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The oldest material that the industry can take back for its future constructions

Posted by Webservices on 17 de November de 2023

In our constant search for more efficient, cost-effective and environmentally friendly building materials, we find ourselves on a circular path that leads back to an ancestral resource: stone. Yes, those same blocks that our ancestors used centuries ago to erect walls, castles and majestic cathedrals. While stone itself is nothing new, its potential in construction has resurfaced with a fresh and compelling argument: in terms of cost, performance and quality, quarried rock may be the answer to reducing the carbon footprint that the construction industry leaves behind when using other resources, such as concrete or steel.

But this is not pure theory; it is already being put into practice. Construction has long had an environmental “pendant”, and it is no secret that it is a major source of pollution. The UN estimates that approximately 38% of global energy-related CO2 emissions come from the construction and operation of buildings, and this impact has worsened in recent years. For example, in the UK, the construction industry is estimated to be responsible for around 18% of the country’s particulate pollution. Brick manufacturing is another significant source of pollution, as has been studied in Bangladesh.

In recent years, attention has focused on the carbon footprint generated during the production of materials such as concrete or steel. In 2021, concrete was attributed at least 8% of global human-caused CO2 emissions, while the steel industry in the European Union accounted for 5% of CO2 emissions, a figure that rises to 7% if we consider a global perspective. Faced with this data, the construction sector has been looking for solutions to maintain its activity while meeting decarbonization targets.

Could stone be the solution? Some architects believe so and see stones, which our ancestors used to build dolmens, castles and cathedrals, as a resource with fascinating characteristics. Stones are resistant, durable, fireproof and available in large quantities, and their use entails notoriously low levels of energy consumption and emissions.

The proposal is not limited to using stones as cladding in sheets covering concrete and steel structures. It goes further and suggests reclaiming stones to create solid structures, such as solid stone columns and beams. “For the past 90 years, most ‘stone’ buildings are really just a tile cladding,” explains Amin Taha, German architect and founder of the London-based Groupwork studio.

But what are the advantages of this strategy? In addition to being strong, fire-resistant and, above all, abundant, stone offers three notable advantages that have captured the attention of the construction industry. In essence, building with solid stone blocks is fast, cost-effective and produces only a fraction of the emissions associated with other building materials.

When it comes to cost, the Groupwork study has calculated that using solid stone instead of concrete blocks with stone cladding can generate substantial savings in building construction. This advantage is especially evident when choosing to leave the stone exposed. This approach can lead to a cost cut of 24%. According to Amin Taha, architect and founder of Groupwork, “stone foundations and basements are more economical than concrete ones”. Moreover, this is not just a theory, as Taha and Webb Yates Engineers have successfully designed stone buildings in London, such as 15 Clerkenwell Lose and 317 Finchley Road, that offer costs per square meter below the average for the area.

Beyond cost, however, there are other considerations. Unlike brick, steel or concrete, quarried blocks can be reused if at some point it is decided to dismantle the building they comprise. In the long term, a stone house can be dismantled and its material can be used elsewhere. This is in contrast to reinforced concrete, which can only be crushed for use as aggregate. Moreover, stone is an incredibly abundant and widely available resource.

In terms of environmental sustainability, stone also offers notable advantages. Steve Webb of Webb Yates Engineers points out that stone ensures immediate carbon savings, in contrast to trees planted for timber, which take decades to mature. Quarrying could allow more efficient use of resources compared to forestry, as a single tree provides approximately 1.5 m³ of usable wood, while significantly greater quantities of stone can be found under the land occupied by a tree.

Studies show that the embodied carbon in a stone building, considering mining, transport and construction, could be 60% lower than that of a reinforced concrete house clad with sheeting. Moreover, additional benefits are highlighted, such as the strength, durability, versatility and low maintenance of stone masonry constructions.

These theoretical advantages have materialized in practice over the past few years in the construction of buildings in which stone plays a key role beyond mere cladding. Examples include the innovative 15 Clerkenwell Close building in London, the residential property on Fichley Road, also in London, or the solid stone building designed by Atelier Archiplien in Geneva. Even in Spain, recent projects have been carried out, such as social housing in the Balearic Islands built with load-bearing stone quarried in Mallorca.

However, it is important to note that while stone has considerable advantages, it is not a perfect solution. Quarrying can generate nuisance, pollution and damage to local habitats. Proponents of stone acknowledge that other factors must be considered, such as the impact on biodiversity and labor conditions at quarries, especially in certain countries. Despite these challenges, they celebrate the great potential of this resource, which our ancestors used to erect dolmens. As Joe Duirwyn, natural materials specialist at Architects Climate Action Network, says, “It is absolutely 100% better than concrete and steel.”

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