในการให ข อม ลท ถ กต องจากท านเป นอย างด ขอขอบค ณ ในความกร ณา 1. ข อม ลท วไป ห อง... พ กอาศ ย...คน สถานภาพ น กศ กษา อาจารย จนท. มหาว ทยาล ย อ นๆ ข อม ลการใช เคร องปร บอากาศ ใช เคร องปร บอากาศเป นประจ า ไม ได ใช เคร องปร บอากาศเป นประจ า ว นธรรมดา (จ.- ศ.) ใช ประมาณว นละ...ชม. รายละเอ ยด (ถ าม )... ช วงกลางว น ใช ประมาณว นละ...ชม. รายละเอ ยด (ถ าม )... ช วงกลางค น ใช ประมาณว นละ...ชม. รายละเอ ยด (ถ าม )... ว นหย ด (ส.- อา.) ใช ประมาณว นละ...ชม. รายละเอ ยด (ถ าม )... เสาร ใช ประมาณว นละ...ชม. รายละเอ ยด (ถ าม )... อาท ตย ใช ประมาณว นละ...ชม. รายละเอ ยด (ถ าม ) ความพ งพอใจในระบบปร บอากาศป จจ บ น ความเย นภายในห อง ได ตามต องการ ไม ได ตามต องการ โปรดระบ ความเย นมากไป ความเย นน อยไป เวลาท ใช ในการท าความเย น ได ตามต องการ ไม ได ตามต องการ โปรดระบ ท าความเย นช าไป ท าความเย นเร วไป 122

133 4. ความพ งพอใจในการจ ดเก บค าไฟฟ า พอใจในการค ดค าไฟฟ าในป จจ บ น ไม พอใจในการค ดค าไฟฟ าในป จจ บ น หากไม พอใจโปรดระบ สาเหต ป ญหาท เก ดข นจากระบบปร บอากาศ การท าความเย น ขาดความสะดวก สบายในการใช งาน เคร องปร บอากาศเส ย หร อม อาการผ ดปกต บ อย ขาดการบ าร งร กษา หร อท าความสะอาด ความช น-เช อรา เส ยงด ง การจ ดเก บค าไฟฟ า อ นๆ หากม มาตรการในการประหย ดพล งงานท านย นด ร วมม อหร อไม ย นด ไม ย นด 7. ข อเสนอแนะอ นๆ 7.1 เร อง เร อง เร อง ขอขอบพระค ณท กท านอ กคร งส าหร บความร วมม อในการตอบแบบสอบถามฉบ บน ร.ท.รณช ย ว ฒ ว ทยาร กษ น กศ กษาปร ญญาโท ว ศวกรรมระบบ (MESE) ม.ช นว ตร 123

134 Appendix C Surveyed Data about the Existing Air Conditioning System Second and Third Floor at Dormitory 1 Using time (hours) Problems Willing to save the Room No: Mon-Fri Sat-Sun Temp. Using time Humidity Maintenance Noise Payment energy

135 Forth and Fifth Floor at Dormitory 1 Using time (hours) Problems Willing to save the Room No: Mon-Fri Sat-Sun Temp. Using time Humidity Maintenance Noise Payment energy

136 Second and Third floor at dormitory 2 Using time (hours) Problems Willing to save the Room No: Mon-Fri Sat-Sun Temp. Using time Humidity Maintenance Noise Payment energy

137 Appendix D Size and Operation Hours of AHUs and FCUs First and Second Floor in Dormitory 1 Power input Operation hours AHU & FCU Room Total (kw) normal day weekend (kwh) 1A-01 LOBBY A-02 FITNESS F-01(DO1) SR F-02(DO1) SR F-03(DO1) OFFICE F-04(DO1) OFFICE F-01[DO1] F-02[DO1] F-03[DO1] F-04[DO1] F-05[DO1] F-06[DO1] F-07[DO1] 214[TV] F-08[DO1] F-09[DO1] F-10[DO1] F-11[DO1] F-12[DO1] F-13[DO1] F-14[DO1] F-15[DO1] F-16[DO1] F-17[DO1] F-18[DO1] F-19[DO1] F-20[DO1] F-21[DO1] F-22[DO1] F-23[DO1] F-24[DO1] F-25[DO1] F-26[DO1] F-27[DO1]

