EnEfG: waste heat and water in numbers
PUE 1.2, staged waste heat use, 100 percent renewables from 2027. And why water is not the bottleneck in practice.
The EnEfG (Energy Efficiency Act) sets three requirements for new data centers. First, efficiency: a PUE of at most 1.2 for facilities commissioned from 1 July 2026. Second, waste heat: 10 percent utilisation for commissioning from July 2026, 15 percent from July 2027, 20 percent from July 2028; if no offtaker exists, a justified exemption is possible. Third, electricity: 50 percent from renewables since 2024, 100 percent from 1 January 2027, on a balance-sheet basis.
The law does not regulate water directly; practice does. Evaporative cooling is not permitted in Germany, so new facilities cool via closed loops. No groundwater and no river water for cooling, and a water demand comparable to a commercial business.
For sites in rural areas, waste heat is the more interesting point: greenhouses, drying processes and local heat networks take heat at 35 to 55 °C.
Source: EnEfG sections 11 ff.; federal data center strategy, 18 March 2026.