Executive Summary
- Data centres account for between 1 and 1.5% of global electricity use and as we shift to more sustainable digital infrastructure and increase the efficiency of data centres, heat recovery systems are an underutilised strategy to become more efficient and for the industry to give back to the community.
- Waste heat is captured through cooling systems and routed to heat-exchanger systems rather than into the atmosphere.
- While the UK is renewing its interest in heat reuse, there are many logistical and cost obstacles, such as legacy sites that weren’t designed or located optimally for recovering thermal energy and transporting it.
The International Energy Agency states that data centres account for 1-1.5% of global electricity use, and cooling systems represent a significant share of that footprint. And the shift to sustainable digital infrastructure is accelerating in the UK and so the need to find innovative solutions to enhance efficiency and reduce carbon emissions is imperative to achieve environmental goals.
Currently, one underused strategy data centres need to stop sleeping on is heat recovery.
What is heat recovery?
Servers inside data centres produce a lot of waste heat that is typically released into the atmosphere through cooling systems.
With heat recovery, this waste heat is captured through cooling systems and routed to heat-exchanger systems rather than into the atmosphere. Often, server heat is low-grade, typically around 25°C-40°C, so for the heat to be useful and meet district-heating standards, the temperature must be boosted through heat pumps and/or cascade heat-exchanger configurations to raise it to 60°C-90°C.
A commercial agreement will be struck between a data centre owner and the utility district-heating company, so the heat is injected into the network through underground pipes and credited against the utility’s supply. This reduces the need for fossil fuels or biomass boilers and also stabilises district-heat prices.
Not every season will produce the same amount of heat. During periods of low demand, such as summer, surplus heat can be stored in short-term thermal stores, used for other processes like greenhouses, or exported to other flexible markets.
Why does it matter?
From an industry perspective, pressure is rising to improve energy efficiency and environmental performance. From a community perspective, having data centres give back to the community can help with the rising cost of energy bills and community opinion and consensus around having data centres built near the community.
Furthermore, data centres operate 24/7, continuously generating excess thermal energy; this is an opportunity that operators shouldn’t miss out on to improve efficiency, especially with PUE plateauing around 1.54 according to Uptime Institute’s 2025 Global Survey.
Challenges and opportunities for change
You won’t see heat recovery rolled out across all data centres in the UK, and that’s because there are still challenges to navigate. Many legacy sites weren’t designed or located optimally for recovering thermal energy and transporting it, which poses cost and logistical obstacles.
Engineers also must navigate site layouts, compatibility between heat recovery systems and HVAC systems, as well as navigating complex differences in temperature. However, modern cooling solutions are now being designed with integration and modularity in mind, thus making heat resuse more viable strategy to implement into more data centres.
The good news is that the UK is giving more of its attention to district heating as utilities are looking to decarbonise buildings, to navigate the rapid growth of AI and the pressures it brings to data centre infrastructure.
