“Natural Stone Shows Huge Potential to Reduce the Carbon-Footprint of Construction”

My research, conducted in collaboration with industry partners, entails development of cutting-edge construction concepts in low-carbon materials. These are fabricated at large scale and proven via advanced laboratory tests coupled to sophisticated structural analysis and field monitoring to ensure their efficacy and structural integrity.

Through cross-pollination between academia and industry, by working with companies and builders to make sure our research can be used in real-world construction, we seek to decarbonise construction in alignment with the UN Sustainable Development Goals and the UK government’s Net Zero strategy. We tailor the concepts to suit the materials, be they natural (e.g. timber, stone) or synthetic (e.g. Portland cement-free concrete, fibre polymer composites).

Construction is a pivotal sector for realising the carbon neutrality objective, because embodied carbon (due to the materials’ extraction, manufacturing, transportation, construction into buildings, maintenance during the building’s life, then demolition into waste and disposal) accounts for 11% of global carbon emissions. My focus on embodied carbon provides a balance to other studies focused on operational carbon which is associated with lighting, temperature regulation, etc of buildings.

The challenges are threefold. First, a study commissioned by Future Observatory revealed that while initiatives exist to reduce operational carbon emissions, there is no government policy requiring control of embodied carbon emissions from buildings. Hence strategies to reduce embodied carbon are now purely voluntary, with the associated challenge of fragmentation and reduced impact. Second, the construction industry is standards driven relying on strict rules and guidelines to ensure buildings are safe and perform as intended.

A structural design standard, or code, is compulsory for designing a building in any given material. The Eurocodes enable such designs in steel, concrete and timber, but despite stone’s tremendous green potential no such code exists for natural stone (the current masonry code is of limited use). A structural stone code must be predicated on large-scale, multi-level lab tests, to understand behaviour under different mechanical and environmental loads.

Third, to successfully use stone sustainably in construction, everyone involved in the stone supply chain including structural engineers, architects, construction insurance assessors, carbon evaluators, quarry owners and stone masons must be fully conversant with each other. This is possible using digitalisation as a medium of communication between professions.

Like timber, natural stone is one of our oldest construction materials. Its durability, abundance and ability to withstand a lot of weight pressing down on it have rendered natural stone the material of choice for globally iconic heritage structures, from the 300+ year old St Paul’s cathedral in London to the pyramids in Egypt. However, the industrial revolution saw stone and timber shelved (except for ornamental uses) in favour of steel and concrete. Now, a quarter millennium later, in response to the climate emergency natural stone shows huge potential to reduce the carbon-footprint of construction, because cutting stone blocks at the quarry, assembling the blocks into structural modules, transporting the modules to site and erecting buildings out of them are low-carbon emitting processes relative to the equivalent processes for conventional construction materials.

We’re now revisiting construction in stone segments through the tri-focal lens of digitalisation, modern cutting equipment and modern fabrication methods such as prestressing originally developed for concrete. Much work has been done to develop the construction potential of timber, the other low-carbon natural construction material, but stone remains ignored by comparison. This combination of factors has made stone the focus of my work.

This Fellowship’s key output will be a document providing guidance for integrated structural and architectural design in stone. The document will be informed by large scale tests at UCL’s structural engineering laboratory for different natural stone types, supported by state-of-the-art numerical analyses, and information from the few existing structural stone construction sites including a multi-storey stone demonstrator structure at Earl’s Court in London. We will develop a consistent carbon evaluation tool for stone construction.

An important feature is my collaboration with industry colleagues at WebbYates and ARUP structural engineers, at Groupwork architects and at the Stonemasonry Company, to ensure that the project remains practically focused. We’re also teaming up with colleagues at the Royal College of Art (RCA), within London’s School of Architecture (LSA), to host roundtable discussions by stakeholders spanning academia, policy and the stone supply chain. Guidelines for University education strategies in this fascinating topic will be output from these discussions and included in the guidance document.

Sustainable housing construction has a very promising future. We have a well established standard for building with timber, called Eurocode 5, which provide a unified approach to designing timber buildings and structures, ensuring they are safe, reliable, and built to last. Our research aims to create a similar standard for stone, so it can be used more widely in sustainable building. Through responsible quarrying and robust first principles design, natural stone can be the basis of sustainable, lightweight, modular, resilient construction either in tandem with other low-carbon materials such as timber, or on its own. We’re grateful for this opportunity from the Design Museum’s Future Observatory to impact these developments.