INCA Case Study: Chapel Gardens, Benwick

As part of its ongoing work to improve the energy efficiency of its homes, over the last two years Clarion Housing Group has retrofitted 505 homes across Fenland, Tonbridge and Malling which had an Energy Performance Certificate (EPC) rating of D or below.

Among them were 13 bungalows in the Chapel Gardens development in Benwick.

Retrofitting older housing stock

 The work was part-financed via the first wave of the government’s Social Housing Decarbonisation Fund (SHDF), which was launched in 2021 to help social housing providers and local authorities increase the EPC rating of their properties to C or above.

All social housing provided by registered providers was eligible for SHDF wave one funding, regardless of archetype, and the work being carried out is designed to tackle issues associated with fuel poverty including mould and condensation.

As a registered provider of social housing, Clarion could apply for the funding as part of a consortium with Fenland District Council and Tonbridge & Malling Borough Council. The £4.35m secured by the two local authorities was match funded by Clarion, which is working closely with its main contractor Equans to upgrade the homes.

“We were already carrying out works to improve residents’ homes under existing maintenance contracts, in line with the government’s 2030 EPC C target, but this funding has allowed us to accelerate and increase the scale of it all, ultimately improving more homes much faster,” said Daniel Archard, asset sustainability manager at Clarion.

Meeting PAS 2035 standards

Sarsvati Varsani is part of Equans’ dedicated specialist retrofit team. As a senior technical retrofit advisor for the contractor, she is overseeing the process in terms of energy efficiency and compliance. She said: “The delivery of all SHDF projects must be PAS 2035 compliant, which specifies a whole-house or whole-building approach to retrofit. It means that energy efficiency measures should be installed with the requirement of the entire building in mind – both from a technical standpoint and considering factors like occupant comfort.

“The SHDF facilitates a multi-measure approach to allow us to upgrade Clarion’s least energy-efficient homes to meet the PAS 2035 specification using more than one measure. For example, as well as replacing insulation we are also installing air source heat pumps at the properties where necessary.

“I’m working closely with the site team, retrofit designer and contracts manager to address any issues throughout and ensure that every measure is compliant with the standard. Representatives from Clarion and the Department for Energy Security & Net Zero also conduct site visits to review progress throughout.”

Adopting a fabric-first approach

One of the key principles of wave one of the SHDF is a fabric-first approach. This ensures heat loss prevention measures are installed before other energy efficiency measures, to maximise the dwelling’s suitability for low carbon heating either now or in the future, and to benefit tenants in terms of comfort, health, well-being and bills. The Chapel Gardens bungalows had an original U-value of 1.43W/m²Km, so this was going to take considerable changes.

Having been built between 1967 and 1975, the cavity insulation in the bungalows was no longer fit for purpose as it had slumped to the bottom or – in some cases – didn’t even exist. It has now been replaced with a polystyrene bead insulation.

The benefits of external wall insulation

As part of the fabric-first approach being taken by Equans and Clarion, Saint-Gobain Weber’s External Wall Insulation (EWI) system was specified for the bungalows to improve their thermal efficiency.

It is being installed by FRT Property Services Ltd, which is PAS 2030:2019 certified – something that is required of all of the subcontractors working on this project. By gaining PAS 2030:2019 certification, retrofit installers can demonstrate that they have installed energy efficiency measures that meet the required specifications, and have delivered on customer requirements and expectations in accordance with TrustMark standards.

FRT Property Services – which began working on Chapel Gardens in January 2023 – specialises in EWI and its director Farhat Ahmed and Operations Director Radu Ursache helped to ensure work was delivered to Weber standards, on time and within budget.

For this project, Farhat’s team installed webertherm XM with 100mm of webertherm MFD insulation. The SHDF stipulates an energy performance outcome of 90kWh/m2/year, with a target U-value of 0.30 W/m²K. The addition of EWI from Weber was critical in enabling Clarion to meet the SHDF space heating demand performance outcome, as the replacement cavity wall insulation alone wouldn’t suffice – with the properties only achieving 0.44W/m²K.

Having requested that the retrofit work didn’t change the aesthetic of the bungalows, the planners wanted to maintain a brick finish. To achieve this, weberwall brick was specified along with the webertherm XM EWI system. This innovative brick slip system is lightweight and quick to install, containing the equivalent of 20 brick faces per sheet. It is available in a wide range of colours including Antique Buff, which meant it was possible to closely match the surrounding buildings.

Farhat said: “The team at Weber has been very helpful throughout the process and applications manager Linda Twidale showed my team how to install the product. It’s very simple and provided the like-for-like result the client wanted; as far as brick slip systems go, weberwall brick provides the closest match to real bricks I’ve seen while working in this sector.”

It was important to Clarion that the residents of the bungalows were able to remain in their homes while the work was completed which is why EWI was the perfect solution. Farhat’s team worked closely with Equans’ retrofit liaison officers and other subcontractors, including the scaffolding and utilities companies, to ensure everything went smoothly and the homeowners were not inconvenienced.

Measuring performance

By installing the webertherm XM EWI system, the U-value at the properties has been improved to an efficient 0.20 W/m²K – far exceeding the target of 0.30W/m²K. Once all of the retrofit work has been completed, the bungalows will undergo a post-works EPC assessment and are expected to achieve a C rating.

The new insulation will provide improved thermal performance all year round, helping to keep residents’ homes cooler throughout the summer and warmer in the winter. It is predicted that those living in upgraded Clarion properties will save between £300 and £500 on their energy bills each year.

Switchee smart thermostats have been installed in some properties to relay data to Clarion, enabling them to monitor the energy consumption of the properties.

Within six months, Equans’ retrofit evaluator will issue a questionnaire to residents to assess whether everything works as it’s supposed to, and Farhat’s team has already received feedback. He said: “Residents have told us they’re already feeling the difference in the temperature of their home.

“It isn’t right that people have had to choose between eating and heating but getting such positive feedback really highlights the role that we’re playing in improving these homes.”

Daniel Archard, asset sustainability manager at Clarion, added: “We’ve received more funding via wave two of the SHDF and are planning to increase our retrofitting tenfold over the next three years, as pressure builds to upgrade all social housing to an EPC rating of C or above by 2030.”

Farhat concluded: “We’re looking forward to continuing our support during the delivery of the future pipeline of work within this area for Clarion Housing under SHDF Wave 2.1.”