Sasja Uhrenholt, Architect

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Approach, idea and concept of the design
Through the design process of this passive house, I let essential passive energy-saving parameters help me give the house form. I will in this narrative sum up the considerations behind the design of this passive house.

A two story house
The house is a two-storey house to make a compact shape with less surface area relative to volume. Also the two levels gives the opportunity of effective natural ventilation in the summertime, because of the buoyancy effect. Small windows in the south facade and in the top of the building makes it possible (and safe) to have open windows at night and when you are at work. These are times when it is important to cool the house.

Sun-studies of the sun-path and temperatures in Bulgaria let to the design of the south facade with an overhang that protects the indoor from overheating in the summertime. Compared with Denmark the sun in Bulgaria moves higher across the sky which means that an overhang is even more effective here. In passive houses in Denmark there is a problem with overheating in the summertime and here the average temperature only exceeds 15 degrees from June until August. In Bulgaria this happens already from may until September. So the risk of problems with overheating and increased energy consumptions for cooling in this period is even greater in Bulgaria. With the overhang of about 1,5 m with additional vertical shading designed in this project the sun only really hits the facade in the cooler period of the year from October until March when you have a positive use of the passive heat gain from the sun. In addition to the overhang I find it important to ad flexible external shading, to provide the people living in the house with the power to influence the indoor climate. In the west and the east facade of the house there is only a small amount of window area, because windows in these directions have a rather big risk of contributing to overheating because of the low angle of the sun.
Additionally green in the garden has a cooling effect by shading and evaporation.

I find it very important to provide the people living in the house with naturally well-lit rooms. This also brings down the energy consumption for artificial lighting. So I have distributed the windows in all facades so most rooms have daylight from more than one side. I find this important for the architectonic perception of the space and the physical and mentally wellbeing of the people living here. I also placed the bathroom and toilet out to the facade. This both saves energy for light but it also benefits the indoor climate to use have the possibility of natural ventilation here.

Organization of space
The rooms are distributed in a classical passive house manner, with the bedrooms which are important not to be overheated to the north and social open spaces such as living room, kitchen, dining room and the multipurpose space to the south. The physical contact between the social spaces gives quality to the perception and the use of the house. The multi-space can be used as office-space, creative space or playroom still in contact with the rest of the family. The volume also have a positive influence on the indoor climate.

When you enter the house a view straight through the house from north to south meets you. From the center of the house there is a view through the house from East to the West, as seen on the East facade.

The house has mechanical ventilation with effective heat recovery (> 75 % efficiency with low electric consumption), to get the full use of the heat already generated in the house and get a good indoor climate. By the entrance there is a room devoted to mechanical installations. A geothermal system provides cool ventilation air in the summer and pre-heated ventilation air in the winter. Also the part of the roof of the house is tilted 8 degrees towards the south, and thereby the sun. This surface as the opportunity of solar panels to generate extra, on site, renewable energy.

The skin of the house is a red metal-sheet material with an irregular profile that gives a interesting vivid surface. The aesthetics of the house from the outside has carefree and playful expression. I chose this because I found it important because I believe that energy efficient architecture is often seen as a very serious and often a little boring. The idea with this material is also to achieve the expression of one whole volume instead of walls with a roof. I wanted the wall to continue into the roof. In the south facade where the terrace is cut into the volume, the cut is in the perceptually warmer surface of wood. In the sustainable perspective the metal sheets can be removed an separated from the other building materials to be recycled.
All in all many considerations about sustainability and energy-efficient for the future single family house are contained in this project. The house aims to live up to the passive house standards, through a number of actions in form and mechanics. But it also strives to be a welcoming aesthetic unpretentious home with good indoor climate in terms of both temperature and daylight.