The Fourth Great American Lie

There is this standing joke about the three great Amercian lies:  1) “the check is in the mail;” 2) “of course I will respect you in the morning;”, and 3) well … let me skip the last one. I think it is time to add a fourth lie to the list — this green project will lower energy use.

In my last post I mentioned that my home town of Oberlin, OH recently purchased new, automatic loader trash/recycling trucks and spent an extra $300,000 so that three of them included fuel-saving, hydraulic-hybrid technology.  Town leaders claimed these trucks would save fuel and reduce carbon emissions.  Simple cost/benefit calculations using their cost and fuel savings figures showed that this was an awful investment that would never pay for itself (in fuel savings) and that the cost per ton of carbon saved was astronomical.

A few weeks ago I requested from the City fuel consumption data for the first six months of operation of the new trucks.  The City Manager and Public Works Director, instead, asked me to wait until after their July 6 report to City Council on the success of the new recycling program.  They both assured me that fuel usage would be covered in this report.  I was promised access to the data following their presentation.

Last Monday, in his presentation to Council, the Public Works Director highlighted data which showed that for the first six months of operation the City recycled 400 tons — as compared with the 337 tons it had recycled in the comparable period prior to acquisition of the new trucks.  This represents a 19% increase in recycling. Unfortunately there was no mention of fuel usage or savings.

Yesterday I obtained fuel consumption data from the Public Works Director for Oberlin’s new garbage/recycing trucks along with comparitive fuel data from previous years using the old trucks. The new trucks are on track to use 2,000 gallons MORE diesel fuel than were used by the old trucks, annually.  That’s right, not less fuel, but MORE fuel.  This is a 19% increase in fuel usage.  Gee what a surprise!

Soon the spin will begin.  City Adminisrators will point out that fuel usage would be even worse were it not for their $300,000 investment in the hybrid technology.  They will point out that the increased fuel usage is due to the new, automatic loading technology included in these trucks (though they failed to mention any expected increased fuel usage when the project was being sold to the public) — which enabled the use of larger recycling containers and the improvement in recycling.  What they will fail to tell us is that they could have achieved the same increase in recycling using the older style truck without automatic loaders.

This is the second recent City project for which the public has been mislead regarding expected enegy savings. The first was the LEED-certified Fire Station renovation.  This green building was supposed to save energy.  It, of course, is bigger and better than the building it replaced — oh yes, and it uses more energy.  But the increase in energy use wasn’t as much as it might have been because it was a green building.  Now we have the same result for the trash and recycle trucks.

Oberlin College is in the process of constructing a new, green hotel — called the “Gateway Project” as it will usher in a new era of green construction.  But people should understand, this new green hotel will use more energy than the old hotel —  it will be bigger and better, and its energy use won’t be as big as it might have been — and this should make us feel good.

And in the next few months Oberlin residents will be asked to approve additional school taxes to construct new, green, energy-efficient public school facilities.  But don’t be surprised when these new facilities actually use more energy than did the old ones.  Don’t get me wrong — they will be more energy efficient than the old facilities, but they will be bigger, and better and — use more energy.

This is the new lie — that our new stuff will use less energy than our old stuff.  But it isn’t true.  Fundamentally we want bigger and better stuff.  People like Donald Trump just build bigger and better stuff and proudly proclaim it.  But isn’t pallitable for most of us — we feel guilty about wanting bigger and better stuff.  So instead we find a way to convince ourseles that our new stuff will be green, it will lower carbon emission, it will make the world a better place — oh, and yes, it will be bigger and better.

We need our lies to make us feel good about doing what we wanted to do all along.  Don’t get me wrong — sometimes the check is in the mail and sometimes the green project does save energy.  But more often than not these lies are offered for temporary expediency,  And, of course, I really will respect you in the morning.

LEED Certification: intent, implementation, and results

Last week I had the opportunity to deliver the keynote address at the annual conference of the Ohio Public Facilities Maintenance Association (OPFMA) held in Columbus, OH.  Here is a link to the slides used for my presentation, LEED Certification: intent, implemenation, and results.