138 Third Floor in Dormitory 1 AHU & FCU Room Power input Operation hours Total kw normal day weekend kw 3F-01[DO1] F-02[DO1] F-03[DO1] F-04[DO1] F-05[DO1] F-06[DO1] F-07[DO1] 314[TV] F-08[DO1] F-09[DO1] F-10[DO1] F-11[DO1] F-12[DO1] F-13[DO1] F-14[DO1] F-15[DO1] F-16[DO1] F-17[DO1] F-18[DO1] F-19[DO1] F-20[DO1] F-21[DO1] F-22[DO1] F-23[DO1] F-24[DO1] F-25[DO1] F-26[DO1] F-27[DO1]

139 Forth Floor in Dormitory 1 AHU & FCU Room Power input Operation hours Total kw normal day weekend kw 4F-01[DO1] F-02[DO1] F-03[DO1] F-04[DO1] F-05[DO1] F-06[DO1] F-07[DO1] 414[TV] F-08[DO1] F-09[DO1] F-10[DO1] F-11[DO1] F-12[DO1] F-13[DO1] F-14[DO1] F-15[DO1] F-16[DO1] F-17[DO1] F-18[DO1] F-19[DO1] F-20[DO1] F-21[DO1] F-22[DO1] F-23[DO1] F-24[DO1] F-25[DO1] F-26[DO1] F-27[DO1]

140 Fifth Floor in Dormitory 1 AHU & FCU Room Power input Operation hours Total kw normal day weekend kw 5F-01[DO1] F-02[DO1] F-03[DO1] F-04[DO1] F-05[DO1] F-06[DO1] F-07[DO1] 514[TV] F-08[DO1] F-09[DO1] F-10[DO1] F-11[DO1] F-12[DO1] F-13[DO1] F-14[DO1] F-15[DO1] F-16[DO1] F-17[DO1] F-18[DO1] F-19[DO1] F-20[DO1] F-21[DO1] F-22[DO1] F-23[DO1] F-24[DO1] F-25[DO1] F-26[DO1] F-27[DO1] RF-01[DO1] ELEVATOR

141 G and M Floor in Dormitory 2 AHU & FCU Room Power input Operation hours Total kw normal day weekend kw GF-01(DO2) STUDENT OFF GF-02(DO2) STUDENT OFF GF-03(DO2) ENTERTAINMENT GF-04(DO2) ENTERTAINMENT GF-05(DO2) MEETING ROOM GF-06(DO2) STUDENT LOUNGE GF-07(DO2) STUDENT LOUNGE GF-08(DO2) STUDENT LOUNGE GF-09(DO2) STUDENT LOUNGE GF-10(DO2) CLOSET&LAUNDRY GF-11(DO2) CLOSET&LAUNDRY GA-01(DO2) HALL GA-02(DO2) HALL MF-01(DO2) CLASS ROOM MF-02(DO2) CLASS ROOM MF-03(DO2) CLASS ROOM MF-04(DO2) CLASS ROOM MF-05(DO2) STUDY ROOM MF-06(DO2) STUDY ROOM MF-07(DO2) NURSE ROOM MF-08(DO2) NURSE ROOM MF-09(DO2) HALL MF-10(DO2) HALL MF-11(DO2) NURSE ROOM

142 Second Floor in Dormitory 2 AHU & FCU Room Power input Operation hours Total kw normal day weekend kw 2F-01(DO2) F-02(DO2) F-03(DO2) F-04(DO2) F-05(DO2) F-06(DO2) F-07(DO2) 213[TV] F-08(DO2) F-09(DO2) F-10(DO2) F-11(DO2) F-12(DO2) F-13(DO2) F-14(DO2) F-15(DO2) F-16(DO2) F-17(DO2) F-18(DO2) F-19(DO2) F-20(DO2) F-21(DO2) F-22(DO2) F-23(DO2) F-24(DO2) F-25(DO2) F-26(DO2)

143 Third Floor in Dormitory 2 AHU & FCU Room Power input Operation hours Total kw normal day weekend kw 3F-01(DO2) F-02(DO2) F-03(DO2) F-04(DO2) F-05(DO2) F-06(DO2) F-07(DO2) 313[TV] F-08(DO2) F-09(DO2) F-10(DO2) F-11(DO2) F-12(DO2) F-13(DO2) 301 3F-14(DO2) F-15(DO2) F-16(DO2) F-17(DO2) F-18(DO2) F-19(DO2) F-20(DO2) F-21(DO2) F-22(DO2) F-23(DO2) F-24(DO2) F-25(DO2) F-26(DO2)

