1. Indoor Environmental Quality (IEQ)

Transcription

1 INDOOR AIR QUALITY : INDOOR AIR QUALITY TO MAXIMISE PRODUCTIVITY By: Ir. Ng Yong Kong 26 TH March Indoor Environmental Quality (IEQ) Primary areas of concern in IEQ Air Quality and Ventilation Thermal Comfort: Design & Controllability of Systems Lighting and Visual Perception Acoustic and Noise Comfort 1

2 1. Indoor Environmental Quality (IEQ) More than just Indoor Air Quality (IAQ) HVAC system provides a comfortable environment for building occupants and contributes significantly to Indoor Health Environment IAQ Definitions by WHO - The physical and chemical nature of indoor air, as delivered to the breathing zone of building occupants, which produces a complete state of mental, physical and social well-being of the occupants, and not merely the absence of disease or infirmity. Good IAQ may be defined as air with no known contaminants at harmful concentrations. Common contaminants or pollutants include gaseous pollutants, such as carbon dioxide (produced by occupants and from combustion appliances), volatile organic compounds (released by carpet glue and other materials), odours and particulates. Good IAQ is essential to ensure the health and comfort of occupants. 2

3 Factors that increase our exposure to indoor air pollutants Reduced ventilation rates to conserve energy The use of synthetic building materials and furnishings The use of chemically formulated personal care products, pesticides, printing inks, and household cleaners. Pollutant Sources Indoor sources Combustion sources Building materials and furnishings Asbestos-containing insulation Household cleaning products HVAC systems Occupants and activities Outdoor sources Radon Pesticides Outdoor air pollution 3

4 Why do we air-condition our buildings? Control Temperature Control Humidity/Moisture Control Air Movement Control Air Quality Control Noise and glare Control the environment increase productivity and comfort Pollutants Types Sick building syndrome (SBS) Sick building syndrome (SBS) is a condition that may be experience by occupants of the buildings. The symptoms include headaches, eye strain and lung irritation. Usually the symptoms disappear when the affected person leaves the mal-functioning building and are of short duration. Sick building syndrome occurs in the buildings which may have a number of defects, including inadequate ventilation, low light levels and /or flickering light fittings, excessive odours, high ambient noise levels, lack of local controls and other factors. 4

5 Pollutants Types Sick building syndrome (SBS) Typically inadequate ventilation may be due to insufficient supplies of fresh air, excessive recirculation of air, poorly maintained air handling units (i.e. filters not replace when needed) or a poorly designed and / or installed ductwork system. Low light levels are the result of light fittings not being replaced, the wrong type of fitting being used, poor lighting controls and / or insufficient numbers of light fittings being installed. Poor levels of daylighting can have the same effect. Pollutants Types Sick building syndrome (SBS) Excessive odours may be due to a poorly designed/installed kitchen ventilation system and inadequate ventilation rates. High noise levels may be present due to the proximity of a space to and adjacent busy road and / or a plant room, insufficient sound insulation and lack of sound absorption materials used on wall and ceiling surfaces. No local controls may be available for an occupant not adjacent to an openable window or window or an adjustable thermostat (in many cases local thermostats may be disabled to prevent excessive adjustment by occupants). 5

6 Pollutants Types Sick building syndrome (SBS) The existence and extent of SBS may be established using questionnaires. Occupants are asked to score their satisfaction level for ambient variables including air temperature, perceived humidity level, local (fresh) air flow, noise, task lighting, glare and odours, and their ability to control some of these values. Pollutants Types Sick building syndrome (SBS) Analysis is then performed on the data to determine whether conditions are satisfactory for the occupants in each assessed area. Results should indicate what modifications might be required to achieve acceptable thermal, lighting and acoustic conditions. In relation to ventilation, this may include increased fresh air flow rates, adjustment of diffusers, more frequent maintenance of ventilation plant and improved occupant access to controls. 6

