AEC Tech News #131 (November 4, 2004)3 Nov, 2004 By: Michael Dakan
Going GreenCosts of LEED Compliance are Generally Low, Concludes GSA Report
The U.S. GSA (General Services Administration) released a
report in October on the construction costs
associated with LEED (Leadership in Energy and Environmental
Design) Green Building Rating System certification at
various levels of compliance. GSA owns and leases more than 8,300 facilities that serve more than one million federal
employees and is one of the largest building owners and
managers in the nation. The agency requires all new
construction, major renovation, and modernization
projects to be certified through the LEED program, with
project teams strongly encouraged to achieve LEED Silver
GSA commissioned this latest report to update its understanding of green building costs and to align its cost assumptions with the latest LEED criteria, according to the agency. The report was prepared by Steven Winter Associates of Norwalk, Connecticut, and Washington, D.C., with the assistance of Skansa USA for cost estimating. Several architectural organizations contributed to the soft costs portion of the report.
The study, which spans 578 pages, examined two building types and several design scenarios for each type. It evaluated current, typical GSA projects: a new midrise courthouse building of approximately 250,000 ft² and a 300,000-ft² midrise federal office building modernization project. These types of projects represent a significant percentage of the building capital projects the GSA expects to commission over the next five years.Hard Costs vs. Soft Costs
The study evaluated separately the hard costs (construction) and soft costs (design and documentation) for the three levels of LEED certification: Basic Certification, Silver Certification, and Gold Certification. To bracket the LEED costs, two estimates were prepared for each level of certification to reflect a low-cost and a high-cost range of values. Buried within the details of the report are estimated values assigned to each LEED prerequisite and credit item for each of the six design scenarios.
As you might expect, the widest range of cost estimate variations was found in the scenarios for the office building renovation. The study evaluated two scenarios: the low-cost scenario included only minimal facade changes and window replacement, and the high-cost scenario anticipated a complete facade redesign, new windows, and insulation. All design scenarios anticipated existing GSA design requirements and criteria, which are very stringent and exceed LEED Basic Certification requirements in some cases. No incremental cost increases for any of the LEED certification levels were included in the estimates for the LEED points items already covered by existing GSA design criteria.
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I didn't find any big surprises in the study results. Incremental cost increases above the baseline estimate for existing GSA design requirements ranged from almost negligible for Basic Certification for new construction to around 8% at the highest Gold Certification level.
Other factors in the cost estimates outside LEED certification were much more significant. For instance, the facade portion of the office building renovation scenarios used "minimal facade renovation" for the low-cost scenario, and "full facade redesign," including new windows and insulation, in the high-cost scenario. In this context, the cost for LEED certification is pretty much insignificant except at the Gold level. Further, the report cautions throughout against trying to extrapolate the results to any building types or design criteria outside the narrow definitions outlined for GSA work. The authors state that the cost estimates reflect a number of GSA-specific design features and project assumptions, and therefore may not be directly transferable to other project types and building owners.
Evaluating LEED Compliance
The report also included a recommended method for evaluating LEED compliance, which is pretty much common sense and is the approach that most architectural organizations currently use. First, take the credits that don't cost extra and are accomplished easily. Such credits include those that are built into current GSA design criteria and assumptions.
Next, evaluate the low-cost credits that are readily accomplished at minimal additional cost and have a high LEED credit value. Then move progressively into higher-cost items and lower point values. There is no correlation between LEED credit values and costs, and many no-cost or low-cost items have the same LEED point value as very costly design options. For instance, none of the cost estimates evaluated included the LEED credit for power generated using renewable resources, such as solar and biomass, because this must be evaluated on a building-specific basis and must include other criteria beyond strictly economic payback.
Dig Deep for Relevant Details
I was a little disappointed that the report didn't have more general applicability to other building types and situations, but I guess it's appropriate that a report commissioned by the GSA would concentrate on GSA requirements foremost and ignore other interests. Still, a lot of interesting, worthwhile information is buried in the report details, but it's up to individual readers to draw their own conclusions about what the details mean to them and their practices.
I found my copy of the full report on the Whole Building Design Guide Web site, at http://www.wbdg.org/media/pdf/gsa_lcs_report.pdf.