144 Appendix E Suitable Capacity (BTU/hour) of Air Conditioning System in Different Size and Characteristic of the Rooms Room s size Bedroom Office / Living room (square Without sunshine With sunshine Without sunshine With sunshine meters) (BTU/hr) (BTU/hr) (BTU/hr) (BTU/hr) ,000 8,000 8,000 9, ,000 9,000 9,000 11, ,500 11,000 11,000 13, ,000 13,500 13,500 16, ,000 16,500 16,500 20, ,000 20,000 20,000 26, ,000 26,500 26,500 30,000 Source: EGAT (n.d.) 134

145 References Air conditioning. (2006). Retrieved August 16, 2006, from wiki/air_conditioning Air conditioning system. (n.d.). Retrieved August 16, 2006, from com/sci123th/cool.html Bunyathikarn, S. (2002). การออกแบบประสานระบบ [Designing and cooperating a system]. Bangkok: G.M. Mag Media. Chokesuwattanaskul, M. (2006). Energy management in Main Hall Building. Bangkok: Shinawatra University. Clausius, R. (2007). Encyclopædia Britannica. Retrieved June 20, 2007, from Daikin Europe N. V. (n.d.). The refrigerant cycle. Retrieved August 16, 2006, from Daorote, T. (2006). Energy saving of induction motor driven pump using variable speed control. Bangkok: Shinawatra University. Department of Alternative Energy Development and Efficiency. (2005). Introduction to energy audits. Retrieved August 16, 2006, from training/ Download/PPAir/Chapter3.pps Department of Architecture, The University of Hong Kong. (2001). Air conditioning system. Retrieved August 16, 2006, from %7Ekpcheung/new2001/ac/ Electricity Generating Authority of Thailand. (2006). Label No:5 air conditioning system. Retrieved August 16, 2006, from air_saving.htm Electricity Generating Authority of Thailand. (n.d.). Variable speed drive. Retrieved August 16, 2006, from energy%20saving%20technogy3.htm Electricity Generating Authority of Thailand. (n.d.). การเล อกเคร องปร บอากาศให เหมาะสมก บ ขนาดห อง [Selecting suitable size of split type air conditioning system]. Retrieved August 16, 2006, from aircleanning/page6.php 87

146 Expat Web Site Association. (n.d.). Air conditioners. Retrieved January 21, 2007, from Foreman, G. (2006). A new air conditioner. Retrieved January 21, 2007, from Hancock, C. E., & Reeves, P. (1999). New Technology Demonstration Program Kennedy Space Center Hangar L Heat Pipe Project. Performance Evaluation Report, (NREL/TP ). Colorado :Golden. Khedari, J., Yamtraipat, N., & Hirunlabh, J. (2001). A new concept for setting thermal standards. Proceedings of the Moving Thermal Comfort Standards into 21 st Century, UK., Little, A. D. (2002). Final report to the alliance for responsible atmospheric policy, Retrieved January 8, 2007, from Piper, J. (2006). Chiller challenge: Energy Efficiency. Retrieved January 21, 2007, from %20energy%20efficiency,%20hvac Shankara, N. K. R. (n.d.). What is a heat pipe? Retrieved August 16, 2006, from Thai HVAC. (n.d.). Price of equipment in air conditioning system. Retrieved December 14, 2006, from price01.htm The Institute of Industrial Energy. (2004). Evaporative Condenser. Retrieved August 16, 2006, from cat=12 88

147 Biography Name: Flg.Off. Ronnachai Vutthivithayarak Date of Birth: June 21, 1982 Place of Birth: Bangkok, Thailand Institutions Attends: Mar Dec2004 Bachelor of Engineering (Aeronautical Engineering) Royal Thai Air Force Academy Bangkok, Thailand Jun2005 May2007 Master of Engineering in Systems Engineering (MESE) Shinawatra University Bangkok, Thailand Position and Office: Engineer, Directorate of Aeronautical Engineering, Royal Thai Air Force Home Address: 57 Soi Yenjit 2/5, Chan Rd., Tungwaddon, Sathorn, Bangkok, Thailand [email protected] 135