The thrust of my presenation was to discuss what we know about primary energy savings reduction in green house gas emission for LEED-certified buildings.  Despite the fact that there are roughly 11,000 U.S. commercial buildings certified before Jan. 1, 2013 under LEED New Construction (NC), Core and Shell (CS), Existing Buildings (EB:OM), and LEED for Schools — all LEED programs that address whole building energy use — we have published data from just 2% of these buildings.  This paltry amount of data is mostly gathered by voluntary submissions by building owners willing to share their energy data.  You can bet that such data are skewed towards the better performing buildings.

And even so, the data available show that, on average, LEED-certified buildings show no significant source energy savings or reduction in GHG emission relative to comparable, non-LEED buildings.  That was the thrust of my presentation.

Note that promoters of LEED certification continue to claim energy savings — but these claims are based on design projections not actual performance measurements.  For instance, promoters of Ohio’s Green schools claim 33% reduction in energy use.  But there has never been a study of energy used by Ohio’s LEED-certified schools to demonstrate this assumed savings.  Such claims of energy savings are based on “faith” not “fact.”

 

DC Benchmarking data show modest energy savings for LEED buildings

A few months ago Washington DC released its 2012 energy benchmarking data for private commercial buildings 150,000 sf and larger.  Credible energy and water consumption data for some 400 buildings were released, of which 246 were office buildings.  A recent article — stemming from the web site LEED Exposed — has claimed that these data show LEED buildings use more energy than non-LEED buildings.  Specifically it is claimed that LEED buildings have an average weather normalized source EUI of 205 kBtu/sf whereas non-LEED buildings have an average EUI of 199 kBtu/sf.   No details are provided to support this claim.

My students and I have cross-listed the DC benchmarking data with the USGBC LEED Project directory and identified 94 LEED-certified buildings in the 2012 DC benchmarking dataset — all but one being classified as office buildings.  The unweighted mean weather normalized source EUI for these 94 LEED certified buildings is 202 kBtu/sf.   The unweighted mean weather normalized source EUI for remaining 305 buildings is 198 kBtu/sf.  No doubt this is the basis for the claim that LEED buildings use more energy than non-LEED.  However, the difference is not statistically significant.

Moreover, the non-LEED dataset, in addition to 154 office buildings, contains 64 (unrefrigerated) warehouses and 90 multifamily housing buildings — all of which use significantly less energy than do office buildings.  The comparison of these two average EUI is not useful — just a meaningless sound bite.

It should also be noted that the unweighted mean EUI for a collection of buildings is an inappropriate measure of their total energy consumption.  The appropriate measure of energy consumption is their gross energy intensity — their total source energy divided by the total gross square footage.  This issue has been discussed in several papers [2008 IEPEC; 2009 Energy & Buildings].

Note that an apples-to-apples comparison of energy consumed by one set of buildings to that consumed by another requires that the two sets contain the same kinds of buildings in similar proportions.  When possible this is best accomplished by sticking to one specific building type. Since office buildings are far and away the most common in both datasets it makes sense to make an office-to-office comparison — pun intended. 

93 of the LEED-certified buildings are offices.  But many of these buildings were not certified during the period for which data were collected.  Some were certified during 2012 and others were not certified until 2013 or 2014.  Only 46 of the office buildings were certified before Jan. 1, 2012 and are then expected to demonstrate energy and GHG emissions savings for 2012.

The 2012 gross weather-normalized source energy intensity for the 46 LEED certified office buildings is 191 kBtu/sf.  This is 16% lower than the gross weather-normalized source energy intensity for the 154 non-certified office buildings in the dataset, 229 kBtu/sf.  These modest savings are real and statistically significant, though much lower than the 30-40% savings routinely claimed by the USGBC.

Note that similar savings were not found in 2011 or 2012 NYC energy benchmarking data. Analysis of these data showed that LEED-certified office buildings in NYC used the same amount of primary energy and emitted no less green house gases than did other large NYC office buildings.  So the 2012 results from Washington DC are significantly different.  It should be noted that NYC office buildings certified at the gold level were found to exhibit similar modest energy savings.  Perhaps this is a clue as to why Washington DC LEED buildings show energy savings.  More analysis is required.

For the last few years the USGBC has pointed to ENERGY STAR scores for LEED certified buildings as evidence of their energy efficiency.  While ENERGY STAR scores have two important characteristics — they use source rather than site energy and they are based on actual energy measurements — they simply do not have sound scientific basis.  The science has never been vetted, and my own analysis shows these scores are little more than placebos to encourage energy efficiency.  They certainly do not have any quantitative value.

