The Clinton Shop in Big Stone County cut its propane use by 46 percent, thanks to new roof insulation.
Clinton Shop was built in 1946 to store and stage equipment for the Big Stone County Highway Department in Ortonville, Minn. The building’s original 2,750 square-foot flat roof was constructed of plywood sheets and thin metal covered with asphalt felt, tar, and gravel, giving an estimated insulating value of about R-1.5.
The problem: heat loss. Using estimating tools from the U.S. Department of Energy website, Nick Anderson, county engineer for Big Stone County, estimated that the heat loss in the roof accounted for about 60 percent of the building’s total heating demand.
The solution: roof insulation. In 2010, Anderson and Gary Haugen, maintenance supervisor for Big Stone Highway Department, applied for and received a grant from the Minnesota Department of Commerce to help fund insulating the roof. To reduce the cost as well as minimize construction waste, the old roof was left in place. Since insulating the roof, the addition of an unconditioned storage room on the north side of the Clinton Shop has further helped reduce the heating needs.
Outcome: Energy saved. The propane use, tracked by the Minnesota B3 Benchmarking tool, decreased 46 percent from 2010, before the project, to 2012, two years post-project (see Figure 1). In addition, there has been a reduction in electricity use, due in part to the furnaces running less frequently. “The B3 tracking has been useful to watch the energy consumption over several winters and get an accurate measure of the savings,” said Haugen.
Propane heating fuel use
Figure 1. This weather-normalized savings chart from the B3 Benchmarking tool shows that Clinton Shop propane consumption dropped by 46 percent after the roof insulation project.
Documenting results. The Minnesota B3 Benchmarking tool is available for public buildings in Minnesota, including state, local government, and public school buildings. It provides the tools to manage your buildings, improve your building portfolio efficiently, and monitor the improvements. To add your building to this benchmarking database, go to the B3 website and click on “Contact Us.”
Funding. The insulation project was funded by a $15,000 Energy Efficiency and Conservation Block Grant from the Minnesota Department of Commerce and U.S. Department of Energy. The funds were provided by the American Recovery and Reinvestment Act of 2009, federal stimulus money designed to save energy and create jobs. Big Stone County paid $5,000; total project cost was $20,000.
Resources for public building projects. The Minnesota Department of Commerce, Division of Energy Resources (DER) provides technical support to local government units, state agencies, school districts, and institutions of higher learning that are seeking energy efficiency and renewable energy measures. Contact DER to discuss which of its energy efficiency programs can be of help.
The U.S. Department of Energy’s Building Technologies Office also provides helpful resources for building retrofits. For more on energy efficiency, including information on Minnesota’s B3 Benchmarking tool, contact the DER Information Center.