The solar thermal system for The Wellstone Apartments is exceeding expectations and meeting 60 percent of the buildings hot water needs. (Photo by Bruce Silcox Photography)
System type: Solar Thermal, 24 Solar Skies NSC40 collector panels (960 square feet) with two 505 gallon Niles B-42-093 storage tanks
State Solar Rebate: $10,000
The Wellstone Apartments on Franklin Avenue in south Minneapolis is doing its part to help Minnesota reduce greenhouse gas emissions. The Wellstone Apartments, a new 49-unit affordable housing development that was completed in December 2008, offers a range of green and sustainable features, including a solar hot water system that provides energy for most of the building’s hot water needs.
“Discussion and planning for the Wellstone hot water system started in 2005 and was part of our early design and construction planning,” said Marcia Cartwright, real estate manager for Hope Community, Inc., co-developer with Aeon for The Wellstone Apartments. “Our goals were to reduce the building’s overall energy costs and consumption and to serve as a demonstration project, especially for larger commercial and multifamily developments.”
Exceeding system expectations
The solar thermal system was designed to meet about 50 percent of The Wellstone’s hot water needs, said Cartwright. “However, it appears that the system is exceeding expectations and meeting 60 percent of our hot water needs. It is working well, and we’re delighted to be tapping a clean energy source.”
The solar thermal system, designed by Craig Tarr, PE, of Energy Concepts in Hudson, Wisconsin, uses 24 4- x 10-foot Solar Skies solar collector panels mounted on the roof of the four-story building. The location is excellent to tap solar energy, with a clear path to the sun. A closed-loop glycol system is employed, and the system includes two 505-gallon storage tanks. A conventional natural gas-fueled backup system with three storage tanks provides for the remainder of the building’s hot water needs.
The cost for the solar thermal system was about $125,000; a $10,000 Minnesota Solar Hot Water Rebate helped defray the costs. The system is projected to pay for itself in 7-9 years.
Tarr notes that solar thermal used for domestic water heating in buildings with a consistent daily hot water demand—such as The Wellstone—is one of the best renewable energy investments (especially when energy costs are high). Multifamily housing, nursing homes, and hospitals are high-value applications of solar water heating as well. However, judging projects solely on return on investment betrays the overall value and understanding of renewable energy. The Wellstone project displays leadership in contributing to a healthier, more stable environment and helps our nation realize energy independence and less reliance on fossil fuel consumption, said Tarr.
Saving energy, reducing CO2
Given that The Wellstone building has been fully occupied for only six months, the estimated annual fuel savings and reduced carbon emissions are not available. But Tarr said the amounts will represent a significant savings to the environment. Also, it’s too early to estimate tenants’ savings in decreased water heating bills, said Cartwright. “We are seeking utility releases from our tenants so we can access tenant accounts and start tracking and measuring utility costs and potential savings.” BTU energy meters were installed recently and will provide data to help measure the percentage of solar contribution to the building’s overall domestic water heating requirements.
The Wellstone development is a Minnesota Green Communities award winner, and has other energy effi cient features such as ENERGY STAR appliances (including front-loading clothes washers), efficient lighting, and energy-efficient heating and cooling systems. Construction field testing and verifi cations were performed by Minneapolis-based Center for Energy and Environment and included air tightness via blower door testing, duct leakage via duct blaster, pressure balancing, and measuring outside air intake. These tests were part of commissioning the building and ensured that The Wellstone was built as designed. Post-construction testing and verifications were also performed. Testing services were part of a national pilot program coordinated by Enterprise and the national Green Communities Initiative.
Alternative energy investments make more economic sense today than in the past, especially for larger commercial projects, said Cartwright. The Wellstone Apartments was not able to take advantage of tax credits for its solar thermal system, but a federal Renewable Energy Tax Credit of 30 percent can be applied to the cost of residential or business solar thermal systems installed between Jan. 1, 2009 and Dec. 31, 2016. Cartwright added that government and utility incentives for solar thermal and other renewable energy technologies are more plentiful now, making them more cost-effective.
To learn more
Minnesota offers a solar rebate program for both solar electric and solar thermal installations. Funds are limited and program details may change. In addition, there is currently a 30% federal tax credit for qualifying solar installations. Many utility companies also offer rebates and incentives for solar installations.
For a complete listing of all available government and utility incentives, visit the Database of State Incentives for Renewables and Efficiency.
For more information, visit the Division of Energy Resources.