So to summarize, in 2012 LEED offices in Washington used 16% less source energy than  did other office buildings in DC.  What this means and whether such savings justify the added costs of LEED are open questions.

USGBC Continues to “cherry pick” LEED energy data

At the 2007 GreenBuild Conference the USGBC released the results of their first major study of energy consumption by LEED-certified buildings.  Then they presented conclusions from the now infamous study conducted by the New Buildings Institute (paid for by the USGBC and EPA) which, based on data “volunteered by willing building owners” for only 22% of the eligible buildings certified under LEED NC v.2, concluded that LEED certified buildings, on average, were demonstrating the anticipated 25-30% savings in (site) energy.

NBI’s analysis and conclusions were subsequently discredited in the popular media by Henry Gifford and in the peer-reviewed literature by me [see IEPEC 2008 and Energy & Buildings 2009].  NBI’s analytical errors included:

  1. comparing the median of one energy distribution to the mean of another;
  2. comparing energy used by a medium energy subset of LEED buildings with that used by all US commercial buildings (which included types of buildings removed from the LEED set);
  3. improper calculation of the mean (site) energy intensity for LEED buildings and comparing this with the gross mean energy intensity from CBECS;
  4. NBI looked only at building energy used on site (i.e., site EUI) rather than on- and off-site energy use (i.e., source EUI).

To NBI’s credit they made their summary data available to others for independent analysis with no “strings attached.”  In the end even the data gathered by NBI, skewed towards the “better performing” LEED buildings by the method for gathering data, when properly analyzed demonstrated no source energy savings by LEED buildings.  LEED office buildings demonstrated site energy savings of 15-17% — about half that claimed by NBI, the difference being associated with NBI’s improper averaging method.  This site energy savings did not translate into a source energy savings because LEED buildings, on average,  used relatively more electric energy, and the off-site losses associated with this increased electric use wiped out the on-site energy savings.

The lack of representative building energy data was addressed in LEED v.3 (2009) by instituting a requirement that all LEED certified buildings supply the USGBC with annual energy consumption data for five years following certification.  Never again would the USGBC have to publish conclusions based on data volunteered by 1 in 5 buildings.  Expectations were high.

But what has this produced?  The USGBC has learned from their experience with NBI — not to hand over such an important task to an outside organization because you can’t control the outcome.  NBI’s analysis was scientifically flawed — but it was transparent, and such transparency gave critics ammunition to reach different conclusions.  Nowadays the USGBC simply issues carefully packaged sound bites without supplying any details to support their conclusions.  There isn’t even a pretense of conducting scientifically valid analysis.

Consider the most recent claims made by the USGBC at the 2013 Greenbuild conference, summarized by Tristan Roberts in “LEED buildings above average in latest energy data release.”  Roberts asserts the following:

  1. The USGBC has received energy data from 1,861 certified buildings for the 12-mos period July 2012 – June 2013;
  2. About 70% of these were certified through LEED-EBOM (existing buildings);
  3. 450 of these buildings reported their data through the EPA’s Portfolio Manager;
  4. the “building-weighted” (or un-weighted) average source EUI for these 450 buildings is 158 kBtu/sf;
  5. this average is 31% lower than the national median source EUI;
  6. 404 (of the 450) buildings above were eligible for (and received) ENERGY STAR scores;
  7. the average ENERGY STAR score for these 404 buildings was 85.

In addressing the above claims it is hard to know where to begin.  Let’s start with the fact that the USGBC only provides energy information for 450 (or 24%) of the 1,861 buildings for which it has gathered data.  Is this simply due to the fact that it is easier to summarize data gathered by Portfolio Manager than data collected manually?  If so I willingly volunteer my services to go through the data from all 1,861 buildings so that we can get a full picture of LEED building energy performance — not just a snapshot of 24% of the buildings which “self-select themselves” to benchmark through Portfolio Manager.  (The EPA has previously asserted that buildings that benchmark through Portfolio manager tend to be skewed towards “better performing” buildings and are not a random snapshot of commercial buildings.)

