GreenStep City Best Practices: Buildings and Lighting
Efficient Existing Public Buildings No. 1
Benchmark energy and water usage, identify savings opportunities in consultation with state programs, utilities and others to implement cost-effective energy and sustainability improvements.
Geothermal heating systems can increase greenhouse gas emissions by 40% over high-efficiency natural gas furnaces due the higher CO2 emissions from the typical coal-fired electricity in Minnesota that runs the geothermal pump. Thus a geothermal system replacement should be analyzed for CO2 emissions, which can be lowered by purchasing renewably generated electricity from sources like wind.
District energy describes a system that produces and distributes one or more of heating, cooling, and electricity for buildings in a neighborhood-scale distribution network. Various ownership and operating models are available for locating generation close to the load being served. This improves the net efficiency of fuels, lowers costs, improves reliability and resiliency, and reduces emissions. The most popular and mature technology uses gas turbines to co-generate heat and power (CHP), utilizing waste heat to drive absorption chillers for cooling. Once the grid is set up, users can incorporate renewables like solar or wind. See the in-depth report Minnesota Microgrids: Barriers, Opportunities, and Pathways Toward Energy Assurance (Microgrid Institute: 2013), which takes an in-depth look at regulatory barriers to and opportunities for microgrid development to enhance energy assurance in the state of Minnesota, with recommendations to address barriers and identify pathways to facilitate microgrid development.
The Combined Heat and Power Action Plan (October 2015) synthesizes MN Department of Commerce findings to inform clear and achievable recommendations that could help lead to potential CHP implementation in Minnesota.
A 2005 microturbine installation at the Hennepin County Home School (Minnetonka) resulted in annual utility savings of $8,000.
For actions and resources related to renewable energy generation/distribution, and combined heat and power, see GreenStep best practices #26 (Renewable Energy) and #29.8 (Resilience).
Geothermal systems should meet a minimum coefficient of performance of 3.3 for closed loop systems.
Use a waste heat stream to heat one or more buildings; create a district energy system/microgrid for several buildings (using waste wood, geothermal energy, gas turbine, fuel cell); harvest rainwater.
Integrate solar thermal or other renewable production into a combined heat & power system; use the constant temperature of drinking water pipes in a geothermal system.
Who's doing it
Duluth - 3 star
Date action report first entered:
Date of last report update:
Year action initially completed: 1936
Implementation details:
Hartley Nature Center is heated by a ground source heat pump that was installed in 2003 and has multiple waste heat collection systems. HNC also has a solar wall on the south side of the building and utilizes passive solar heating through east-west building orientation, a concrete slab that absorbs and radiates heat, and roof-overhangs to shade windows during summer months.
Duluth Energy Systems is a steam plant owned by the City that has provided steam to several city buildings as well as downtown businesses for the past 80 years. The steam plant is in the process of switching to a closed loop hot water system that will reduce energy and water use.
A ground-source, closed loop geothermal system was installed in City Hall in 2012. In 2016, solar panels (capacity of 796,000 kWh) were installed on the roof of City Hall and the Veteran's Memorial Community Center to supply energy to these buildings.
Through the installation of a GeoExchange system at the Municipal Athletic Complex, the community has a high-performance green arena that reduces gas usage by 95% and electric usage by 30%. Nearly 4,000,000 gallons of water usage will be eliminated along with the yearly elimination of 300,000 pounds of greenhouse gases.
St. Cloud utilizes a combined heat and power system (CHP) at their NEW Recovery Facility. The city has a 1.26 MW CHP system. The system consists of two Jenbacher 633 kW CHP internal combustion engines; the first engine has been in operation since 2017 and the second since 2020. The system integrates renewable biofuel energy production with heat recovery from the generators. The site utilizes biogas processed onsite using municipal wastewater and high strength waste in their anaerobic digesters. The generators produce over 5 million kWh of renewable electric energy annually and the heat recovery has reduced natural gas demand at the facility by over 40%.
Outcome measures/metrics/money saved:
Geothermal System at the MAC:
Through the recent installation of a GeoExchange system at the Municipal Athletic Complex, the community has a high-performance green arena that reduces gas usage by 95% and electric usage by 30%. Nearly 4,000,000 gallons of water usage will be eliminated along with the yearly elimination of 300,000 pounds of greenhouse gases.