7 Pollutants Types External (outdoor) air pollution Poor outdoor air quality will have significant impact on indoor air quality. External pollutants include vehicle exhausts, discharges from combustion appliances, industrial process and power station exhausts. Fungal spores and pollen from vegetation may also cause air quality problems. Vehicle exhausts include CO, CO 2, NO x and SO 2, particulates (especially from diesel engines) and VOCs (e.g from petrol and oil). Pollutants Types External (outdoor) air pollution Ozone is generated by the action of sunlight on nitrous oxides (present in vehicle exhausts). Power station release the same pollutants to vehicles, but are usually located in rural or semi-rural areas, so the impact of their pollutants is much reduced. In urban areas, traffic is a significant contributor to external pollution, with additional pollutant emissions coming from building exhausts and industrial processes. 7

8 Outdoor Air Quality Motorists passed a highway toll gate covered by thick haze in Kuala Lumpur, Malaysia, Thursday, Aug. 11, The ominous haze that has shrouded parts of Southeast Asia this month is just one visible element of a much larger problem that is choking hundreds of thousands to death every year across the region, the World Health Organization said. (AP Photo/Andy Wong) What Are OA Intake Restrictions? Significant contaminated exhaust Noxious or dangerous exhaust Chimneys and flues Truck loading area Driveway, street Thoroughfare w/high traffic Garbage dumpster Cooling tower 8

9 RNC/NRNC - Air Cool Split Units It basically comprises an indoor unit with the evaporator and blower and an outdoor unit with the compressor, condenser coil and fan coupled with refrigeration piping. The indoor units is often known as Fan Coil Units ( FCUs )and the outdoor units known as Condensing Units.( C.U.) As a whole, they are known as the Air Cooled Split Units. (ACSUs) Air Cooled Split Units Warm air (recirculating) Fan Coil Unit Cool air Outdoor air Condensing Unit 9

10 Air Cooled Split Units (ACSUs) Inverter type Both indoor and outdoor units are housed in robust casings. The outdoor unit is basically the same construction for all the various types of indoor units. The difference lies in the type of indoor unit. Cassette Wall Mounted Floor Standing Ceiling Exposed Air Cooled Split Units Many Business Establishments are housed in Small Premises using ACSUs. Office Restaurant 10

11 ACSUs ( incld. Inverter type ) : Fresh Air Intake? The wall mounted, floor standing and under ceiling split system has no provision for intake of outdoor air and/or exhaust of stale room. air. Room air is just filtered and recirculated. Can you consider this for large buildings? 11

12 Ducted Systems Introducing OA IAQ Definitions Building-Related Illness (BRI) is a term referring to illness brought on by exposure to the building air, where symptoms of diagnosable illness are identified and can be directly attributed to environmental agents in the air. Eg. of BRI is Legionnaires Disease commonly found in aquatic environment. 12

13 CODES and STANDARDS FOR IAQ PERFORMNCE AND THERMAL COMFORT EQ1: Minimum IAQ Performance Meet the minimum requirements of ventilation rate in ASHRAE Standard 62.1:2010 or the local building code whichever is the more stringent. 13

14 ASHRAE STD Ventilation For Acceptable For Indoor Air Quality Ventilation is the key to Sustainable IAQ and ASHRAE Std 62.1 is the most widely recognised Standard Internationally by most countries and HVAC Engineers in the world. EQ1: Minimum IAQ Performance MS 1525: Air Conditioning and Mechanical Ventilation (ACMV) System Indoor Design Condition Recommended Design DB Temperature 23-26ºC ( F ) Minimum DB Temperature 22ºC Recommended Design RH 55% - 70% Recommended Air Movement 0.15 m/s 0.50m/s Maximum Air Movement 0.7 m/s Outdoor Design Conditions Recommended Outdoor Design 33.3ºC / 27.2ºC Conditions DB / WB ( 92 F/ 81 F ) 14

