| Summary: | The building sector accounted for around a fourth of the total energy usage in Sweden in year 2010 (Energimyndigheten, 2012). Therefore it has become very interesting to achieve a lower energy usage in residential buildings. One way to achieve that is to build so called passive houses. By being very well insulated and have low leakage through the walls, they can reduce the energy usage for heating with a substantial amount. The first passive house was built during the 90’s in Germany; and in Sweden the first passive house was built in Gothenburg 2001. Both Sweden and EU have goals to reduce the overall energy usage and greenhouse emission by 2020 and 2050. The concept of the passive house is one way to achieve the goals. In short, the concept of the passive house in Sweden is: The air tightness for the walls should be tighter than 0,3 l/m2,s at 50 Pa overpressure The heat loss factor must not exceed 15 W/m2 Atemp for climate zone III The delivered energy must not exceed 50 kWh/m2 Atemp,year for purely non electrically heated systems in climate zone III The average u-value for windows should be as highest 0,8 W/m2,K. The term primary energy is a term that is frequently used in the EU when talking about energy usage. Apart from the above mentioned criteria, passive houses in Germany must also use less than 120 kWh/m2Atemp,year in primary energy. Primary energy usage for the passive houses is calculated by multiplying the energy usage with the respective primary energy factor. The primary energy factors were set to be the following: Electricity mix – 2,7 District heating mix – 0,79 District heating from waste – 0,04 Electricity from wind power – 0,05 The results show that the passive houses in Trettondagen and Oxtorget were the only ones that passed the German limit of 120 kWh/m2Atemp,year. The low energy usage in Trettondagen could be explained by the fact that the input values for calculating primary energy usage were simulated and not measured. Moreover, the passive house in Trettondagen was connected to the district heating from waste, which has a very low primary energy factor. The passive houses in Oxtorget were not connected to district heating and relied only on solar panels and heat recovery in the ventilation unit. An electric heater was installed in both the ventilation unit and the storage tank to provide extra heating. What set the passive house in Oxtorget apart from the others was that the electricity used in the houses only came from wind power. The low primary energy factor for wind power contributed to the extremely low primary energy of Oxtorget. The domestic electricity was relatively high in most of the passive houses, a reason to why they had problem with passing the German limit. One house had low enough domestic electricity usage to possibly pass the limit if the source of energy for heating was changed. It was the passive house in Falkenberg which was connected to district heating from biofuels (1,035). By switching to district heating from waste instead, the passive house in Falkenberg will then pass the limit. Primary energy usage for the passive houses in Oxtorget was also calculated with one half from electricity mix and the other half from electricity from wind power. Despite a large increase in primary energy, the passive houses still passed the limit. The passive house in Trettondagen was also calculated with switching district heating from waste to district heating mix. The primary energy increased a little bit but remained under the limit. The conclusion form this thesis showed that certain passive houses in Sweden were able to fall beneath the German limit for primary energy. One obstacle could be the high domestic electricity that has to decrease, perhaps by informing and involving the residents. Another problem is the absence of proper framework for calculating primary energy. There are some calculations mentioned in FEBY that resembles calculations for primary energy. The definitions though are too unclear and thus difficult to compare with the German standard.
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