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Charlotte’s First Green Public Building Using Double the Energy Predicted by LEED Model

According to a recent energy study that was prompted by an inquiry from the Charlotte Observer, Charlotte, North Carolina’s ImaginOn library building is using twice as much energy as predicted by the project’s LEED Version 2.0 for New Construction energy model. The $41 million project was completed back in 2005, earned LEED Silver on April 29, 2006, and both satisfied LEED-NC Version 2.0′s Minimum Energy Performance Prerequisite No. 2 under the Energy & Atmosphere credit category and earned 4 points under Credits 1.1 and 1.2, Optimize Energy Performance (by 30 percent over the energy cost budget for regulated energy components as described in ASHRAE/IESNA Standard 90.1-1999).

Factors that the study identified as responsible for the increase included:

  • The building averages 450,000 visitors per year, not the 300,000 anticipated by the model;
  • Its two theaters operate for 7 hours daily, not the 2 hours anticipated by the model; and
  • Office space is used 7 days a week, not 5.

According to a spokesperson quoted in the Observer article, the library did not track its energy consumption “due to the cost.” Rather, it was “a reflection of [the library's] faith in the LEED certification process that [it] did not go back and second-guess the efficiency of the equipment.” As the Observer notes, the building’s increased energy requirements are, in some sense, due to its own success. However, as ASHRAE Fellow and Distinguished Lecturer Larry Spielvogel, P.E. pointed out in a letter to the New York Times which we reproduced here at GRELJ last summer, “[b]uildings alone do not use energy. The occupants, operators, and systems do.” The factors driving ImaginOn’s performance gap are another example of why the type of predictive energy modeling on which LEED relies is so imprecise and why project teams need to remain careful about the types of representations they make to their clients about the performance-related results of potential LEED certification.

I also think it is also useful here to emphasize again that, under LEED 2009, this type of performance gap would not be the basis for a LEED 2009 decertification proceeding. Rather, the decertification discussion which was so heated last summer related to LEED 2009 projects which fail to commit to sharing performance data or to satisfy any of the other new Minimum Program Requirements- not if projects simply use more energy than anticipated.

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3 Responses to Charlotte’s First Green Public Building Using Double the Energy Predicted by LEED Model

  1. B. Carson February 12, 2010 at 6:44 pm #

    Great post; users matter most.

    Not to be nit-picky, but couldn’t the performance data be used as evidence of a design or construction flaw that could cause a decertification under a different MPR or under the Certification Challenge policy?

    I’m pro USGBC, but the Supplemental Guidance v 1.0 released in November didn’t categorically rule it out, it just said “does not intend to penalize project teams with buildings that do not perform as well as intended.” I’m cynical by training, but “does not intend” does not get me comfortable enough. Love to hear your thoughts on this.


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