15 Industry Code of Practice on Indoor Air Quality 2010 DOSH Malaysia* Ministry of Human Resources Table 1: List of Indoor Air Contaminants and the Maximum Limits Acceptable Range for Specific Physical Parameters 2010 Parameter Acceptable range (a) (b) (c) Air temperature Relative humidity Air movement ºC 40 70%

16 List of Indoor Air Contaminants and acceptable limits Indoor Air Contaminants Eight-hours time-weighted average airborne concentration ppm mg/m³ cfu/m³ Chemical contaminants (a) Carbon dioxide (b) Carbon monoxide (c) Formaldehyde (d) Ozone (e) Respirable particulates (f) Total volatile organic compounds (TVOC) C Biological contaminants (a) Total bacterial counts (b) Total fungal counts ASHRAE Standard Specifies conditions likely to be thermally acceptable to at least 80% of the adult occupants in a space 16

17 Indoor Environmental Quality Thermal Comfort (EQ6) Design to ASHRAE : Thermal Environmental Conditions for Human Occupancy in conjunction with relevant localised parameters as listed in MS 1525:2007 Specifies Conditions likely to be thermally acceptable to at least 80% of the adult occupants in a space 6 Primary factors that must be addressed when defining conditions for thermal comfort are: 1.) Metabolic rate 2.) Clothing insulation 3.) Air temperature 4.) Radiant temperature 5.) Air speed 6.) Humidity 17

18 1.) Factors affecting comfort and Indoor Air Quality (IAQ) Space Temperature Relative Humidity Air Velocity Noise and Acoustic Level Ventilation - Supply of Acceptable Air & removal of Unacceptable Air Lack of Maintenance of ACMV ( HVAC ) system ( eg. Filters not cleaned or replace regularly ) What are the IAQ Problems in Buildings? IAQ during design and construction Lack of Commissioning Moisture in Building Assemblies Poor Outdoor Air Quality Moisture and Dirt in Ventilation Indoor Contaminant Sources Contaminants from Indoor Equipment and Activities Inadequate Ventilation Rates Ineffective Filtration and Air Cleaning 18

19 Minimum IAQ Performance *EQ1: Minimum IAQ Performance Meet the minimum requirements of ventilation rate in ASHRAE Standard 62.1:2007 or the local building code whichever is the more stringent. MS 1525:2007 Section Ventilation Outdoor Air-Ventilation Rates should comply with Third Schedule (By Law 41) Article 12 (1) of Uniform Building By Laws, 1984 ( UBBL ) 19

20 Building code requirements Extract from Third Schedule (By-law 41) ASHRAE Comfort Zone 20

21 ASHRAE STD Ventilation For Acceptable For Indoor Air Quality Ventilation is the key to Sustainable IAQ and ASHRAE Std 62.1 is the Leading Standard adopted by most Local Authorities and HVAC Engineers in the world. EQ1: Minimum IAQ Performance ASHRAE Std Ventilation For Acceptable Indoor Air Quality 1.) Ventilation Rate Procedure ( VRP ) 2.) Indoor Air Quality Procedure ( IAQ ) 3.) Natural Ventilation permitted to be used in conjunction with Mechanical Ventilation. 21

22 Acceptable Indoor Air Quality is defined as air in which there are no known Contaminants at harmful Concentrations as determined by Cognizant Authorities and with which a substantial majority ( 80% or more ) of the people exposed do not express dissatisfaction. 1.) Ventilation Rate Procedure ( VRP ) is a prescriptive procedure with a table of minimum required outdoor airflow rates per occupant for a variety of nonresidential occupancies. The airflow rate per square foot of building floor area is basedon the design occupancy density and the required flow rate per person, adjusted to reflect the air distribution system used. 1.) Ventilation Rate Procedure ( VRP ) V bz = R p.p z + R A.A Z ( PEOPLE + AREA COMPONENT ) Where V bz = Design outdoor airflow required in the breathing zone of the occupied space or spaces in a zone,i.e the breathing zone outdoor air flow A z = Zone floor area: the net occupiable floor area of the zone m 2 ( ft 2 ) P z = zone population: the largest number of people expected to occupy the zone during typical usage. R p = outdoor airflow rate required per person as determined from Table 6-1 R a = outdoor airflow rate required per unit area as determined from Table

