AJ Climate Champions podcast: AKTII’s David Watson on how to reduce the environmental impacts of brick

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 have a significant impact on 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 david.watson@akt-uk.com.

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About David Watson

David Watson is a technical director at AKT II, where he co-leads on matters related to climate action with a particular focus on adaptive reuse, design efficiency and material innovation. His current research includes the structural fire engineering of timber and steel structures, evidence-based loading to facilitate reuse, development of low-carbon concrete and masonry, structural stone sourcing and dynamic life cycle assessments of novel biogenic materials.

He graduated from the University of Sheffield in structural engineering and architecture before joining AKTII in 2006. His projects include Hopkins Architects’ Stirling Prize-nominated 100 Liverpool Street and Shrewsbury Flaxmill Maltings with Feilden Clegg Bradley Studios. He is currently working with Stanton Williams on the Museum of London.

He has taught at universities across the UK, Ireland, Sweden and the United States and is currently running a seminar series at Harvard GSD with AKT II co-founder Hanif Kara entitled Embodied Carbon: Material Cycles, Circularity and Advances in Reverse Engineering.

Watson is a contributor to ConcreteZero and the BCSA working group on steel reuse.