About this site
Governments and the building industry are passing policies and designing and building zero net energy (ZNE) projects to eliminate impacts of building energy use and resultant carbon emissions while reducing operating costs. These zero net energy initiatives are occurring in states and locals with winter heating seasons as well as in Sun Belt areas. Primarily, ZNE is accomplished through large energy efficiencies of 60-70% coupled with on-site renewable energy generation that meets the remaining annual energy needs.
This site inventories the policies, projects and research in the US and beyond that are moving zero net energy into goals and the marketplace. It includes federal, state and local policies and programs. Zero net energy or near ZNE developments and individual houses and buildings are described as are research projects. Links to all information and additional resources are provided as well. The Zero Net Energy web site is geared to a broad audience including policy makers, energy, design and building professionals, students and the public.
Zero net energy building - a residential or commercial building that, on an annual basis, produces as much energy for electricity, heating and cooling from renewable sources as it consumes. Typically, ZNE buildings have greatly reduced needs for energy through efficiency gains (60% to 70% less than conventional practice), with the balance of energy supplied by renewable sources.
[Note: Technically, however, these are near zero energy buildings or communities given the other energy inputs into buildings and development including transportation and construction energy and the embodied energy of materials production and shipping.]
Zero net energy community (or campus) - a community that on an annual basis, produces (ideally within its own borders) as much energy for electricity, heating and cooling from renewable sources as it consumes. This is achieved either by combining district heating and/or cooling from renewable sources with highly energy efficient buildings that also include on-site renewable energy, or by developing each building within the community as a zero net energy building.
At certain times of the year a ZNE community may produce more energy than needed, while at other times produce less. Where grid-tied, the balance can be traded back and forth between the building (or a community of buildings) and utility company in the form of electricity. The energy used must be “clean,” produced from renewable sources by energy systems that minimize carbon emissions and environmental impacts.
Many changes are occurring in building and development to address their enormous impacts on the environment, the economy and society. These impacts encompass significant energy, water, land and resource consumption along with impacts on human and ecological health. With regard to energy, buildings use 40% of primary energy, 72% of electricity and produce 39% of greenhouse gas emissions in the US. This equals the annual carbon dioxide emissions of the United Kingdom, Japan and France combined. The move toward sustainable, high performance design is predominately addressed by applying the LEED Green Building Rating System (www.usgbc.org) and ENERGY STAR (www.energystar.gov/). The benchmarks of those programs are to lessen impacts by reducing energy consumption, typically by 15-30 % below code standard buildings. In the case of ENERGY STAR for commercial buildings, buildings qualify that are within the top 25% of energy efficiency performance for their building type in the region.
However, there is a movement to go beyond using less energy to generating as much energy as is consumed through a zero net energy approach. This involves advanced energy efficiency combined with on-site energy generation.
Further, a few designers and builders are going beyond ZNE or near-zero and are designing projects that produce more energy than needed. These are called energy-plus projects. Such projects might also generate enough electricity to power an electric vehicle in addition to the building.
Some are pursuing restorative design in addition to energy by taking a systems approach to restore the land and other impacts of building with regard to water, waste, health and site (for example, see The Living Building Challenge and for impacts on cost, see The Living Building Financial Study- Executive Summary: The Effects of Climate, Building Type and Incentives on Creating the Buildings of Tomorrow, Reed, Bill, Progressing Beyond Sustainable to Regenerative Design, Solar Today, Nov/Dec 2007).