URBED’s retrofit team share their experience and advice on how to approach the retrofit of social housing
The Social Housing Decarbonisation Fund was set up by the government in 2020 with £3.8bn pledged over 10 years. The money was allocated to retrofit council homes and thus improve lives, cut fuel poverty and reduce emissions.
We have worked in this field since early 2021, and this article shares our collective experiences of a sector that we anticipate will grow significantly over the coming years. We start with our general observations and then share tips on how others may get involved.
This work currently falls under the PAS 2035 standard for skills and processes, created to protect publicly-funded clients and residents from poor quality design and installation. Architects typically take on the role of “Retrofit Designer” for any projects more complex than very basic installations.
This valuable work is however impeded by unaddressed structural pressures which dilute the improvements and could derail the larger project. The principles are logical – start small, learn, and expand the programme. But the execution and collateral provisions are often poor and can impose unsustainable stresses on contractors and consultants.
A realistic programme for social housing retrofit would include:
- Generously spread funding to reduce the bidding uncertainty and create a more reliable workflow.
- A longer bidding and lead-in period, with expert advice from the start.
- A related education and training programme, integrated with site work but including building physics and multi-skill qualifications, with trainees paid to take part.
- Expansion of building control and its link to retrofit.
- Shared knowledge and regular forums drawing in builders and consultants.
- Shared monitoring information to understand what works best.
- Recognition that this work is expensive and will therefore have a taxation impact if it’s to be done properly.
In order to fulfil the PAS 2035 requirements the Retrofit Designer team typically needs to have the following qualifications:
- Architecture (ARB registration) or a similar construction industry qualification.
- Level 5 Diploma in Retrofit Coordination and Risk Management (the PAS 2035 qualification).
- For work on solid wall or pre 1919 homes - accreditation in building conservation by an approved scheme. For example, the RIBA’s Conservation Architect register or the AABC.
As well as good detailing and construction awareness a retrofit team will need to have access to thermal modelling skills. SAP modelling of proposals will be needed, along with thermal bridge analysis of all key details. Monitoring and evaluation expertise is useful, although this is often commissioned separately by clients.
Programme: we would advise architects to get involved as early as possible and (depending on your experience) not be afraid to lead the design process. Programme in the critical milestones - for example, opening up of key areas and review of drawings from contractor, key suppliers and installers.
Workflow: for small to medium practices we suggest that only one or two of these schemes could be run at the same time. And it should be noted that with the current funding cycle the workload will vary over the course of a year, with the first months relatively light.
Archetypes and variations: defining archetypes is an iterative process, starting with desktop studies. But even when you have the basic forms of dwelling surveyed and categorised, there is no guarantee that individual homes won’t spring surprises. So it’s useful to bake in a process of “variation checks” (by the contractor) during the period between identifying the archetypes, and issuing final drawings and specification for construction (a tracker can help to log these).
We would also advise insisting on early access to assessment information and to the interiors of selected homes. Intrusive investigations should be a pre-condition for meeting any programme. This may involve offering to organise opening up, as well as air pressure tests (before and during construction) and measured surveys.
Drawings: GA plans and elevations can generally be done by archetype (so four sets of plans and elevations might cover a hundred homes) but handed door and window types should be drawn, to avoid installation mistakes. GA drawings should also make it clear by listing to which homes they apply. “Sub-archetypes” with differences impacting on installation work and/or thermal performance (e.g. an identical house with a subdivided bathroom) may need their own drawings.
Detail drawings need to be clear and site-friendly without losing any critical building physics or specification notes. We would advise limiting repetitive notes, to allow space to describe the assumed build sequence, and using photographs to show how the work should look when executed. Sketch drawings will be necessary, both in design development and in addressing “new” conditions.
We would advise making it clear approximately how many drawings and how many iterations you have allowed for prior to start on site, and that substantial revisions after that may need to be charged for. As an example of drawing intensity on a difficult scheme, for 69 homes we produced 65 GA plans and elevations together with 65 A3 construction details, and more than 70 sketches.
Specifications: be prepared for substantial re-writes during the lead-in to site. If you remain in the field you can reuse sections for ensuing jobs. Try to reduce the amount of “protective” wording and irrelevant clauses, so it’s easy to read. Don’t be afraid to send out sections to a new supplier, to check they are aware of what is required, and have an opportunity to respond if they are providing something different.
Site visits and reports: these are crucial. Make it clear how many visits you have priced for, and the fee rate for a visit and for a report. Projects may run on for a long time beyond the planned completion date. And have some clear criteria on the level of reporting you do. You are not there as a clerk of works, yet there may be a lack of oversight and you may be the only person who spots things.
Captioned and time-stamped photos (and where appropriate thermal images) are essential.
Discussing the work informally with installers can be very useful, and relayed back to both main contractor and the design team. We also offered formal toolbox talks on using unfamiliar airtightness materials.
Despite these “challenges” this is a valuable and rewarding area of work that architects can – and should – be involved in. We plan to publish data soon but the completed homes are already noticeably warmer.
Readers may be aware that URBED has, sadly, decided to cease trading as a result of a number of different issues. We are all nevertheless glad to have had this experience and look forward to using it elsewhere going forward.
A longer study including case study examples and post-completion data will be published in the near future.
Postscript
The URBED retrofit team included: Diana Tarcatu, Helen Berg, Helen Grimshaw, Kimberley Androliakos, Marianne Heaslip, Ste Garlick and Wolfgang Küchler.
No comments yet