February 2002
What is a net-zero fossil energy use home?
Introduction
A net-zero fossil fuel energy use home is designed so that annually, on average, the consumption of electrical energy from utility sources is offset, or equaled by the production of electrical energy from renewable sources, such as solar energy or wind.
This case study, sponsored fully by the NAHB Research Center, is a preliminary effort to understand how a new house design may be modified so that the use of renewable energy technologies supply all of the annual energy needs of the home to achieve net-zero energy consumption. The effort makes use of a “typical” home design using new technologies in the building shell as well as new technologies for heating and cooling to reduce energy consumption. The modified home design design - an all-electric home - then includes the use of standard solar thermal and photovoltaic systems to offset the electric demand, on an annual basis, so that the home is estimated to be a net-zero consumer of fossil fuel produced electricity. In other words, the home produces as much energy surplus as it consumes from conventional (electricity or natural gas) energy sources at times of peak consumption or low solar gain.
How we studied the net-zero fossil energy use home
This case study is based on energy use estimates for heating and cooling, ventilation fan, hot water, and general appliance energy. Simple analytical tools available to builders and designers for estimating the heating and cooling energy use is combined with other less common software to estimate energy production from solar thermal (hot water) and solar electric (photovoltaic) systems. Estimates for general energy use for clothes washing and drying, cooking, entertainment etc. are based on specific utility estimates or available reports. For hot water energy consumption, data obtained through previous testing and simulations is used to estimate the hot water consumption and the use of back-up energy to the solar hot water system.
Results include dramatically lower energy consumption
The case studies provides quantitative estimates of how the energy consumption of a home can be significantly reduced by using energy efficient technologies in the shell and in the heating and cooling systems. For example, heating and cooling energy consumption can be reduced by over 80%.
Sponsored and Prepared by the
NAHB Research Center, Inc.
400 Prince George’s Boulevard
Upper Marlboro, MD 20774-8731
43 pages