Examples of Energy Efficient Architecture in Bosnia and Herzegovina and Macedonia

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1 Examples of Energy Efficient Architecture in Bosnia and Herzegovina and Macedonia H. Bradic 1 1 Department of Architectural Constructions and Building Technology, Faculty of Architecture in Sarajevo, Bosnia and Herzegovina Abstract: This paper aims to provide analysis of the energy efficient architecture by presenting several designs produced by the architect Haris Bradić in Bosnia and Herzegovina and Macedonia. Houses that will be presented in this paper are residential facilities, which are currently under construction, or in the preparation phase of the construction. This short overview of the aforementioned designs will focus on the analysis of energy efficient construction. The paper will also show how specific software can be used from the earliest stage of a design process all the way to the final calculations. Besides the energy calculations, the goal is to provide information on how to build an energy efficient structure in Bosnia and Herzegovina and Macedonia, which procedure is still very difficult for all participants in the project, including investors, designers and constructors. The first example presented here is a reconstruction of an existing, over 400 years old, house in Sarajevo into a passive house. The next example is a newly designed house on the outskirts of Sarajevo Poljine, Kromolj, which is still under construction; finally, the third structure is a private villa in Macedonia, near Tetovo. The paper next considers the relationship between the designer and investor, who is an important figure in creation of the energy efficient architecture, and also the social circumstances under which a specific design is being produced. The main purpose of this type of architecture is to build a structure with as minimum energy needs as possible that will be secured through alternative sources of energy, and ultimately resulting in a Zero Emission House. Keywords: Energy efficient architecture, energy, environment, economy, man. 1. INTRODUCTION This paper considers the particularities of designing energy efficient residential buildings by presenting three such examples designed by the architect Haris Bradić, which are currently under construction. The referenced houses are located in Sarajevo, Bosnia and Herzegovina, and Senekos, a small village near Gostivar in Macedonia. Climatic data for both geographical areas have been analyzed in terms of minimum and maximum air temperatures per year, number of clear days and wind speed. The main purpose of energy efficient building designs is to find ways to use the potential of a specific area, i.e. how to exploit the solar and geothermal energy. In above mentioned examples, borehole drilling was carried out as to obtain results about the geothermal potential of the referenced area. Two computer programs were used for calculation of the annual energy demands: ENSI software 8.1 BiH and PHPP 007, which is primarily used in passive house designs. Final objectives included: to build structures with minimum carbon emissions, or zero carbon emissions, to build structures with minimum energy needs, i.e. not exceeding 50kwh/m per annum, to increase the comfort of the interior space in terms of architectural physics, to provide clients with the obtained results regarding the quality of the structure in which they will reside, which is very important because these projects are designs of private houses that are often clients most important life investments. Finances, i.e. the construction price, are usually an impediment which needs to be overcome by both the client and designer as to define the path to be taken throughout the entire construction process. The biggest obstacle in the aforementioned process is the fact that Bosnia and Herzegovina does not have appropriate regulations on the referenced issues, or institutions to support the energy efficient construction in any way whatsoever. GDC01 Conference

2 . EXAMPLES OF LOW ENERGY HOUSES The first house presented in this paper is a residential facility located in Sarajevo, Center Municipality. The location is somewhat away from the city center towards the slopes of the Kromolj hill. The longer side of the parcel is both east and south oriented. The site is accessible from the local road and has certain infrastructure assets, which include electricity and water supply. Gas installations are 50m away from the plot. The plot is located at an Figure 1: Google Earth location elevation of 695 m, and its geographical coordinates are as follows: north latitude and east longitude. The new house was rotated by 15 degrees southward in relation to the existing building so that the longest sides of the house could be exposed to the south in order to make the glazed planes absorb as much solar energy as possible during the winter period, which is then converted into heat energy. Figure : Site plan Figure 3, 4, 5: House design 3d model Total heated area ( A ) 68 m Total heated volume (V) 743 m Total envelope area ( Ae ) 580,8 m Total openings area ( Aw) m 73 Window factor ( Aw/A)x100 7 Compactness ratio 0.78 Table 1: Information about the house Table 1 indicates the relation between certain components that form a part of the design. The most relevant parameter is a so called compactness ratio, which is 0.78, meaning that this building has a very large external envelope, i.e. physical separator between heated and unheated space, which is the architectural concept used in this particular design. This design was produced with several inputs in mind: the wishes of the family members who will live in the house and with whom the author defined the project and certain components of the building, and also the geodetic survey of the site on which the building was supposed to be erected, and that is an east and south oriented slope. Rotation of the building should provide more openness towards south, securing accumulation of the solar radiation

