Ambient-loop heat networks

Energy self-sufficiency is gaining importance in climate action. While households contribute, municipalities and cities offer the greatest potential for impact. In practice, increasing self-sufficiency means moving to a smarter energy system that makes use of ambient-loop heat networks.

The idea is to reuse local heat sources and, at the same time, minimise purchased energy.

We design ambient-loop solutions for, for example, school buildings, campus areas and outdoor sports facilities.

Towards energy self-sufficiency with ambient loops

An ambient-loop heat network creates the right thermal conditions by utilising local heat sources and minimising the need for purchased energy. Internal heat gains from occupants, sunlight, lighting and equipment are recovered for space heating and domestic hot water. Surplus heat can be stored in the ground for later use. During brighter months, electricity is produced with solar power.

At a technical level, separate district heating and cooling networks are replaced by a single pair of low-temperature pipes – a heat corridor – that transfers heating energy bidirectionally between buildings.

Ambient-loop networks enable carbon-neutral properties

With ambient loops, buildings alternately inject heat into and extract heat from the network, efficiently. Heating energy is upgraded in each building only to the temperatures required there, which minimises distribution losses. Cooling via the ambient loop means cost-effective recycling of waste heat between buildings using the heat corridor, combined with seasonal storage of surplus heat in the ground via boreholes.

In summer, boreholes are charged with solar heat entering through windows using a heat-collection system. The electricity used by the heat-pump system is produced with solar power, reducing the need for purchased electricity. Solar power also produces part of the lighting and equipment electricity. In colder months, when the heat-collection system alone is not sufficient, space heating uses heat stored in the ground.

The aim is to move towards carbon neutrality by using local energy sources – the goal is an optimal, energy self-sufficient heating solution.

Our current priorities include improving the energy efficiency of schools, outdoor artificial-turf fields and artificial-ice facilities – delivering solutions that are cost-effective across the lifecycle. Case-by-case designed ambient-loop systems involve lower purchased energy, operating and maintenance costs than alternative methods – and above all are energy self-sufficient.

Case studies

Municipality of Sipoo: Söderkulla artificial turf pitch heated with ambient-loop energy

FCG was involved in renewing the heating system for the Söderkulla artificial turf pitch in Sipoo, moving from district heating to an ambient-loop solution. The system uses solar and ground-source heat as primary sources, with district heating as an auxiliary. In summer, heat is collected from the pitch and stored in the ground, then used during the heating season to warm the field.

The project was implemented in phases from 2018 to 2022. The pitch and heating-system pipework were renewed in 2018, the borehole field was installed in 2021, and the heat-recovery system and heat pump in 2022. Costs for the boreholes and heat pumps were about €660,000, influenced by component shortages and material price rises during the pandemic.

The system is expected to deliver substantial savings. Solar and ground-source heat will cover about two thirds of the pitch’s heat-energy demand, saving tens of thousands of euros annually. The payback period is estimated at 16 years compared with the current district-heating solution and seven years compared with the original snow-melt system.

“During the heating seasons 2010–2013, keeping the Söderkulla artificial turf pitch ice-free used up to 1,500 MWh of district heat per year. Once the ambient-loop system in Söderkulla operates as planned, electricity use for heating will be about 100 MWh per year, plus around 100 MWh of district heat. The savings achieved with ambient-loop energy, compared with the 2010–2013 heating system, will be roughly €90,000 per year.” – Mika Autiopelto, Lead Specialist, Energy Systems, FCG

Learn more by contacting our specialists

Teemu Linnakoski
Customer Relations Director
firstname.lastname@fcg.fi
+358 44 278 7324

Mika Autiopelto
Lead Specialist, Energy Systems
firstname.lastname@fcg.fi
+358 40 130 7017