Why waste heat from data centers is a valuable resource

Every watt of electricity consumed by a server turns into heat. According to an analysis by Uptime Institute, less than 0.1% of the energy consumed by IT equipment is used for actual data transfer. The rest is heat.

For data centers, this has traditionally been an important issue to solve: "How can we efficiently remove this heat to keep the equipment within operational parameters?" This is why cooling systems are among the main expense items in the budget of any facility.

However, in Europe, an increasing number of operators and municipalities are viewing this heat differently: as a valuable resource that can be utilized.

The Infrastructure Challenge

Servers emit heat at different temperatures depending on the type of cooling (air or liquid), ranging from 40-55°C to 60-70°C. These temperatures are high enough for direct use in heating systems or (with the help of a heat pump) for supplying local heating networks with higher temperatures.

In theory, the mechanism is well-known: a heat exchanger captures the heat from the cooling system of the data center and transfers it to the heating network of a building or district. At lower output temperatures, a heat pump is used to raise the temperature to the levels required by the network.

The infrastructure challenge lies in the connection: the data center must be physically close enough to the heat consumer, or there must be a network to transport the thermal energy. This is why urban projects are easier to implement, as distances are smaller and the transmission infrastructure either already exists or is easier to build.

The Idea Has Grown on a Serious Scale in Europe

In many countries, the utilization of heat from data centers has long surpassed individual pilot projects and is now part of green policies in several regions, where thousands of households are heated thanks to such energy. 

• Stockholm utilizes data center heat in an open district heating scheme, which provides heating for 30,000 apartments annually, reducing carbon emissions by 50 grams per kilowatt-hour.
• In Finland, Microsoft and a local energy company partner to cover about 40% of the local heating needs of approximately 250,000 people by using waste heat from new data centers.
• In Denmark, a data center of an international tech company already provides heating for nearly 11,000 households through an indirect evaporative cooling system with an integrated heat exchanger.
• During the Paris Olympics in 2024, a data center heated the training pool at the Olympic Aquatic Center. The system is planned to reach capacity for heating 1,000 homes annually.
• In Ireland, a local heating scheme in Tallaght saves over 1,100 metric tons of carbon dioxide in just one year by redirecting waste heat from a nearby Amazon data center to local buildings.
• In the UK, waste heat from the Gatwick Airport data center is set to provide 46 GWh of heating to homes in Crawley.

The scale of these projects is already large enough to replace significant quantities of fossil fuels in the heating systems of European cities.

Regulations Are Also Catching Up

Utilizing waste heat is no longer just a matter of goodwill by operators. European legislation is making it a requirement.

With the revised EU Energy Efficiency Directive (EU/2023/1791) from October 2025, new rules apply to data centers over 1 MW: operators must technically assess the possibility for reusing waste heat, submit a cost-benefit analysis, and report key data to the EU annually.

National regulations are following suit. Germany, France, Sweden, Denmark, and the Netherlands already regulate targets for waste heat utilization between 10 and 35% by 2030. The Netherlands has already banned new hyperscale data centers outside two designated locations, and the country requires integration with a heating network as a condition for building permits.

The data show that the utilization of waste heat is turning from an ecological added value into a regulatory requirement and a criterion for site selection in the construction of new projects.

Economic Benefits or Social Responsibility?

Utilizing waste heat comes with its own costs. It requires investment in heat exchangers, pipelines, and possibly heat pumps, coordination with local heating networks, and contractual relations with heat consumers.

The distance to the nearest district heating network, the operating temperature of the network, and the availability of a ready buyer for the heat are now criteria for site selection, alongside the availability of electrical power and optical connectivity.

In some cases, however, the data center may provide the waste heat to the local network for free, if the strategy treats it not as part of the revenue model but as social responsibility and a sustainable approach.

In a green data center, heat is an asset

The discussion on data center sustainability has traditionally focused on PUE (power usage effectiveness)—how efficiently consumed energy is used. Waste heat utilization adds a new perspective: not only how efficiently we use energy, but also whether the byproduct of this consumption is reused.

For AC☁DC, designed as a green data center with a focus on energy efficiency, the topic of waste heat was embedded from the very foundation of our infrastructure. 

Our approach stands out with the idea of utilizing the heat from the servers in our data center and storing it in special containers for subsequent use in district heating for the "Mladost" area in Varna. The initiative is being implemented in partnership with the local “Veolia Energy Varna” EAD, which is responsible for the city's heating system. 

We believe this approach ranks AC☁DC and the city of Varna among the best examples and pioneers in green policies for building and developing server infrastructure. If you want to learn more about the topic, you can contact our team or book a visit to our data center.

We also advise you to read more:

• Preparing for Summer: Why Server Cooling Is Critical
• Are Data Centers Big Energy Consumers?

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