Hampshire to host UK’s largest water-source heating and cooling network

A CGI mock up of a house in the garden village

Development is underway on the Welborne Garden Village in Hampshire to build 6,000 homes with shops, schools, commercial buildings and healthcare sites. As part of the development, plans have been confirmed for the buildings to tap into Portsmouth Water’s underground Hoads Hill Reservoir to gain access to a new low-carbon water-source heating and cooling network.

Buckland Development and Portsmouth Water have built a system that will allow water from the reservoir to be used to both heat and cool homes. The organisations involved, including Rendesco, which built the system, claim that the solution is more efficient than using air source heat pumps due to the stable and higher average temperature of the water.

The organisations claim the water-source system will emit 90% less carbon emissions than a gas boiler and 50% less than air source heat pumps. It will also save an average three-bedroom house around £160 per year compared with an air source heat pump.

The network will initially supply 700 homes and commercial buildings, but could reach 6,000 homes as the village of Welborne expands. The network will also cool buildings in the warmer months by expelling heat from homes back into the reservoir.

Buckland Group’s chairman Mark Thistlethwayte said: “Welborne is a new generation sustainable garden village, so our residents and businesses will rightly expect their buildings to be energy efficient and climate-change resilient. Partnering with Last Mile Heat and Portsmouth Water we are delivering the largest water-source heating and cooling network in the UK, which will cut carbon emissions and reduce people’s energy bills.

“Being involved in Welborne for the long-term both financially and practically, Buckland is taking a different development approach to mainstream housebuilders. We are designing and developing the community holistically, so we can take strategic decisions to invest in innovative technology and deploy it at scale.”

Gas phase-outs

The organisations claim it is the UK’s largest water-source low-carbon heating and cooling network.

An additional feature of the network is that heat can be transferred and exchanged between buildings. When one is cooling, it can supply excess heat to others in the network.

It is estimated that the complete network could save more than 272,000 tonnes of carbon in the first 25 years of operation compared to using gas boilers.

At present, some 23 million of the UK’s 25 million homes use gas boilers for heating and hot water. These will need to be replaced with alternatives as the nation works towards net-zero emissions by 2050.

The Government is yet to make a strategic decision on whether hydrogen will have a major role to play in replacing gas in home heating. It is set to make that choice in 2026, following a series of local trials of increasing size.

Gas networks are pushing hydrogen blending as a key option. Other organisations including MPs’ committees and think-tanks argue that electrifying heating would be appropriate for most homes, and that hydrogen should be used in harder-to-abate sectors like heavy industry to maximise carbon savings and cost-effectiveness.