THE NEED
Shortcomings Found in Rehab of Vacant Homes for Affordable Housing
Our 2021-22 study assessed 13 finished rehab properties for affordable housing market. Each home received an energy audit using DOE’s Home Energy Score (HES) methodology, including the blower door test.
In this example, a bathroom remodel required access to bathroom ceiling. Upon completion, the attic insulation was not replaced in that area, contributing to energy waste. (Bathroom vent was also installed incorrectly).
Dark areas caught with infrared camera indicate “thermal holes” through which heat will escape – signs of missing insulation (sloppy execution) in this newly rehabbed home.
Insufficient attention to knee walls was a common oversight. When knee walls are present, access is usually through small doors in finished attics. It's crucial to incorporate these areas into the creation of a continuous thermal envelope and an effective air barrier for the entire house.
The gaps between the door jamb and the wall, when merely covered with trim without proper air sealing, lead to air leakage and heat loss. Addressing these and many other gaps and holes is required to enhance overall home performance.
Our data set shows a systematic missed opportunity to make homes more efficient, across different nonprofit developers.
- HES Scores: The average Home Energy Score (HES) for these homes was notably low, at 2.8 on a scale of 1 to 10, where 10 indicates maximum efficiency. This falls below the Pennsylvania state average of 4 for homes.
- High Predicted Energy Usage: Median anticipated energy consumption in these recently completed homes was substantial, totaling 109 MBTUs/year, despite the median home size being only 1240 square feet. Energy Use Intensity (EUI) was 87 kBTU/sf/y. (For comparison, new construction homes’ EUI is about 45 kBTU/sf/y, and Passive House standard EUI is 15 kBTU/sf/y.) Implementing cost-effective improvements offers significant, ~30% potential for savings, amounting to about $580 savings in energy costs annually.
- Carbon Footprint Impact: The carbon dioxide emissions associated with the projected energy consumption were high at 18,706 lb. per year. However, should the recommended measures be adopted, this figure could be reduced to 14,871 lb., reflecting a considerable decrease in environmental impact.
- Critical Role of Air Sealing: Given the measured air leakage of 22 Air Changes at 50 Pascals pressure, on average, the most cost-effective avenue for energy savings lies in the meticulous air sealing of these homes. This process is most efficiently executed during renovation phase, capitalizing on opportunities when windows and doors are replaced, walls are open, and access to the attic is unobstructed (before insulation is added). It is important to note that achieving effective air sealing becomes significantly more challenging outside the renovation phase.
- Strategic Equipment Selection for Increased Efficiency: Choosing high-efficiency equipment, such as heat pumps for hot water heating, induction cookstoves, and heat pumps for air conditioning and heating, would play a crucial role in enhancing the overall sustainability of these homes. This electrification transition proves most economically viable during new equipment installation, promising substantial savings dividends for homeowners in the long run.
- Importance of measurement and verification. The data speaks for itself!