Next, consider the “un-weighted” source EUI figure for the 450 buildings.  This is a useless metric.  All EUI reported by CBECS for sets of buildings are “gross energy intensities” equivalent to the gsf-weighted mean EUI (not the un-weighted or building-weighted mean EUI).  This was a major source of error in the 2008 NBI report — leading NBI to incorrectly calculate a 25-30% site energy savings rather than the actual 15-17% site energy savings achieved by that set of LEED buildings.

Consider the assertion that the 158 kBtu/sf source EUI figure is 31% lower than the median source EUI (presumably for all US commercial buildings).  To be correct this would require the median source EUI for all US commercial buildings be 229 kBtu/sf.  This is rubbish.  The best way to obtain such a median EUI figure is from the 2003 CBECS data.  The Energy Information Administration (EIA) does not report source energy figures in any of its CBECS reports.  But the EIA does report site and primary electric energy used by buildings, and these may be combined to calculate source EUI for all 2003 CBECS sampled buildings.  This results in a median source EUI for the estimated 4.9 million commercial buildings to be 118 kBtu/sf.  If you instead restrict this calculation to all buildings with non-zero energy consumption you find these estimated 4.6 million buildings have a median source EUI of 127 kBtu/sf — way below the 229 kBtu/sf figure asserted by the USGBC.  This USGBC claim is patently false.  Of course the USGBC may be referring to the median source EUI of some unspecified subset of U.S. buildings.  By choosing an arbitrary subset you can justify any claim.  And if you don’t specify the subset — well, the claim is nothing more than noise.

What about the average ENERGY STAR score of 85?  Is this impressive?  The answer is no.  Even if you believed that ENERGY STAR scores were, themselves, meaningful, such an average would still mean nothing.  ENERGY STAR scores are supposed to represent percentile rankings in the U.S. building population.  Since there are 4.8 million buildings, by definition we would expect 10% of these (or 480,000) to rank in the top 10% and we would expect another 480,000 of these to rank in the bottom 10%.  That means that if 1,861 buildings are chosen at random from the building population, we expect 10% of these to have ENERGY STAR scores from 91-100.  Similarly, we expect 30% of these (or 558) to have ENERGY STAR scores ranging from 71-100.  Guess what — the average ENERGY STAR scores of these 558 buildings is expected to be 85.  Only those who are mathematically challenged should be impressed that the USGBC has found 404 buildings in its set of 1,861 that have an average ENERGY STAR score of 85.  If you cherry pick your data you can demonstrate any conclusion you like.

And, of course, these 1,861 buildings are not chosen at random — they represent buildings whose owners have a demonstrated interest in energy efficiency apart from LEED.  I would guess that the vast majority of the 404 buildings were certified under the EBOM program and have used Portfolio Manager to benchmark their buildings long before they ever registered for LEED.  LEED certification is just another trophy to be added to their portfolio.  No doubt their ENERGY STAR scores in previous years were much higher than 50 already.  What was the value added by LEED?

I openly offer my services to analyze the USGBC energy data in an unbiased way to accurately asses the collective site and source energy savings by these LEED buildings.  How about it Brendan Owens (VP of technical development for USGBC) — do you have enough confidence in your data to take the challenge?  Which is more important to you, protecting the LEED brand or scientific truth?

NYC LEED Office buildings underperform for second year straight

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.

Compare LEED31 with NYC1043 Source

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.

NYC Energy Benchmarking raises questions about LEED-certification

With growing concern over global climate change and the US Federal government frozen in political gridlock a number of U.S. cities have decided to unilaterally take action to reduce their own green house gas (GHG) emission.  Any serious effort to reduce GHG emission must involve the implementation of some kind of system to track energy consumption.  To this end these same cities have instituted Energy Benchmarking laws — laws that require building owners to annually submit energy consumption data (by fuel) to a designated agency that collects and processes these data.  The Institute for Market Transformation (IMT) has been instrumental in coordinating this effort.

The requirement is typically phased in over a couple of years — starting with municipal buildings, followed by large commercial buildings, smaller commercial buildings, and finally residential buildings.  New York City, Philadelphia, Washington DC, San Francisco, Austin, and Seattle were the first to pass such ordinances.  Minneapolis, Chicago, and Boston have all taken steps to follow suit.

