Heat reuse: when a datacenter's waste heat has a buyer

Heat reuse means putting a datacenter's waste heat to work instead of releasing it, most often in a district heating network, and sometimes in greenhouses, fish farms or industrial processes. Nearly all the electricity a datacenter uses becomes heat, so a large site produces a steady, year-round supply. It works when there is a buyer close enough and the heat is warm enough to use.

Air-cooled halls return heat at low temperatures, too cool for most heating networks on its own. Heat pumps raise it to a usable temperature, at the cost of some electricity.

Liquid-cooled racks change the picture. Direct liquid cooling can return water warm enough to need less lifting, so AI halls with direct liquid cooling are often better heat sources than traditional ones.

• Distance: heat travels poorly, so the network or user should be close.
• Demand: heating networks need most heat in winter, while a datacenter produces it all year, so summer heat needs another use or is released.
• Contract: the heat buyer wants reliable delivery; the datacenter wants its cooling never to depend on the buyer taking the heat.

The EU's recast Energy Efficiency Directive (2023) requires larger datacenters to report their energy performance each year, and expects sites above 1 MW to use their waste heat, or other heat recovery, unless they can show it is not technically or economically feasible. National rules add detail, so check how the country you build in applies it.

Heat reuse is a standard field on every listing. It earns a small bonus in the fit score, alongside renewable supply and certifications, so a site that reuses its heat ranks a little higher for every request it fits. See the glossary for the short definition.