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21 Jan 2026
AES Sustainability has recently completed a comprehensive programme of retrofit improvements for Cambridge Housing Society (CHS), delivering end‑to‑end retrofit assessment, air testing and coordination across 118 homes located throughout Cambridgeshire and Essex.
The project formed part of a wider strategic review, which began with AES conducting an assessment of CHS’s broader portfolio of around 3,000 homes. From this early work, AES and property and construction consultancy McBains, identified 15 distinct archetypes that helped shape the client’s long‑term approach to asset improvement. AES also supported CHS with a funding application that successfully secured just under £1 million towards the delivery of retrofit works.
The homes included in the programme varied significantly in age and construction type. Many of the oldest houses were pre‑1930 solid wall homes, with some featuring 1970s cavity wall extensions. Others were 1990s cavity wall construction. A small number of low‑rise flats were also included.
Before retrofit activity commenced, AES undertook a detailed series of assessments to establish a reliable baseline. This included air‑tightness testing, borescope inspections, property typology verification, occupant surveys and the collection of technical evidence required for pre‑improvement EPCs. These investigations helped inform a fabric‑first approach, designed to achieve an EPC rating of at least C.
Delivery of the retrofit measures required close collaboration between AES and the primary contractor, Aran Insulation. AES provided on‑site coordination throughout the project, overseeing that the sequencing of works was compliant with PAS2035, acting as liaison between contractor and the client and ensuring that residents remained informed and supported at every stage.
AES’s Retrofit assessors, coordinators and advisors were regularly present on site, offering the practical, day‑to‑day oversight required to maintain quality, resolve issues quickly and keep the programme moving efficiently. As part of the role, AES helped managed resident queries and feedback that came via CHS’s Asset Management team, providing the human connection that frequently becomes the first and last point of contact for households undergoing retrofit works.
The measures installed across the 118 homes reflected their differing construction types and needs. Solid wall properties received external wall insulation (EWI) whilst homes with cavity walls benefited from new cavity wall insulation. Where appropriate, properties also benefitted from improved ventilation and new windows and doors, alongside loft and flat‑roof insulation. Several off‑grid homes received modern high heat retention storage heaters, while solar PV was installed on selected properties with suitable roof conditions.
One Cambridge property has provided a particularly clear illustration of the impact achieved. Following AES’s assessment and design recommendations, the home was upgraded with new windows and doors, EWI, new loft insulation and improved ventilation. The resident commented that she “couldn’t believe the difference” the measures had made, emphasising both the improved comfort and the visual transformation of her home. Similar feedback was received across the programme, with residents consistently reporting positive experiences linked to AES’s on‑site presence and communication.
Quality assurance remained a central element of AES’s involvement. The team completed full post‑retrofit assessments, air‑tightness testing, photographic and technical evidence gathering, and responses to audit requests, ensuring full PAS compliance and providing CHS with a clear, transparent record of the improvements delivered. Regular communication with the client ensured that any resident concerns or issues were rapidly relayed and addressed, supporting high levels of satisfaction throughout the programme.
With all works across 118 homes completed and final documentation in preparation, the outcomes clearly demonstrate the value of AES’s integrated approach. By managing every phase – from initial portfolio analysis and funding support through assessment, design, coordination, resident engagement, contractor liaison and final compliance – AES has delivered a seamless retrofit experience that improved energy performance, reduced costs and enhanced comfort for households across the region.
Successful retrofit delivery relies as much on maintaining trust with residents as it does on technical expertise, and this programme exemplifies how both elements can be combined effectively.