Public disclosure of energy data is an important component of many (but not all) of these local ordinances.  New York City (NYC) is further along than other cities and last October released 2011 energy benchmarking data for commercial buildings that were 50,000 sf or larger — excluding condominiums.  Public benchmarking data were released for more than 4,000 large commercial buildings in the NYC’s five boroughs.  NYC, like many of the other cities engaged in benchmarking, utilized the EPA’s ENERGY STAR Portfolio Manager for gathering and processing benchmarking data.  Data released included building address, building type, total gsf, site energy intensity, weather-normalized source energy intensity, water usage, and total GHG emission.

The NYC benchmarking data included data for more than 1,000 office buildings.  Some of these buildings are certified green buildings, so would be expected to use less energy and have less GHG emission than other NYC office buildings.  These green buildings are not identified in the NYC Benchmarking data, but many may be identified by searching other data bases – such as the US Green Building Council’s LEED project database or the EPA’s list of ENERGY STAR certified buildings.

A few dozen LEED-certified office buildings have been identified in the 2011 NYC Benchmarking database.  (The full peer-reviewed paper is to be published in Energy and Buildings.)  Of these, 21 were certified before 2011 by new construction (NC), existing buildings operation and maintenance (EB:O&M), or core and shell (CS) LEED programs which address whole building energy use.  These 21 buildings constitute 21.6 million gsf.  Their 2011 source energy consumption and GHG emission has been compared with those for the other NYC office buildings with rather surprising results.  The LEED-certified office buildings, collectively are responsible for 3% more source energy consumption and GHG emission than other large NYC office buildings (adjusted for total gsf, of course).  The graph below compares source energy intensity histograms for the two building sets.

Source LEED-21 vs NYC 953pos

The graph shows that the difference in the mean source energy intensities of the two building sets is not statistically meaningful.  In other words, the source energy consumption and green house emission of these LEED-certified office buildings is no different from that of other NYC office buildings — no more and no less.

As of a few months ago there were something like 8,300 buildings certified under one of the LEED programs that claim to reduce whole building energy use.  Measured energy consumption data have been published for 3% of these (now about 250).  While many of these LEED buildings surely save energy, many do not.  Collectively the evidence suggests, that LEED certification does not produce any significant reduction in primary energy use or GHG emission.

Why then does the Federal Government — and other governments (including NYC) — require new government buildings to be LEED certified?   The Federal Drug Administration (FDA) would never certify a medical drug with so little scientific evidence offered — let alone require its use.  The standards here are inverted — apparently the Federal Government believes convincing scientific data must be offered to demonstrate that LEED-certified buildings do not save energy before they will change their policy.

No evidence LEED building certification is saving primary energy

This essay is reproduced from the July 2013 issue of APS News.

Buildings are responsible for 39% of our nation’s energy consumption and associated green house gas (GHG) emission and they use 72% of the nation’s electricity [1].  It has long been established that cost-effective improvements in energy efficiency has great potential to reduce primary energy consumption and GHG emission associated with buildings.   The American Physical Society first took up this topic in 1974 [2].  A more recent APS study confirmed the potential remains [1].  Despite forty years of building technology research and public policy efforts to promote energy efficiency the energy efficiency potential for buildings remains largely untapped.

The Environmental Protection Agency (EPA) began promoting building energy efficiency in 1993 as part of its ENERGY STAR (ES) program, introducing its ES building score in 1999 [www.energystar.gov].  This score is based on measured energy consumption and is supposed to represent a building’s energy efficiency percentile ranking with respect to similar buildings in the U.S. commercial building stock.  A score of 75, required for ES Certification, implies that the building uses less primary energy than 75% of similar buildings under similar operating conditions nationally.

In 2000 the US Green Building Council (USGBC) introduced its Leadership in Energy and Environmental Design (LEED) green building rating system [www.usgbc.org].  Unlike ES, LEED certification was not based on measured energy performance but rather on “points achieved” through a checklist of items included in the building design and/or design process – all intended to make the building “green” or more energy efficient.  Four levels of certification are awarded depending on the total number of LEED points achieved – Certified, Silver, Gold, and Platinum.

LEED’s contribution was to marry the substance of energy efficiency with the popular appeal of green design.  It was a brilliant marketing strategy and, since its introduction, LEED certification has far surpassed ES certification in popularity.  Today nearly every large organization owns one or more LEED-certified buildings and many institutions – particularly governmental – have mandated that all their future buildings must be LEED certified at the silver level or higher.

