In 2011, media outlets such as the New Yorker started touting news around the “Rebound Effect” of residential energy efficiency. According to the US think tank, Breakthrough Institute (BTI), a rebound effect causes consumers who choose energy efficient products to consume more energy through new purchases. If accurate, this effect would call into question the efficacy of energy efficiency as a strategy.
Climate Progress evaluated the data used to support BTI’s argument along with other consumption data sets and found that BTI’s data doesn’t hold up under the magnifying glass. They published an article refuting the “rebound effect” in energy efficiency in January.
The truth may be somewhere in between. The data the Climate Progress shows for the energy per capita usage in California vs. the rest of the country seems to clearly indicate that energy efficiency works over the long term. On the other hand, our customers have seen anecdotal cases where a homeowner, upon completing an energy retrofit sees their energy bills drop substantially, decides to put that savings into the purchase of a new hot tub.
That uncertainty, on a home by home basis, and more broadly across utility energy efficiency programs, is why measurement and evaluation is important. But it’s not easy. The savings from efficiency measures implemented in homes are often measured through different methods. The common approaches include a deemed savings calculation (from regional technical forums or approved technical manuals), modeled savings (from approved and calibrated home energy modeling tools) and actual post-implementation utility billing data (often compared to a control group). Measures may be saving more or less than expected or modeled in each home, depending on the characteristics of the home and behavior of the occupants after a retrofit.
If your utility program is wrestling with these post-implementation savings calculations and monitoring, share your thoughts. Is there a “rebound effect” in your home energy efficiency programs?