Dive Brief:
- The Tennessee Valley Authority has wrapped up a five-year research project that starkly illustrates the differences between energy use in a typical home and one built with efficiency in mind.
- Since 2009, TVA has used three similar Knoxville-area homes to test energy efficiency measures, ultimately concluding that a home retrofitted to be energy efficient uses about 37% less energy than a typical build house.
- The TVA also studied a "Near Zero Energy" home, constructed to be as efficient as possible while also utilizing a rooftop solar system. That house used about 55% less energy than the typical build home, and had a power bill of about $35 per month.
Dive Insight:
For the last five years, TVA used three homes in a Knoxville, Tenn., subdivision to test energy efficiency ideas. TVA installed automated systems to simulate the same energy consumption in each residence.
The homes are similar, each having two floors, their broad side to the sun, and 2,400 to 2,500 square feet. The typical-build home represented an up-to-code spec house, TVA said, while the retrofitted house was supposed to represent a home with upgrades that could be achieved by a typical homeowner. These included better windows, a sealed attic with foam insulation, Energy Star appliances, compact fluorescent lights, a high efficiency heat pump and a heat pump water heater.
TVA said its Near Zero Energy home "was built from the ground up with efficiency in mind. The home features thicker walls and more insulation; appliances and heat pumps similar to the Retrofit house, and a 2.5-kilowatt solar photovoltaic electric system on the roof."
The project made daily data available online. For example, on Sept. 28 the spec house used 40.56 kWh, the retrofitted home used 29.89 kWh; the Near Zero home used 29.24 kWh total and 21.79 kWh net after a solar credit.
Now that the project is finished, the three homes will go up for sale.