Chadwell St Mary’s, Thurrock Council

Chadwell St Mary’s, Thurrock Council

3 x high-rise tower blocks in Essex received new ground source heat pumps, 3 x more energy-efficient than their old night storage heaters, reducing heating and hot water bills by up to 66%.

Award-winning project:

  • Winner of ‘Regional Large Scale Project of the Year’ at The South East Energy Efficiency Awards 2023
  • Winner of ‘National Renewable Heat Project of the Year’ at The National Energy Efficiency Awards 2023
  • Winner of ‘Climate Action – Decarbonisation / Retrofit Award’ at the Essex Housing Awards 2023
  • Shortlisted for ‘Domestic Installation of the Year’ at the PHAM Energy Saving Awards
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Social housing tower block retrofit provides a blueprint for rapid decarbonisation

Kensa Contracting and Thurrock Council delivered the flagship project, the largest ground source heat pump scheme to be part-funded by the DESNZ Social Housing Decarbonisation Fund. This project will save 7,166 tonnes of carbon on this site over 25 years, which is the life of the ground source heat pumps in each flat.

It also demonstrated the potential for Networked Heat Pumps and Shared Ground Loop arrays to rapidly and affordably decarbonise multiple properties across all social housing archetypes – offering a viable solution to deliver against the UK’s net zero targets. This project is strategically important because over 34% of all UK emissions are attributed to the provision of heat, and the Government has committed to delivering 600,000 heat pump installations per year by 2028.

In existing homes, space and water heating accounts for two-thirds of a typical household bill. Social landlords can immediately improve tenant well-being by replacing less efficient, more expensive heating systems – such as night storage heaters – with low-running-cost ground source heat pumps.

For every 1kW of electricity paid for to run the heat pump, 3 to 4kW of heat are provided to deliver 100% of a property’s heating and hot water needs. By providing resilience against rising fuel prices and energy security, they can prevent future fuel poverty in homes and cut carbon emissions.

Project details

The retrofit saw 273 flats with storage heaters across three tower blocks in Chadwell St Mary’s – Gooderham House, Poole House and George Tilbury House, owned by Thurrock Council – replaced with Kensa ground source heat pumps inside each of them.

Thurrock Council secured £3.2 million from Wave 1 of the Government’s Social Housing Decarbonisation Fund (SHDF) to help finance the scheme. The SHDF, a £3.8 billion 2019 manifesto commitment, aims to support local authorities and social landlords in retrofitting their housing stock at scale over 10 years.

Ground source heat pumps utilise free, naturally occurring renewable heat stored below ground to cut heating bills by 66% when replacing night storage heaters. The ground source system is 300% efficient, which means for every unit of electricity, they can access two to three units of free renewable energy from underground to get considerable savings on heating costs. 

Kensa’s compact Shoebox ground source heat pump commonly replaces ageing night storage heaters in tower blocks. Its small size means the Shoebox fits easily into an airing cupboard in each apartment. In the tower blocks at Chadwell St Mary’s, the Shoebox is paired with the similarly space-saving SunAmp heat battery to provide 100% of the property’s heating and hot water needs.

In the Hard to decarbonise social homes’ report by NHF & LGA, it is cited that “[a] lack of internal or external space is a key barrier to retrofitting small properties, so technologies such as…shared loop heat pumps will have important roles to play for these homes.” The report also highlights the Kensa’s solution, saying, “The Kensa Shoebox system may be particularly beneficial for social landlords with high-rise flats, as individual units can be installed in each dwelling, preventing problems such as overheating or heat losses and the complications of shared heating bills.” 

At Chadwell St Mary’s, Kensa designed a Networked Heat Pump and Shared Ground loop Installation scheme connecting the 273 properties to 109 boreholes via an Ambient Temperature Loop. They were drilled underneath in the car park of the flats and totalled nearly 30 km of vertical drilling over 6 months. 

Considerable engineering challenges were involved, but Kensa kept the car park semi-open for residents. The boreholes provide ambient heat of around 5 to 10℃ to 273 individual Shoebox heat pumps in the flats. The heat pump upgrades the ambient heat through a reverse refrigeration cycle, providing 55℃ heat that can be fed into a wet central heating system inside each flat with radiators. A Sunamp heat battery, which is fed by the ground source heat pump,  uses phase change materials to provide hot water at mains pressure. 

Critically important is that each heat pump is individually connected to the tenant’s electricity meter, and no heat metering or billing is required. The tenants have complete control and can choose any energy provider for the lowest tariff possible. There is also no plant room or associated cost for the landlord to operate this heating system, and the tenants only pay for what they use equitably and fairly.

