Heat reuse · Updated
Why district heating takes only 5–10% of a rural data centre's heat
District heating is the default answer to data centre heat. For a large AI campus in the countryside it covers only a small share, for three reasons: season, distance and temperature.
Data centre waste heat arrives evenly, the demand does not
A data centre makes heat every hour of the year, about 7.5 GWh per IT megawatt at typical utilisation. District heating demand follows the weather: in Finland it is more than five times higher in the winter months than in summer (Finnish Energy). A network sized for winter has little room for heat in July.
New campuses are built far from towns
According to JLL, hyperscale data centre campuses planned for 2026–2028 are on average 175 km from major hub cities, compared with 46 km for projects delivered in 2022–2025. Far from cities, there is seldom a ready buyer for the heat. In one Finnish example, a 60 MW project would make about 450 GWh of heat a year, of which the local network could take 3–4%, and only in winter.
The temperature is too low for the network
Liquid-cooled servers return water at about 50–55 °C. District heating networks run at 65–90 °C, so the heat needs heat pumps before it can be used. That costs electricity and capital, and makes sense only for part of the heat.
The alternative: many users, sorted by temperature
Many productive uses need exactly the temperature a data centre gives: drying and greenhouses at 40–50 °C, biogas and biochar at 37–42 °C, fish and insect farming at 20–30 °C, and buildings and snow melt at 25–40 °C. Run as one cascade next to the data centre, they use heat all year. At a 100 MW campus, built one Heat Hub per 10 MW modular block, such a cascade puts about half of the year's heat to use, roughly 335 of 670 GWh, against 5–10% for district heating alone.
District heating still has a place in the portfolio, for the share that pays. The point is not to replace it but to stop treating it as the only buyer.
Why it matters
According to the European Commission, reusing on average 50% of all data centres' waste heat could cover the total heating demand of almost 4 million households in Europe. Getting there requires heat users that work in July as well as in January.