The goal of the Real Property Association of Canada’s (REALpac) 20 by ’15 initiative is to reduce the average energy intensity in Canadian office buildings to 20 equivalent kilowatt-hours (ekWh) per rentable square foot by 2015. What are the challenges of establishing a straightforward, consistent energy intensity target in the building sector?

A fundamental challenge is agreeing on a unit of measure for energy intensity. In Canada, equivalent kilowatt-hours (ekWH) per square metre and gigajoules per square metre (GJ/m2) are usually seen. In the U.S., it is most frequently expressed as thousands of British thermal units per square foot (kBtu/ft2), though it’s possible to get a dimensionless “score” that indicates where a building lies within the range of energy intensities of its peers.

There are also many ways of defining floor area. Traditional energy benchmarks are based on gross floor area. Energy Star uses a modified form of gross floor area, while 20 by ’15 is based on rentable floor area. This may lead to some discrepancies between private and public sector office buildings since rentable floor area may not be so relevant in public buildings.

Adjusting for other atypical building usage (for example, atria, indoor versus outdoor parking, data centres and 24-hour call centres) is also an issue.

Michael Lithgow is the manager of corporate energy services at the Regional Municipality of York.