Heat Pumps

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What i​​​s a Heat ​Pum​​p? 

A heat pump is a device that warms or cools a space by transferring thermal energy from a cooler area to a warmer one, using the refrigeration cycle.  In the summer a heat pump will pull warm air out of your home and deposit it outdoors, just as a conventi​onal air conditioner wouldIn the winter, it reverses, and pulls warm air from the outdoors (even when it’s very cold) and transfers that air into your home.   

Why Should I Con​sider Switching to a Heat P​​​​ump? 

Most homes in the Midwest are currently heated with gas.  Unfortunately, gas is primarily made up of methane, which is an extremely potent Greenhouse Gas (GHG)and a significant contributor to climate change.  Methane leaks at a number of points along the path from extraction to transmission to distribution (see Fig. 1).  This includes leakage in our homes, which can contribute to poor indoor air quality and health impacts (including asthma, allergies and learning deficits), as well as climate change (RMI, 2019).  The only way we can get off fracked gas is to switch our gas-burning appliances to electric, as we clean up the grid. ​

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Recent research indicates that reducing methane in our atmosphere is a powerful way for us to relatively quickly combat global warming, as methane breaks up more quickly than carbon, leading to more immediate slowing of temperature increases.  For homes currently heating with resistance heat (approximately 22% of Ann Arbor), heat pumps are a much more efficient option and will save money.  The same holds true when compared with window air conditioning units.  In addition, while heat pumps require some learning for those of us accustomed to gas furnaces, they can produce more even temperatures and greater comfort in the home compared to gas furnaces.  For example, heat pumps work better and more efficiently when the temperature is set to comfort, and then left there, instead of adjusting the thermostat at night or when leaving the home.  They also cycle between heating and AC seamlesslycontrolled by the smart thermostat that accompanies the heat pump.  

Types of H​​eat Pu​mps 

Air Source H​eat​ Pumps 

Air Source Heat Pumps (ASHPs) can either be ducted (working with an established duct system in a home) or ductless, and usually have an outdoor and an indoor component.  They are easy to install, and can be customized very specifically to the needs of the home.  They are considerably more energy efficient than natural gas furnaces or resistance heaters (like baseboard units).   

Can a Heat Pump Handle ​Ann Arbor's Cold Climate?

Despite clear ​efficiency and low-carbon benefits, heat pumps from 20 and 30 years ago struggled to operate in sub-freezing temperatures. Proven t​echnical advances have drastically improved heat pump performance in cold climates; cold climate heat pump models maintain efficiency down to 5 deg F, and some are even able to perform below -10 deg F. These heat pumps have been successfully field tested in climates like Minnesota and the Arctic Circle​. Improved integration with backup electric resistance systems provide an extra layer of security. 

The heat pumps of today a​re capable of far more than those from previous decades. In response to concerns about cold climate performance, cold-climate specific standards are being rapidly developed to provide real-world performance information on cold climates. Both the Northeast Energy Efficiency Partnership and the Canadian Standards Association are working on these standards. ​

G​​round Sou​​rce H​​eat Pumps 

Ground Source Heat Pumps (geothermal) work in a similar way as ASHPs, but they transfer temperatures to and from the ground.  They require digging deep wells for installation, and are therefore sometimes difficult to install on small city lots.  They are extremely efficient, and currently qualify for a 26% federal tax credit, helping significantly with cost of installation. 

Water​​ Heaters and ​​Clothes Dryers 

Heat Pump Hot Water Heaters and Clothes Dryers are a very viable option when replacing an old gas appliance.  They work in a similar fashion to ASHPs, pulling heat out of the ambient air to warm the water or air.  There are a number of manufacturers making heat pump water heaters now, including some with lifetime warranties.    

What is an Ener​​gy Audi​t​,​ and do I Need One? 

Energy Audits can be a great investment.  They generally cost between $150-$350, and can provide a comprehensive assessment of how your home is functioning, whether air sealing or insulation could be improved, and whether older appliances are spiking electrical costs.  In addition, if you get an energy audit that is comprehensive and includes an electrification assessment, it will help to right-size your Heat Pump, leading to significant improvements in both cost and comfort. 

​Sticker Cam​​p​aig​​n

Committing to replacing​ your current gas appliance with an electric heat pump option when the time comes? Join our sticker campaign. The QR code points to our website, which will be updated with educational materials, incentivization programs, and other useful materials around electrification. Take the A2ZERO Pledge​, and indicate you would like to switch from a gas appliance to an electric one.

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Heat Pump W​orkshops​

In May, the City held a Heat Pump Workshop discussing how heat pumps work and their many benefits. A recording of this workshop can be found here​. In addition, in September, the GreenHome Institute and OSI hosted a workshop for residents to learn about heating their homes and water with cleaner electricity. Representatives from heat pump manufacturers were on hand to provide detailed information and answer questions. You can access a recording of this workshop here​.​

Finding a Contractor

electrificationbadge.pngHomeowners searching for contractors to help them switch from gas-burning furnaces to heat pumps, or to learn how to prepare their homes for future electrification or solar, are often met with conflicting advice and/or outdated information. The City of Ann Arbor has partnered with Michigan Saves to create an Electrification Badging program to help homeowners find contractors who are well-versed in electrification, solar,​ and efficiency.  Contractors who earn the Badge have completed a series of 5 training modules, as well as continuing education for badge maintenance.  You can search for “Electrification” in the Contractor Locator, or else search for the type of contractor you are looking for, and look for the badge by their name. Learn more about the Michigan Saves ​home electrification program on their Residential Electrification webpage​.​​

Mo​re In​for​​m​at​ion 

https://rmi.org/heat-pumps-a-practical-solution-for-cold-climates/ - This resource provides an in-depth examination of the use of heat pumps in cold climates.
https://rmi.org/insight/the-impact-of-fossil-fuels-in-buildings/ ​​- Examines the impacts of using fossil fuel-burning appliances inside our buildings.
​https://www.youtube.com/watch?v=PIulbHyK0bc - A short, 6-minute YouTube video on heat pumps and their use in cooling buildings.​
https://www.youtube.com/playlist?list=PLtOuBSUfZX7rIzaVm8XYhYkLGZXtdT2ro​​ - A playlist curated by the GreenHome Institute, ​featuring videos discussing topics such as air-source ducted heat pump solutions, mini-splits, water heaters, home electrification, and electrifying boilers.
https://www.swinter.com/wp-content/uploads/NYSERDA_heatpump_patternbook_comprehensive_031221.pdf - A heat pump planner, developed by the New York State ​Energy Research and Development Authority. This resource explores the different types of heat pumps and their use in different homes - from single- and double-story homes to mobile homes and apartments - and different climates.​​​