International Energy Agency Says Heat Pumps Are Hot

The International Energy Agency (IEA) released a special report, "The Future of Heat Pumps," in which they start with a strong statement: "Heat pumps, powered by low-emissions electricity, are the central technology in the global transition to secure and sustainable heating."

“Heat pumps are an indispensable part of any plan to cut emissions and natural gas use, and an urgent priority in the European Union today,” said IEA Executive Director Fatih Birol in a statement. “The technology is tried and tested, even in the coldest of climates. Policy makers should be putting their weight behind this technology that is witnessing unprecedented momentum at the moment. Heat pumps will be central to efforts to ensure everyone can heat their homes this winter and next, to protect vulnerable households and businesses from high prices, and to meet climate objectives.”

Heat pumps have been truly hot as of late. The IEA says that "around 10% of space heating needs globally were met by heat pumps in 2021, but the pace of installation is growing rapidly." This is a technology that started slowly because of the high cost of drilling for ground-source heat pumps but has taken off as air-source units got better in low temperatures. In North America, you will still have contractors saying they won't work in the depths of winter. Yet in Norway, 60% of buildings are now "heatpumpified," and in Sweden and Finland over 40% are.

Heat pumps alone are expected to account for about half of the reduction in fossil fuel use for heating by 2030, with the remaining coming from other efficiency measures. "In a scenario consistent with the global climate target of 1.5 °C, heat pumps accelerate faster—their capacity nearly triples by 2030 and their share in heating reaches one‐quarter," said the IEA, which estimates heat pumps can reduce global carbon dioxide emissions by 500 million tons in 2030.

Birol concluded:

“All the pieces are in place for the heat pump market to take off, reminiscent of the trajectory we have seen in other key climate technologies like solar PV and electric vehicles,” said Dr. Birol. “Heat pumps address many of policy makers’ most pressing concerns on energy affordability, supply security and the climate crisis. Policy measures are in place today, but they need to be reinforced urgently to allow heat pumps fulfil their significant economic and environmental potential.”

Treehugger has been extolling the virtues of heat pumps for some time but has worried about the "rah-rah fist pumps for heat pumps" crowd that sees them as a solution to the supply side of heat without ever considering the demand side—the amount of heat that is needed, which has a big impact on the size and type of the heat pumps—their impact on the electrical supply, and the refrigerants they are charged with.

Fundamentally it is a question of balance between heatpumpification and insulation, and it is addressed in the report: "The growing role of heat pumps also requires policymakers to pay careful attention to electricity security implications. Combining heat pump deployment with energy efficiency retrofits of buildings can reduce these risks, and leveraging smart controls can turn heat pumps into a grid asset, when employed alongside appropriate planning for electricity grids."

Chapter 1 of the report explains how heat pumps work and shows they are not carrying all the load. In fact, they cannot—there are other demands on the grid as well.

"For households that add a heat pump without improving efficiency in parallel, this can nearly triple their peak demand during winter. Improving a home’s efficiency rating by two grades (e.g. from D to B in European countries) can halve heating energy demand and reduce the size of the heat pump needed, saving consumers money and reducing the growth in peak demand by one‐third. Together with careful grid planning and demand‐side management, this moderates the need for distribution grid upgrades caused by electrifying heat and minimises the need for additional flexible generation capacity to 2030."

I have spent some time trying to understand what is involved in going from D (the average British house) to B, but cannot figure it out. Like most North American standards, it is talking about energy and not carbon and seems in desperate need of an update. A Passivhaus design will usually come in at A, and as we have noted before, can act as an effective thermal battery.

The report acknowledges the value of thermal storage and notes that installing heat pumps in well-insulated buildings can significantly reduce peak demand. "In well‐insulated buildings, switching off a heat pump for several hours can have little impact on indoor temperatures," which adds to system flexibility. It describes an experiment in Germany where heat pump manufacturer Viessmann connected their heat pumps to the transmission system operators (TSOs), which could turn them off at peak times.

"In order to maintain indoor temperatures, heat is stored in a hot water buffer tank. The thermal inertia of the hydronic heating system and the building itself (especially if well‐insulated) also limits the impact on temperatures of switching off the heat pump, which usually takes several hours. Customers are remunerated according to their contribution to lowering load."

So if you have a well-insulated house and sign on to this program, they pay you for the power you save.

Fist Pumps for R-290 Monoblocks!

The report mentioned what it calls "a potential catch in the environmental case for heat pumps"— the leakage of F-gases. "Emissions of these gases, which are powerful GHGs, threaten to offset part of the climate benefits from switching away from fossil fuels for heating." This issue causes significant eye-rolling when we talk about it on Treehugger, but it is a big deal.

"F-gases make up about 2.4% of global GHG emissions (IPCC, 2022). Emissions could grow rapidly in the coming years with the increased uptake of heat pumps and air conditioners if no further action is taken to control their use."

The report noted that there are now alternatives, but it has they have their own issues.

"For example, the use of propane as a refrigerant is restricted under EU building regulations due to its higher flammability. While the installation of monobloc hydronic units, where the refrigerant cycle is entirely located outdoors, gets around this problem, split systems are also an important option to make heat pumps usable in the majority of buildings."

This is not insignificant when one is talking about a major roll-out. As noted earlier, "Fist pumps for R-290 Monoblocs" doesn't have the ring of Dave Roberts' Fist Pumps for Heat Pumps.

According to the report, "A rapid scaling‐up of the deployment of heat pumps would necessitate a commensurate expansion of the workforce in manufacturing and installing them."

Monoblocs, where all the refrigerant is in the unit, are simpler to install. You just need a plumber to connect water lines; no special refrigerant training is required. And as the graph shows, greenhouse gas emissions from heat pumps with hydrocarbon (HC) refrigerants are significantly lower than those with HFCs.

We Need to Insulate, Electrify, and Heatpumpify

The report acknowledges the intersection between insulation and heatpumpification.

"Well‐insulated buildings and efficient heat pumps, which can be encouraged through minimum energy performance standards and labeling, are essential to reduce the capacity of heat pumps needed to warm a given amount of space and volume of water, thereby cutting the cost of operating as well as installing them. This also allows for lower flow temperatures, enabling heat pumps to operate more efficiently and cheaply. In Denmark, electricity consumption by heat pumps has been found to be up to 30 times lower in homes with the highest efficiency rating compared with the lowest efficiency rating (Figure 3.4). Improving a home’s efficiency rating by two grades (e.g. from D to B) can half the heating energy demand."

Engineer Toby Cambray, the verber who invented the word "heatpumpify," anticipated this in an article in Passivehouse Plus Magazine. Speaking from the United Kingdom, he thinks heat pumps are great, but warned: "This does not, however, mean that it’s a good idea to put a heat pump in a building with poor fabric efficiency. Although there are cases where other constraints mean we have little choice, ultimately, we need to both (mostly) Insulate Britain and (mostly) Heatpumpify Britain." 

So let's circle back to that first line of the IEA report: "Heat pumps, powered by low-emissions electricity, are the central technology in the global transition to secure and sustainable heating."

Yes, heat pumps are important, but they are one leg of a stool here, and it doesn't stand up unless we have three legs. "Fluffy stuff," as Toby Cambray calls insulation, isn't sexy, but it's critical. Or as I noted earlier, we need to electrify, heatpumpify, and insulate our way out of the current crises. Heat pumps alone are not enough.