Rethinking Resi 2023 – ADC

Watch the AT webinar, in partnership with Knauf Insulation and SIG Design & Technology, which explores how the UK is addressing the problems posed by the housing crisis.

Speakers (clockwise from top left): Ben Derbyshire, Kath Scanlon, Matthew Morgan, Matthew Prowse, Miles Attenborough, and Gerard Ferris

Miles Attenborough kicked off by sharing findings from a five-year research project into ways to accelerate the large-scale delivery of low-cost carbon homes. The project tracked four small-to-medium-sized fabric-first residential projects from inception through design, planning, construction and post-occupancy evaluation. Findings showed that energy use was between two and four times higher than predictions made at the design stage, a discrepancy attributed to a greater number of thermal bridges than accounted for at the design stage, a failure to meet airtightness targets, and insufficient early design coordination, particularly for M&E services including MVHR.

Mole Architects’ Marmalade Lane residential development in Cambridge is also part of the Building 2050 project, and adopts a fabric-first approach, passive energy design principles, and offsite manufactured closed timber panel construction (ph: David Butler)

On the plus side, research showed that, for simpler projects with no complex technology, improved environmental performance had been provided at a cost uplift of between 1 and 2.5 per cent, which developers had absorbed within their project so that there was no additional cost to the house buyer at all. This cost uplift rose to 10-20 per cent – often funded by grants – for more complex schemes, leading to the conclusion that the emphasis needs to be on simple buildings that are cheaper to deliver and straightforward to build and run.

Examples of high-rise residential developments at transport hubs in Lewisham and East Croydon (phs: Kath Scanlon)

Kath Scanlon shared findings from her research into wellbeing within residential towers, particularly in London. Key issues include lack of storage,  shortage of internal and external play space, and concern over the responsiveness and accountability of management regimes. Scanlon pointed out that very little of the existing research into high-rise living is applicable to current and recent UK projects that include mixed-tenure blocks within masterplans with a strong emphasis on placemaking, and called for government to fund further research into user wellbeing, the real costs of living in high-rise housing for leaseholders, and options for building high-rise schemes that reduce life-time costs and carbon take.

SIGA 32 slates measuring 600x300mm from SIGA Natural Slate were specified for this David Wilson Homes development in Shrewsbury (ph: SIG)

Gerard Ferris presented a range of projects that demonstrated the provenance, performance characteristics, environmental credentials, and flexibility of natural slate. An overview of the embodied carbon of the most common roofing materials underlined the fact that natural slate has the advantage of being unprocessed, in so far as there is no heat or energy used to transform the chemical or physical composition of the raw material into the final product. A 100-square-metre slate roof impacts the environment almost three times less than a fibre cement roof, while slate extraction uses 15 times less CO2 than other natural materials.

Resident Review post-occupancy evaluation at Beaulieu in Chelmsford for Countryside Partnerships (ph: Quality of Life Foundation)

Matthew Morgan presented the work that the Quality of Life Foundation is doing to place health and wellbeing at the heart of the way homes and communities are designed, with a particular emphasis on effective community consultation. Using its work at Harlow & Gilston Garden Town as a case study, Morgan showed how its inclusive engagement toolkit can aid online and face-to-face community engagement making the development process more inclusive and democratic.

Part L 2021 is a stepping stone to more significant changes to come, including the Future Homes Standard

Matthew Prowse offered practical recommendations on ways to future proof specifications for residential projects in a commercially viable way. First, architects should be mindful of the fact that the new Part L 2021 is simply a stepping-stone, due to be replaced by the Future Homes Standard in 2025, and should be making specification decisions that anticipate this change. As an example, he recommended that low-rise housing should be designed with a 150mm cavity ­– the ‘sweet spot’ for optimising fabric performance with minimal impact on floor space or unit numbers ­­– as opposed to a 100mm cavity, which, while Part L complaint, limits future options. Designing with wider cavities also provides more choice on the insulation specified and more options for retrofitting to meet any future changes in requirements.

Insitu performance measurement is coming, which means architects need to design using materials that are easier to get right on site

Second, architects should consider specification in a holistic way so, for example, evolving thermal performance requirements alongside changes in regulations governing other aspects of performance, such as fire safety, acoustics and embodied carbon. Prowse emphasised the current paradigm shift towards as-built performance scrutiny and offered practical pointers to ensure that specifications are designed with buildability in mind.

Designed by HTA Design, Officer’s Field in Weymouth provides a modern take on traditional family houses in a variety of terraced, semi and detached types. It also make good use of the locally-sourced quality Portland stone (ph: HTA)

Finally, Ben Derbyshire shared HTA’s experience of implementing the RIBA 2030 Climate Challenge citing a range of obstacles including a lack of ambition amongst residential clients and a lack of widely available standard methodologies for measuring progress, particularly with regard to social value. That said, the practice has drawn on an existing partnership with three other housing specialists – PRP, Pollard Thomas Edwards and Levitt Bernstein – to pool knowledge, develop methodologies, present a united front to clients and, crucially, establish an agreement to carry out post-occupancy evaluation on each other’s projects.