Geothermal heat pump systems can provide as much as a 50% reduction in annual energy costs

Ten years ago, the theory of high performance green buildings was hard to define and the practice even more obscure. However, the building industry is undergoing rapid change. According to one estimate, since 2000, as many as 5% of all new construction projects in the United States have registered for certification under the LEED (Leadership in Energy and Environmental Design) Green Building Rating System developed by the U.S. Green Building Council (USGBC). According to some estimates, a building's HVAC system accounts for about 30% of the annual building energy cost in northern climates, and almost 50% of the annual building energy cost in warm, humid climates. Therefore, HVAC efficiency improvements can go a long way towards reducing the overall life-cycle costs of an HVAC system. A geothermal heat pump (GHP) system is an extremely energy-efficient HVAC system that can provide as much as a 50% reduction in annual energy costs as compared to a conventional system, e.g., oil-fired boiler and cooling tower/chiller system. A GHP is a single, electric-based mechanical system used for heating and cooling that relies on the earth materials below the building (soil, rock, groundwater) as a heat source and sink. P. W. Grosser Consulting has been involved in numerous LEED-certified or registered new construction projects that have incorporated GHPs. The main LEED category applicable to GHPs is the Energy and Atmosphere category (EA), for both New Construction and Existing Buildings. LEED-NC rewards energy efficiency in two ways under the EA category. First is a prerequisite for meeting the ASHRAE Standard 90.1-2004 minimum requirements for energy efficiency. Secondly, LEED rewards projects that exceed these minimum requirements and "optimize energy performance." Up to 10 points could be achieved in Credit 1 of EA category, depending upon the percent savings in the design energy cost over the performance baseline (LEED Version 2.2; note LEED Version 3.0 is now in effect and has a modified point system). The major heat pump manufacturers recognize the part that GHPs can play towards earning LEED credits, and each has developed supporting literature. ClimateMaster claims that their top-of-the-line GHP is 30% more efficient than ASHRAE 90.1 minimums, thus can add 6 points for existing construction or 4 points for new construction, and other ClimateMaster equipment selections can add between 1 and 4 points (LEED Version 2.2). Actual building energy savings data developed by McQuay showed percent energy cost savings ranging from 9.4% (Chicago) to 15.8% (Philadelphia) over ASHRAE Standard 90.1 minimums, for a baseline packaged variable air volume (VAV) rooftop HVAC system. These percent savings would earn 1 or 2 points under EA Credit 1 (LEED Version 2.2). It should be noted that the HVAC system selection alone does not account for all of the possible credits under the EA category. Other design elements including the lighting, envelope construction, and other electric loads and efficiency measures, together with supporting modeling and analyses, determine the total credits that are achieved. There are significant other aspects of using GHPs that contribute towards a project's sustainability but do not currently earn specific credits under LEED. For example, the major heat pump manufacturers are committed to using non-HCFC refrigerants, and the use of GHPs reduces consumptive water demands of a cooling tower system. USGBC excludes GHPs as a renewable energy source, e.g., solar, wind, CHP, etc. under EA Credit 2. PWGC and others in the industry are not in agreement with this determination, and it will no doubt be challenged in the future now that GHPs have been designated as "energy property" by the federal government, under the same category as other renewables. John Rhyner, PG, LEED AP, is senior project manager for P.W. Grosser Consulting, Bohemia, N.Y.