Data centers produce a lot of heat, but at a low temperature. So where can this lukewarm data center waste heat be used?
Where lukewarm heat is enough, it is used as it is; where hotter heat is needed, heat pumps raise its temperature first. This post looks at how data center waste heat is used, real examples, and what it would take for it to be used more widely.
Uses of data center waste heat
| Use | How data center heat fits | Examples |
|---|---|---|
| District heating | Liquid cooling is close to the right temperature; air cooling needs heat pumps | Odense, Denmark (Meta); Hamina, Finland (Google) |
| Fish farming | Keeps water moderately warm | Green Mountain, Norway, and the world’s largest land-based trout farm |
| Greenhouses | Warms the air enough to grow crops | Luleå University of Technology, Sweden; University of Notre Dame, US |
| Swimming pools | Heats pool water | Exmouth Leisure Centre, UK |
| Industrial drying | Serves low-temperature drying processes | Falun, Sweden, wood pellet drying |
District heating
In colder regions, district heating is seen as the most effective use of data center waste heat. Nordic district heating networks send out water at 60–70°C and take it back at around 50°C, a good match for the 45–70°C heat from liquid-cooled data centers, where servers are cooled with water. In air-cooled data centers, heat pumps have to raise the temperature.
Meta’s data center in Odense, Denmark, has since 2020 sent waste heat, raised in temperature by heat pumps, into the district heating network, warming more than 7,000 homes. In Hamina, Finland, Google’s data center began supplying heat to the district heating network in late 2025 and, once fully operational, is expected to cover around 70–75% of Hamina’s district heating needs.
Fish farms and greenhouses
Fish farms and greenhouses only need water and air kept moderately warm, so lukewarm data center heat can be put to use. Norway’s Green Mountain data center sends waste heat to the world’s largest land-based trout farm, and Luleå University of Technology in Sweden and the University of Notre Dame in the US heat greenhouses with data center heat.
These uses have the advantage of being, in many cases, less seasonal than district heating.
Swimming pools
Swimming pools also need their water heated all year round. Since March 2023, a leisure centre in Exmouth, England, has heated its indoor pool with heat from a small data center. The servers are immersed in oil, and the heat the oil picks up is passed to the pool water through a heat exchanger. The data center operator pays for the electricity and gives the heat away free, so the leisure centre has been able to cut its gas use.
Industrial drying
Industrial processes that run at low temperatures can also take data center waste heat. The EcoDataCenter in Falun, Sweden, supplies heat to a plant that uses it to dry wood for pellet production.
What it takes to scale
Data center heat reuse is growing quickly. Google is spending $1 billion to expand its data center in Hamina, Finland, and will give the heat to the local community, and one analysis suggests that data centers near Europe’s district heating networks could supply 75TWh a year by 2030, about 10% of the EU’s heating demand.
To be used more widely, though, one thing has to be solved: time. A data center gives off heat steadily all year, while heating demand peaks in winter and drops sharply in summer. If the times when heat is spare and when it is needed can be bridged, data center waste heat could be used in far more places.
The bottom line
Even at low temperatures, data center waste heat can serve district heating, fish farms, greenhouses, swimming pools and drying processes. Because the times when heat comes out and when it is used drift apart with the seasons, matching not only where the heat goes but also when it is used would let data center waste heat be used in far more places.
If you would like to work out where the heat from your facility could be used, request a technical meeting.
If you are wondering how the gap between spare heat and heat demand can be bridged, the next post is a light read.
Sources
- Heat Reuse, Sustainable Data Centers Roadmap — Innovation for Cool Earth Forum (ICEF) (2025-10) — Nordic district heating supply 60–70°C and return around 50°C, liquid cooling 45–70°C, Meta Odense (since 2020, heat pumps, over 7,000 homes), Green Mountain land-based trout farm, Luleå and Notre Dame greenhouses, Falun EcoDataCenter wood pellet drying, Google’s $1 billion Hamina expansion with heat given to the community, cited analysis of 75TWh a year by 2030 from data centers near European district heating networks (about 10% of EU heating demand), many fish farm, greenhouse and drying uses lack district heating’s seasonality, seasonality of district heating
- Hamina heat recovery inaugurated — CapMan (2026-05-18) — Google Hamina data center heat recovery, first heat supplied in Q4 2025, inaugurated 12 May 2026, around 70–75% of Hamina’s district heating needs once fully operational
- Green Mountain’s data center heat reuse by Hima Seafood is up and running — WeAreAquaculture (2026-02-04) — Rjukan, Norway: heat from Green Mountain’s DC2-Telemark warms the water at Hima Seafood’s trout farm
- Small but powerful: Tiny data center heats UK swimming pool — AFP via Tech Xplore (2023-06-23) — Exmouth Leisure Centre, installed March 2023, servers immersed in mineral oil with heat passed to pool water via a heat exchanger, operator pays for electricity and gives heat free, reduced gas use
- Cover image: AI-generated (colour-adjusted)