Since its inception nearly 18 years ago, NBI has maintained a strong emphasis on energy codes. Current NBI staff and board members continue the focus established early on by the organization’s founders. We know codes make a difference—a big difference.
A recent paper by Arik Levinson, “How Much Energy Do Building Energy Codes Really Save? Evidence from California,” purports to demonstrate that, “. . . there is no evidence that homes constructed since California instituted its building energy codes use less electricity today than homes built before the codes came into effect.” It should come as no surprise that we at NBI were bemused by this study and its conclusions.ACEEE Executive Director (and NBI board member) Steve Nadel in his blog points out several studies that come to opposite conclusions: “On the surface [Levinson’s] conclusions about the efficacy of building codes are very different from other recent analyses such as papers by Aroonruengsawat et al., Deason and Hobbs, and Jacobsen and Kotchen.” Nadel also questioned the study’s peculiar lack of analysis of fuel diversity:A good analysis of the impact of California’s building codes should focus on natural gas use. Levinson does do one analysis of natural gas use finding that homes, built since California’s building energy code began, use less natural gas than earlier homes. However he then dismisses this finding since the trend started before the building codes took effect. He presents no evidence that prior trends would have continued, and therefore his claim that building codes had no effect is speculation.There’s another dumbfounding aspect of the study—its failure to study the correct variable. Energy codes are construction codes and thus regulate the construction phase of a building’s life. They do not cover the appliances or other “plug load” devices installed during and after construction. For that reason, these plug loads are known in the energy code world as “unregulated loads.” Levinson’s major study variable is total energy loads—not distinguishing the fact that the fastest growing component of that variable is unregulated plug loads. He acknowledges the problem by saying, “Why would houses built under tighter building codes not use less electricity? Newer houses may have more electricity-using features, including more televisions, cable boxes, and garage door openers, not all of which I can account for, and that might explain part of the trend.”
It just may be more than “part of the trend.” The latest data from the Energy Information Administration shows that during the period Levinson is studying, 1993-2012, these “unregulated” loads increased from 24.0% to 36.6% of residential energy use. So even if one accepts Levinson’s statistical contention that per residence total energy use didn’t go down during the period, since as a share of total energy use plug loads increased a whopping 50% (from 24 to 36.6% of total energy use), the energy use due to house components regulated by the energy codes must have been reduced by an offsetting number of therms or kWh.
Building energy codes do save energy—this can and has been measured by looking at a building’s energy use that is regulated by those codes.