Nausassiche Heimstadt claims to have build the very first plus energy-apartment building in Germany in Frankfurt Riedberg, a large new housing area on the northern outskirts of the city.
Both the tilted roof and the closed parts of the south façade are completely covered in Photovoltaic cells which provide the single energy source of the full electric building. The building, which has a peculiar shape, due to the site, contains 17 apartments in different sizes.
The nicest part of the building is the light and spatial central staircase. German fire regulations did not require a second or closed staircase, therefor the architects could make an open staircase with light from above.
A lot of technical spaces are integrated under the roof and in the basement: rooms for batteries, air treat system, heating system, etcetera. An underground ice storage is used to warm air and water for household use. The apartments are equipped with floor heating and heat recovery ventilation.
An underground parking is provided for ten electric cars. Calculations show that the building generates an energy surplus that could facilitate ten electrical cars to drive 13.000 km per year.
Building an ‘energie-plus-geschoss-haus’ is a complicated assignment. This project is not an apartment building with additional installation technique, but a consistent design in which well integrated technique. If the building fulfils its promises, then it shows that in order to build energy efficient, architectural concessions are not necessary in order to reach the energetic ambition.
Interesting is to mention that the competitive housing corporation of Frankfurt is building an even bigger ‘activ-stadt- haus’ in de centre of Frankfurt. If housing corporations compete with each other like this, these type of experiments can generate new integrated concepts and hopefully evolve into architecturally attractive mature energy efficient buildings.