Mitsubishi Electric and SNG’s innovative heat pump approach leads the way in cost-saving, low-disruption residential retrofits to accelerate decarbonisation 

– Time: heat pump system installation can be as little as two days – around 40% quicker

– Cost: installation cost savings by using existing radiators and pipework

– Residents: improved resident perception and reduced disruption

Mitsubishi Electric and SNG (Sovereign Network Group) have joined forces to deliver a pioneering retrofit programme that has the opportunity to transform the social housing renewable heating landscape in the UK. By leveraging Mitsubishi Electric’s Ecodan R290 high-temperature air source heat pumps in homes with existing microbore/small bore pipework, the initiative cuts costs, reduces disruption, and could accelerate decarbonisation across SNG’s housing portfolio.

SNG, which manages more than 84,000 homes for 210,000 customers across London and southern England, is piloting the use of high-temperature Ecodan heat pumps which work effectively and efficiently with legacy microbore/small bore systems—narrow pipework once thought incompatible with heat pump technology. This innovative approach, backed by Mitsubishi Electric and SNG’s extensive research and paper on microbore/small bore compatibility, removes one of the biggest barriers to large-scale heat pump retrofitting in older homes.

Jim Dyer, Built Environment Director at SNG, explains:

“This solution emerged from our desire to innovate and balance key priorities for both our customers and SNG: minimising disruption, cutting fuel bills, avoiding early replacement of components, and reducing both installation cost and the ongoing maintenance costs. It’s an ambitious holistic approach that places our customers’ wellbeing and operational cost-effectiveness at its core.”

The benefits of this retrofit strategy are far-reaching:

• Reduced disruption to residents by avoiding the need to replace radiators and pipework or remove and replace floor coverings
• Significant capital savings by retaining existing pipework and radiators
• Improved energy efficiency and fuel bill reduction—crucial for tackling fuel poverty
• Lower operational and long-term maintenance costs
• Faster installation timelines, with SNG’s trusted contractor reporting installations completed in as little as two days

The project builds on the strengths of Mitsubishi Electric’s R290 Ecodan system, which offers up to 300% efficiency, reliable performance in sub-zero temperatures, and the use of a natural refrigerant with a global warming potential of just 0.02. It is an ideal match for both retrofit and new-build social housing.

By retaining the radiators and microbore/small bore infrastructure (plastic and copper pipework), the direct replacement of gas heating with a heat pump is possible. Mitsubishi’s Electric R290’s Ecodan system is the key enabler in this approach.

James Chaplen, Mitsubishi Electric Head of Product Marketing and Communications said:

“The ability to retain microbore/small bore pipework of all types is a game-changer for retrofit projects. With our Ecodan heat pumps working effectively with existing systems, we’re removing a major financial and logistical hurdle. This opens the door for housing providers like SNG to scale-up their net zero efforts without compromising on resident comfort or driving up costs.”

Mitsubishi Electric’s and SNG’s partnership reflects a priority in the housing sector for smart, scalable, and resident-friendly solutions to decarbonise UK homes. With a firm commitment to achieving net zero by 2050, this programme demonstrates how innovation, when paired with local insight, can drive real change—now.

Visit the microbore information page

About SNG

SNG (Sovereign Network Group) is one of the largest housing associations, providing over 84,000 homes in areas facing some of the most acute housing need across London and the South of England, with an ambition to build an additional 25,000 homes over the next decade. It was formed on 1 October 2023 through the bringing together of Sovereign Housing Association and Network Homes.

SNG is a leading builder of affordable homes, including for social rent, and it has a clear pathway to maximise its social and environmental sustainability through its ambitious Homes and Place Standard alongside its planned £100m Community Foundation.

SNG is a member of the G15 group of London’s largest housing associations. The G15 is the collective voice of some of the leading organisations in the housing sector. Its members house one in ten Londoners and are the largest providers of affordable homes in the capital, building a quarter of all London’s new homes, and owning or managing more than 600,000 homes.