Sustainable design remains a priority in the race to supply homes to alleviate the housing crisis. Industry experts discuss some of the issues – and potential solutions
Building the homes Britain desperately needs has become a key priority for the new Labour administration and the planning system is again the focus of attempts to boost development and funding. Ministers will need to be vigilant to ensure their mandate to deliver 1.5 million new homes over the next term results in sufficient numbers for social rent, and that the £7 billion allocated to upgrade the energy performance of millions of existing homes delivers enough bang-for-buck to keep net zero targets within reach.
This was also a concern for the expert panel of architects at our PiP webinar, relating their experiences in delivering some of the most effective, elegant and sustainable residential architecture and interiors, with products by sponsors VMZinc, 2N and Velux.
Bob Prewett, director of Prewett Bizley, shared carbon-saving insights gleaned from his 20 years’ working in the retrofit space. Among all building elements, windows provide the greatest opportunity to reduce heat loss, he said, especially in properties where there is a high proportion of glazing.
Replacing just the single glazed windows on one project resulted in a 30% saving on space heating demand, ‘a significant improvement, which can often be easily packaged up and rolled out,’ said Prewett. The practice aims to maximise efficiency gains on projects, which means either triple glazing, vacuum double glazing or advanced secondary glazing.
The ‘magic of heat pumps’, said Prewett, was not just that they eradicate need for dirty gas boilers. Metered energy consumption can be five times less, resulting in much lower bills for consumers. With grid electricity already lower carbon and tending towards zero carbon in the next 10 to 15 years, it’s hard to argue against their specification on projects, he added.
Next up, Jonathan Lowy, operational marketing manager at VMZinc, highlighted projects where the robust and malleable metal has elevated the performance and appearance of roofs and walls. Among other things, he noted that the radical reduction in acid rain levels in western Europe has fortuitously also resulted in increased durability of zinc sheeting. A zinc roof is typically 700 microns thick and corrosion rates are around one or two microns a year.
Heritage conservation was a guiding principle for shedkm’s award-winning regeneration of Grade II*-listed Crusader Works in Manchester, a collection of cotton spinning mills from the 1840s transformed into new housing.
Practice director Mark Sidebotham explained the efforts taken to avoid carving out sections of the brick and cast-iron structures, including original timber beams and staircases, by adding external access and circulation areas, along with a separate newbuild apartment block.
The main move was to run corridors along the side of the mill buildings around the central courtyard, connecting them via footbridges to new, bright yellow cores that stand as separate architectural elements. ‘This animates the courtyard space and allows for cross-ventilation,’ said Sidebotham. The steel frames are a modern counterpoint to the historic buildings, as is the newbuild block with its concrete external frame – nod to the mills’ lattice brickwork – infilled with stack-bonded blue brick, a contrast to the existing red brick.
Shedkm designed a range of one, two and three-bed apartments across the historic site, all procured under a traditional form of contract. ‘We’ve always vouched for traditional contracts with existing buildings,’ explained Sidebotham, ‘as the cost premium that a contractor will put on the job under D&B will blow things out of the water. Having your own budget doesn’t always work out – it can be more expensive ultimately – but at least you’re in control.’
From cost control to access control, as Jez Hildred, pre-sales manager for UK and Ireland at 2N, discussed simple approaches to secure entry and movement in residential buildings.
Mobile devices are now part of the mix, he says, used to receive calls from a front door intercom or functioning as a biometric lock to enter and move around a building. Greater benefits can be achieved when entry systems are combined with a smart building management system. Hildred pointed to a recent apartment project in Bratislava where units located by the door of each flat enabled residents to interact with the HVAC and other building systems.
Steven Kierney, director, and Danielle Simpson, architect at SKArchitects, then shared their insights on Bluebird, a project of high social value for Southend-on-Sea charity HARP (Homeless Action Resource Project) that is highly sustainable, despite a limited budget.
The mix of shared houses, bedsits and flats for homeless people includes a large building split into six houses, designed to full Passivhaus certification. Efforts to limit surface area, to prevent thermal losses and simplify air tightness detailing, were complicated by the need for dormers to avoid overlooking, which increased the emphasis on a fabric-first approach.
Marmox load-bearing thermal insulation blocks made it possible to meet Passivhaus requirements, despite the use of standard concrete foundations and blockwork walls. A limited choice of local contractors with the right skills led to a focus on prefabrication. Concerns about overheating were addressed by reducing the size of north-facing windows, and introducing solar shading canopies to the rear. ‘It reduced overheating risk to zero and improved the design, giving residents all-weather enjoyment of the gardens,’ explained Simpson.
Weather of the windswept variety is familiar to residents of Tynemouth, in North Tyneside, where three innovative Velux Heritage Conservation windows have been installed on a large Edwardian semi-detached home, part of a retrofit by Spence & Dower Architects. Above the bathroom and stairs, they are flush-fitting with fine black mullions and traditional winding cranking handles. ‘The stairwell was dark, but it opened up the area to create a light-filled environment,’ revealed Velux senior architectural development manager, Richard Williams.
Tim Chapman-Cavanagh, director at Assael Architecture, rounded off the webinar with the RIBA award-winning Sunday Mills co-living development in Earlsfield, south London. The 315-flat scheme is like a ‘scaled-up version of a house-share’ and features double-bed studios of varying sizes (the standard is around 17m²) and shared co-living amenities, including private dining space, co-working and flexible space, cinema rooms, breakout space, laundry, a communal kitchen, lounges and gyms. The architecture’s form and materiality draws on the rich history of working mills that once occupied the site, with a factory-like roof form, warm red brick tones, and Crittall-style metal windows.
To ensure ‘this was not a building in isolation,’ co-living areas are accessible to the community, with the facade facing onto the River Wandle, and feature a mix of co-working space and an independent café and restaurant. Interestingly, the building is lived in by a ‘mix of people at different stages in their life’, from foreign students starting in their first jobs, to a 66-year-old on a 12-month contract getting experience of the area before deciding whether to buy a property there.
This commendable spirit of inclusion and diversity – architecture that aims to better serve the community rather than isolate itself – is something any designer, or indeed new government, should aspire to in the drive to deliver more quality homes at scale.