3 in winter, and establish a visual contact of the interior with the outside greenery. Terrain evaluation was carried out in terms of stability and consistency of groundwater flows. Analysis showed that this is a relatively stable ground with few groundwater flows. These data were taken into consideration while selecting the heating systems, which will be explained further in the text. Overall envelope surface area is 580.8m. The window factor is 7, which means there is a large proportion of transparent in relation to nontransparent planes. Given these planes have the largest U factor they constitute major problems associated with reducing the amount of energy needed for heating. % 15% 1% 6% 36% External wall, Concrete External wall, termo block Basement wall Diagram 1: Envelope structure External opening, wooden door External openings, PVC windows The envelope elements have approximately the same U factor values, and they are as follows: flat roof U factor is the lowest and amounts 0.13, wall U factor is 0.15 and floor U factor is 0.3. Heat transfer coefficients could have been even lower, but this would increase the investment costs by large, whereas the effects would not be significantly improved, unless the client decided to install certified passive house windows, whose coefficient does not exceed 0.8w/m K. The envelope was designed as to be active, that is, to control the energy inflow: south, east and west façades contain the largest number of windows, whereas the north façade is completely closed. The walls are massive structures which absorb large amounts of heat, which is at night released into the interior. Ventilation system was not designed, because venting out is done by means of controlled openings on the ground floor and in the part of the single pitched roof, where, due to the difference in pressures, air can circulate inside the entire house. On the northern façade recuperators have been installed, allowing the air to flow into the building with controlled temperature values. The calculation of energy needs carried out in both of the aforementioned computer programs showed results of 3kwh/m /year, which are great, especially if the safety factor is added, which then means that heating requirements are 30kwh, and energy needed for preparation of domestic hot water is 1kwh/m /year. Figure 6: A detail from the ENSI software Heating requirements of 30kwh/m /year need to be secured somehow and properly emitted in the house. Even though the investment costs have already been increased due to the increased quality of the envelope, here money becomes an issue again. Modern technology offers many solutions for efficient energy use and production. Analysis of the microclimate and soil structure showed that installation of a heat pump would be one of the best Figure 7: A detail from the ENSI software long-term solutions. The pump used in this case is the air to water heat pump, which can be used even if the outside temperature is below 0 C. In this way, the energy needed for heating would be reduced by or.5 times, and in this way the house could become a house with a 15kwh/m heating demand, which was ultimately the objective of this project. The central system also includes preparation of domestic hot water, supported by the

4 diffuse light solar panels installed on the roof. They transfer solar energy into the central boiler, which heats the water with the help of the energy obtained from the heat pump. Finally, the energy need will be reduced from 45kwh/m to 18kwh/m with zero CO emission, which is an exceptional result given the time and place in which the referenced project was designed and executed. Another example is a building located in Sarajevo, which has been under construction for more than a year now. It is located in the old part of the city, in the neighborhood called Vrbanjuša. The original building was a typical villa from the Ottoman period. This house is listed as a more than 350 year old house. During the reconstruction it was completely Figure 8: Google Earth Location demolished and a new building was designed, but only partially built. During the second phase of the construction the client asked the architect Haris Bradić to make a new design, on which occasion designs of the courtyard, interior and energy efficiency were produced. The house is located at an elevation of 611m, with the following geographical coordinates: north latitude and east longitude. This position is similar to the previously described example, but with certain differences. The house has a basement, ground floor, first floor and loft. Orientation-wise, the house has a very good position, because there is an unobstructed accumulation of solar energy from all sides throughout the entire day. Figure 9: Court yard and ground floor plan Figure 10,11: House design 3d model Figure 1: Existing condition as of ,6 m Total heated area ( A ) Total heated volume (V) 114 m3 Total envelope area ( Ae ) 73,33m Total openings area ( Aw) m 100,95 Window factor ( Aw/A)x100 Compactness ratio 0,65 Table : Information about the house Table shows that the compactness ratio is better than in the previous example, because the shape of this house is a cube with minimum disruptions to the façade, except on the entrance. Total heated area is quite large and it requires large heating demands. One of the main reasons for this is not a very low U factor of the external walls whose values range between 0.31 and 0.39W/m K, and which take up 55% of the entire envelope. The building s heating demands are 5kWh/m/year, and those for preparation of domestic hot water amount to 13.7 kwh/m /year. Total energy need of the house is