23 TABLE 6-1 MINIMUM VENTILATION RATES IN BREATHING ZONE People Outdoor Area Outdoor Default Values Occupancy Air Rate Air Rate Category R p Ra Office Buildings cfm/ person COPY L/s person cfm/ft ² L/s m² Occupant Density #1000 ft² cfm/ or #100 m² person Combined Outdoor Air Rate L/s person Office Space Reception areas TABLE 6-1 MINIMUM VENTILATION RATES IN BREATHING ZONE Hotels, Motels, Resort, Dormitories Bedroom / living room Barracks sleeping areas Laundry rooms, central Laundry rooms within dwelling units Lobbies / pre-function Multipurpose assembly

24 ASHRAE Std Ventilation For Acceptable Indoor Air Qualy 1.) Example : Ventilation Rate Procedure ( VRP ) V bz = R p.p z + R a.a z Where V bz = Design outdoor airflow required A z = floor area = 1,000 sq. ft., P z = population = 5 people (20m2/person ) R p = outdoor airflow rate required per person as determined from Table 6-1 = 5 cfm/person R a = outdoor airflow rate required per unit area as determined from Table 6-1 = 0.06 cfm/ft2 V bz = R p.p z + R a.a z = 5 x x 1,000 = 85 cfm i.e 17cfm/person ASHRAE Std Ventilation For Acceptable Indoor Air Qualy 2.) Example : Ventilation Rate Procedure ( VRP ) V bz = R p.p z + R a.a z Where V bz = Design outdoor airflow required A z = floor area = 10,000 sq. ft., P z = population = 100 people R p = outdoor airflow rate required per person as determined from Table 6-1 = 5 cfm/person R a = outdoor airflow rate required per unit area as determined from Table 6-1 = 0.06 cfm/ft2 V bz = R p.p z + R a.a z = 5 x x 10,000 = 1,100 cfm i.e 11cfm/person 24

25 ASHRAE Std Ventilation For Acceptable Indoor Air Quality Ventilation Rate Procedure ( VRP ) V bz = R p.p z + R a.a z Where V bz = Design outdoor airflow required Eg. 2 Banks or bank lobbies ( Default Values ) A z = floor area = 100 m2, P z = population = 15 people R p = outdoor airflow rate required per person as determined from Table 6-1 = 3.8 L/s.person R a = outdoor airflow rate required per unit area as determined from Table 6-1 = 0.3 L/s.m2 V bz = R p.p z + R a.a z = 3.8 x x 100 = = 87 L/s = 6.0 L/s.person MINIMUM VENTILATION RATES IN BREATHING ZONE Occupancy People Outdoor Area Outdoor Design Values Air Rate Air Rate Occupant Density Combined Outdoor Category R p Ra Air Rate cfm/ person L/s person cfm/ft ² L/s m² #1000 ft² cfm/ or #100 m² person L/s person Office Buildings Office Space Banks or Bank lobbies ft2/person ft2/person

26 MINIMUM VENTILATION RATES IN BREATHING ZONE Occupancy Category People Outdoor Area Outdoor Design Values Air Rate R p Air Rate Ra Occupant Density Combined Outdoor Air Rate cfm/ person L/s person cfm/ft² L/s m² #1000 ft² or #100 m² cfm/ person L/s person Hotels, Motels, Resort, Dormitories Places of religious worship ft2/person Libraries ft2/person Retail Mall common areas ft2/person Lecture Classroom ft2/person MINIMUM VENTILATION RATES IN BREATHING ZONE Occupancy Category People Outdoor Area Outdoor Design Values Air Rate R p Air Rate Ra Occupant Density Combined Outdoor Air Rate cfm/ person L/s person cfm/ft² L/s m² #1000 ft² or #100 m² cfm/ person L/s person Hotels, Motels, Resort, Dormitories Lobbies/ prefunction Multi purpose assembly Educational Facilities Computer lab Restaurant Dining rooms ft2/person ft2/person ft2/person 50 10ft2/person

