Thurrock Council and the heat pump manufacturer Kensa began retrofitting three tower blocks in Chadwell St Mary's, Thurrock, Essex, in July 2022, with work running until November 20231. The scheme covered 273 flats across Gooderham House, Poole House and George Tilbury House, replacing old night storage heaters with networked ground source heat pumps1.
Thurrock Council secured £3.2 million from wave one of the government's Social Housing Decarbonisation Fund for the work1. That fund is described as a £3.8 billion 2019 manifesto commitment intended to support local authorities and social landlords in retrofitting their housing stock at scale over 10 years1. Kensa installed a shared ground loop beneath the car park, comprising 109 boreholes and nearly 30 km of vertical drilling over six months1.
The reported performance figures are as follows1:
| Measure | Before | After |
|---|---|---|
| Heating system efficiency | 100% (night storage heaters) | 300% (ground source heat pumps) |
| Heating and hot water bills | More than £3,000 per year for many residents | Expected 66% savings |
The upgrade increased energy efficiency threefold and reduced heating and hot water bills for residents by up to 66%, according to the case study1. Over half of participants were identified as being at risk of fuel poverty prior to the scheme1. The project was named Energy Project of the Year, Social Housing at the Energy Awards 20241.
"Chadwell St Mary's residents are expected to see 66% savings on their heating and hot water bills"
The case study also states that the retrofit will reduce carbon emissions by over 70%, and that over the system's lifecycle the heat pumps are projected to save 7,080 tons of CO2 compared with the night storage heaters, equivalent to taking 1,540 cars off the road for one year1. The drilling and ground loop arrangements are typical of ground loops and boreholes used in shared-loop schemes, and the installed units fall within Kensa's Shoebox range of small ground source heat pumps.
Why it matters for households
The Chadwell St Mary's scheme is an example of a shared ground loop serving multiple dwellings from one set of boreholes, rather than a separate ground array for each home1. For households in flats and other high-density buildings, that arrangement is one route to ground source heating where individual gardens or drilling space are not available1.
The reported bill reduction of up to 66% rests on the difference between night storage heaters running at what the case study calls 100% efficiency and heat pumps operating at 300%1. That gap is the practical measure of what the change means for a household's running costs, and it is the figure the case study uses to describe the benefit for residents, more than half of whom were identified as being at risk of fuel poverty before the work1.
For energy independence at the level of an individual home, the significance is that the heat comes from the ground beneath the site rather than from a delivered fuel. The case study does not report how the electricity powering the heat pumps is generated, so the extent to which the scheme displaces imported fuel has not been reported1. The carbon figures given, a reduction of over 70% and a projected 7,080 tons of CO2 saved over the system's lifecycle, are the case study's own projections1.
What happens next
The retrofit ran from July 2022 until November 2023 and is complete1. No further phases, extensions or additional blocks have been reported1.