It’s Much Harder To Get Where You Want To Go When You Don’t Know Where You Are

On Wednesday the City of Seattle announced some excellent new proposals to promote energy efficiency in buildings, see related stories here, here, and here (too bad the DJC is a pay site). It’s all good stuff, but what I find particularly compelling is the proposal to require commercial and multifamily buildings to track and report their energy use.

Starting in 2010, the new reporting rules will apply to residential buildings with 20 or more units. For the past three years GGLO (my employer) has been conducting a study of energy use that has focussed on midrise mixed-use buildings that fall in this category. One of the motivations for the study is that there is very little information available on real-world energy use in multifamily buildings.

The plot above shows a summary of energy use for all the buildings in the GGLO study, expressed in terms of energy use intensity (EUI), which is energy use, per square foot of floor space, per year. So how do these buildings rate compared to the status quo? That’s a much harder question to answer than you would think — there simply isn’t a reliable regional average EUI for this building type.

The best available data source is the EIA’s Residential Energy Consumption Survey, but their sample is not large enough to produce accurate numbers for a specific region and building type. Furthermore, for multifamily buildings the survey does not include energy use in the building common spaces, i.e. hallways, rec rooms, parking garages, etc. But the GGLO study has shown that energy consumed in common spaces accounts for about 20 to 30 percent of total building energy use.

In the U.S, buildings consume nearly half of all energy, and produce 43 percent of CO2 emissions. The importance of reducing energy use in buildings is becoming widely acknowledged, and programs like the 2030 Challenge are beginning penetrate popular consciousness. But one wrinkle is that the 2030 Challenge calls for buildings to reduce their energy use in comparison to a regional average for existing buildings — and for multifamily that baseline data point doesn’t exist.

When the new City of Seattle program for reporting on energy use kicks in, we will finally start to amass the data we need to assess where we are, and how far we need to go. But I’ll also add that based on experience, although collecting energy use data would seem like a relatively straightforward task, it’s going to be a massive undertaking to obtain and process this data city-wide.

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