So how much do energy-efficient upgrades cost? The upgrades included in the retrofit home cost $4 per square foot or about $9,800 more than the control home. Upgrades to the near zero energy home cost $21 per square foot or $51,576 more than the control home. Based simply on projected energy savings, homeowners who implement the retrofit upgrades would recoup their costs in eight and one-half years. It will take homeowners who implement the near zero energy upgrades 22 years to recoup their costs.

While the current round of results includes the heating season only, monitoring will continue during summer, and results for a full year of the homes’ operation should be available this fall.

The study is sponsored by the Tennessee Valley Authority and is being conducted in cooperation with researchers from the Oak Ridge National Laboratory. BioBased Insulation donated the insulation for the study, and Endless Supply, a BioBased Insulation certified dealer based in Ashville, N.C., donated the labor to install the product.