Passive Houses in Sweden. From Design to Evaluation of Four Demonstration Projects.

Abstract: The use of energy is a major global issue both according to climate changes but also in the aspect of national safety tied to the trade with energy sources. Of the total energy use in the member states of the European Union, about 40% is used in residential and commercial buildings. Passive houses are one way to reduce the energy use in buildings and at the same time keep a good indoor comfort. The basic idea of the passive house concept is to have well insulated and air tight climate shell together with a mechanical ventilation system. Within this research, four Swedish passive house projects have been followed from the early planning stage to evaluation of the actual buildings; three apartment building projects in Värnamo, Frillesås and Alingsås and one single-family house in Lidköping. Three of the projects were new built and the fourth, in Alingsås, was a renovation project. The research was funded by the Swedish Energy Agency and has been a five year project. The main purpose with the study was to see how energy efficient residential buildings, mainly passive houses, can be built in Sweden and on a more widespread scale than before. The total measured energy use for space heating, domestic hot water and common electricity was in Värnamo 36 kWh/m2a, in Frillesås 50.5 kWh/m2a, in Alingsås 65.7 kWh/m2a and in Lidköping 51 kWh/m2a, revised to a normal year. The peak load for space heating is measured to be somewhat higher than the required 10 W/m2 (12 W/m2 required in the single family house). Previous research shows that a ventilation air change rate of 0.5 ach seems to be necessary in order to achieve a good indoor air quality. Simulations made in this research shows that not much energy is saved by decreasing the ventilation rate below 0.5 ach and should be avoided to assure a good indoor comfort. Some products have been detected to be in need of development to ease the building of passive houses in the future, e.g. easier used ventilation units, supply air devices suitable for space heating distribution and woodburning stoves with a power to the room of 1 – 3 kW. There were some additional costs in these demonstration projects for e.g. education, air-tight solutions and more expensive products which can be decreased in future projects when more suitable products are available on the market and when the knowledge and experience of how to build energy effi cient buildings is natural and well spread. The three clients of the apartment buildings have all continued with building new passive houses or renovating according to the passive house principles after their demonstration project was finished.