Center for the Built Environment

Plug loads use 12% of site energy in U.S. office buildings. The relative importance of plug loads is rising and it is projected to increase more in years to come. We studied the predicted and simulated plug load energy consumption using data submitted to the U.S. Green Building Council for LEED certification. The study included 660 LEED for Commercial Interiors projects and 429 LEED for New Construction projects. This is the first study to analyze LEED submittal data related to plug load energy use. The submittal data from these projects was mined and statistically analyzed. The results show that 73% of the projects under LEED-CI that attempted the credit dedicated to plug loads earned 2 of 2 points available (90% or more of eligible equipment is ENERGY STAR rate). Additionally, we found that projects most frequently specify ENERGY STAR rated laptops, monitors, desktops and printers, whereas televisions, fax machines, refrigerators and dishwashers were less frequently specified. Under LEED-NC, the median peak plug load power intensity reported among the projects was 10.8 W/m2. Most of the projects complied with the LEED requirement of 25% process load energy use, with the median percentage being 25% and the 1st and 3rd quartiles ranging from 18% to 31%. 32% of the projects reported using eQUEST as an energy simulation tool. Only 5 of 429 LEED-NC projects reviewed attempted and were approved exceptional calculations for claiming energy savings on efficient plug loads or office equipment.