Strandslottet is a large seaside holiday apartment complex on Bornholm. Previously, this historic building was heated only with direct electric heating panels.
Situation
The annual electricity consumption for heating was about 206,925 kWhWith the average electricity price on Bornholm in 2025—about 3.10 DKK/kWh (including taxes)—this amounted to approximately 640,000 DKK in annual heating costs.
High energy costs and the desire to find a more durable, future-proof solution prompted the client to undertake a comprehensive modernization of the building’s heating system.
Solution
Step 1: a new hydronic heating system
Since the building had previously been heated only by electric panels, it did not have a water-based heating system. During the project, a completely new hydronic heating system was installed throughout the building.
About 100 radiators were installed, selected according to the building’s heating needs. This made it possible to implement a centralized heat pump system with significantly higher energy efficiency.
Step 2: IGLU air-to-water heat pumps
The building is now heated to 6 IGLU INUIT MONO heat pumps, each with 16 kW of power.
The system is configured in a cascade — multiple units work together and adapt to the building’s overall heating demand. This solution ensures both high output and flexible operation.
Key advantages of a cascade system:
• high total heating capacity for larger buildings;
• stepwise power modulation based on actual demand;
• high reliability — even if one unit stops, the system continues to supply heat;
• higher efficiency under partial load.
Installation was carried out by Vejleby VVS, while X-Energy and IGLU TECH supplied the heat pumps and provided technical support for system design and configuration.
Results
1) Energy savings
Direct electric heating operates at 1:1 efficiency — 1 kWh of electricity produces 1 kWh of heat. The heat pumps installed at Strandslottet produce on average about 3 kWh of heat from 1 kWh of electricity (COP ≈ 3). This allows for an expected energy saving of around 60–65% compared to the previous system.
2) Greater comfort
The project has also significantly improved comfort throughout the building. Temperatures were raised in several common areas, and heat is now distributed more evenly. This ensures a more stable microclimate both in the apartments and in the building’s common areas.
3) Future-proof solution
The heating upgrade is part of a broader building renovation plan. The Strandslottet board has prepared a 10-year maintenance and improvement plan, prioritizing energy optimization and modernization of engineering systems.
Additional benefit
Bornholm is an island, so transportation and service visits cost more and take longer than on the mainland. For this reason, reliability was one of the most important selection criteria.
The cascade system ensures redundancy — even if one unit temporarily stops, the others continue to supply heat.
In addition, remote monitoring and diagnostics via the IGLU platform allow continuous tracking of system performance. Operational data are analyzed remotely, and fine adjustments can be made without a site visit. This reduces service needs and gives greater peace of mind to both installers and building residents. Explore all IGLU heat pump solutions here here.
