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Monday, September 19, 2011

Net Zero Energy Homes

Mary Campbell, Extension Director and Urban Sustainability Agent

What would it be like to have a home that sold as much energy back to the power company as it uses? Think of the money that would be saved! The term used for those homes is net zero energy homes (ZEHs). Net zero energy homes and buildings (ZEBs) are “on-grid” structures (connected to the power company) that produce renewable energy onsite at a value equal to, or greater than, the building’s total annual energy consumption. The “net” portion means the building may use energy from the utility grid (electricity and/or natural gas) during some times of the day (such as at night) but supplies renewable energy back to the grid during other times, in a balance that equals out over the course of a year. It is now possible to make a home so energy efficient that when it also includes a renewable energy source (like solar), the net result is that the home generates as much energy as it uses.

In Florida, solar photovoltaic (PV) and solar thermal water heating are the most common renewable energy generation sources of choice. However, ZEHs are not the mere addition of onsite renewable energy to a conventional home. True ZEH status (a federal goal by 2020) is currently a rare occurrence. In the reality of 2010, a ZEH needs approximately 50-70% reduction in site energy use through efficiency measures with the remaining 30-50% in energy needs provided by on-site renewable energy. So a home must maximize all the energy efficiency first to work together with renewable energy to create a net zero home.

Progress Energy supports the use of renewable energy. At any time your renewable system produces more energy than required to power your home or building, the excess energy may be applied as a credit to any current and future bills. This process is known as net-metering. Interested in net-metering with Progress Energy Florida? Then download this Net Meter Tariff overview (PDF) to learn more about the rates and other requirements.



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