Dr Stuart Gadsden, Commercial Director of Kensa Contracting, said:

Ambitious, large-scale projects like this one undertaken by Thurrock Council are vital to meeting the Government’s targets of 600,000 heat pump installs per year by 2028. Over 80% of UK homes will still be in use in 2050, so existing buildings must undergo significant improvements/ deep retrofitting to meet the decarbonisation challenge.

“Networked heat pumps provide the lowest carbon, running costs, and whole-life cost solutions, especially for high-rise heating developments. These systems help housing providers lower their environmental impact and future-proof their assets whilst protecting their tenants from fuel poverty.

Cllr Luke Spillman, Cabinet Member for Housing, said:

The old storage radiators and hot water systems in each one of the 273 flats were replaced with a significantly better, cost-effective and greener solution.

This is great news for our residents, and I would like to thank the government for awarding this funding and helping us better support our residents and tackle fuel poverty by driving down fuel bills and keeping our homes warmer and greener.

Project benefits


Installing the low-carbon heating systems at Chadwell St Mary’s is expected to provide a 70%+ reduction in carbon emissions (based on a 40-year lifecycle and carbon factor obtained from SAP 10.1, published 8/11/19). Over the life cycle of this installation, the total emissions saving of the heat pumps is projected to be 7,080 tons of CO2. This is the equivalent of taking 1,540 cars off the road*, significantly improving local air quality and reducing the carbon footprint of the residences.

The project is set to secure 67% savings on residents’ heating and hot water bills, a significant benefit considering over half of the recipients have been identified as currently at risk of experiencing fuel poverty.

During the COVID-19 pandemic, Thurrock Council undertook NEA-funded training with its front-line staff. This enabled housing officers who were home working to conduct remote fuel poverty surveys with residents who lived in these tower blocks. Through their research, they realised the actual levels of fuel poverty were much higher than reported through national statistics. Many residents had heating bills over £3000 before the energy cost increases of 2022 that plunged many more households into financial crisis.

Thurrock Council identified the urgent need to lift residents out of fuel poverty and built a business case to rectify years of underinvestment in the old heating systems with the support of Kensa Contracting’s strategic partnerships team. 

As well as the heat pump installation, Kensa recommended that Thurrock Council undertake cavity wall insulation. This was done via abseil, which helped save the council further money due to not having to erect scaffolding. 

Diane Barr, a resident, stated:

After 16 years of living here with an outdated Economy 7 heating system, I am so happy to have a low-cost, energy-efficient heat pump; it has made a big  difference. The heating before was a big expense, and we all dreaded the winter months.

“The heat pump is much warmer, and the hot water is so fast compared to the old system. Plus it’s so cheap – I pay around £21 a week, and that’s with doing the washing, using the tumble-drier and dehumidifier. With the storage heaters, it cost around £70 a week, and I only used to have the heating on in three rooms, and the hot water ran out pretty quickly, so we couldn’t have a shower.

Zohra Naeem was the first resident to have her ground source heat pump switched on. She said:

The new heating system is easy to use, keeps our home warm and is much cheaper than the old system that we had, which took a while to heat the radiators up. The best part is we can use it whenever we need to. The contractors also worked nicely, were quick and tidied up after themselves. Thank you to everyone who has supported us.

This project had a far-reaching social impact, bringing green jobs into the local community, alleviating households from fuel poverty, promoting community spirit, cutting carbon and removing the need to choose between eating and heating. 

Social impact

Some of the key initiatives the project covered were: 

  • Regular resident engagement sessions in the community warm room funded by Kensa
  • 1-2-1 sessions with each resident in their home.
  • The provision of warm spaces for those struggling to keep up with energy costs.
  • A food pantry that has been provided for resident’s use.
  • User training on using heat pumps and simple controls such as twin channel programmers, thermostats and TRVs.
  • Individual QR codes were provided on each heat pump for residents to scan and download a 10-minute video detailing all aspects of their system operation.
  • The use of local labour for site management, labourers, and resident liaison.
  • Educational talks on geothermal and renewable heating using GSHP to local schools and colleges.
  • Training of local maintenance teams employed by the council on maintaining the heat pump systems.
  • Local economic impact through the reduction in energy bills leading to potentially more spending power in the local area.
  • Affordable warmth and provision of healthy heating, which means residents not having to choose between heating and eating.

In addition to the heat pump retrofit, Thurrock Council and Kensa Contracting created community enrichment opportunities to improve tenant welfare, funded through Kensa’s Social Impact Fund and achieved by Kensa staff volunteering.

Kensa’s Social Impact Fund aims to help households facing financial hardship and making difficult choices, such as choosing between heating and eating in communities in which Kensa operates. Kensa uses the fund to develop solutions that will leave a lasting legacy, such as reducing fuel poverty, improving the quality of life in communities where Kensa operates, and increasing social resilience and cohesion.

