The concept of zero-net-energy buildings and zero-net-energy neighborhoods is quickly capturing the attention of many green building designers and even some developers. A zero-net-energy building would provide all of its own energy on an annual basis from onsite renewable resources or offsite renewable energy purchases. In this way it would still be connected to the grid, providing power when it had a surplus and drawing from the grid when it needed power, such as at night.
This approach typically involves using solar energy for electricity, water heating and space heating and employing such design measures as passive solar design, natural ventilation and operable windows for space cooling (with some electric power assist). In practice complete energy independence is quite achievable at the level of homes and small buildings. Much depends on the local microclimate; yet if one thinks about it, all homes were “zero-net-energy” before the Industrial Revolution, so there are many sources of indigenous architecture for inspiration!
A single-family home in Paterson, New Jersey, certified at LEED for Homes Platinum level in 2006, shows how to move toward the goal of zero-net-energy. Called The BASF Near-Zero Energy Home, it includes expanded polystyrene insulation, polyurethane foam sealants and cool metal roof coatings to reduce energy use 80% below a typical home.
On a larger scale, in March 2006 the World Business Council for Sustainable Development announced that it is forming an alliance to develop zero-energy buildings. They have an ambitious target: by 2050 new buildings will consume zero net energy from external power sources and produce zeronet carbon dioxide emissions while being economically viable to construct and operate.
In December 2006 the UK government announced a program for zero-carbon new homes; by 2016 all new homes are to be zero-carbon, with a 25% improvement on energy use over current building regulations by 2010 and a 44% improvement by 2013. A 100-home project near London, the BedZED (Beddington Zero Energy Development) set a goal of becoming carbon neutral; they have cut carbon emissions by 56% through energy-efficiency measures and an onsite solar photovoltaics system.