The City of Ottawa’s environment committee recently raised questions about the value of pursuing LEED green building certification for City buildings. While it appears the City will not immediately stop pursuing LEED certification for City buildings, the question remains: do LEED buildings offer better value than their conventional counterparts to Ottawa taxpayers? A study out of the National Research Council (NRC) quantified one of the chief advantages of LEED buildings: improved energy efficiency.
The NRC study examined energy-use data from 100 LEED-certified commercial and institutional buildings in North America. These data were then compared to conventional building energy-use data from the Commercial Building Energy Consumption Survey (CBECS) out of the US. Comparisons were made across similar occupancy types, building age, and climate zones. Some of the study’s key findings are:
- The average LEED building uses 18-39% less energy than the average conventional building.
- 28-35% of LEED buildings use more energy than their conventional counterparts.
- The LEED certification level (and number of energy credits achieved) is a poor indicator of actual energy consumption of LEED buildings.
While some work clearly remains to be done to ensure more predictable performance from LEED-certified buildings, pursuing certification does appear to yield tangible energy cost savings.
Using the report results, an estimate of the annual cost savings resulting from improved energy efficiency can be made. From the report, the median LEED building energy use intensity (EUI, in kBtu/sq-ft) is 68.1 kBtu/sq-ft, while the median conventional building EUI is 97.7 kBtu/sq-ft, for an annual EUI savings of 29.7 kBtu/sq-ft. Using the study’s average building floor area (110,930 sq-ft), the median LEED building saves 3470 GJ of energy per year. Assuming natural gas and electricity consume 40% and 60% of overall building energy use respectively, with equivalent charges (including commodity, distribution, transportation fees and taxes) of $0.20/cu-m and $0.10/kWh, the average LEED building in the study saves approximately $65,000 in energy costs per year.
The annual energy cost savings are an order of magnitude higher than the LEED certification fee ($2,000). While this is obviously a very rough estimate, it nevertheless suggests that the energy cost savings alone are sufficient to justify pursuing LEED green building certification to the Ottawa taxpayers.