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Case Study: Cottage Grove Public Works Garage, Fire Station 2 

Lighting, heating retrofits achieve energy savings in two buildings

Aims and objectives. The City of Cottage Grove sought opportunities to reduce energy use and achieve cost-saving outcomes. Based on information from the Minnesota B3 Benchmarking tool, Cottage Grove identified two public buildings that were in need of energy improvements: the Public Works Garage and Fire Station 2. A report by Clean Energy Resource Teams details the city’s energy-saving project.

Implementation. In the 47,000 square-foot Public Works Garage, the city replaced 137 inefficient light fixtures, 24 lighting occupancy sensors, and one complex and inefficient heating system. In the 13,200 square-foot Fire Station 2 building, the city replaced 245 inefficient light fixtures and two lighting occupancy sensors. Many of the lighting upgrades replaced high wattage incandescent lights with high output T5 fixtures, while others replaced older T12 lamps and magnetic ballasts with efficient T8 lamps and electronic ballasts. Both buildings added occupancy sensors to control lights.

Outcomes—energy saved, enhanced comfort. Comparing the baseline year 2010, before the lighting upgrade, to 2012, when the project was completed, Fire Station 2’s electric use decreased six percent. For the Public Works building, B3 energy records have yet to show any energy savings. The projects resulted in not only improved energy efficiency, but a more comfortable working environment, according to city staff.

Annual electric use for Fire Station 2
Fire Station Electric Usage
Figure 1. This chart from the Minnesota B3 Benchmarking database shows electrical savings for Fire Station 2.

Documenting results. Cottage Grove is able to track the energy use of its buildings through the Minnesota B3 Benchmarking database. The B3 tool is available for all state, local government, and public school buildings. In addition to electric and heating fuel consumption charts, B3 Benchmarking offers displays of CO2 emission reductions for participating buildings. 

To add your building to this database, go to the B3 website and click on “Contact Us.”

Funding. The building upgrades were funded by a $54,200 Energy Efficiency and Conservation Block Grant from the Minnesota Department of Commerce (via the American Recovery and Reinvestment Act of 2009) and an Xcel Energy rebate of $18,200. Total cost for the project was $112,080. The city paid about $40,000.

With the national phase out of magnetic ballasts and T12 lamps, many Minnesota utilities no longer offer rebates for converting such lighting systems. However, with rising demand and energy charges for commercial consumers, companies that still have these in place may find it cost-effective to replace them even without rebates. Most electric utilities provide rebates to support change outs of other older lighting systems and to help fund other lighting efficiency improvements. Minnesota natural gas utilities often provide rebates for heating system upgrades. 

Resources for local government projects. When seeking energy efficiency improvements, cities are encouraged to consult with the Minnesota Department of Commerce, Division of Energy Resources (DER) and their local utilities. 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 at energysavingsprograms@state.mn.us to discuss which of its energy efficiency programs can be of help.

Utility representatives can help assess opportunities for efficiency and identify rebates to help finance projects. Utilities in Minnesota are mandated to achieve an annual energy savings of 1.5 percent of annual retail energy sales.

The U.S. Department of Energy’s Building Technologies Office also provides helpful resources for building retrofits.