Passive houses in Sweden - Experiences from design and construction

The sector of residential buildings and service organizations uses 36% of the total energy in Sweden. In June 2006, it was decided by the Swedish parliament that the energy use in residential buildings and premises should decrease by 20% per heated unit area before 2020. To reach this goal, more energy efficient buildings must be produced as well as energy efficient improvements must be performed on the existing building stock. One way to reduce the energy use in buildings is to build passive houses. A passive house is a mechanically ventilated building that with a highly insulated and air tight building envelope uses a minimum of energy for heating. The method used in this research is to practically participate in four passive house demonstration projects. The results expected are to find guiding principles and tools needed for passive house planning and make the system solutions usable for planning in more general terms. Joining as a part of the planning group; advice and help is given to architects, consultants and to the client. The demonstration projects studied are located in the south-west of Sweden. Three of the projects are new constructions and one is a renovation project. In the centre of Varnamo 40 rental apartments were built in 2005/2006 according to the passive house standard. Solar collectors on the roof contribute to the domestic hot water production. Every apartment has its own mechanical ventilation system with efficient heat recovery. Auxiliary heating is supplied by electricity. The load bearing structure were made of concrete and cast at site. The exterior walls and roof were made of wooden frame construction and mounted at site. The tenants moved in during summer 2006. The passive house project in Frillesas consists of three houses with 12 rental apartments. The air is supplied by mechanical ventilation with an air to air heat exchanger, one in each apartment. The domestic hot water is prepared by solar collectors and auxiliary heating is supplied by district heating. The two storeys are separated by an intermediate floor with a prefabricated filigree system. The wooden outer walls and roof are prefabricated. The tenants moved in during December 2006. In Lidkoping close to Lake Vanern, a single-family house in two storeys was built with passive house standard and has a total living area of 170 m2. The house is heated by air. The air is supplied by mechanical ventilation with an air–to–air heat exchanger. The prefabricated blocks in the exterior walls have a wooden frame construction with mineral wool, each made in two parts, mounted at site with a polystyrene layer between. The family moved in during April 2007. Alingsashem, the public housing company in Alingsas owns 300 apartments in the Brogarden area. These apartments were built in 1970 and are in great need of renovation. The apartments will be renovated aiming to the energy levels of a passive house. Well accomplished demonstration projects are seen as reference objects and are used as a basis for future projects. The results show that the project leader has here a key role. The proud carpenters with straight backs are priceless as advertisers for building passive houses. It is possible to build passive houses with good results even if the project leader does not lead the project in a perfect way. Skilled contractors and external experts can together create a very good final result. Clear goals that are followed up during the whole process are a key issue. It is expensive to make corrections and changes at a late stage in the project. Lack of good leadership might not affect the final result but the final cost. (Less)