For two decades, the heating and cooling community has spent most of its political capital on heat. Decarbonising space heating, replacing gas boilers, decarbonising industrial process heat, building out district heating. That focus was correct, and it is still unfinished. But while we were looking at heat, cooling quietly became one of the largest single drivers of global electricity demand growth, and it is now arriving faster than the energy systems meant to serve it. Demand for comfort cooling is rising fastest in hot and humid climates, but it has also grown in moderately temperate regions like central Europe due to severe heat waves.
The numbers are no longer marginal. Global electricity demand for space cooling has grown by 50 per cent since 2015, reaching around 2,900 TWh, which is more than the total electricity demand of the entire European Union [1]. Since 2015 cooling has accounted for 14 per cent of global electricity demand growth, rising to as much as 25 per cent in the Middle East and North Africa [1]. On today’s policy settings, the IEA expects cooling demand to grow by a further 1,600 TWh by 2035, roughly equivalent to the combined annual electricity demand of Japan and Korea [1].
The peak problem, not the energy problem
The annual TWh figures are the least interesting part of the story for anyone working on security of supply.
Cooling represents around 10 per cent of annual global electricity consumption, but accounts for 30 per cent of peak electricity demand [1]. That ratio is the whole problem in a single line. Cooling load is not merely large, it is synchronised. Everyone reaches for the same relief on the same afternoon, in the same city, under the same weather system. In 2025 alone, cooling contributed 1,400 GW of peak electricity demand across markets, equivalent to the total installed power generation capacity of the United States [1].
The 2025 early summer heatwaves in Europe made this concrete. France, where air conditioning ownership remains comparatively low, recorded an evening electricity peak 25 per cent above the off-season average. In New York, where ownership is high, the equivalent figure was 90 per cent [2]. That contrast is not reassurance for the low-ownership markets. It is a preview. It shows what happens to a European load curve as ownership converges toward the levels that heat and rising incomes make inevitable. The Indian case shows the same effect in a different form: each 1 degree Celsius increase in outdoor temperature in 2024 was associated with a 7 GW increase in peak demand, and without further efficiency action that sensitivity could reach 12 GW per degree by 2030 [2].
Meteorologists are warning that El Niño could drive a further series of extreme weather events in 2026 and 2027 [1]. The IEA has modelled what that would mean if events of similar magnitude recurred every three years: an additional 700 TWh of cooling demand by 2035, with more than 60 per cent of the increase coming from accelerated air conditioner adoption rather than harder running of existing units [1]. The underlying climate signal is already visible. Cooling degree days in China and Europe were 25 per cent higher in 2024 than in 2020, and in Japan and Korea they were almost 50 per cent higher [1].
For Nordic energy planners, this is the part that deserves attention. We have built our resilience thinking around winter. Our reserve margins, storage logic, supply security narratives, and regulatory attention all assume the hard hour falls in January. A summer-peaking stress event sits outside most of that framing. It is worth noting that EU electricity demand growth in 2025 was driven partly by a sharp rise in air conditioning use in the commercial and residential sectors following record-breaking summer heatwaves [3].
Efficiency is working, and it is not enough
There is genuine progress on the equipment side. The average air conditioner sold globally in 2024 was around 20 per cent more efficient than the average unit sold a decade earlier, supported by efficiency regulations now in place in over 100 countries [1]. India illustrates what sustained policy tightening achieves: requirements have been updated every two to four years since 2009, and the average unit sold there today exceeds the highest efficiency standard of a decade ago by around 30 per cent [1].
But the headroom that remains is large, and the volume is larger. The most efficient models available today are up to four times as efficient as the least efficient, and more than twice as efficient as the average unit sold [1]. India’s minimum performance requirements are still only about half of those applying in Japan [1]. Meanwhile, global AC shipments reached 200 million units in 2024, some 25 per cent above the level of five years earlier [1]. China alone produces around 170 million units annually and exports around 60 million, against a maximum manufacturing capacity closer to 300 million [1].
The growth curve is defined by an access gap. Around 40 per cent of the world’s population currently has access to air conditioning, while more than 80 per cent experiences cooling needs during at least part of the year [1]. There are roughly 1.5 billion air conditioners in use today, a figure that could reach 5.5 billion by 2050 [6]. That gap lies overwhelmingly in markets with the weakest regulatory frameworks.
