District Heating Thermal Storage Tanks: Insulation Work Requires Specialized Expertise and the Right Equipment

District heating thermal storage (accumulator) tanks are being built at an exceptionally high rate in Finland and the surrounding region. The energy transition, electricity price volatility, and decarbonisation targets for district heating networks have together created a situation in which thermal energy storage has become a major investment priority. According to Energiateollisuus ry’s Energiavuosi 2025 review, the energy transition in district heat production is already well advanced: electric boilers generated 2,580 GWh of heat in 2025, and storage capacity is needed to balance production when electricity is cheap. Demand for storage capacity will grow considerably further, so construction will continue for years to come.

A district heating accumulator is a simple concept but a demanding structure to build. It is a heavily insulated, cylindrical water tank that stores thermal energy in hot water. The tanks are physically large: height can reach up to 70 metres and diameter can exceed 40 metres. Insulation thickness is typically 300–500 mm, using rock wool or glass wool. A structure of this kind sets very specific requirements for insulation work.

Kymsol’s Experience in District Heating Accumulator Projects

Kymsol has carried out insulation work on district heating accumulators at multiple sites. Some of these projects are subject to confidentiality obligations, so we list the sites below without further detail.

Reference Projects

The tallest accumulator we have completed stands close to 50 metres. These projects frequently involve demanding architectural solutions that require a high level of expertise in both technical detailing and execution. One example is the completed accumulator in Nuijala, Espoo.

Projects of this kind demand a level of precision from cladding and insulation workers that goes beyond standard industrial insulation. Kymsol has delivered both straightforward industrial facades and the most demanding architectural details across its accumulator projects.

What District Heating Accumulator Insulation Requires

A district heating accumulator is not a standard insulation project. Three factors clearly set it apart from conventional industrial insulation: height, volume, and facade quality requirements.

Height and Occupational Safety

When a tank is – as in our Kirkkonummi project – approximately 50 metres tall and around 20 metres in diameter, simply providing a safe working platform is a significant task in itself. The German Alblitz Modul scaffolding system used by Kymsol performs excellently in this context.

Scaffolding is not always the most productive solution. Alongside scaffolding, Kymsol uses Scanclimber SC6000 mast climbers with Snake Platform work platforms on accumulator projects. The Snake platform is designed specifically for curved structures: it follows the contour of the tank surface, enables a working platform up to 16 metres wide, and reaches heights of up to 100 metres. In practice, this means insulation work can be carried out safely and efficiently without surrounding the entire tank with scaffolding.

Insulation Volume and Execution Efficiency

A 300–500 mm insulation thickness means enormous quantities of mineral wool on a district heating accumulator. Materials must reach the right height at the right time, and insulation work must proceed systematically without the site becoming congested or schedules slipping. Kymsol’s approach on accumulator projects is built on careful work phasing and advance planning of material handling alongside lifting equipment operations.

Facade: Technical Precision Meets Architecture

District heating accumulators are frequently located in prominent positions on the urban fringe or on power plant sites where they function as landmarks. Because district heating networks serve built-up areas, the tanks are typically sited there too. Architects are increasingly specifying decorative facade elements, demanding sheet metal patterns, and other visual details on tank facades that make the structure worthy of its surroundings.

We asked our site manager, who has delivered multiple accumulator projects, for his perspective.

“Logistics related to mineral wool handling is an extremely important area. Lifting sheet metal panels also needs to be carried out safely using the right equipment. On the cladding side, penetration details must be planned so that the structure performs correctly – Kymsol has good solutions for this.”

— Pekka Leskinen, Site Manager, Kymsol

The scale of these projects means that insulation work is closer to a major industrial project delivery than conventional building insulation: wool volumes are large, schedules are tight, and working conditions are demanding.

What Kymsol Delivers on a District Heating Accumulator Project

In a district heating accumulator project, insulation work including facade cladding is a critical phase that affects the tank’s energy efficiency, the project schedule, and the visual quality of the finished structure. Kymsol delivers a complete solution for accumulator projects that covers all of these dimensions.

A typical Kymsol scope on a district heating accumulator includes:

• Rock wool and glass wool insulation at 300–500 mm thickness
• Cladding and facade work in accordance with architectural details
• Scaffolding and lifting equipment, including Scanclimber SC6000 Snake Platform mast climbers for curved surfaces
• Coordination of material handling and work phasing
• Occupational safety management for high working heights

Kymsol’s completed and ongoing projects are currently concentrated in the Nordic region, but we also carry out large projects further afield. Work on district heating accumulators continues actively across multiple sites simultaneously. Our experience base grows with every project, which translates directly into execution efficiency and the ability to anticipate site-specific challenges already at the planning stage.

If you are involved in district heating accumulator projects, contact Kymsol via the request for quotation form or directly through the contact page.

Written by: Kymsol Experts
Published: October 2026