The ever-expanding array of computers and IT-related equipment in most offices has prompted ASHRAE’s new standard to aid building system design. While electrical plug loads are undeniably rising in commercial buildings, energy management experts stress that office equipment isn’t necessarily producing as much heat as cooling system designers presume.

“Most plug loads operate at a fraction of their nameplate electrical load so, as a result, produce significantly less heat load than engineers may use in their cooling load calculations based on those nameplate values,” explains Glenn Friedman, chair of the committee advising on ASHRAE/ANSI Standard 203-2014, which sets out methods for determining true heat gain from office equipment. “This can result in over-sizing of air-conditioning equipment, resulting in extra initial cost for that equipment, as well as higher operating cost.”

Development of the new standard follows ASHRAE-funded research to test methods for measuring power consumption and heat output from office equipment — an ongoing challenge given the steady growth in new types of products and changes in equipment design. Plug loads can account for 20 to 50 per cent of an office building’s energy consumption.