There are about 370,000 housing units within Minnesota’s rental multifamily building stock. Nearly three-quarters of these are located in the seven-county Twin Cities region. For CenterPoint Energy and Xcel Energy, gas sales to the multifamily sector are greater than to any other commercial market sector, accounting for approximately 20 percent of gas sales. In the Twin Cities, building size is skewed toward the large end of the range, with structures having 20 or more units accounting for about 70 percent of the rental multifamily housing units. In Greater Minnesota, size is more evenly distributed with approximately a 50-50 split between housing units in buildings with 20 or more units and those with fewer than 20 units.
Addressing the multifamily sector is a key component to achieving the state's annual 1.5 percent savings goal. In addition, delivering effective conservation programs to multifamily customers is one way to serve rental and low-income populations since many renters are low-income. However, the multifamily sector has been underrepresented in efficiency/conservation program portfolios. This is due to a number of different factors, including a lack of accurate information on structural and system characteristics, resident demographics, and energy use patterns of multifamily buildings. The Minnesota Department of Commerce, Division of Energy Resources specifically solicited projects to support multifamily program development during the FY 2011 CARD funding round.
The Energy Efficiency Potential in Minnesota’s Multifamily Sector CARD project, awarded to Franklin Energy Services LLC and their subcontractor Energy Center of Wisconsin (ECW), consisted of two components: a best practices study and a building characterization study. We reported on the best practices study (.pdf) in May 2012. The characterization study was recently completed in June 2013.
In preparing the characterization study, Franklin Energy and ECW sampled 120 buildings from across the state, 78 of which are located in the Twin Cities area. Field researchers visited selected sites to obtain building shell, equipment and appliance-related information, and obtained utility energy and water usage histories for most buildings. Researchers also placed data-logging equipment in 17 of these buildings in the Twin Cities area to capture in-unit and common-area temperature and relative humidity data, in-unit lighting usage, and boiler supply and return water temperatures.
The characterization study presents findings by building size (number of units) and vintage (original construction date). The researchers identified three primary vintage groups based on construction practices and heating systems in vogue at the time the buildings were erected (Pre-World War II, Post-World War II, and Post-Energy Crisis). Researchers also evaluated the payback period of 25 common energy (and water) savings measures in multifamily housing, which included:
They found that a large portion of buildings have opportunities for energy savings measures (see Figure 1).
Figure 1. Percent of measure opportunity for 5-year or better payback
CenterPoint Energy, Minnesota Energy Resources Corporation, and Xcel Energy are all offering multifamily programs during their 2013-2015 CIPs. According to Sue Nathan with Applied Energy Group, MERC’s CIP administrator, the “report provided a great overview of what was out there in the market. It was easy to understand and the tables were succinct and helpful. It had a good balance of electric and gas information and was well written without a lot of technical jargon.”
Kelsey Genung, Senior Regulatory Analyst with Xcel Energy, says that “considering the unique challenges the multifamily segment presents, understanding these customers is key to a successful program design and delivery, and the characterization study is enabling that for us.”
A full copy of the report is available. For more on the Energy Efficiency Potential in Minnesota’s Multifamily Sector project, contact grant project manager Laura Silver (email@example.com or 651-539-1873).