In September 2012 NYC released public data for its first year (2011) of energy benchmarking for large (> 50,000 sf) commercial buildings. This list included data for roughly 1,000 office/financial buildings. (Note that the EPA ENERGY STAR building rating system makes no distinction between large office buildings and financial centers — henceforth referred to as office buildings.) These data were cross-listed with the USGBC LEED project database to identify a subset of 21 LEED office buildings (totaling 24.5 million sf) that were certified before 2011 in one of three LEED programs that should impact energy consumption and green house gas emission — New Construction (NC), Existing Buildings (EB) and Core & Shell (CS). The energy consumption and GHG emission of these LEED-certified buildings were compared to those for other NYC office buildings and found to be unremarkable. Specifically, LEED certified office buildings showed no reduction in GHG emission or energy consumption as compared with other NYC office buildings. This work was summarized previously. The peer-reviewed publication detailing this work, “Efficacy of LEED-certification in reducing energy consumption and greenhouse gas emission for large New York City office buildings” is published this month in Buildings and Energy Journal.
In October this year NYC released a second year of benchmarking data (2012). This year’s public disclosure includes buildings classified as condominiums (exempted last year) such as the New York Times building (with two owners). The question arises — how are LEED-certified office buildings doing in year two? For 2012 we can now include LEED buildings certified in 2011 (buildings excluded from those studies last year because they were not certified for the entire 2011 year for which energy data were gathered) — in principal yielding an even larger set of LEED-certified buildings.
The 2012 NYC benchmarking data includes energy and GHG emission data for 32 large LEED-certified office buildings (totaling 37 million sf). Collectively these buildings have a gross (weather normalized) source energy use intensity (EUI) of 252 kBtu/sf and a gross site EUI of 104 kBtu/sf. There GHG emission collectively is 8.9 kg/sf of CO2. However, the means are skewed by the inclusion of just one building — the Bank of America Tower. This building was also omitted from the previous analysis of 2011 LEED office data. Omitting this “energy-guzzler” the remaining 31 LEED certified office buildings have a gross (weather normalized) source energy EUI of 245 kBtu/sf and a gross site EUI of 98 kBtu/sf.
When you compare these numbers with the 2011 data for the 21 LEED buildings included in last year’s study you find that, this year, LEED office buildings showed 8% reduction in site energy, 7% reduction in source energy, and 9% reduction in GHG emission. But are these changes significant and, if so, is this progress to be credited to the LEED buildings?
It turns out that all of these reductions are significant, though probably not at the 95% confidence level (have not completed that calculation). The uncertainties in the gross site and source EUI for LEED buildings is 6% which means these reductions are slightly higher than “the noise.”
To determine whether these reductions are to be credited to the LEED buildings we need to look at similar numbers for conventional NYC office buildings. The 2012 gross site and source EUI for the roughly 1,000 NYC office buildings are 92 and 230 kBtu/sf, respectively. Comparing these to the energy data for the LEED offices we see that in 2012 LEED buildings used 7% more site energy and 6% more source energy than did conventional office buildings (on a per sf basis, of course). Comparing their gross GHG intensities for 2012 we see that the 32 LEED certified office buildings are responsible for 8% more GHG emissions than conventional NYC office buildings. The source EUI for the two building sets are compared in the figure below.
Bottom line, for the second year in a row LEED-certified NYC office buildings show no energy or GHG savings as compared with other NYC office buildings. In fact they use more energy and emit more GHG than other NYC office buildings (on a per sf basis, of course). These differences are more statistically significant than those between the LEED 2012 and 2011 performances — but need to be nailed down with further calculations.
When you compare the 2012 energy and GHG performance of all NYC office buildings with their performances in 2011 we an average decrease in Site EUI, Source EUI, and GHG emission of 11%, 10%, and 8% respectively. In other words, the 2012 improvement in LEED performance simply tracks that for other NYC office buildings. As they say, “all boats rise with the tide” — or in this case, go down with the tide.
The good news out of the 2012 Energy Benchmarking data is that all NYC office buildings made progress in lowering their GHG emission. This is likely associated with the steady replacement of coal with natural gas at electric generating plants. The abundance of natural gas released by fracking is most definitely lowering the carbon content of NYC’s electric supply. A recent article by Alexis Madrigal describes greater advances yet to come in this area.
There is one more interesting fact about LEED office buildings included in the 2012 NYC benchmarking data. Five of the 21 LEED office buildings who reported 2011 benchmarking data (the basis for my earlier study) are noticeably missing in the 2012 public benchmarking disclosure. That means that these five building owners either 1) elected to pay the modest fine to NYC for failure to comply with LL84 or 2) have convinced the city to exempt them from mandatory benchmarking. Either way this does not bode well for the future of energy transparency. The USGBC has been collecting annual energy data for buildings certified under its v2009 and later yet publishes none of these data — only selected statistics as part of its marketing literature. I think we all know what it means when someone invokes the “fifth amendment” and refuses to testify. The same applies here to refusal to disclose energy data. It is a good be that owners of really efficient buildings are not refusing to disclose their data.
I should also mention that Luke Rosiak of has published an article in the Washington Examiner regarding what the 2012 NYC Energy Benchmarking data have to say about the performance of LEED buildings as compared to other NYC buildings. He focuses on Site EUI (rather than Source EUI) and also looks at the relationship between the number of LEED points awarded and Site EUI. He finds negative correlation — in other words, the buildings that score higher LEED points tend to use relatively more site energy!
A special thanks to Oberlin College student Marisa Aikins for doing most of the work in cross-listing the NYC 2012 benchmarking data with the LEED project database.