Waste-heat recovery solutions harness thermal energy that would otherwise be discarded by industrial sites, data centers or other large energy users. This captured heat is transferred into district-heating networks via heat exchangers, heat pumps and insulated pipelines, where it can serve residential and commercial buildings. By turning low- and medium-temperature waste heat into a usable resource, these systems reduce primary-energy demand and reliance on combustion-based boilers. Data centers are particularly suitable for this approach: liquid-cooling technologies can provide a relatively stable stream of recoverable heat that can be upgraded to district-heating temperatures. Waste-heat utilization supports urban decarbonization by replacing fossil-based heat generation and improving overall energy efficiency in dense population centers. 

According to the International Renewable Energy Agency (IRENA), waste-heat recovery from data centers remains a largely untapped resource that can reduce system-wide heating costs and emissions when connected to modern district-heating networks. IRENA also notes that pairing data-center waste heat with heat pumps raises output temperatures to district-heating standards, enabling scalable, low-carbon heat supply.[1]

Main outcomes of the solution 

• Sustainability: Replacing fossil-fuel heat generation with recovered thermal energy can significantly reduce CO₂ emissions, lower primary-energy demand and support climate-neutral district-heating strategies. 
• Affordability: Recovered waste heat lowers heating costs for district-heating operators and consumers by reducing fuel purchases and mitigating exposure to volatile gas markets; large and stable heat sources such as data centers support predictable, long-term operating costs. 
• System Resilience: Diversifying heat supply with stable waste-heat sources strengthens resilience during peak-load conditions and cold seasons; heat-pump integration enables flexible operation and maintains temperature-stable output even when outdoor conditions fluctuate. 

Key deployment and scaling factors 

1. Identify waste-heat sources (e.g., data centers, industrial sites) and evaluate thermal capacity, temperature profiles and proximity to district-heating networks. 
2. Standardize interconnection solutions – heat exchangers, heat pumps and insulated pipelines – where feasible to reduce engineering complexity and enable replication. 
3. Establish commercial and regulatory frameworks for long-term heat-offtake agreements, transparent pricing models and incentives for low-carbon heat supply. 
4. Implement robust monitoring and safety systems to maintain stable outlet temperatures, water quality and reliable year-round operation. 
5. Coordinate with municipalities and district-heating operators to align projects with urban-decarbonization strategies and the expansion of low-temperature networks. 
6. Ensure accurate thermal-load data and heat-profile validation, supporting the sizing of pumps, exchangers and distribution infrastructure. 
7. Plan for temperature-control and redundancy requirements, especially in climates with large seasonal swings. 

Case Study 

Microsoft, Fortum and AFRY (2025), Finland 

Fortum is developing a major data-center waste-heat recovery project by integrating Microsoft’s new hyperscale data centers in Espoo and Kirkkonummi into the regional district-heating network. Waste heat from Microsoft’s servers will be captured through liquid-cooling systems, upgraded via large-scale heat pumps and fed into the district-heating grid operated by Fortum Power and Heat Oy. Once fully operational, the recovered heat is expected to provide up to 350 MW of thermal capacity and supply around 40% of the district-heating demand across Espoo, Kauniainen and Kirkkonummi. 

The system is being developed with AFRY providing engineering, procurement and construction-management (EPCM) services. Initial heat delivery is planned for 2025/2026 with phased expansion in subsequent heating seasons. According to Fortum and Microsoft, the project is among the world’s largest data-center heat-recovery initiatives and forms a key component of regional plans to decarbonize district heating. The project demonstrates how hyperscale data-center clusters can act as stable, long-term heat sources and accelerate the transition to carbon-neutral urban heating in northern climates.[2,3,4]

References:

1. Waste heat recovery from data centres I IRENA 
2. Fortum and Microsoft's datacentre project spearheads energy efficiency I Fortum (March 2022) 
3. Capturing data centre waste heat for Fortum’s district heating in Finland I AFRY  
4. Building the future: How datacenters are innovating with sustainability I Microsoft (October 2025)