CHP System at NEW Recovery Facility:
The generators produce over 5 million kWh of renewable electric energy annually and the heat recovery has reduced natural gas demand at the facility by over 40%.
Through reduced natural gas consumption and onsite electrical generation, the plant removes an equivalent of over 8.5 million pounds of CO2 annually from the atmosphere.
a. Arlington Hills Community Center has a geothermal system in the building.
b.The City has several buildings that are connected to District Energy St. Paul including the Griffin Building, Central Library and City Hall/Courthouse.
The City of Elko New Market's Public Works building has recently constructed and now operates a storm water harvesting system. A storm water drainage pond is used for building water use whereby water taken from a holding pond on-site is filtered and reused for 1.) heating the building via a hot water floor heating system and 2.) the water is reused in the public works building for operations. Furthermore, the Public Works building has been retrofitted with 3-pane skylights and a circulating fan air circulation system. (Police Department and City Hall/upgraded HVAC system)
In Decemeber of 2011 a wide gap plate heat exchanger was installed at the Grand Rapids Public Library which utilizes waste water from the Blandin Paper Co.
Outcome measures/metrics/money saved:
Use of this new heating system has reduced our natural gas usage by nearly 70%.
Although not solely within the jurisdiction of the City of Mankato, development of the Breckenridge Townhomes affordable housing project located in neighboring Eagle Lake was overseen by City staff as part of the Housing and Redevelopment Authority (HRA), in conjunction with Blue Earth County staff. These townhomes were planned and developed in accordance with Minnesota Green Communities standards, and included preservation of wetland areas, maximum utilization of passive solar heating/cooling, native plantings as part of raingarden and bio-swales, and Energy Star standards for construction and furnished appliances. Roof panels were also designed on an East/West axis to easily accommodate future solar panels.
Additionally, the Orness Plaza Apartment Complex, owned and operated by the Mankato Housing and Redevelopment Authority, received grant funding to assist with its rehabilitation. The 1970s era building has been revitalized with a geothermal heating system and central air conditioning, among other improvements, and has been granted LEED certification. Reserved parking stalls for designated fuel efficient and hybrid vehicles have also been included as part of the rehabilitation program.
A passive solar array was integrated into the roof of the recently-renovated Public Safety Center building in late 2013.
The City of Maple Grove's Government Center uses a closed loop Geothermal system that utilizes the human made groundwater ponds that were dug in the gravel mining area. The success of this system (i.e. energy savings and quick payback) led Great River Energy and Hennepin County Library to construct similar systems at their facilities.
Olmsted County's Waste to Energy facility uses solid waste to heat and cool, as well as provide electricity to most of the Government buildings on the campus as well as some other city owned buildings. This is a very efficient system for the campus and is estimated to have saved 90% of waste that would have gone to a landfill from the County.
The Roseville Oval Skating Rink uses a geothermal system for heating and cooling and to make ice. Waste heat and ground source energy to warm buildings; heat pumps and exchangers then cool the facilities and make ice.
A closed loop geothermal system has been installed in three city facilities, including: Woodbury City Hall in 2007, Bielenberg Sports Center in 2009, and the Public Safety Building in 2011.
Outcome measures/metrics/money saved:
The Woodbury City Hall project included a 13,841 square foot expansion to the current building. In addition to the geothermal system, other energy efficiency upgrades included lighting and occupancy sensors, and an energy management system. Even after the expansion, the total energy used at City Hall has remained steady compared to energy use prior to the expansion.
The geothermal system at the Bielenberg Sports Complex replaced the existing ice arena refrigeration system. Other energy improvements included low emissivity ceilings, and an energy management system. Following project completion, total energy use at the facility dropped 35% in 2010 and has continued to drop each year after.
The city installed a geothermal system for two ice rinks located at the Community Activity Center (CAC) in 2010 at a cost of $4.6 million.
The City of Brooklyn Park underwent a complete redesign of the two ice rinks located at the Community Activity Center (CAC). The improvements use geothermal heat from the city’s water system to efficiently cool the rinks and heat portions of the building. The project was completed in October 2010 and is one of the most energy efficient ice rinks in the world.
The ice rink project is part of a larger energy efficiency retrofit project that used a combination of stimulus money from the federal government's Energy Efficiency and Conservation Block Grants, Heritage Infrastructure Funds, sale of bonds and utility rebates related to energy savings. The City hired an outside firm, McKinstry, to complete the arena overhaul as part of a $6.3 million citywide energy-efficiency project. The whole project will pay for itself in just over twelve years.