27 Air Classification and Recirculation Class 1: Air with low contaminant concentration, low sensory-irritation intensity, and inoffensive odor. Class 2: Air with moderate contaminant concentration, mild sensory-irritation intensity, or mildly offensive odors. Class 2 air also includes air that is not necessarily harmful or objectionable but that is inappropriate for transfer or recirculation to spaces used for different purposes. 27

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29 Variable Refrigerant System ( VRS )/ Variable Refrigerant Flow ( VRF ) On a single refrigerant pipe, many indoor units can be connected. Many Fan Coil Units ( up to 60 units) Remedial measures- 1.HVAC Specifying engineers Cassette unit with fan, filter and ducting for outdoor air Ashrae Malaysia Chapter one day seminar April

30 Remedial measures-1.hvac Specifying engineers Cassette unit with fan, filter and ducting for outdoor air Ashrae Malaysia Chapter one day seminar April ASHRAE Std Ventilation For Acceptable Indoor Air Quality 2.) Indoor Air Quality Procedure ( IAQ ) is a performance based design approach in which the building and its ventilation system are designed to maintain the concentrations of specific contaminants at or below certain limits identified during the building design and to achieve the design target level of perceived IAQ acceptability by occupants. 30

31 ASHRAE Std Ventilation For Acceptable Indoor Air Quality 2.) Indoor Air Quality Procedure ( IAQ ) It provides an engineered approach to an acceptable IAQ in a building :- i) identify contaminants of concern ii) likely rates of generation and acceptable levels of these contaminants iii) defining a system and outdoor ventilation rate that together will maintain the contaminants concentration below maximum acceptable level Air Purification to remove some or all of the contaminants of concern can be part of the system ASHRAE Standard , Ventilation for Acceptable Indoor Air Quality, specifies minimum ventilation rates and indoor air quality that will be acceptable to the human occupants of a building. Considers chemical, physical, and biological contaminants. Table 6-1 Minimum Ventilation Rates in Breathing Zone (PEOPLE COMPONENT ONLY ) Rp, Flow rate per person or per unit area (ASHRAE ) e.g. Office space 5cfm/person Mall & supermarket 7.5 cfm/person Restaurant & Café 7.5 cfm/person Lecture hall 7.5 Cfm/person Games arcade / Casino 7.5 Cfm/person Computer & Science Lab 10 Cfm/person Disco & Aerobics room 20 Cfm/person 31

32 COST OF USING HIGH FA At Ambient of 92 F DB/81 FWB (33.3 C/ 27.2 C) Cfm ( 300 M³/Hr) of FA Requires 1 Ton ( 3.517KW ) of AC Load High use of Fresh Air Results in High Capital Cost High Operating Cost (Energy & Water Cost) 63 ASHRAE STANDARDS 62 Ventilation for Acceptable Indoor Air Quality LOCATION OFFICE SPACE OA REQUIRMENTS FOR VENTILATION CFM/Person ( ,1999 & 2001) CFM/PERSON 20 MIN.VENTILATION RATES IN BREATHING ZONE ( & 2007) CFM/Person 5 CONFERENCE ROOM CFM/PERSON 20 CFM/Person

33 ASHRAE STANDARDS 62.1 Ventilation for Acceptable Indoor Air Quality LOCATION AUDITORIUM CLASS ROOM OA REQUIRMENTS FOR VENTILATION CFM/Person ( ,1999 & 2001) CFM/PERSON 20 CFM/PERSON 20 MIN.VENTILATION RATES IN BREATHING ZONE ( ,2007 & 2010 ) CFM/Person 5 ( People Component) CFM/Person 7.5 (People Component) 65 CALCULATION FOR ENERGY SAVINGS WITH REDUCTION OF OUTDOOR AIR 66 33

