‘Over-specification of concrete is an industry addiction’

Episode 55. AJ Climate Champions with Hattie Hartman and Rachael Owens.  AJ Climate Champions’ latest series focuses on retrofit. Our guest today is Thom Brisco of Brisco Loran, who talks to us about Costa's Barbers, a live-work shopfront which triumphed in the Project under £500,000 category at the AJ Architecture Awards last week. Brisco describes the conversion of a former barbers in Battersea High Street for Arrant Industries into a home/office for himself and his partner Pandora Loran. Enabled by the recent expansion of ‘retail to residential’ permitted development rights, Costa’s Barbers sports a yellow shopfront, maroon signage and a deep awning which is rolled out on sunny afternoons or when ‘it’s spitting’, providing a popular place to linger and chat.   The architects have packed ingenuity into Costa Barbers’ 54 square metres. The shopfront incorporates sliding sash windows with panels of translucent patterned glass that can be adjusted for degrees of privacy. Behind is a tiled front room - which is used as an office and living space - and at the back the bedrooms are raised above ground level, due to flood risk from the nearby Thames.  The project incorporates numerous salvaged materials, including corbels which support the awning box that are made of quarter sawn snooker table legs. ‘We definitely feel like a different kind of architect now,’ says Brisco. ‘The process of going through a build like this has made us less precious about having all the decisions made up front and knowing where our materials are going to come from.’  The architects designed and self-built the project while living on site, which meant ‘two years without a shower, two years without heating and two years of all of our stuff covered in dust.’ Sponsored by Holcim Foundation Awards. For show notes and to catch up on all AJ Climate Champions episodes, click here.

Episode 54. AJ Climate Champions with Hattie Hartman and Rachael Owens.  AJ Climate Champions latest series focuses on retrofit. Our guest today is IF_DO founder Sarah Castle, who explains that community engagement is not just asking people what they want, but what they can do. ‘It’s about giving people the power to change their environments and making them feel part of it,’ Castle explains in this episode. It’s an approach that is at the heart of IF_DO’s work and is manifest in their work in Hastings, East Sussex, where they have transformed derelict buildings into affordable, community-centric spaces for social enterprise Hasting Commons. We discuss the refurbishment of the grand 1924 Observer Building which had suffered more than three decades of neglect and a dozen owners when IF_DO took on the project. The first phase created a cultural venue with exhibition, theatre and music spaces, workspace, a cafe and gym. ‘It’s a space that can hold everything - from raves to weddings,’ says Castle. IF_DO’s approach prioritises ‘essential improvements over cosmetic enhancements.’ Rather than allowing ourselves to get ‘overexcited about tile colours,’ we have to focus on making the building ‘robust, well-insulated and easy to look after,’ says Castle. The building’s intricately detailed faience facade has been upgraded through a careful balance of repair and renewal. Central to IF_DO’s work is an understanding of procurement that is driven by available grant funding, which Castle terms ‘pod,’ phased organic development. Hastings Commons has secured over 100 grants over the last decade. The Observer Building is owned as a community land trust, which provides a legal framework to ensure affordability and perpetuity. ‘This creates protected spaces within a sphere of gentrification, where rents are controlled below market rates,’ Castle explains. ‘It’s about forever,’ she says. Sponsored by Holcim Foundation Awards. For show notes and to catch up on all AJ Climate Champions episodes, click here.

Episode 53. AJ Climate Champions with Hattie Hartman and Rachael Owens.  AJ Climate Champions is back, with a new series focusing on retrofit. Our guest today is Maria-Chiara Piccinelli, associate director and project lead on the London School of Economics’ Firoz Lalji Global Hub (FLGH). In the episode she explains how each building element requires one-to-one conversations to determine the best reuse, and that the contractor must be on the same journey. After deconstruction at FLGH, up to 70% of bricks  were broken or crushed powder.  Piccinelli argues that a new design aesthetic, a hyperlocal vernacular, can emerge from the specificity of the building, its materials and its location. She cautions against the standard default response of using timber, insisting that all materials should be explored. Sponsored by Holcim Foundation Awards. For show notes and to catch up on all AJ Climate Champions episodes, click here.