This is where equity enters the discussion rather than as an afterthought. Cooling access is a health intervention before it is a comfort product. The policy question is not whether that gap closes, but what technology fills it, and at what system cost.
Where the sector has answers already
The encouraging part is that the heat pumping and district energy communities are not starting from zero. Much of the relevant technology and system knowledge already exists; it has simply been developed under the heating banner.
Many heat pumps installed in buildings to cover the heat demand in wintertime – or to heat tap water – often replacing fossil fuel heaters, can also be used to efficiently provide comfort cooling, sometimes even simultaneously. However, in some existing buildings, modifications to the distribution systems might be needed, which is often doable. According to the IEA’s analysis, heat pump and air conditioner uptake are deeply intertwined. Cooling markets in advanced economies lead heat pump uptake and heat pumps are most cost-efficient in mixed climate regions.
District cooling is another clear example. Malla and Kranzl take a spatially explicit approach, comparing the levelised cost of cooling for networked versus individual supply at hectare resolution across Vienna, factoring in pipe sizing, network length and supply costs [4]. The result is instructive precisely because it is not a blanket endorsement: at electricity prices between 80 and 200 EUR/MWh, feasibility ranged from 1 to 70 per cent of the actual useful cooling energy demand, increasing with higher connection rates [4]. Cooling networks are not universally the answer, but where density and connection rates align, the case is strong, quantifiable, and highly sensitive to the policy instruments that drive connection.
The waste heat pathway is developing on the same footing. A study of hybrid data centre cooling integrated into the Kozala district heating system in Rijeka compares integration into third, fourth and fifth generation networks using measured hourly IT load and climate data. Payback is under one year for the fourth and fifth generation cases, against 14 years for third generation integration, where higher capital cost and the electricity needed for the temperature lift dominate [5]. A data centre is a cooling load that produces a heat resource, and the temperature level of the receiving network decides whether that resource is worth anything. Note the scale of what is currently being thrown away: the IEA estimates cooling demand in data centres alone at 80 TWh in 2025 [1].
Analysts working on the Global South are reaching similar conclusions from a different direction, positioning district energy as the efficient alternative to unmanaged household air conditioning, with energy savings of up to 50 per cent and scope to integrate waste heat from sources including data centres and municipal solid waste processing [6].
The unfinished business of refrigerants
One dimension is conspicuously missing from the current wave of cooling coverage: refrigerant management. Rapid growth in installed cooling stock means rapid growth in installed refrigerant charge, and the recovery, recycling and reclamation infrastructure to handle it at end of life is uneven across exactly the markets where growth is fastest.
This is not a new observation. The IEA HPT TCP produced an international assessment of refrigerant management programmes under Annex 16 more than two decades ago, examining how national policies, regulations and enforcement practices differed across Australia, Canada, France, Japan, the Netherlands and the USA [7]. The questions it asked, about programme design, incentives, effectiveness and penalties for non-compliance, are the questions being asked again now under the F-gas phasedown and the A2L transition, but at a far larger scale of installed base.
This work has been continued on the ongoing HPT TCP Project 64 Safety Measures for Flammable Refrigerant and follow-up work to this project is already under development.
New HPT TCP projects entering this space
Much of the groundwork for this was laid in Vienna. On the first day of the 15th IEA Heat Pump Conference in May, the Heat Pump Centre team, Dr Caroline Haglund Stignor and Dr Monica Axell, organised a workshop on comfort cooling concepts for different types of climates and regions, in collaboration with a team from the ZHAW School of Engineering, IEFE Institute of Energy Systems and Fluid-Engineering, in Switzerland. Its objective was to define the focus and scope of potential international collaboration projects within the HPT TCP. More details of the workshop can be found here.
The programme is responding to exactly these gaps. Two new HPT TCP projects are starting shortly, and between them they address the two ends of the problem set out above: what goes inside the equipment, and how the equipment actually performs once it is installed.
