Are Heat Pumps a Climate-Friendly Solution to Reduce Carbon Footprint?

As global temperature rises, governments seek ways to fight climate change. Heat pumps are becoming a popular solution to reduce households’ carbon footprint and offering them savings in their power bills.

In the United Kingdom, domestic households consume 29% of the total energy generated and emit a quarter of their total GHG emission. Being the second largest energy consumer in the U.K., the government sets targets to lower U.K. households’ carbon footprint.

Thanks to the heat pumps installed in U.K. households, a total of 182,300 heat pumps, and 976,197 solar panels installed by 2017, the country was able to decrease its CO2 emissions by 18% since 1990.

According to the IEA’s “The Future of Heat Pumps,” heat pumps, powered by low-carbon electricity, are the central technology in the global transition to secure and sustainable heating. Available heat pumps are three to five times more energy efficient than natural gas boilers. Building heating is responsible for four gigatonnes (Gt) of CO2 emissions annually – 10% of global emissions. Installing heat pumps instead of fossil‐fuel‐based boilers can significantly reduce emissions even with the current energy mix and will rise further as electricity systems decarbonise.

Increasing renewable sources to generate electricity is a key pathway for the country to meet its 2030 emissions targets (reducing 57% by 2030). By increasing their renewable energy sources by 25%, the U.K. has reduced GHG emissions by 43% compared to 1990 levels.

The Economist reports that twelve European countries plan to replace fossil-fueled heaters in their buildings, and they consider heat pumps the best alternative for energy efficiency and lower carbon footprint. Regarding energy efficiency, a kilowatt of electrical energy that heat pumps consume.

But there is a catch.

Swapping a boiler to a heat pump is more complex. There are costs and space involved. First, heat pumps are larger than gas boilers and require outside space. Second, heat pumps run at cooler temperatures than boilers do, and for the freezing winter temperatures, old and leaky homes comprise 60% of European properties.

These properties would need to be insulated, which means additional costs to homeowners on top of installing a heat pump. The price of switching to heat pumps could quickly become problematic and politically toxic, the article notes. The least that governments can do is to cover some of the cost and ensure that there are enough skilled workers to retrofit homes, the article suggests.

Heat pump use in the United States

Meanwhile, in the U.S., only 10% of homes use heat pumps. Most of their heating comes from carbon-containing fuel (natural gas, propane or oil) within the house, including those used to heat water and cook. 

Findings from the University of Michigan study published in the Environmental Research Letters in July 2021 show that switching around 30% of U.S. single-family homes to heat pumps would cut GHG emissions and save them money.

Reducing households’ carbon emissions will entail replacing the traditional gas and oil boilers with electrification, says Michael Waite, associate research scientist at Columbia University who is not involved in the study.

While many households in the U.S. could benefit from switching to heat pumps, the study also notes that wide-scale heat pump adoption may have unintended, undesirable consequences.

Study authors simulated widespread heat pump adoption outcomes to determine the circumstance that makes heat pumps a wise choice. They modelled 400 locally representative single-family homes in each of the 55 cities for a total of 22,000 houses. Each set of houses is chosen as a representative of the housing stock in a particular city.

“The key finding is that for around a third of the single-family homes in the U.S., if you installed the heat pump, you would reduce environmental and health damages,” according to Parth Vaishnav, an assistant professor at the School for Environment and Sustainability at the University of Michigan and a co-author of the paper (Rocheleau, 2021).

The study notes that installing heat pumps would avoid $600 million in health damages and $1.7 billion in climate damages yearly and would also directly save homeowners money on energy costs. The study finds that using heat pumps lowers greenhouse gas emissions for all homes by assuming a moderate electric grid decarbonization.

However, installing a heat pump would only benefit some. For others, installing a heat pump would be more expensive because the cost of generating electricity is higher than the cost of in situ fossil fuel use. Heat pumps are also less efficient to heat houses in colder climates and will increase power bills. In 24 of the studied cities, mostly in colder climates, peak residential electricity demand increased by over 100% if all houses adopted heat pumps, which would require grid upgrades.

The study suggests that switching about 30% of single-family homes to heat pumps will reduce harm to the environment and human health and allow savings for households. The best places to start are the parts of the country with a moderate climate. The authors also suggest cleaning up the grid as fast as possible to allow wider uptake of heat pumps and noting that heat pumps will continue improving and increase efficiency in colder climates.