Episode 52. AJ Climate Champions with Hattie Hartman and Joe Jack Williams.  To achieve replication at scale, Nicolas Coeckelberghs of Brussels-based BC Materials favours compressed earth blocks over rammed earth. ‘Our goal is to bring earthen construction from a niche to a growing market,’ says  Coeckelberghs. He likens this challenge to playing chess on multiple fronts, creating demand while simultaneously supplying the market. While acknowledging the aesthetic appeal of rammed earth,  Coeckelberghs cautions that it is technically complex and unaffordable at scale. In this episode, Coeckelberghs describes BC Architects’ 15-year trajectory from its first earth building in Burundi, to the proliferation of collaborative workshops which led to a strand of consultancy work, to the creation of cooperative BC Materials in 2018. This led in turn to the recent launch of Léém, a manufacturing company that produces circular materials: unfired bricks, and clay plasters and paints. While  Coeckelberghs is an innovator, he is also pragmatic and advocates focusing on easy wins. ‘Don’t use earth to make facades, just use it to make structures inside,’ he says. He sees enormous scope for application of earth blocks internally where they are protected from the weather and hence more durable. In search of a way to scale the earth blocks production, BC Materials visited concrete and brick manufacturers across Belgium to understand their manufacturing techniques and explore possibilities for collaboration. Partnerships with large manufacturers are now underway, and BC Materials produces its blocks through  ‘industrial co-working’,  using the larger plants’ production line during their ‘off’ hours. For show notes and to catch up on all AJ Climate Champions episodes, click here.

Episode 51. AJ Climate Champions with Hattie Hartman and Joe Jack Williams.  Daniel views mud and waste as opportunities, not obstacles. He advocates an approach of ‘maximum optimism’, explaining that mud and waste enhance his designs. ‘I follow the materials; they do not follow me,’ he says. Sourcing materials primarily from within five miles of a site, Daniel describes how mud and waste can be transformed into beautiful buildings. But this was not the case from the outset.  Daniel first incorporated waste bottles into an early project because the budget ran out before the windows had been purchased. He then realised that a new aesthetic had emerged from this approach. Daniel argues that architects need to be on site, not in the office, in order to observe their surroundings. ‘Open your eyes. Be out there!’ he advises. Architecture is not a white collar job; it’s about going to site, according to Daniel. ‘Today architects are not able to see because we are simply oblivious to what is happening around us. This way of practice has to change,’ he insists. Daniel’s ambition is to bring earth construction to the mainstream and he is not opposed to adding small amounts of cement to his earth mixes to increase structural strength. ‘We need to enter commercial construction. If that means using a bit more steel or cement than the purest form of mud architecture, I’m open to it,’ he says. For show notes and to catch up on all AJ Climate Champions episodes, click here.

Episode 50. AJ Climate Champions with Hattie Hartman and Joe Jack Williams.  Carmody Groarke sustainability lead Sian Ricketts explains how architecture can adapt to the reality of finite resources and an abundance of waste. Ricketts says that architects should develop their intuition and new rules of thumb to design for a changing climate. Architecture needs to adapt to incorporate materials from waste streams, and this requires a new approach to detailing and ongoing maintenance. ‘The industry is going through a huge learning process and we should not be scared of getting it wrong,’ she says. Marginal gains on every project are important. In this episode, Ricketts describes the process of developing a bespoke brick for the Design Museum Gent in Belgium. She explains that the practice did not start with a bespoke brick in mind. Because conventional clay-fired bricks are high in embodied carbon, an exploration of less carbon intensive alternatives led to an in depth collaboration with Local Works Studio and Brussels-based bcmaterials that in turn led to incorporating local waste streams into the design of the new brick. Ricketts observes that the process of developing the bespoke brick for Ghent has strengthened the practice’s confidence in seeking opportunities for both innovation and circularity in future projects. Carmody Groarke is currently working with Imperial College-based startup Seratech to explore the use of magnesium carbonate as a binder for bricks. For show notes and to catch up on all AJ Climate Champions episodes, click here.

Ep 49. Structural engineer David Watson describes the enduring appeal of brick and its underexploited superpower: reuse Brick has many advantages: durability, aesthetics, use as both envelope and structure, and the possibility of local (even artisanal) production. This last point differentiates it from steel and concrete, due to the Ordinary Portland Cement needed for concrete production. ‘We need to ‘build our intuition about what impacts embodied carbon and emissions from different materials,’ says Watson. Watson highlights the importance of querying the firing required to achieve different finishes, because it varies between brick types and can significantly impact overall embodied carbon. It’s also important to understand the fuel used in the kilns where bricks are fired.  While in the UK this is predominantly natural gas, abroad it might be charcoal or coal, both of which generate significant amounts of particulates. In non-loadbearing cladding applications, the embodied carbon of the support systems must be taken into account because they can comprise as much embodied carbon as the brick and mortar combined. These hidden impacts are often difficult to calculate due to lack of EPD data, explains Watson. Brick reuse is on the increase but currently comprises less than five per cent of the market because of the challenge of removing the mortar, particularly those bound with Ordinary Portland Cement. Traditional lime-bound mortars are easier to remove. Current research is exploring mechanised removal of cement-bound mortars, and increased demand should prompt the market to respond, says Watson. In this episode, we also discuss ConcreteZero targets (AKTII is a signatory) and the extent to which they rely on GGBS. Watson stresses the necessity of ‘using less’, for example, exploring ribbed, coffered or troughed slabs as an alternative to flat slabs. He advocates form-effective design, marrying structure with architectural expression in a lean use of materials. David Watson can be contacted at [email protected]. To catch up on all episodes of AJ Climate Champions, click here.

