Consulting-Specifying Engineer - March 2008 - (Page 30)

showed that the heat pump system, along with two enthalpy energy-recovery wheels, kept RH within ASHRAE 55 comfort ranges. Because the school faculty actively use the operable windows in each classroom, they also have a reasonable expectation of RH levels in the classroom. Each classroom has a thermostat for both the ventilation air and the radiant heating slab. The school uses approximately 7.15 kWh/sq. ft/year. The building performs 60% better than ASHRAE 90.1-1999 requirements using the USGBC LEED Energy Cost Budget (ECB) methodology. Compared to 90.1-2004, the system is about 40% better. Because the energyanalysis software cannot model the radiant loop, it was ignored for their analysis. The analysis was based on climactic data for Chicago (Table D-1 of ASHRAE 90.1-1999) and the building envelope requirements prescribed in Table B-17 of ASHRAE 90.1-1999. Additional insulation: The U-value for exterior walls is 0.038 versus 0.089 allowed. Energy-recovery ventilation units: The building uses two units that have enthalpy wheels for air tempering, with two-speed control motors. The units are rated at 76% efficient. High-efficiency glazing: The assembly U-value for the windows and glass doors is 0.31 versus 0.63 allowed. High-efficiency heat exchanger: The building uses a geothermal well consisting of 36 vertical wells at an average of 175 ft deep. The energy cost budget model uses an air-cooled condenser for heat rejection. The cooling capacity of the system is estimated at 45 tons. High-efficiency terminal equipment: The classroom building’s heat pumps have an energy-efficiency ratio (EER) of 17.1 and a coefficient of performance (COP) of 3.5, versus code at EER of 9.3 and COP of 3.8. It also has a boiler efficiency of 80% for the baseline high-performance equipment. Variable speed drives: The fan motors on the classroom heat pumps have variable-speed electronically commutated motors. Input #220 at csemag.com/quickResponse 30 Consulting-Specifying Engineer • MARCH 2008 http://www.dual-lite.com http://www.dual-lite.com http://csemag.com/quickResponse

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Consulting-Specifying Engineer - March 2008 Contents Viewpoint Letters News M/E Roundtable Grade A HVAC When UPS and Gensets Have Issues Ignite Opportunities To Mentor Fire Protection Engineers Cooling People, Not Buildings Codes & Standards Case Study New Products Equipment Lifecycles Advertiser Index Green Space Pure Power Supplement Edison Institute Honors Recovery Efforts Canada Launches Clean Energy Software Climate Change Drives Increased Investment Critical Power for R&D Heating Calculations for Electrical Duct Bank Submetering for Energy Profiling New Products

Consulting-Specifying Engineer - March 2008

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