The purpose of the project was simply to extend the life of our ice arenas. However, it quickly evolved into something much more. The Project did extend the life of the rink by 20 plus years; but because of the innovative design of the new system, we have one of the most energy efficient ice operations in the nation – and likely the world.
A closed loop geothermal system was installed in the Burnsville Ice Center in 2010. The project was funded by an Energy and Efficiency and Conservation Block Grant, a Dakota Electric Rebate, as well as city funds. Burnsville incorporated stormwater reuse into the design of the new Fire Station 1 that opened in May 2022. The system harvests rainwater from the roof of the fire station, directs it to a cistern underground, and it is used irrigation.
Outcome measures/metrics/money saved:
The Ice Center emits 20% less carbon, and uses 80% less natural gas annually than pre-geothermal installation. The annual operating costs have been reduced by 43%. The actual coefficient of performance for the system has not been determined yet, however, it is a closed system. Over the next several years the City will be monitoring the system closely to determine its performance and to calculate the efficiency of the system.
The City of Cologne has a closed loop geothermal field which heats and cools the City Hall.
Cologne also entered into a contract to receive solar energy from municipal solar gardens which should be 100% off-setting the City's energy use in all public buildings as well as the two water towers, the lift stations and the wells.
The Delano Municipal Utilities in 2010 completed the installation and activation of a closed loop geothermal system. The system provides temperature control for the main power plant building, operated by the City's electric enterprise. The power plant building contains generators used to generate emergency power for the City and houses the administrative offices of the electric and water enterprises. The installation involved retrofitting the 80+ year old facility to this new technology.
Geothermal heating was installed at the Eagan Civic (Ice) Arena, which includes 33 new wells. The project was possible due to a $1.3 million federal grant from the DOE. The project was completed in September 2010.
Outcome measures/metrics/money saved:
33 new wells.
The project was possible due to a $1.3 million federal grant from the DOE.
The geothermal project added an additional electric meter in June 2010 to operate the new equipment that was installed. While the natural gas consumption decreased significantly, electrical costs remained the same or increased slightly from the pre-geothermal project. The addition of an enclosed training space within the arena along with additional daytime meeting rentals generated more people and use of the building, which added to the electrical consumption.
The overall system continues to be monitored by Harris Companies, Dakota Electric and City staff to stabilize electrical use.
Complete: A closed loop geothermal system was installed at the Public Works building with a minimum coefficient of performance of 3.3. The facility was opened in August 2010.
The Elk River public safety building features a ground source, closed loop geothermal system.
Outcome measures/metrics/money saved:
Efficiency measures in the building annually save:
22,110 gallons of water
1,472.34 gallons of oil
1867 pounds of air pollution (NOT emitted to the atmosphere)
9.73 cubic yards of landfill air space
12,964.86 Kilowatt Hours of energy!!
Independent School District 544 (Fergus Falls) has installed the ground-source, closed loop geothermal system into their elementary school buildings. One of the schools (Adams Elementary) has a rain garden they operate. The Police Station also has installed a ground-source, closed loop geothermal system.
The new Marshall-Lyon County Library was constructed in 2011 and features a closed loop geothermal heating and cooling system using 54 wells. The Geothermal HVAC system provides efficient heating, cooling, and snow melting.
Outcome measures/metrics/money saved:
Engineers estimate 2,605,000 kBtu and $36,000 saved per year, and a simple payback of less than 3 years after utility rebates.
Mounds View is part of a three city JPA Fire Department. When constructed in 2007, the training/public education, maintenance station was building with a ground source Geo Thermal heating and cooling system.
Outcome measures/metrics/money saved:
Reduced energy costs. Station One and Station Three have similar energy costs (Station one being traditional gas/boiler heat and Electric AC). However, Station Three is 35,000 Sq. Ft. while Station one is 12,000 Sq. Ft.
Completed installation of water-source, closed loop geothermal heat pump system at our Public Works facility. The system was designed to replace the traditional HVAC equipment that heated/cooled the facility. The new system utilizes an existing and clean energy source, the nearby water filtration facility.
City of Savage constructed the McColl Pond Environmental Learning Center (ELC). A closed loop geothermal system was designed and implemented during construction.
