Zero-energy homes: reducing residential energy consumption

Zero-energy houses represent the next generation of dwellings. Their total energy needs are generated on site. Today, residential renewable energy systems are still some years away from being cost effective. Through energy efficiency measures, the overall energy demand of the building can be reduced, thus magnifying the potential of renewable energy to provide a high proportion of the energy demand.

Building low-energy houses

The Building Industry Research Alliance (BIRA), part of the Building America Program, established a Zero Energy House (ZEH) programme. At present, 416 low-energy houses have been built in California alone through this program. Those houses have reduced their grid energy consumption by an average of 51 per cent compared to a standard house. 32 per cent of this savings was realized by energy savings and 19 per cent by a photovoltaic system.

Low-energy houses obviously benefit homeowners through reduced home electricity bills. They benefit the utility companies through significant peak demand savings. Other benefits include:

• Reduced GHG emissions
• A stimulation for the home-buying market and the local economy
• They keep growth in electricity demand by residential buildings to a minimum

Still R&D required

By 2020, the Building America Program aims to produce 'real' ZEH homes that require zero energy from utilities and pump electricity back into the grid during peak hours. Reaching this goal still requires substantial R&D to reduce the cost of ZEH and facilitate its market penetration.