Last week the U.S. Energy Information Administration (EIA) released summary energy use data from its 2012 Commercial Building Energy Consumption Survey (CBECS). The EIA reports that, as compared with 2003 results, the energy use intensity (EUI) for all U.S. commercial buildings has decreased by 12%. They also report that for office buildings and educational buildings EUI have decreased by 16% and 17%, respectively. These numbers, taken at face value, would appear to be encouraging.
But dig a little deeper and you find there is not much to celebrate. The first thing to note is that mother nature does not care about energy use intensity. This is a man-made metric for comparing energy use between buildings of different size. What really matters is total green house gas emission and total fossil fuel consumption. To arrest global climate change, or at least to stabilize it, will require a global reduction in annual green house gas emission.
The 2012 CBECS data show that the total gross square footage (gsf) of the U.S. commercial building stock has expanded by 21% since 2003. Its total (site) energy consumption has expanded by 7%. That’s right — U.S. buildings are using more (not less) energy. During this same time the U.S. population grew by 7.6%. If world energy consumption and green house gas emission continues to grow with world population we are doomed! Energy use in undeveloped countries will grow much faster than population as they increase their standard of living. This growth is especially notable in India and China. Developed countries like the US — which already use 5X-10X more energy per capita than non-developed countries — must decrease their energy consumption and green house gas emission. Yet the U.S. is not even holding steady.
The above figures are based on site energy — not primary or source energy which is what really matters. Building source energy — which includes the off-site energy use associated with energy generation and transportation — is a better indicator of primary energy consumed by buildings.
I have made crude source energy calculations based on the 2012 CBECS summary data and find that for all U.S. commercial buildings source EUI decreases by only 7% and source EUI for offices and educational buildings decreased by 12 and 13% respectively.
But again, what matters is total primary, or equivalently, source energy consumption. When you combine these figures with the 21% growth in building gsf you find that the total source energy for all buildings increased by 13% — faster than the rate of population growth! For offices and educational buildings the increases in source energy were 15 and 8%, respectively. For offices that is double the rate of U.S. population growth and for educational buildings it is about the same as population growth.
2003 to 2012 is the decade of ENERGY STAR and LEED building certification. These programs both provide cover for building owners to “feel good” about their ever-growing buildings that consume more energy and produce more green-house gas emission — yet are judged to be “green” and “energy-efficient.” Proponents of these programs will claim that, while their accomplishments are disappointing, things would be far worse if these programs and their goals did not exist. I doubt the truth of this assertion. There is no evidence that ENERGY STAR and LEED-certified buildings are performing any better, on average, than other commercial buildings. These programs are pretty much a distraction from the important societal goals to reduce green house gas emission.
The 2012 CBECS data also put the EPA’s claims that ENERGY STAR benchmarking is saving energy into perspective. In 2012 the EPA published marketing literature which claimed that 35,000 buildings that used Portfolio Manager to benchmark for the consecutive years 2008, 2009,, 2010, and 2011 demonstrated a 7% reduction in source EUI over this same time period. The analysis is sophomoric because they literally average the EUI for these 35,000 buildings rather than calculate their total gross source EUI (as does CBECS) which is the sum of all their source energy divided by the sum of their gsf. It is entirely possible that the gross EUI for these buildings did not decrease at all while their average showed 7% reduction. The 35,000 buildings in the EPA study is dominated by office buildings — by far the largest set of buildings that use their benchmarking software. Hence their claim of 7% reduction in source energy over the three year period must be seen in a context in which all U.S. office buildings saw a reduction in source EUI of 12% over a 9 year period. There is simply little reason to believe that buildings that benchmark perform any better than those that don’t.
Once again real energy performance data cast doubt on energy savings claims for U.S. buildings.