In order to get an impression of the energy balance of the surPLUShome, we simulated on one hand all appliances during a normal use of one day. On the other hand, we calculated the energy rates of the different surfaces in relation of orientation and allocated areas. Due to balance which is shown on the graphic, one gets an impression of the situation we simulated for the competition in Washington in October 2009. The result of the calculation is that our surPLUShome produces about two times more useful energy than it is needed. Obvious is as well, that the roof is the main energy gaining surface. But nevertheless in addition all four facades have got an impact of 35% on the energy surPLUS.
Regarding a common building with an energy demand of 80-100 kWh/m²a our surPLUShome has a 50% lower energy demand. With its 54 kWh/m²a it complies with the German Passive House Standard. The total primary energy demand including the photovoltaic system on the roof and the façade goes down to -257kWh/m²a (calculated with German primary energy factors). This makes 100% savings and 250% gains.
As the 2009 Solar Decathlon allows using a net-grid we designed a system similar to the way solar energy is gained in Germany for years. The government has stated in the EEG, that the energy supply firms have to pay around 40 euro-cent for each kWh that is induce into the net. Therefore we do not have to focus on a zero energy home but can head to a plus energy home without losing any market potential.