In a UK first, older people living in social housing in Midlothian are to benefit from reduced fuel costs thanks to a new, smart mini district heating network providing low-carbon warmth by combining thermal storage batteries with communal gas boilers and communal air-source heat pumps.

Lowering carbon emissions by integrating thermal batteries with hybrid heat pump micro-scale district heating networks

Alleviating fuel poverty while improving heating comfort levels

Understanding how Demand Side Response (DSR) services assist in reducing tenants fuel bills and support the provision of low- to zero-carbon heating

The challenge

The need for social landlords to move away from traditional gas boilers to drive down carbon emissions and help their residents, particularly the elderly, with heating costs is ever present.

Thinking creatively about changing to communal, mini district heating networks is one way.

The solution

The SP Energy Networks Green Economy Fund backed the Heatshare project which means the existing heating system for 36 retirement homes in Midlothian can be refitted to create a new, low-carbon smart mini district heating system that combines communal gas boilers, communal air source heat pumps and a Sunamp thermal storage battery in each home.

The Heatshare project is the first of its kind in the UK and is a partnership with Sunamp and social landlord Places for People Scotland (previously called Castle Rock Edinvar Housing Association).

This project demonstrates the technical integration between thermal batteries and five micro-scale district heating networks that also have Demand Side Response (DSR) services for domestic customers.

Solar panels on a house part of the EastHeat project

Some of the retirement homes in Midlothian with air source pump heat pumps installed outside (Places for People Scotland).

The benefits

The system is dynamically managed by a smart control from PassivSystems (now part of BUUK Infrastructure) which continually scans for the cheapest fuel tariffs and automatically switches between gas and electric supply to match each resident’s demand for heat.

It means cheap electricity can be used overnight for the heat pump to warm homes ready for the morning. The gas boiler and heat stored in the Sunamp thermal battery, which has been charged using cheapest available fuel, can be called on when required to boost warmth and provide hot water in the most cost-effective way.

The housing development is already fitted with solar PV which is providing power to the air source heat pumps, further reducing costs for residents.

Storage space is always an issue. Therefore, using space-saving thermal batteries, which are up to four times smaller than traditional hot water cylinders and neatly fit in a cupboard, is a bonus.

For social landlords, thermal batteries require no regulatory annual maintenance – unlike domestic gas boilers – and greatly simplify installation. When considered in the context of Heatshare’s district heating set up, thermal batteries also allow the central plantroom and distribution pipework to be significantly smaller and simpler than a traditional scheme; saving both capital and operation expenses.

A Sunamp thermal battery inside a small cupboard below a gas boiler

Installing a Sunamp thermal battery inside a home (Places for People Scotland).  

“Once the hybrid system is installed, everything happens automatically, making it easy for customers to remain warm and comfortable at lower cost. Data gathered from the project will inform our future sustainability decisions and will hopefully open doors to future collaborations in the sector.”

Mark Coyle

Trade Supervisor, Places for People Scotland

The technical details:

  • Carbon savings: estimated 4,589 kg CO2 per year compared with before the installation
  • Storage capacity: 36 x UniQ HW+i thermal batteries (252kWh)
  • Heating source: electricity, air-source heat pumps and gas connected to Sunamp thermal batteries
  • Heat pump supply temperature: space heating up to 55°C and heat battery charging up to 65°C

Additional information:

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