Validating electric use intensity in multi‐use buildings

In the Poudre School District of Northern Colorado, USA, Fort Collins High School (FCHS) and Fossil Ridge High School (FRHS) have similar square footages, mechanical systems, and architectural capacities. While FRHS (built 2005) is leadership in energy and environmental design (LEED)‐Silver and Energy Star (2009) certified, FCHS (built 1995) is not. Despite the sustainable features of FRHS, the whole‐building electric use intensities (EUIs) were comparable for the schools. The purpose of this paper is to evaluate electricity consumption and use patterns at these schools.

To investigate whole‐building EUI and identify areas of high consumption, the buildings were divided into workspaces for which workspace‐specific EUIs were calculated and compared. Further, workspace EUIs were partitioned into their heating ventilation and air conditioning (HVAC), lighting, plug load, food service and residual components for analysis.

Significantly, more electricity is used for lighting and HVAC at FCHS (44.04 and 33.16 per cent of total, respectively) compared to FRHS (36.90 and 29.17 per cent of total, respectively). However, plug load consumption accounted for 24.99 per cent of electric use at FRHS but only 16.35 per cent at FCHS. Component EUI analysis identified high‐wattage lighting at FCHS and high computer density at FRHS as areas for possible efficiency improvements.

Whole‐building EUI values are most useful for comparing energy performance of buildings dedicated to a single use. Workspace‐to‐workspace EUI comparisons offer improved energy performance indicators for facility managers. Component EUI analysis identifies specific consumptive activities which should be targeted for potential reduction in electricity use and expenditure.

Workspace and component EUIs provide for more insight than whole‐building EUI when comparing electric consumption of multi‐use facilities.