WHAT WE DO
From potential to operational heat recovery
FOR DISTRICT HEATING OPERATORS
Turn data centre waste heat into a long-term supply for your district heating network
Every data centre near your network generates more heat than it can use — and currently rejects most of it into the atmosphere. Calentix captures that heat, upgrades it, and delivers it to your network under a long-term Heat Purchase Agreement. You get a reliable, low-carbon heat source without investing capital or managing the data centre relationship.
THE OPPORTUNITY FOR DISTRICT HEATING OPERATORS
Data centres are one of Europe's fastest-growing sources of recoverable heat.
European data centres consumed an estimated 150–200 TWh of electricity in 2023 — a figure that is growing rapidly as AI infrastructure expands. Almost all of that electricity ultimately becomes heat. The International Energy Agency projects that recoverable heat from European data centres could exceed 300 TWh by 2030.
For district heating operators, this represents a significant and largely untapped supply opportunity. Data centres run continuously, 24 hours a day, 365 days a year — making them one of the most reliable sources of waste heat available, more predictable than many industrial sources. The challenge has been connecting data centres to district heating networks commercially and technically. That is exactly what Calentix does.
WHAT CALENTIX DELIVERS
Calentix is a heat producer. The raw material is waste heat from data centres.
Calentix designs, finances and operates heat extraction systems inside or adjacent to data centres. We capture the waste heat from the data centre's cooling infrastructure, upgrade it to the temperature your network requires using industrial heat pumps, and sell it to you under a Heat Purchase Agreement.
From your perspective, the arrangement is straightforward:
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You sign a Heat Purchase Agreement with Calentix for a defined heat volume at a defined price over a long-term contract (typically 15–25 years).
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Calentix manages everything on the supply side: the relationship with the data centre, the heat extraction equipment, the operation and maintenance, and the metering and reporting.
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You receive heat that meets your network's temperature and quality specifications — the same way you would from any other heat supplier.
You do not need to manage the data centre relationship, invest in heat extraction equipment, or build in-house expertise in data centre heat recovery.
WHAT YOU GET
The IHP proposition for DH operators
✓ At least 10% lower heat production costs
DC waste heat at COP 3.5–6 consistently undercuts biomass, gas and conventional heat-pump alternatives on levelised cost. The electricity cost per MWh is one-quarter to one-third of the electricity price — the primary driver of economics.
✓ Zero capital investment from you
Calentix owns the entire heat-recovery asset — heat exchangers, heat pumps, pipework and monitoring infrastructure. You sign an HPA and receive heat. All investment risk sits with us.
✓ One-third of the carbon footprint vs. gas
DC waste heat carries minimal additional carbon — directly supporting decarbonisation targets. Verified carbon accounting provided for your reporting obligations.
✓ 20-year price stability
HPA pricing indexed to an agreed formula — insulating your network from gas and biomass price volatility. A predictable cost structure for your long-term planning.
✓ Exceptional supply stability
Data centres operate at consistent loads year-round. Unlike industrial waste heat, servers don't take holidays or seasonal shutdowns. Our contracts specify a heat delivery band with guaranteed minimum volumes and uptime obligations backed by buffer storage.
TECHNICAL: HEAT DELIVERY
Temperature, volume and reliability: what to expect from a Calentix heat supply
What temperature can Calentix deliver?
Calentix heat pump systems are designed to meet your network's supply temperature requirement. For fourth-generation district heating (4GDH) networks operating at lower supply temperatures (typically 50–70°C), the economics are particularly favourable — lower required output temperatures mean higher heat pump COP and lower cost per MWh delivered.
For networks currently operating at higher temperatures (80–105°C), we conduct a detailed feasibility assessment to confirm viability and optimise the system design. In many cases, a network review reveals that operating temperatures can be reduced without affecting customer delivery — with significant efficiency gains for the heat pump system.
How much heat can one data centre supply?
A data centre with 10 MW of IT load generates approximately 10–12 MW of waste heat continuously. A well-designed Calentix installation can deliver 8–10 MW of net heat to your network from a facility of this size. Larger hyperscale data centres (50–100+ MW IT load) can supply 40–80+ MW of heat. Calentix conducts a detailed heat volume analysis during feasibility, based on the actual load profile and cooling configuration.
How stable is the heat supply?
Data centres are designed for maximum uptime — typically 99.9%+ availability (Tier III and Tier IV facilities). Unlike many industrial waste heat sources, data centres do not shut down for maintenance seasons, do not reduce output in winter, and are not subject to production variability. Calentix systems include redundancy provisions as part of the standard design, and our HPA includes defined availability guarantees.
What monitoring and operational data do we receive?
Calentix provides continuous metered data on heat delivered, supply and return temperatures, and system performance. This data is available via a digital interface and can be integrated with your network management system. For your annual EED and sustainability reporting, we provide certified energy output statements covering all deliveries under the HPA.
PRE-FEASIBILITY ASSESSMENT
We help data center owners reduce energy use, recover excess heat, and strengthen sustainability performance. By integrating efficient heat-recovery systems to your cooling systems we lower operating costs and ensure compliance with EU energy-efficiency requirements. Calentix acts as both advisor and developer, making your energy systems smarter, cleaner, and more profitable.