But do LEED-certified buildings actually save primary energy and reduce GHG emission? LEED certification has clearly captured the public’s fancy – not unlike organic farming or herbal medicines.  But also like these fields there is a woeful lack of scientific data supporting LEED’s efficacy.  And what little measured building energy consumption data there are have been gathered through a “self-selected” process that is clearly biased towards the “better-performing” buildings.  In these data proponents find evidence that LEED-certification is saving energy [3].  But careful analysis of even these biased data show that LEED-certified buildings, with regard to primary (or source) energy consumption and GHG emission, perform like other buildings – no better and no worse [4].

First consider the amount and quality of energy consumption data published for LEED-certified buildings.  The vast majority of energy savings claims are not based on measured building energy performance but rather on design team projections.  LEED points for energy savings are based on these design projections – providing incentive for the design team to produce optimistic energy projections and to construct an inefficient “baseline” model to which these are compared.  Studies show there to be little correlation between design energy projections and subsequent measured energy performance [3, 4].  These design projections demonstrate intent not accomplishment.

There are, however, a dozen or so published studies containing measured energy consumption data for LEED-certified buildings.  These collectively provide energy data for, at most, 229 buildings – roughly 3% of the 8,309 LEED buildings certified before 2012.  Only four of these studies appear in peer-reviewed venues (two of these written by me) – the rest are reports written by or paid for by the USGBC or organizations closely aligned with it.  Buildings included in these studies are unlikely to be representative of the larger population.  Building owners control access to their energy data.  Nature – galaxies, rocks, atoms – doesn’t care what humans learn from their experiments.  Buildings do – or rather, their owners and design teams do – they have a vested interest in controlling energy data for the building for which they have already enjoyed extensive green publicity.  Owners are unlikely to voluntarily disclose embarrassing energy consumption data.  In a many cases requisite meters are not even installed – rendering the question moot.

The largest and most-widely publicized of these studies, conducted by the New Buildings Institute (NBI) in 2008 for the USGBC, concluded that “… average LEED energy use [is] 25-30% better than the national average” [3].  But the APS Energy Efficiency Study Committee concluded that the LEED buildings in the NBI study used more energy per square foot than the average for all existing commercial buildings [1].  NBI’s conclusion – similar to those published by other studies, is obtained by 1) a mathematical error in calculating the gross energy intensity for the LEED buildings, and 2) focusing on site energy – energy used at the buildings while ignoring off-site energy losses associated with electric generation and distribution.

First consider the mathematical error.  A building’s energy use intensity (EUI) is the ratio of its annual energy use to its gross square footage (gsf) or total floor area (surrogate for building volume).  EUI is convenient for comparing the energy use of two similar buildings differing only in size.  The Energy Information Agency (EIA) similarly defines the gross energy intensity of a set of N buildings to be their total energy divided by their total gsf – mathematically equivalent to the gsf-weighted mean EUI of the N buildings.  The EIA’s Commercial Building Energy Consumption Survey uses this metric to characterize the energy use of subsets of the national commercial building stock [5].  In the NBI study – indeed, in most LEED building studies – energy used by LEED sets of buildings are characterized by summing their individual EUI and dividing N.  This unweighted or “building-weighted” EUI is unrelated to the total energy used by the buildings.  When this error is corrected we find the LEED buildings in the NBI study use 10-15% less energy on site as compared with other buildings [4].

But energy used on site – called site energy – is only part of the story.  Site energy fails to account for the off-site losses incurred in producing the energy and delivering it to the building – particularly important for electric energy that, on average, is generated and distributed with 31% efficiency [1].  The EPA defines source energy to account for both on- and off-site energy consumption associated with a building; building ES scores are based on source energy consumption.  When you compare the source energy consumed by the LEED buildings in the NBI data set with that of comparable non-LEED buildings you find no difference – within the margin of error [4].

How do we understand these results?  First, LEED-certified buildings, similar to other new or renovated buildings are showing a modest reduction in energy used on site.  But these buildings are relying more on electric energy – and the off-site losses in the electric power sector are offsetting any savings in site energy.