5 75kWh/m /year, which is a quite large value in energy efficient architecture. According to the design, all of the aforementioned parameters should be decreased by using the energy from the ground and installing five 100m probes and two ground source heat pumps, connected into one system which is supported by the system with thermal energy obtained from diffuse light solar panels installed on the roof. In this way, the overall energy need will be 1kWh/m /year. If more attention was given to the envelope in the very beginning of the project, the aforementioned energy need could have been reduced even to 15kWh/m /year, with zero CO emission. Figure 13: Taken from the ENSI Software Third example is a house in Macedonia, Senekos near Gostivar, Tetovo, Macedonia, which is still under construction. The area has similar climate as Sarajevo, with cold winters and warm summers. The design of this house is based on the traditional architecture which had been present in the territory with mainly Albanian population for more than 5 centuries. Such architecture is manifested as individual residential structures with multi-pitch roofs, usually housing ground and first floors, surrounded by greenery within high walls enclosing the entire property. The main purpose of this design was to combine the aforementioned tradition with contemporary human needs. This resulted in a building with a basement, ground floor, first floor and loft. Irregular angles of the façade which separates the interior and outside greenery by means of large glazed planes, with overhangs above the ground floor, increased the size of the envelope, which negatively affected the overall calculation of the building s energy needs. The data obtained upon calculation show that the compactness ratio is 0.79, with large heated air volumes and large envelope that serves as a boundary between the interior and exterior. The decision was made together with the client that particular attention should be given to proper design of the envelope, that is, the U factor Figure 14, 15, 16: House design 3d model Table 3: Information about the house Total heated area ( A ) 505 m Total heated volume (V) 1361 m Total envelope area ( Ae ) 1079 m Total openings area ( Aw) m 133,93 Window factor ( Aw/A)x100 6 Compactness ratio 0,79 of walls, floors and roofs must not exceed 0.15 W/m K, and that of external openings 0,9 W/m K. Even though the end result was a structure of a very complex shape in terms of energy efficiency, the total energy demand for heating and preparation of domestic hot water of 37kWh/m per year is an excellent final result and confirmation that every architectural concept can become energy efficient provided that significant financial resources are available. This building will not have a controlled cooling system, which might be a slight negative aspect, but as for the heating, the house will have a

6 central system with a pellet boiler supported by solar collectors on the roof. The aforementioned system will contribute to reducing the overall energy needs required for heating and preparation of domestic hot water to 5kWh/m per year, making this house the first low-energy house in Macedonia with very low carbon emission. Cooperation between the client and designer in this project was excellent, which ultimately led to the above mentioned results and construction of an energy efficient house. Figure 17: Calculation results, ENSI software CONCLUSION Construction of energy efficient architecture in developed countries is a common standard nowadays, whereas in developing countries, such as Bosnia and Herzegovina, this is still a quite big issue. This paper presented three houses which are currently being built and which represent positive examples where clients recognized, in the long run, the quality of energy efficient construction. Payback period calculations show these investments are not yet cost-effective due to both low price of energy sources in our region and price of the systems that use renewable energy resources, including the solar, wind and geothermal energy, but it is expected that this will change in the near future and consequently lead to construction of large numbers of buildings with the above mentioned characteristics. Every region is distinct in terms of using renewable energy sources, and therefore architectural designs, which define the benefits of a certain area, are very important [1]. One particular point can be emphasized here, and that is the exploitation of the solar energy, both in terms of absorption and protection from excessive radiation during summer periods by properly planning the orientation of a building, designing adequate layouts and envelopes. In all three examples mentioned above building physics equations were used to calculate the energy flows through the boundary between heated and unheated space, whereas the standards regarding construction of passive and energy efficient buildings were taken from the German Passivehause Institute in Darmstadt. [4] Finally, the entire process can be divided into several phases: thorough analysis of the site s microclimate [3], precise definition of the design with the client, focusing on the overall budget, detailed calculation and simulation of energy flows from the inside towards outside and vice versa, in cooperation with different engineers, including mechanical and electrical engineers, and finally creation of a concept for energy production for a particular structure, both in terms of renewable energy sources and pricing. The main objective of the projects was achieved, and that is energy independent architecture with minimum CO emission. Figure 18: Exploitation of solar energy [1] REFERENCES [1] Duran, S.C.: Architecture & Energy Efficiency, Publisher: Loft Publications, 011., Barcelona, Spain [] Hadrovic, A.: Architectural Physics new edition, Publisher: Faculty of Architecture in Sarajevo, 010., Sarajevo, BiH [3] Hadrovic, A.: Bioclimatic Architecture, Publisher: Faculty of Architecture in Sarajevo, 008., Sarajevo, BiH, [4] Schoch, T.: EnEV 009 und DIN V Wohnbau, Publisher: Bauwerk, 010., Berlin, Germany, [5] Sternthal, B., Eisenberger, H.: Die Schonsten Passivhauser, Publisher: Christian Brandstatter Verlag, 011., Vienna, Austria