ARCHITECTURAL DESIGN COMPETITION

FOR PASSIVE HOUSE IN BULGARIA

Lyuba Shekerova Dipl. Arch.

(355 - user rating)

Building-Metric-Sheet-34.xls

The house designed by our team represents one family house very close to the traditional life of an average Bulgarian family.
The building sites in Bulgaria are usually narrow – 12 to 20 m, and the average area is from 500 to 1000sq.m., so a two storey house is quite typical ,and provides a small foot print.
The house consists of a daytime zone – living room with TV, dining room and kitchen, situated on the ground floor, and two bedrooms and a study on the first floor. The composition includes the necessary storerooms – the mechanical room on the ground floor, and a wardrobe on the first floor. There is a toilet serving the day zone, and two bathrooms – an en suite one for the master bedroom and a smaller one for the second bedroom and the study. The two storey house gives the possibility of the division of the areas into different heating zones for achieving of effective usage and heat saving when a controlled heating systems are applied. The house is designed with flat roof, easily maintained and giving a possibility to position additional sources of solar energy, easily accessible.
The gross area of the house is 180 sq.m including the 200mm insulation of the walls.
The main objective of the design work is to provide a low energy home at reasonable cost for the Bulgarian climate, using building materials offered on the Bulgarian market. In creating of the architectural image of the house, we wished to have the freedom to apply the term Passive house to any Passive design, irrespective of whether this house meets the requirements of the Passive house standards set in other countries, and to be free to design individual houses for different people.
We tried to follow the main principles of the passive house design i.e. orientation,shape of the house, insulation, shading and architectural requirements about windows, glazing and avoiding thermal bridges.
The orientation of the house is set along the East-West axe, so that all the rooms are situated to have windows to the south. A buffer zone on the north side of the building, including bathrooms, storeroom and technical room, as well as the lobby and the staircase is created to reduce the heat losses from the living zone. That is why the main entrance of the house is found from the north direction.
The shape of the house is not of high compactness but of a medium one, so that in summer the cooling demands to be reduced. There is a high percentage of glazing on the south wall ,on one hand to increase heat gains due to solar radiation in winter, and on the other hand to give the inhabitants the possibility to enjoy the beautiful sight to the Lozen mountain.The veranda on the ground floor and the balconies on the first floor are planned to prevent the living room and the bedrooms from
overheating as well as decorative sliding solar screens outside in front of the south and west windows.
The screens in front of the north windows are mainly decorative to match the style of the house, but they can be designed more compact , to prevent the buffer zone from heat losses in the night in winter. In the rooms facing south internal night blinds are provided to stop the heat losses at night in winter. Very effective are the Hunter Douglas blinds , Duette Architella used especially at night.
Assuming that the house requires controlled ventilation in summer, a “night purge” principle is proposed to cool the rooms in the living zone when not used at night and in that way the cooling of the walls at night will postpone the daily usage of air conditioning.
Planting of trees in the western part of the yard will improve the microclimate in the house as well.
The deciduous trees will stop the direct solar heating in summer, and the coniferous trees will stop the cold winds from west ,so typical for the Sofia field.
One of the main objectives in achieving a low energy consumption is using the proper building materials.The structure of the house consists of concrete slabs and columns, and ceramic bricks for the walls. Insulation of all the external walls is provided, insulation of the floor and the roof. The bricks are planned to be Wienerberger, 250mm , Porotherm , and the insulation of the walls is 200mm EPS. The insulation of the floor and the roof is XPS – 300mm.
An important item in the passive house design is choosing of the windows. Windows with frame from softwood are preferable and triple glazing as well. Very important is the positioning of the windows. The window frame should be placed aligned to the inner edge of the insulation so that thermal bridges to be avoided. The triple glazing is designed as followed:

4mm Planibel Clear, 16 mm Krypton 90%, 4mm Planibel Top N+T pos.3, -16mm Krypton90% , 4mm Planibel Tri pos.5

The thermal transmittance of the window Uw (W/(m2K)=0.84

Insulating the flat roof defends the house from overheating in summer. The design includes a green roof system minimum 120mm thick, waterproof membrane, insulation with 300mm XPS , on top of a concrete slab.

The thermal transmittance of the roof is Uf (W/(m2K)=0.11

Insulating the ground floor includes 300mm XPS, the floor finishes are parquette and ceramic tiles.

The thermal transmittance of the ground floor is Uf(W/m2K)=0.11

Dealing with the problems of the Passive house design, we came to the conclusion that energy consumption can be reduced to 15 Wh per m2 per year without total subordination and the extreme applying of all the requirements of the passive house standards, but using the flexibility of the architectural design in its main principles – utility, tectonics and aesthetics.