The first step of the 2030 Challenge is to determine the appropriate baseline used to calculate reduction targets. For mixed-use multifamily buildings, this is not as straightforward as it may seem.
Just as commercial projects target Site Energy Use Intensity (EUI) reductions compared to Commercial Building Energy Use Survey (CBECS) 2003 baseline, residential projects reference the Residential Energy Consumption Survey (RECS) 2001.
The chart above shows regional energy use averages and targets for the West Coast US
In the Pacific Northwest, this means 40.0 EUI is a commonly used baseline for average building EUI. However, GGLO's discussions with RECS Survey Managers revealed the RECS Average Site EUI is not a whole building EUI. RECS is a unit-only EUI and does not include the energy use of common spaces.
GGLO's Building Performance Evaluation (BPE) studies show common spaces consume a disproportionately larger share of energy in comparison to their area. This common area energy usage should be tracked, monitored, and included to establish a whole building EUI. Therefore we compare each multifamily residential building's whole building Local Average Site EUI to data collected from projects participating in our BPE. For example:
Typical Mixed Use Residential:
5 Stories
4 Levels Residential
1 Grade-level Commercial
Below grade Parking
Energy Use Intensity (EUI) Delineation:
As depicted in Figure 1, exclude commercial energy use and area from the EUI calculation. Commercial spaces can be calculated separately using Energy Star Target Finder.
Also exclude parking garage area. There are two main reasons to include parking energy use while excluding parking area from the EUI calculation. First, energy consumption for a parking garage is commonly included on the same meter as the building’s common spaces. Second, building performance evaluations and tools such Portfolio Manager will include this energy associated with ventilation and lighting while excluding the parking area. By calculating a multifamily building’s EUI in this manner, buildings that do not provide parking given their smart location are no longer penalized in comparison to buildings that have energy consumption associated with large structured parking areas.
Figure 1
+Exclude Commercial Energy Use
++Exclude Commercial and Parking Area
Area:
Total gross square footage as measured to exterior face of wall
Establish Whole Building Baseline EUI:
Whole Building Average EUI is calculated by the project team and will vary depending on the percentage of common area space. Use the GGLO Target Calculator for multifamily residential projects to establish the baseline below:
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