We believe that energy-positive buildings are the buildings of the future. An energy-positive building is a building which during its operational phase generates more energy than what was used for the production of building materials, its construction, operation and disposal. The building is therefore transformed from being part of the energy problem to becoming part of the energy solution.
Is this crazy talk?
This is really tough to do; the designer has to calculate the embodied energy of everything that goes into the building and offset it with on-site generated power over the life of the building. Some might say it's nuts.
During the course of its anticipated life expectancy of 60 years, Powerhouse Kjørbo will generate enough energy to cover the total amount of energy used to produce the building materials, construction, operation and disposal. The utilization of geothermal energy for heating as well as the largest rooftop solar photovoltaic system in Norway are among the features that will put the building in the “plus” category.
Even the Living Building Challenge's Net Zero Energy building certification doesn't go so far as to take the energy used to produce the building into account. It means that the designer has to be really selective in their choices of materials. In America, the plastics industry would go crazy over a standard like this; measured per square square foot of R-20 insulation, cellulose insulation embodies 600 BTU, Mineral wool 2,980 BTU, and Expanded polystyrene is 18,000 BTU (according to GBA) The concrete industry, responsible for 5% of the CO2 emitted in the world, would be making cement overshoes.
But what about the Bullitt Centre?
When I first saw the headline "World’s most environmentally friendly office building opens in Norway" I thought it was an over-reach; I thought that title belonged to the Bullitt Center in Seattle with its design to the Living Building Challenge. I would also note that the Bullitt Center, like all good green building, is about a lot more than just energy savings. However I think that PowerHouse Kjørbo might give it a run for its money.
PowerHouse Kjørbo is a renovation of an existing office building, which is a green head start. Its 200,000 kWh of photovoltaics is twice what it needs for the building.
The total energy requirement for the buildings’ heating, cooling, ventilation and lighting is likely to be around 100,000 kWh, excluding user equipment. The energy used in the production of materials used in the buildings also needs to be taken into account, so that the overall result will be a small energy surplus.
Conceptually the PowerHouse concept makes sense; we should care about the embodied energy of our buildings and how long it takes to pay it back. We should have to justify our choices in materials and the carbon footprint of their manufacture. There should be a bonus for refitting old buildings instead of knocking them down. The PowerHouse consortium is on to something big here.