Heat Reuse Ratio

Heat reuse ratio is the share of the heat a data center produces that is supplied to another user instead of being rejected to the atmosphere. Such a user can be a district heating network. It is the practical measure behind the Energy Reuse Factor in ISO/IEC 30134-6. Liquid-cooled systems return water at 45 to 60 degrees Celsius, which is warm enough to feed heat pumps and district networks, whereas air-cooled halls reject heat at around 30 to 40 degrees and need a heat pump to be useful. Nordic and German operators already sell heat to homes and greenhouses, and Germany's Energy Efficiency Act requires larger sites to meet minimum reuse shares over time. Reuse depends on a nearby heat buyer, so it is a siting factor as much as a design one.