FEASIBILITY STUDY
We support data center developers and landlords in creating more valuable and compliant sites. By connecting data centers to local district-heating networks, we turn waste heat into a new revenue stream and enhance your license to operate. Calentix designs, builds, and operates energy systems that make your facilities future-proof and attractive for your customers and investors.
PROJECT DEVELOPMENT
Once feasibility is confirmed, we structure the full project: technical design, permitting, contracts, and financing. Calentix acts as an independent heat producer, developing the project under an Independent Heat Produced model in cooperation with data center owners, utilities, and investors.
CONSTRUCTION AND OPERATION
We finance, build, and operate the heat-recovery system. We ensure performance, reliability, and long-term value. Over time, ownership can be structured in different ways depending on partner preferences and investment strategy.
TECHNICAL: HEAT DELIVERY
Temperature, volume and reliability: what to expect from a Calentix heat supply
Delivery temperatures
Modern industrial heat pumps in DC applications reliably deliver 70–90°C. Fourth Generation District Heating networks (4GDH) at 55–70°C supply are particularly well suited and allow higher COP. Higher temperature requirements are achievable but affect efficiency.
Heat volumes & stability
A data centre with 10 MW IT load can supply 5–8 MWth. Unlike industrial sources, data centres operate at consistent loads year-round — servers don't take holidays. Buffer storage provides reserves during planned maintenance windows.
COP & economics
COP of 3.5–6 depending on season and network return temperature. At COP 5, electricity cost per MWh is one-fifth of the electricity price — significantly cheaper than gas or biomass alternatives on a levelised basis.
REGULATORY CONTEXT
What EU regulation requires of district heating operators regarding waste heat
EU Energy Efficiency Directive (EED) — Article 24
Member states must ensure that district heating and cooling operators assess the potential for using waste heat and renewable energy sources in their networks. Networks that refuse technically and economically viable waste heat connections may be required to justify this decision.
Germany — Energieeffizienzgesetz (EnEfG)
German data centres above 1 MW are required to make their waste heat available and to register on the national Abwärmeplattform. This creates a documented pipeline of available waste heat sources that district heating operators can access — and in some cases, regional authorities may actively require connections.
The strategic opportunity
Early movers in securing long-term Heat Purchase Agreements with data centres gain first access to the best-located and highest-volume heat sources. As data centre development accelerates across Northern Europe, the window for favourable HPA terms is open now.
COMMERCIAL STRUCTURE
The Heat Purchase Agreement: how the commercial relationship works
Under the Calentix model, the Heat Purchase Agreement (HPA) is the central commercial document between Calentix and the district heating operator. Key terms typically covered:
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Contract duration: 15–25 years, with options for extension or ownership transfer
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Heat volume: Defined annual and seasonal delivery volumes, with agreed minimum and maximum bands
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Delivery temperature: Supply temperature guaranteed to meet network specifications, with defined tolerance ranges
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Pricing: Fixed price, index-linked, or formula-based — structured to give long-term cost predictability while allowing fair adjustment for major market changes
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Availability guarantees: Minimum heat availability expressed as a percentage of contracted volume, with defined remedies for shortfall
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Metering and verification: Independent metered data, certified annually
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Step-in rights: In the unlikely event that Calentix cannot deliver, the HPA includes defined step-in provisions to protect your supply security
The HPA is intentionally structured to be familiar to district heating operators — it mirrors the commercial structure used for other long-term heat supply agreements, making legal review and board approval straightforward.
COMMON QUESTIONS
What DH operators ask us
The key criteria: (1) Data centre with liquid cooling and IT load above 2–5 MW. (2) Project within 1–2 km of
your network connection point. (3) Your network return temperature below ~55°C in summer – higher
return temperatures are harder for the heat pump. (4) Mandatory supply temperature we can match.
The feasibility study establishes all of this precisely.Our HAA with the data centre includes provisions for load variability. The HPA with you specifies a
delivery band rather than a fixed volume, giving both parties flexibility. Our monitoring tracks IT load
trends, and we design for scenarios where the facility expands — as is the typical trajectory for European
DCs in the AI era. We carry the risk of the DC relationship, not you.At a COP of 4, our electricity cost per MWh of heat is approximately 2.5 kWh of electricity —
versus ~11 kWh of gas at 90%+ thermal efficiency. At current electricity-to-gas price ratios across
our markets, DC waste heat recovery is consistently cheaper on a levelised basis than gas, biomass,
or conventional heat pump alternatives drawing from ambient sources.Only a metered connection point at the agreed delivery temperature. Everything upstream — the data
centre relationship, the heat pump system, construction, monitoring, regulatory reporting — is Calentix's
responsibility. A buffer storage tank at the heat pump station provides thermal reserve, giving you time
to bring alternative sources online if needed.Calentix manages the entire relationship with the data centre — from initial engagement through the site
access agreement, technical integration and ongoing operation. As the district heating operator, you deal only
with Calentix under the Heat Purchase Agreement. You are not a party to the data centre agreement and have
no direct operational dependency on the data centre.
The HPA includes availability guarantees backed by Calentix, not the data centre. If a data centre's output falls
below contracted levels, Calentix is responsible for sourcing alternative heat or compensating you under the
agreed shortfall provisions. Our project development process also includes redundancy analysis —
we assess the risk of load reduction and the availability of backup heat sources before committing to an HPA.