CLImate-friendly COmfort units with focus on NATural refrigerants will be led by Zurich University of Applied Sciences (ZHAW) in Switzerland. Comfort cooling is the fastest growing part of the installed base and the segment where refrigerant choice is least scrutinised, so a project focused specifically on natural refrigerants in comfort units addresses the volume market. It also connects the equipment question to the end of life question raised above: the cheapest refrigerant management programme is the one made unnecessary by the refrigerant selected at the design stage. The cooling challenge and this project proposal were discussed extensively at that workshop. Readers wanting to know more can contact Serena Danesi (dane@zhaw.ch) and Tillenkamp Frank (till@zhaw.ch) at ZHAW.
Heat Pumps in action! Operating heat pumps in multi-family residential buildings, a follow-up to Project 62 [8], will be led by Marek Miara. Multi-family buildings are where the heating and cooling agendas are hardest to separate. They carry the largest concentrated loads, the most constrained retrofit conditions and, increasingly, summer overheating problems that single measures do not solve. Field data on how units actually operate in this building class, rather than how they are specified to operate, is the evidence base that both peak modelling and policy design currently lack. Contact Marek Miara at marek.miara@heatpumpswatch.org.
Safe Use of Refrigerants in Heat Pumping Technologies
This is a follow-up to Project 64 and will be led by one of the Project 64 participants, Thore Oltersdorf (thore.oltersdorf@ise.fraunhofer.de).
The proposed project would broaden the scope compared to Project 64 to include additional refrigerants, leakage to air as well as to secondary loops, risk assessment, and appropriate procedures for managing refrigerant-related safety risks.
These projects are open to participation from HPT TCP member countries, and both would benefit from partners able to contribute field measurement data.
What should change
Three things would help the sector move from observation to action.
First, treat cooling as a resilience question rather than a comfort question. Summer peak adequacy deserves the same analytical seriousness that winter peak adequacy already receives, particularly in northern European systems where it currently receives almost none.
Second, plan heating and cooling as one system. Reversible heat pumps, fifth generation networks, seasonal storage and waste heat recovery are not separate agendas. As the Rijeka results show, the infrastructure that decarbonises heat is, in most cases, the same infrastructure that can serve cooling at a fraction of the marginal system cost, provided the network temperature is right.
Third, close the loop on refrigerants before the installed base doubles, not after.
Cooling has been the sector’s quiet variable for a long time. It is not quiet any more.
References
[1] IEA (2026), Cooling a hotter world: El Niño meets strong growth in global electricity demand, commentary by A. Vautrin, J. Dou, A. Nordin Furdos and F. Voswinkel, 10 July 2026, IEA, Paris. Licence CC BY 4.0. https://www.iea.org/commentaries/cooling-a-hotter-world-el-nino-meets-strong-growth-in-global-electricity-demand
[2] IEA (2025), Staying cool without overheating the energy system, commentary, 28 July 2025, IEA, Paris. Licence CC BY 4.0. https://www.iea.org/commentaries/staying-cool-without-overheating-the-energy-system
[3] IEA (2026), Electricity 2026: Analysis and forecast to 2030, February 2026, IEA, Paris. Demand chapter. Licence CC BY 4.0. https://www.iea.org/reports/electricity-2026/demand
[4] Malla, A. and Kranzl, L. (2025), Strategic planning and viability assessment for implementing district cooling networks, Energy, vol. 319, 134846. https://doi.org/10.1016/j.energy.2025.134846
[5] Energy Efficiency Through Waste-Heat Recovery: Hybrid Data-Centre Cooling in District Heating Applications, Applied Sciences, 2026, 16(1), 323. https://doi.org/10.3390/app16010323
[6] Carnegie Endowment for International Peace (2026), As Heat Waves Spike, the Global South Needs New Cooling Solutions, August 2026. https://carnegieendowment.org/research/2026/08/as-heat-waves-spike-the-global-south-needs-new-cooling-solutions
[7] Snelson, K. and Bouma, J. (2002), Refrigerant Recovery, Recycling and Reclamation, Part 1, IEA Heat Pump Centre, Annex 16, order nr HPC-AR11. https://heatpumpingtechnologies.org/publications/refrigerant-recovery-recycling-and-reclamationpart-1/
[8] IEA HPT TCP, Project 62. https://heatpumpingtechnologies.org/project62/