Solar cells on the roof – Recycled materials – Super insulated and air-tight envelope – Energy efficient windows – Energy efficient ventilation – Thermal mass – Geothermal heating/cooling and letting in the maximum amount of daylight.
The BREEAM-NOR Outstanding environmentally certified building is probably the world's first refurbished building to be energy-plus.
Solar panels on the roof, geothermal heating and cooling, a well-sealed and highly insulated building structure combined with very efficient integrated systems for heating, cooling, ventilation, lighting and technology all transform an energy-guzzling office building into a supplier of pure and renewable energy.
Those willing to test something new and challenge conventions are the members of an alliance consisting of state-owned property company Entra Eiendom, architecture firm Snøhetta, environmental organization ZERO, consulting firm Asplan Viak aluminum company Hydro, SAPA Group and Skanska, which also was executing the reconstruction work. The energy efficient solutions are being developed by these parties and Skanska Technology in cooperation with researchers in Zero Emissions Buildings (ZEB).
Innovative solutions to the climate challenge
Powerhouse Kjørbo in Sandvika west of Oslo is a pilot project for so-called energy-plus buildings. During its lifetime a Powerhouse should generate more energy than is used in construction, operation and use of the building as well as the manufacture of the materials used in the building – naturally recycling materials is an important factor. The energy balance and account is followed up by detailed life cycle analysis (LCA).
Powerhouse Kjørbo is part of an office complex from 1980. The retrofitted energy-plus building stands on around 5,200 sq m. On an annual basis the building will generate around 200,000 kWh, about half of which will be used in the building's operation. The remaining will compensate for energy used during rehabilitation of the building, including manufacture of the materials used, as well as future renovation during its lifetime.
A geothermal system provides both cooling and heating via pumps that use a limited amount of energy. The total energy used in operating the building is estimated at around 20 kWh per sq m, which can be compared with a typical renovation object that uses around 200 kWh per sq m. In other words, the retrofitted building will have an energy requirement that is reduced by 90 percent.
Plus for the environment, plus for the client
"Through Powerhouse Kjørbo we are showing that it's possible to construct a building that provides a positive result, not just environmentally, but financially as well. Making a commercial gain is a basic precondition for investing in this type of project in the future," says Klaus-Anders Nysteen, CEO at Entra Eiendom.
"This isn't hocus pocus," says Kim Robert Lisø, Regional Director at Skanska Norway and head of Skanska Technology Norway. "The key to the success lies in innovative and holistic solutions - and close cooperation throughout the entire value chain. Individually, the solutions are not new, the innovation lies in the way we have combined the different solutions."
Powerhouse Kjørbo was aiming for – and achieved – a rating of Outstanding, the highest level in the BREEAM-NOR environmental certification system. It is probably the world's first energy-plus building created by energy-retrofitting in an older building.
"This is a great show-case for our Green Business. It demonstrates what we can accomplish with the technology and expertise we already have. And it strongly proves that also old buildings can be transformed and become energy positive and highly sustainable. The success is based on partnering and our client's wise choices. It takes bold decisions to go for BREEAM Outstanding in a refurbishment project which makes this a remarkable and truly unique project," says Staffan Haglind, Skanska's Green Business Officer.