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Case Study: Chaska City Hall

New high efficiency boilers, energy management system help achieve $14,000 per year in energy savings

Aims and objectives. To reduce energy use and save on utility bills, the City of Chaska identified several opportunities for energy savings in its 31,000 square-foot City Hall. Two new boilers and a new energy management system were among the improvements. A report by Clean Energy Resource Teams details the many energy-saving projects.

Implementation. The Chaska City Hall project included the following upgrades:

  • Replacement of two inefficient boilers with 95% efficient condensing boilers
  • Installation of variable frequency drives on air handler unit motors
  • Installation of a new energy management system 
  • Replacement of a number of controls throughout the heating, ventilating, and air-conditioning system: variable air volume system controls, economizer controls, outdoor temperature reset controls, night setback controls, and CO2 controls

Outcomes--energy saved, CO2 reduced. Comparing the baseline year 2010, before the upgrades were finalized, to 2012, when the project was completed, City Hall electric use decreased 14 percent, natural gas use was cut by 50 percent, and CO2 emissions were reduced by 20 percent. The savings are shown in the B3 Benchmarking charts below and represent an annual savings of $14,000 (at current energy prices) for the building.


Annual natural gas consumption
Natural Gas Use Table 

Figure 1. This Minnesota B3 Benchmarking chart shows 50 percent natural gas savings for Chaska City Hall.


Annual electric consumption
Annual electric consumption table

Figure 2. Electric use decreased 14 percent from 2010 to 2012.


Annual CO2 emissions
Annual CO2 emissions table

Figure 3. CO2 emissions were reduced by 20 percent.


Documenting results. The City of Chaska measures its savings through Minnesota B3 Benchmarking, a tool to help manage buildings, improve the building’s portfolio, and monitor building performance. B3 is available to all state, local government, and public school buildings. To add your building to this database, go to the B3 website and click on “Contact Us.”

Funding. The City Hall upgrades were funded by a $100,000 Energy Efficiency and Conservation Block Grant from the Minnesota Department of Commerce and U.S. Department of Energy. The grant was provided by the American Recovery and Reinvestment Act of 2009, federal stimulus funds designed to save energy and create jobs. A rebate from the Chaska Electric Department municipal utility helped pay for the project. Total cost for the project: $160,000. The project is expected to pay for itself via energy savings in about 11 years.

All utilities in the state, including municipals, are mandated to achieve an annual energy savings of 1.5 percent of annual retail energy sales. Projects like Chaska’s support the annual savings of cities and municipal utilities alike.

Resources for local government projects. All public institutions seeking energy efficiency improvements are encouraged to consult with their local gas or electric utility. Utility representatives can help assess opportunities for efficiency and identify rebates to help finance 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, including “The Advanced Energy Retrofit Guide for Office Buildings.” For more on energy efficiency, including information on Minnesota’s B3 Benchmarking tool, contact the DER Information Center at energy.info@state.mn.us or 800-657-3710.