to design and construct high-performance or green buildings. Actual incremental construction cost data for both LEED-certified and Green Globes-certified buildings were not available. To generate the incremental construction cost data, which are essential to calculations of NPV benefits, the consultant used two methods. The total cost of a building that is not LEED-certified or Green Globes-certified (a baseline building) was calculated using square foot data gathered from R.S. Means. For the LEED-certified and Green Globes-certified buildings, the consultant used the actual costs of construction for entire buildings, which were then adjusted based on an assumption that 35 percent of the project costs were attributable to architect and engineering fees and other costs. The committee notes that for the purpose of calculating the cost of energy, water, and green systems, the R.S. Means square foot data cannot be directly compared to the cost of actual buildings, because the R.S. Means data make assumptions about building configurations, while actual buildings have specifics. There can be many differences between an actual building and a prototypical building used by R.S. Means in the square foot tabulations that are not attributable to water, energy, or green systems. If the specifics of the actual building are unknown, the comparison can be significantly skewed.

Second, to conduct the analyses of cost-effectiveness for ASHRAE standards 189.1-2011 and 90.1-2010, the data provided by ASHRAE were the same data used in the models run for the development of those standards. The source of the data, therefore, did not allow for an independent verification of the cost-effectiveness of those standards.

The committee was particularly concerned about the estimated NPV benefits attributable to water savings associated with ASHRAE 189.1-2011, which the committee believes would be very difficult to achieve absent extraordinary measures that may not be cost-effective for DOD.

Third, the consultant used estimated data assembled by ASHRAE staff for the ASHRAE standards analysis. The consultant used a combination of data from actual buildings and estimated data (R.S. Means square foot data) for the analysis of the green building certification systems. The use of data from such different sources makes it difficult to compare the cost-effectiveness of the ASHRAE standards to the cost-effectiveness of the LEED and Green Globes green building certification systems.

The lack of actual incremental cost data calls into question the consultant’s calculations for incremental costs and, therefore, it calls into question the consultant’s findings related to NPV benefits. As noted in Finding 3, the studies analyzed in the committee’s review of the literature indicate that the incremental construction costs for LEED-certified buildings are significantly lower than the incremental construction costs estimated by the DOD consultant. The NPV benefits calculated by the DOD consultant would likely have been higher if the consultant had used the average incremental construction costs from those studies.

As a consequence, the committee cannot support the consultant’s findings related to the absolute NPV benefits calculated for the ASHRAE standards, LEED, or Green Globes.

Finding 5. The evidence from the literature search indicates that high-performance or green buildings can result in significant reductions in energy use and water use. The cost savings associated with the reductions in energy and water use will vary by geographic region, by climate zone, and by building type.

Thirteen of the 25 studies evaluated focused on measured actual energy use in buildings based on utility bills. Despite a wide variation in baselines, sample sizes, types of buildings, methodologies, and geographic distributions, all 13 studies found that high-performance or green buildings, on average (i.e., over a group of buildings), used 5 to 30 percent less site energy than similar conventional buildings.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement