The main definition of a Powerhouse is a building that shall produce at least the same amount of energy from on-site renewables as the energy used during construction, manufacturering of materials, renovation, demolition and operation exclusive energy used during manufacturering of equipment such as PCs, coffee machines etc. In addition the exported energy shall in average not have less quality than the imported energy. This implies that produced and exported electricity can offset corresponding amount of imported energy for both electricity and thermal purposes, while produced and exported thermal energy cannot offset imported electricity. The building shall also as a minimum fulfil all the requirements of the Passive House standard according to NS 3701.

The first Powerhouse renovation building will be built at the Kjørbo site in Bærum, and start of construction was in March (2013). For the Powerhouse Kjørbo project, PV panels will balance the energy needed during it’s lifetime. The two buildings will thus export more electricity than it will use for operation. A geothermal heat pump, in addition to waste heat from the data/server room, will cover the heating and cooling demand. There will be no export of thermal energy. In a broader environmental perspective, an aim of this project is also to achieve the classification “Outstanding” in the BREEAM-NOR environmental certification scheme.

The heated useful floor area of the two office buildings at Kjørbo, which will be renovated to plus-energy standard, is about 5.180 m2, distributed on 3 or 4 floors. Energy efficiency measures and materials with low embodied energy have been crucial for obtaining the energy goal. A very efficient ventilation concept has been developed.

Powerhouse Kjørbo is a ZEB pilot building, i.e. a pilot within the Research Centre on Zero Emission Buildings (www.zeb.no). Therefore an aim is also very low greenhouse gas emissions during the building’s lifetime.

Calculations indicate that the energy balance during the building’s lifetime, and within the defined definition, fulfils the goal of plus-energy.