PREP Talks: Michael Nadeau – Busting the myths about heat pumps

Michael Nadeau COURTESY PHOTO
Published: 12-20-2024 8:33 AM |
Heat pumps are becoming the residential heating and cooling technology of choice. In June, 3.6 million heat pump systems were installed in the United States versus 2.9 million gas-fired furnaces, according to research from the Rocky Mountain Institute (RMI).
The reasons are clear. Heat pumps are more efficient and cost far less to operate than oil- or gas-based systems. You might not know that, however, depending on where you get your information about heat pumps. Many myths persist about the technology. Some are based on old information, while others are merely bad assumptions.
Here are the most-common heat pump myths and reasons why they are not true. I'm keeping this discussion specific to the more common air-source heat pump systems.
If this were true, then why do the coldest countries in Europe – Finland, Sweden, and Norway – have the highest sales of heat pumps in the world, according to the European Heat Pump Association?
In the United States, Maine has adopted heat pumps faster than any other state. While it is true that early generations of heat pumps lost their efficiency advantage at sub-freezing temperatures, the current generation includes cold-climate models that can maintain high efficiency at sub-zero temperatures.
Heating system efficiency is determined by its coefficient of performance, which is a measure of the amount of energy put into the heating system compared to the units of heat it produces. A COP of one represents an efficiency rating of 100% because one unit of energy consumed produces one unit of heat.
Any heating system that burns fossil fuel can never be more than 100% efficient due to heat loss. Gas furnaces are the most-efficient fossil-fuel-based systems with a maximum COP of 0.85.
Heat pumps work like an air conditioner to transfer rather than produce heat. They pull heat from outside air and move it to inside the home in winter, reversing the process in warm weather. Because they move rather than generate heat, heat pumps have a much higher COP than systems that need to burn fuel though their efficiency declines as the temperature drops.
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According to a 2023 report by the Regulatory Assistance Project, cold-climate heat pumps can maintain a COP rating of just below two at minus-20 degrees Celsius. That means that for every unit of electricity the heat pump consumes, it produces twice as much heat, even in extreme cold. The average rating at 10 degrees Celsius is just under four, but some units are above five.
If the temperature drops below the efficiency threshold of a particular heat pump unit, it is equipped to produce heat through resistive heating that uses an electrical heating element.
Heat pump units come in a wide variety of configurations, some designed for existing buildings. Low ceilings? Floor-mount or baseboard units can be mounted low. Don't have an existing air ducting system? Ductless heat pumps, also called mini-splits, don't need them.
The biggest concern when installing a heat pump in an existing building is weatherization. If your home is poorly insulated, then you should consider addressing that before investing in a heat pump. Heat pumps can work effectively in buildings that are not well insulated, but you will need a larger and more expensive system.
Weatherization no matter how you heat your home is always a good investment, and you should have a home weatherization assessment done before your contractor determines what size heating or cooling system you need.
As explained above, a modern cold-climate heat pump can keep you warm even on the coldest days. Worst case, it will switch to resistive heating in extreme cold, which will be less efficient but still keep you cozy. A backup heating system like a wood stove would have more value in the event of a power outage.
Heat pumps generate noise from condensers and fans that circulate air, but complaints about noise have been few. A UK study found that there were only about 100 noise complaints for every 300,000 outdoor heat pump installations.
The current generation of indoor systems is relatively quiet. Data from the U.S. Centers for Disease Control shows the average noise level for heat pumps is 50 decibels, less than an average refrigerator. Noise ratings of some units on the market are as low as 43 decibels.
Demand on the United States electrical grid is expected to rise between 4% and 15% through 2029, according to a report from Gridlock. Electrification, which includes heat pumps and electric vehicles, is a contributor to that growth, but it's not the primary driver of new power demand.
The rapid expansion of data centers that provide processing power for artificial intelligence applications, cloud services and cryptocurrency mining is the primary source of electrical grid stress. Data centers account for 2.5% of United States electricity demand, according to the Boston Consulting Group, and that's expected to triple to 7.5% by 2030.
A heat pump is likely to lower your heating and cooling costs if you address significant weatherization issues and have it professionally installed to ensure it is properly sized and designed. A poorly designed system will work less efficiently, and a well-designed heat pump system will work harder than it should if your home is not well weatherized.
So, if you install a heat pump in your home this year and significantly lower your annual heating and cooling costs, the documented savings will be compelling to prospective buyers when you put your home on the market.
The expectation is that the current generation of heat pumps will last about 20 years. A Lawrence Berkeley National Laboratory on heat pumps installed between 2001 and 2007 showed a lifespan of 15 years. Better technology has improved reliability since then.
This decision depends on your financial situation. The size and layout of your home largely determines the cost of installing a heat pump. You also need to factor in any weatherization costs needed to allow the heat pump to work at top efficiency and any electrical upgrades needed to support the increased demand.
I know of contractor quotes to install heat pump systems locally ranging from about $15,000 to $25,000. Some people have installed them in only areas of their homes, typically to heat or cool spaces where their current system performs poorly, for a few thousand dollars.
Weigh the installation cost against what you'll save long-term in operating costs. A contractor should be able to estimate operating costs when they provide their quote for installation.
Incentives can lower that cost significantly. The Inflation Reduction Act currently offers up to $8,000 in rebates for a heat pump. Local incentives might also be available. The towns of Peterborough and Harrisville, for example, have launched a new program, HeatSmart+, which includes incentives for heat pumps. It's funded through a federal grant and offers cash incentives of up to $3,300 to eligible homeowners to implement energy efficient home upgrades.
For information, visit tinyurl.com/heatsmartplus. If multiple incentives are available, be aware that you might be able to use only one.
Michael Nadeau is a member of the Peterborough Renewable Energy Project.