Episode 48. AJ Climate Champions with Hattie Hartman and Joe Jack Williams. Structural engineer Eva MacNamara of Expedition Engineering explains how we can radically reduce our use of concrete and how to better understand the biodiversity impacts of material choices. In this episode, we dive into the tricky topic of concrete and unpick the widespread mantra that ‘concrete is bad’.  Concrete is ‘an addiction’ that has led to an obese construction industry, says Expedition’s MacNamara; it is not going to go away but we can radically reduce our use of it. She describes a porposed slab design for the Eden Project site in Dundee which would achieve an 80% reduction in concrete volume. MacNamara stresses that ‘using less’ is much more impactful than substituting low-carbon concretes and notes that she repeatedly sees practitioners over-specifying. We discuss some of the nuances of concrete use: which applications are most appropriate, how to reduce the volumes we use, and why low-carbon concrete – especially GGBS – is not a silver bullet. We also touch on upcoming innovations including Seratech, ‘funnel’ slabs and smart crushing. McNamara explains how to bring both carbon and biodiversity into the concrete procurement process. Highlighting findings from the recent report The Embodied Biodiversity Impacts of Construction Materials (Expedition/ICE, November 2023), she notes that 95% of biodiversity impacts occur off site and that the new biodiversity net gain requirements only address the 5% on site, so designers must look beyond a site’s boundary. Finally, MacNamara advocates finding a place to innovate on every project. ‘We can make the most difference by using our projects as springboards for incubating innovation,’ she says. For show notes and to catch up on all AJ Climate Champions episodes, click here.

For the first in a new six-part series on materials, Hattie is joined by co-host Joe Jack Williams to interview Martha Lewis, head of materials at Danish practice Henning Larsen. Lewis argues that a baseline of health and environmental impacts should inform material specification, and explains why a holistic approach is essential to navigate the nuances of material selection. She describes how the European focus on life cycle analysis and the Global Warming Potential of materials is starting to be integrated with the earlier American focus on healthy materials and toxic chemical content. ‘The glut of information is a challenge of our time. How do we navigate too much information to make the right decisions?’ asks Lewis. She advocates for material passports which would consolidate the relevant data needed to make informed decisions: carbon emissions, chemical content and circularity. She also argues that certification schemes, despite their weaknesses, are the most effective route to ensuring that a project delivers on its sustainability aspirations. Also in this episode, Lewis describes Unboxing Carbon, a database with an accompanying course which she has developed to upskill architects on the carbon aspects of material selection. Lewis has rolled out Unboxing Carbon across Henning Larsen’s 700-strong practice and also offers it to external practices. For show notes and to catch up on all AJ Climate Champions episodes, click here.

Episode 46. AJ Climate Champions with Hattie Hartman and George Morgan. Andrew Waugh explains how building with timber can address industry transformation at scale. ‘I want to transform the whole industry,’ says Waugh, founding director of Waugh Thistleton which was recently named Practice of the Year at the AJ Architecture Awards. In this episode Waugh explains why tall buildings have no place in sustainable cities of the future; how building housing with timber can reduce its carbon burden by as much as 75%; and why we should stop building basements (they are up to five times as carbon intensive as upper floors). Waugh advocates building with timber primarily as a low-carbon alternative to concrete and steel, rather than for aesthetic reasons. He shares recent research that clarifies end-of-life alternatives for timber that are not incineration or landfill. He makes it clear that current subsidies that encourage burning of timber for biomass must be revamped to support use of UK-grown timber for construction. This episode was recorded the day after Waugh toured co-hosts Hattie and George through Waugh Thistleton’s recently completed Black & White Building in Shoreditch. The building is nearly all timber: structure, core, floors, cladding and brise-soleils. Waugh describes where the timber was sourced and that the transport footprint of timber is a relatively minor consideration. Finally, Waugh explains why he recently withdrew from the Architects Declare steering group. For show notes and to catch up on all AJ Climate Champions episodes, click here. With support from the American Hardwood Export Council A previous version of this podcast mistakenly suggested that Waugh Thistleton had withdrawn from Architects Declare. In fact, Andrew Waugh withdrew from the Architects Declare steering group in May on an individual basis and Waugh Thistleton remains a member of Architects Declare. We apologise for any confusion.