Residents and their families at the tower blocks benefit from a newly improved community room that was refurbished and filled with donated items, including kids’ games, toys, and books, and kept well-heated by Thurrock Council.

A community pantry has also been installed at the tower blocks, offering in-date donated food items and surplus stock from local businesses. Topped up regularly, the residents can take any food they need or make food donations if they can.

This has created social cohesion and a good community spirit among residents. Many community events have already been run in the previously underused community space, including Easter egg hunts, Christmas craft making and even mental health awareness sessions. The community room will remain a lasting social impact legacy of this project for the tenants to enjoy.

Cllr Luke Spillman, Cabinet Member for Housing at Thurrock Council, said:

The community initiatives we have undertaken with Kensa are so valuable to residents living in these tower blocks. The refurbished community room can be used for events or offer a warm cosy place for residents and their families to enjoy.

The pantry offers residents cupboard staples that may have gone straight to landfill. Dates on donated stock will be checked, and shelves will be refilled. Now that the heating upgrade scheme is completed, we will contact other contractors we work with to help keep the pantry running.

Ieman Barmaki, Sustainability Director for Kensa Contracting, said:

Kensa was delighted to work with Thurrock Council to support the community to transition to low-carbon heating inside their flats. As part of this initiative, we have worked for the community to revamp the space on the ground floor of George Tilbury House to provide a warm area for all residents. We hope that the warm community room will be used to help alleviate some of the concerns and pressures associated with the energy market and cost of living increases.

Retrofit measures

The properties also benefited from cavity wall insulation installed using an experienced abseiling team provided by ARP Energy Services, negating the need for expensive scaffolding costs.

Darren Peacock, Managing Director, ARP Energy Services, commented:

As an Essex-based company and the only insulation installer in the UK carrying out cavity wall insulation by rope access, we are delighted to be involved in this project.  Our rope access delivery ensured minimal disruption to residents as no scaffolding was needed.  Ensuring the cavity walls are insulated will maximise the new heating systems in the blocks by keeping the heat in homes and not escaping through uninsulated walls.

High profile visitors

As the largest ground source heat pump project funded by the Social Housing Decarbonisation Fund (SHDF) to date, the project has garnered the attention of many councils and government ministers.

On the 8th of December 2022, Lord Callanan, Parliamentary Under Secretary of State at the Department for Business, Energy and Industrial Strategy (BEIS), visited residents from Chadwell St Mary to discuss the project’s impact on upgrading the energy performance of their homes.

Energy Minister, Lord Callanan, said:

It is fantastic to see first-hand how government funding is not only being used to lower carbon emissions but also reduce fuel bills for low-income households, including here in Thurrock.

Projects like this demonstrate how we are committed to making homes greener and cheaper to keep warm, and we’re training thousands more skilled heat pump installers to ensure we continue to deliver cleaner and more energy-efficient homes across the country.

Cllr Deb Arnold, Deputy Leader of Thurrock Council, said:

I am delighted to have seen the work being carried out in Chadwell St Mary and had the opportunity to visit residents benefitting from the project alongside Lord Callanan.

Fuel poverty is a genuine concern for many local authorities and across the council, our services are offering their support to residents. Councils and social housing providers are responsible for reducing the number of households in fuel poverty. I look forward to seeing the results of this worthwhile project which will enhance our properties’ energy efficiency and cut fuel bills.

Thank you to the government for awarding us the funding to carry out this trailblazing work through its social housing decarbonisation initiative.

Key Facts

  • 3 x tower blocks at Chadwell St Mary’s, Essex
  • 273 x Kensa ground source heat pumps
  • Replacing direct electric storage heaters
  • 109 x boreholes drilled under the car park
  • 270-300m deep, nearly 30km of vertical drilling in total
  • Wet radiator system and Sunamp heat batteries
  • Part-funded by £3.2m from Wave 1 of the SHDF
  • Largest GSHP project funded by SHDF to date
  • Expected 70%+ reduction in carbon emissions compared to storage heaters
  • Over the lifecycle of the installation, the total emissions saving is projected at 7,080 CO2
  • Equivalent to taking 1,540 cars off the road
  • Reducing resident’s annual energy bills by 67%
  • Cavity wall insulation installed via abseil on Kensa’s recommendation
  • A new and improved community warm room
  • A new community food pantry initiative
  • New green jobs created locally
  • Over 40 people were employed on the project
  • Local staff were recruited for internal jobs
  • Lord Callanan, Energy Minister
  • Cllr Deb Arnold, Deputy Leader, Thurrock Council
  • Cllr Luke Spillman, Cabinet Minister for Housing, Thurrock Council
  • Cllr Qaisar Abbas, Cabinet Member of Culture and Communities, Thurrock Council

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