Rating System

LEED ID+C: Commercial Interiors, LEED ID+C: Commercial Interiors

Rating System Version

v2 - LEED 2.0, v3 - LEED 2009

Inquiry

The design of an 11,000 square foot library and offices in a new LEED NC building targeted low energy use and superior indoor air quality as two of its most important green building goals. From the beginning of design, our mechanical engineering team has prioritized efficient equipment to meet the E-Benchmark prescriptive criteria for efficiency requirements (EQc1.3 Option A point 1) and EQ credit 5 for high filtration media. We are limited by those requirements to a single proprietary mechanical system of water source heat pumps. As-built conditions in the space revealed that in order to fit our heat pump units in the available head heights, two units serving the Entry Lobby/Children\'s Room and Auditorium needed to be changed to split units. This split effectively reduces the EER and COP standards to slightly lower than the E-Benchmark standards. The total average of system efficiency by capacity remains well above the EER and COP E-Benchmark threshold requirements. These HP-2 split units are sized for a maximum occupancy load that will only occur several times a year in the Lobby and occasionally in the Children\'s Room and Auditorium. As it is not required for LEED-CI, we do not have an energy model to show annual expected use. However, since these split units are sized for a maximum capacity that does not occur regularly, we conclude that the actual average of system efficiency by usage will be much higher than the average by capacity which already meets the threshold. Unit AC-1/ Quantity 1 / Capacity 3 tons / EER=14.0/COP=5.0 Unit AC-2/ Quantity 1 / Capacity 2 tons / EER=18.1/COP=5.7 Unit HP-1/ Quantity 4 / Capacity 10 tons/ EER=16.0/COP=5.0 Unit HP-2/ Quantity 2 / Capacity 8 tons / EER=13.1/COP=4.5 Unit HP-3/ Quantity 1 / Capacity 2 tons / EER=16.5/COP=5.6 Average by capacity: EER=15.25/COP=4.91 E-Benchmark Standard: EER=14.00/COP=4.60 * * 2005 New Building Institute E-Benchmark Standard, Table 2.5.2 Unitary & Applied Heat Pumps, Electrically Operated, p. 69 We propose that we meet the intent of the credit to provide highly efficient HVAC units which meet a high standard, increase our level of energy conservation, and associated environmental impacts.