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comment Updated Guide Shows the Way to Cost-Effective Energy Optimization
In July 2007 the New Buildings Institute (NBI) released its Advanced Buildings Core Performance Guide. The guide describes a series of energy-efficiency measures, selected by the NBI using a comprehensive energy-modeling exercise, as the most cost-effective ways to achieve 20 to 30 percent energy savings in buildings throughout the U.S.
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This guide supplants the Advanced Buildings Benchmark, originally published in 2003, which has been used by participating utilities as the basis for providing financial incentives to customers that implement energy conservation measures. Benchmark was also cited by the U.S. Green Building Council (USGBC) in its LEED rating system as a means by which buildings could qualify for an energy optimization credit without energy modeling. The new Core Performance Guide is updated to the 2004 version of ASHRAE Standard 90.1 (American Society of Heating, Refrigerating, and Air Conditioning Engineers) and simpler in structure, with a refined set of criteria based on more sophisticated and extensive energy simulations.
The release of Core Performance was well timed, given USGBC’s June 2007 announcement of a new requirement in LEED that all projects earn at least two energy optimization points. With this requirement in effect, the Advanced Buildings Benchmark is no longer relevant in LEED. At press time, the USGBC had not yet ruled on how many points would be awarded to projects following Core Performance, but “we have a strong argument for two points, and a pretty strong argument for three,” said Mark Frankel, technical director at the NBI and author of the guide. “Of the 186 permutations of building types, prototype systems, and climate zones, only three—all retail buildings in humid climates—are below 20 percent energy savings,” Frankel noted. LEED requires a 17.5 percent energy cost reduction from the ASHRAE 90.1-2004 baseline to earn three points, and 21 percent to earn four.
The other option for achieving energy optimization points in LEED without undertaking energy modeling, based on ASHRAE’s Energy Design Guide for Small Office Buildings, provides four points but is restricted to office buildings up to 20,000 square feet in size. The Core Performance measures apply specifically to office, retail, education, and public assembly buildings between 10,000 and 70,000 square feet in which glazed areas do not exceed 40 percent of gross wall area. Most of the measures themselves, especially the ones affecting building-envelope performance, are applicable in larger buildings as well, according to Frankel.
There are two sets of criteria in Core Performance: the first addresses design process strategies, and the second addresses the building’s envelope, lighting, and mechanical systems. Based on energy modeling, “these required criteria are predictably significant in every climate,” says Frankel. A third section lists additional energy-saving measures that the NBI recommends considering, even though they are not cost-effective in all circumstances. Core Performance is not a complex model for projects seeking to achieve exemplary energy performance, but rather “simple guidelines for use on simple buildings to do a much better job than they are currently doing,” according to Frankel. “We’re just trying to show how state-of-the-shelf technology can get you much better buildings than are required by code.”
For more information:
New Buildings Institute
White Salmon, Washington
509-493-4468
www.advancedbuildings.net
This article was produced by BuildingGreen, Inc.- www.buildinggreen.com
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