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On Track toward the 20 by '15 Target
June 9, 2011
Normalization Methodology Key to Establishing Meaningful Baseline
In September 2009, the Real Property Association of Canada (REALpac), in collaboration with the Canada Green Building Council (CaGBC) and the Building Owners and Managers Association (BOMA) of Canada, adopted an energy consumption target for office buildings of 20 equivalent kilowatt-hours of energy use per square footage of building area per year (20 ekWh/ft²/yr) by 2015 – a target to be known as 20 by ’15.
After launching the 20 by ’15 energy reduction target, REALpac again collaborated with the CaGBC, BOMA Canada and various energy experts to develop tools to help enable the real estate industry to understand energy use and measure it in a meaningful way. Both the REALpac Energy Normalization Methodology and the REALpac Energy Normalization Template were released in the summer of 2010, which paved the way for a Canada-wide building energy consumption survey to be performed.
The 2010 survey provides an initial baseline measurement for the industry to begin to understand where it stands collectively, and individually, and to use as a foundation for initiatives and improvements. In future, it will be conducted annually in the latter half of the calendar year, and will be followed by an updated report with comparative analyses of trends and results.
ENABLING COMPARISON
Data supporting the original 20 by ’15 target was based on normalized energy usage that was collected from national large-scale pilot projects conducted by the CaGBC in 2008. These pilot projects engaged more than 40 commercial office and government buildings totaling 48 million square feet and created a large, detailed database of Canadian office building energy performance.
The pilot project data was normalized for weather differences across the country, as well as for material space, occupancy and energy source differences between buildings. These normalization procedures were re-conceptualized and enhanced in the development of the methodology and template.
To participate in the 2010 Energy Benchmarking Survey, building owners, managers and/or consultants were asked to collect both building characteristics data (e.g. exterior gross area, gross floor area, numbers of occupants, average weekly operating hours, vacancy rate) and 2009 energy use data for their buildings from utility bills and/or meters. Once they had entered data for each building in the template, following the guidance in the methodology, both the buildings’ actual energy use intensity and its normalized energy use intensity in ekWh/ft²/yr were automatically calculated.
The normalized value adjusts the total energy consumption from 2009 from all major energy sources for variables such as: the building’s gross floor area; different heating power of various energy sources (e.g. natural gas or steam); high intensity or exceptional energy use space types (e.g. data centres); plus occupant dependent variables (e.g. occupant density, vacancy and operating hours). A normalized approach to calculate a building’s annual energy use accounts fairly for buildings with different characteristics and allows for more meaningful and robust energy intensity reporting and benchmarking among buildings across the country.
2010 SURVEY PARTICIPANTS
Although 56% of participating buildings had gross floor area less than 250,000 square feet, 25% were larger buildings with more than 500,000 square feet of gross floor area. Buildings of at least 1 million square feet made up 10% of the sample.
A wide range of building vintages was recorded, even though 20% of participants didn’t report a construction date. There was a significant minority of older and newer buildings with 10% built prior to 1970, and 11% built on or after 2000. The largest segment of buildings – 26% – was built in 1980-89, while 16% were built in the 1990-99 period.
Surveyed buildings predominantly had lower building occupancies, with more than one-third in the range of 3 to 3.9 occupants per 1,000 square feet. Only 6% of the buildings were in the densest category with more than 5 occupants per 1,000 square feet.
Weekly operating hours were calculated for the entire building, as there was no allowance for adjustments in individual tenant spaces. Accordingly, it is not surprising that the vast majority of buildings reported average operating hours at or below 65 hours per week. Only 5% of the data set’s buildings had operating hours greater than 65 hours per week, and none operated for more than 85 hours per week.
Many of the 2010 survey participants reported having sub-metered high intensity space types (e.g. data centre, retail) or exceptional space types within the building area. 31 buildings, or 12% of the data set, included data centres with annual energy use ranging from 37.5 to 824.9 kWh/ft²/yr. The mean intensity for such spaces was 280.1 kWh/ft²/yr. Retail spaces, which were found in 25 buildings, recorded a mean energy use intensity of 66.2 kWh/ft²/yr, ranging from a low of 11.1 kWh/ft²/yr to a high of 367.9 kWh/ft²/yr.
The majority of participating buildings, or 59%, are located in Ontario. Just less than one-quarter are in the Prairie region encompassing Alberta, Saskatchewan and Manitoba, while another 14% are in British Columbia. Buildings in Quebec and other provinces comprise 4% of the sample.
FINDINGS
The Canada-wide data set of annual building energy intensity shows the mean actual energy use intensity to be 33 ekWh/ft²/yr, and the mean normalized energy use intensity to be 28.7 ekWh/ft²/yr. Both results are below the Natural Resources Canada (NRCan) 2007 national average annual energy use intensity for office buildings of 1.42 GJ/m3 or 36.65 ekWh/ft²/yr.
The mean actual energy use intensity represents a 10% decrease in energy intensity per square foot over the NRCan 2007 national average, while the mean normalized energy use intensity represents a 22% decrease over the 2007 national average.
The lowest normalized building energy use intensity in the data set is at 11.5 ekWh/ft²/yr and the highest is at 61.2 ekWh/ft²/yr, which equals a multiple of 5.3 over the lowest building. There are 18 buildings with normalized energy use intensities below 20 ekWh/ft²/yr; 15 buildings with intensities between 20 and 21ekWh/ft²/yr; and there are 65 buildings in total with energy use performance within the top quartile, below 23.7 ekWh/ft²/yr.
Looking deeper into the normalized data set, 84% of the buildings in the sample set experienced an overall lowering of annual energy use from normalization. The average absolute reduction in annual building energy use through the use of normalization was 4.3 ekWh/ft²/yr, which corresponds to an 11.6% average decrease per building. The most common factors contributing to the lowering of a building’s normalized energy use is higher than normal occupant density and the sub-metering of data centres and other high intensity energy use spaces, as well as weather normalization.
The normalized energy use intensity distribution of buildings highlights the large number of buildings performing below the national average of 36.65 ekWh/ft²/yr. More than half of the buildings in the Canada-wide data set perform better than 28 ekWh/ft²/yr, and the most common concentration of energy use intensity is between 20 and 30 ekWh/ft²/yr.
The complete text of REALpac’s 2010 Energy Benchmarking Report can be found at www.realpac.ca.
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