This project explored the development and demonstration of a roof/attic energy retrofit solution using nail-base insulated panels for existing homes for which traditional attic insulation approaches are not effective or feasible.
For this study, prefabricated panels were installed above the existing roof deck during a reroofing effort. Vented attics were converted to unvented attics and mechanical systems were installed in the attic. These types of retrofits have been shown in older, existing homes to improve energy savings and comfort as well as air quality. This project made a number of key findings demonstrating the efficiency and durability that comes with using this type of retrofit panels:
- Estimated heating/cooling energy savings were approximately 23% heating and 13% cooling for Michigan, and 11% heating and cooling for Georgia.
- Overall house tightness improved by 29% for Michigan and 12% for Georgia.
- The data set collected showed that moisture conditions at retrofit panels and existing roof decks were well within acceptable limits.
The potential energy-savings impact of this technology in the market is large. The current reroofing cycle is 21 years for the average house, and 5.7 million houses had a whole-roof replacement in 2016. If the portion of existing houses with these attic types homes was 10%, the number of candidate houses for the installation of retrofit panels would be 570,000 annually, at an estimated annual heating/cooling energy savings of 10%–15% or more.
Read more about this success story on the project web page.