Full Description

Single family building envelope energy retrofits have been an underutilized efficiency measure in very cold climates due to more attractive efficiency opportunities, individual project complexities, and cost effectiveness pressure from low natural gas costs. However increasing emphasis on space heating electrification as a decarbonization measure highlights the role of building envelope performance, particularly considering the capacity and performance limitations of air source heat pumps and large space heating loads in climate zones 6 and 7. This paper describes a model developed to understand variations in envelope performance across Minnesota single family homes as a function of building characteristics and performance data assembled from home energy audit datasets. The model was paired with efficiency program results to estimate the costs and energy savings of conventional weatherization measures and then used to assess the incremental costs of various continuous exterior insulation (CEI) measures across this single family building stock. Costs were estimated from contractor cost data and energy savings outcomes were modeled based on changes to insulation and air tightness levels of the major building envelope components. The results show a wide diversity in energy savings and project costs, consistent with the large diversity in building stock. Model results show mean and median weatherization savings of 19% and 15% across the modeled homes, increasing up to 49% and 41% with added CEI measures. While cheaper weatherization measures generally lead to lower cost per savings than projects pairing weatherization with CEI, about 27% and 12% of homes have lower cost per savings when R-6 EPS CEI and R-9.8 PIR CEI are added to weatherization measures. These results provide energy savings and cost estimates that are useful to understand and prioritize building envelope improvements for the optimization of very cold climate decarbonization investments for single family homes.

Product Details

Published: 2022 Number of Pages: 9 Units of Measure: Dual Product Code(s): DBldgsXV-C014