The other issue is that larger buildings tend to have higher EUI than smaller buildings.  This may seem counter-intuitive since energy use in simple buildings (like houses) is dominated by surface losses/gains (windows, insulation, etc.).  But energy use in large commercial buildings is driven by internal loads – equipment, people, and lighting.  Large office buildings are typically air-conditioned year-round.  This is seen nationally as well as in LEED-certified buildings.  Roughly 5% of the nation’s commercial buildings account for half of the gsf of the building stock – and an even larger fraction of primary energy consumption [5].

In recognition of the need for actual performance data the USGBC has required all buildings certified under its 2009 version of LEED to measure and report annual energy consumption data to the USGBC for five years following certification.  And, for its Existing Buildings program – which targets renovated buildings – the USGBC has adopted the ES building rating system as its method for determining energy efficiency points – for the first time rewarding measured energy performance.

But these changes have not yielded convincing scientific data that demonstrate energy savings for LEED.  More than 2,400 buildings have been certified under LEED 2009 – with 711 of these certified before 2012.  Yet the USGBC has released no scientific report analyzing the energy data they have collected.  Instead they “cherry-pick” the data to create clever marketing sound bites that have no scientific value.  A USGBC press release last November claimed their data reveals that 195 LEED certified buildings received ES scores averaging 89 – demonstrating a 43% energy savings [6].  So what – presumably a million (of the 5 million) buildings in the commercial building stock have an “average” ES score of 89.  Scientists should not be impressed.  Moreover, while the source energy savings of a single building may be inferred from its ES score it is mathematically impossible to determine the energy savings for a collection of buildings from their average ES score (unless they all are identical in size and function) – hence the claim of 43% energy savings is unjustified.

These days the USGBC points to the high ES scores of its Existing Buildings program as evidence of energy savings for this program.  But the “value added” by LEED-certification is not established by comparing the certified building’s ES score to 50 – the presumed mean for all US buildings – it is found by comparing its ES score to those of similar, newly-renovated buildings that did not use the LEED process.  Any newly-renovated commercial building (LEED certified or otherwise) ought to see reduced energy consumption owing to cost-effective efficiency upgrades in lighting and heating, ventilation, and air-conditioning equipment.  Moreover, many of the buildings certified under the LEED Existing Buildings program have previously been certified by ES with scores significantly higher than 50.

The lack of energy consumption data for LEED and other commercial buildings is soon to change.  Six of our nation’s largest cities have passed ordinances requiring all commercial buildings to annually submit their energy consumption data into the ES system for subsequent municipal use.  New York City is the first such city, and last fall it made public 2011 energy consumption data for some 4,000 buildings of 50,000 sf or larger – and this list included nearly 1,000 office buildings of which 21 were identified as LEED certified.  These data clearly show there to be no statistically significant difference between the source energy consumed by or GHG emitted by LEED certified buildings as compared with other large NYC office buildings.  It should be noted that LEED office buildings certified at the Gold level and higher did outperform other office buildings.

At present there simply is no justification for governments mandating LEED building certification – using public dollars to subsidize a private enterprise with no scientific data to demonstrate efficacy in lowering primary energy consumption or GHG emission.  The problem is that LEED does not require public disclosure of energy consumption data and it does not have a mandatory energy performance requirement.  LEED certification clearly delivers green publicity but there is no evidence for primary energy savings, except possibly at the highest levels of certification (Gold and Platinum).  The USGBC could implement changes that would result in substantive savings – but this might negatively affect “sales of their product.”  We need to stop awarding buildings green publicity at the front end of a project and, instead, save the accolades for demonstrated reduction in GHG emission and primary energy use.

References

1.   Burton Richter et al. , “How America can look within to achieve energy security and reduce global warming,” Reviews of Modern Physics, Vol. 80, no. 4, S1 (Dec. 2008).

2.   Walter Carnahan et al., “Efficient Use of Energy,” American Physical Society, 1974.

3.   C. Turner and M. Frankel, 2008, “Energy Performance of LEED for New Construction Buildings – Final Report,” New Buildings Institute, White Salmon, WA.

4.   John H. Scofield, “Re-evaluation of the NBI LEED Energy Consumption Study,” Proceedings of the International Energy Program Evaluation Conference (IEPEC), Portland, OR, Aug. 12-15, 2009, pp. 765-777.

5.   See http://www.eia.gov/consumption/commercial/

6.   http://www.usgbc.org/articles/new-analysis-leed-buildings-are-top-11th-percentile-energy-performance-nation