34 ASHRAE (Cfm/person) (Cfm/person) OFFICE 20 5 (15) 67 DB WB ENTHALPY F F Btu/lb of dry air OUTDOOR AIR DESIGN TEMP

35 FOR AN OFFICE WITH 200 PERSONS Savings = 4.45 x CFM x Enthaply = 4.45 x (200 x 15) x = 17.2 tons (60.5kw) 69 No of People Savings in Chiller Tonnage ton (30.3KW) ton (60.5KW) ton (151.3KW) 1, ton (302.6KW) 2, ton (605.3KW) 70 35

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39 CO2 Monitoring and Demand Control Ventilation ( EQ3) Ventilation Is Fixed Question: How could we ventilate the space more efficiently? Answers: Measure Ventilation In The Space Like Temperature Vary Ventilation Based On Occupancy Zone Control Ventilation With CO 2 39

40 The effect of CO 2 on man 8,0% Convulsions, immediate paralysis and death Main alarm 3,0% Muscular pain, unconsciousness, convulsions and risk of death Pre alarm 1,50% 0,50% 0,10% 0,04% Shortness of breath and increased heart frequency Hygienic limit value Recommended indoor limit value Fresh air Carbon Dioxide and DCV. Humans are the main indoor source of CO2. Indoor carbon dioxide concentrations can be used to indicate specific and limited aspects of indoor air quality but are not an overall indicator of the quality of indoor air. Demand Control Ventilation adjusts ventilation air based on the number of occupants and the ventilation demands that the occupants create. 40

41 Carbon Dioxide and DCV (2) CO 2 -based DCV has the most energy savings potential in buildings where occupancy fluctuates & when ventilation is over designed. Office buildings, government facilities, retail stores and shopping malls, airports, theaters, auditoriums, conference or lecture halls, entertainment areas are good candidates for DCV CO 2 Demand Controlled Ventilation Examples: Assuming a Conference room with Max. capacity of = 200 people If Designed Ventilation rate = 7 l/s/ person The Amount of ventilation required = 1,400 l/s Now if the Conference room is not fully occupied, say with No. of People = 70 If Ventilation rate is maintained at 7 l/s/ person Amount of ventilation = 490 l/s DCV uses CO2 measurement to indirectly determine level of occupancy and thus ventilation 41

42 Typical Installation AHU Room Return Air CO2 sensor AHU Room AHU Supply Air Fresh Air Fresh air damper Damper Actuator Typical Installation AHU Room Return Air CO 2 sensor AHU Room Return Air AHU Supply Air CO 2 sensor PLC Fresh Air Fresh air damper Damper Actuator 42

43 Carbon Dioxide (CO 2 ) Sensors/Controllers Wall Mount Application Duct Mount Application Great potential for Energy savings when: i.) the space has less than maximum occupancy ii.) the space has variable occupancy pattern iii.) the ventilation is over designed Sensors are recommended to be verified every 3 years n = # of sensors R = terminating resistor 500 n Ω R 2-10 V input 4 20 ma Com V G+ G 0 I 0 G+ G 0 I 0 CO 2 sensor CO 2 sensor 3ph Supply Variable Speed Drive G+ G 0 I 0 CO 2 sensor G+ G 0 I 0 CO 2 sensor FAN Averaging CO 2 Sensor Monitoring & Control using VSD G+ G 0 I 0 CO 2 sensor 43

44 IAQ Before and During Occupancy All ventilation air filters will be changed after the flush-out Pressure sensor to detect filter blockage Purging to eliminate bad odors and improve air quality especially for building space that does not have adequate openable windows Ventilation of the encapsulation, hood or extraction type should be provided so that the spread of contaminants is prevented Building materials and surface finishes should not contain any substances that emit chemicals, bacteria or fungi THANK YOU By: Ir. Ng Yong Kong, ( nyk@nyk.com.my h/p no ) and others. 26 th March