Building Performance Evaluations
Since 2006, GGLO has been conducting ongoing building performance evaluations of multifamily projects in the Seattle area. Over multiple phases of the study, we have collected and analyzed energy and water use data for a total of 54 buildings in 13 projects (all but three designed by GGLO), and have modeled an extensive list of potential energy-efficiency measures.
The building performance evaluation has two primary goals : (1) to assess building performance relative to design intention, and (2) to elucidate the challenges of meeting the energy efficiency needs of our future.
The main conclusions of the study include:
- Green design strategies can reduce energy and water use, but occupant behavior is a key variable
- Comparing predicted to measured performance can be an effective means for identifying issues in building operations
- Performance measurement and modeling reveal that significant reductions in energy use are possible in multifamily buildings
- There is a huge opportunity to design and construct multifamily buildings with improved energy performance
Utility data were obtained in cooperation with Seattle City Light, Puget Sound Energy, Seattle Public Utilities, and Seattle Steam.
2009 Net Zero Exploration: energy modeling support by Glumac
2009 Net Zero Exploration: cost estimating support by Walsh Construction
2009 partnered with the City of Seattle and Ecotope for:
Multifamily Billing Analysis: New Mid-Rise Buildings in Seattle
Related Presentations & Publications:
Seattle Municipal Buildings Energy Performance reports, 2011-2012, 2012-2013, 2013-2014
Living Future Conference, Seattle, April 28, 2011
The Future of Sustainable Design, Washington State University, October 8, 2010
AIA Montana Fall Conference, October 1, 2010
Living Future Conference, Seattle, May 7, 2010
BuiltGreen Conference, Seattle, March 12, 2010
Buildex Seattle, October 15, 2009
Cost of Green Analysis for Affordable Housing in Seattle and Portland, by David Langdon, July 2009
Multifamily Billing Analysis: New Mid-Rise Buildings in Seattle
BuiltGreen Conference, Seattle, March 6, 2009
Housing Washington Conference, Tacoma, September 15, 2008
Sustainable Industries, February 29, 2008
Cascadia Chapter USGBC, Seatle City Hall, Fall 2007
Ecostructure, May-June 2007
BuiltGreen Conference, Everett, WA, March 13, 2007
Housing Washington Conference, Bellevue, September 11, 2006
Request a copy of GGLO’s presentation.
How are residential buildings performing? As green building becomes increasingly accepted and demanded in the marketplace, there remains a lack of information on the actual, real-world performance of completed projects. Residential buildings have proven to be particularly difficult to evaluate due to ownership and privacy issues, as well as variability in the living habits of residents. Of all building uses, residential — which accounts for 21 percent of total U.S. energy consumption — is one of the least documented in terms of building performance. This study aims to help close the information gap.
|Methodology:Data on energy and water use were collected from utilities on mid-rises and one low-rise project with multiple buildings. Commercial portions of the mixed-use buildings were excluded from the analysis. Four of the projects are market rate housing, while the remainder are affordable. All of the mid-rise buildings participated in Seattle’s Built Smart program, and all but three of the projects were certified by one or more green building rating systems, including Built Green, Sea Green, and LEED®. To investigate in more detail the potential for reducing energy use in a typical mid-rise residential mixed-use building, we performed in-depth energy modeling on a selected project. eQuest was used to model a series of energy-efficiency measures (EEMs), with the goal of understanding both the strategies and costs necessary to reach net-zero energy performance.Results:Who takes a five minute shower?Water consumption data reveal wide variations between buildings, and between predicted and measured use. Much of this variation is believed to be caused by discrepancies between water use assumptions and actual occupant behavior. Also, because only one water meter per address is allowed in Seattle, estimates of commercial use had to be made — sub metering would be necessary to eliminate this uncertainty.Are we meeting the 2030 Challenge?The average energy use intensity (EUI) for all the buildings studied was 45 kBtu/sf/year, with significant variation between buildings. The project with the best energy performance had an EUI forty percent below the study average. In three cases, the observation of unexpectedly high energy use called attention to likely issues with building systems and operation. The 2030 Challenge target for 2009 is a 50 percent reduction from the regional average. Based on the best available regional standard, the most efficient building in our study achieved a 36 percent reduction.How much will it cost?In 2009, EEM modeling demonstrated a range of potential energy use reductions. A 50 percent reduction should be achievable with the application of “low hanging fruit” strategies that are reasonably economical. Relative first costs rise for reductions beyond 50 percent. “Netzero” operation would require either a major changes in approach to multifamily design, or strategies with significant up front costs applied to a conventional building design.How is the 2030 Challenge applied to residential projects?Residential projects reference the Residential Energy Consumption Survey (RECS) 2001. However, based on a conversation with the RECS Survey Managers, the RECS Average Site EUI is not a whole building EUI. Because our BPE studies show common spaces consume a disproportionately larger share of energy in comparison to their area, we calculate each residential building’s whole building Local Average Site EUI with data collected from projects participating in our BPE.|
How low can we go?
Building on the previous phase which studied the strategies and costs associated with achieving net-zero energy, in 2010, GGLO explored the application of the Living Building Challenge to a ‘typical’ multi-family, mid-rise project in Seattle. We explored the key issues for this project type including: balancing net-zero water with density, modifying building form to reduce energy use; and providing community spaces to engage building users. See the full presentation here.
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.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
4 Levels Residential
1 Grade-level Commercial
Below Grade Parking
Energy Use Intensity (EUI) Delineation
Exclude commercial energy use and area from the EUI calculation (see image below). Commercial spaces can be calculated separately using the 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 as 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.
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.