Clay bricks have an important role to play in a net-zero carbon built environment. Head of Sustainability Stephanie Palmer discusses the future of bricks and sustainability.
It’s evident that the construction industry must rise to the global challenges of climate change, biodiversity loss and resource scarcity. Creating a built environment that generates net-zero carbon emissions is no easy feat – and it all starts with the types of materials and construction methods we choose. That includes clay bricks, which have a vital role to play in the low-carbon built environment of the future.
“When we think about striving for ‘net-zero’, we first need to question what we mean by that,” says Stephanie Palmer. Stephanie is Head of Sustainability at Wienerberger UK, working not only towards a net-zero emission, nature-positive business, but to provide sustainable building material solutions to the construction industry - all with our people, customers and communities in mind.
“Traditionally, government policy uses the term ‘net-zero’ to refer to operational carbon only. That means the carbon generated from energy production, subsequently used during a building’s operation. For example, that might be heating or lighting. So, a lot of efforts towards net-zero focus on improving the fabric efficiency of the building to reduce the operational energy demand of the building.”
The government is already acting to tackle building operational energy performance. Upcoming updates to Part L of the Building Regulations mean that new buildings should deliver a 31% improvement in CO2 emissions versus current standards. These changes are a stepping stone to the Future Homes Standard in 2025, when buildings will have an operational energy efficiency of at least 75% lower than the current Building Standard.
“However, the full definition of net-zero in terms of the built environment takes into account the whole life impact of the building, including both the ‘operational’ and the ‘embodied’ carbon of the building over its lifespan.”
Creating a net-zero built environment that takes into account the whole life-cycle carbon emissions isn’t a task for the faint-hearted, but sustainability experts like Stephanie and the team at Wienerberger are leading the charge into a decarbonised future.
How can we make bricks more sustainable?
As the traditional definition of ‘net-zero’ has focused on operational energy only, the carbon released ‘upfront’ during the sourcing and production of building materials, has been somewhat overlooked. But commentators, sustainability experts and policy-makers are starting to look at this crucial part of the net-zero journey.
“To make a brick, we fire clay at over 1000 degrees celsius to turn it into a ceramic product. Through that transition of clay to ceramic material, you get the durability that gives bricks their long service life, fire-rated protection and thermal efficiency. However, a lot of fuel is required to reach that temperature.
“At the moment we are relying predominantly on natural gas to create those high temperatures. The challenge for us is how we transition to a low-carbon fuel source.”
One option is hydrogen, which the UK government has committed to trialling through local hydrogen networks in the UK Hydrogen Strategy.
“If we’re able to adjust our technology to accept a mix of natural gas and hydrogen, and if the hydrogen is created in a low environmental impact process, then that would help to decarbonise without major changes to the production process as it looks today,” says Stephanie.
“The other option is to electrify the production process, using renewable electricity. That would dramatically reduce our company’s carbon emissions and in turn the embodied carbon of our products. However, there's still a lot of work needed until we would be ready to use electric firing technologies at the scale we need.”
While work is underway looking at firing alternatives, Wienerberger is also optimising materials in its production processes.
“We do currently add a small percentage of additives to the clay, about two percent of total ingredient mass, and these help to reduce the firing temperature or time spent in our kilns,” Stephanie explains. “That also helps reduce carbon emissions. There's more work we can do around materials optimisation, and that is one of the strands within our decarbonisation strategy.”
How can bricks be used in net zero building designs?
Despite the challenges involved in decarbonising the production of bricks, this building material has a vital part to play in the built environment of the future. The changes to Part L and the upcoming Future Homes Standard focus on the operational emissions of a building, such as the energy required to regulate temperature - and this is where clay bricks come into their element.
“The high thermal efficiency of brick can really contribute to reducing the operational energy demand of a building,” says Stephanie. “If you've got a more airtight building that can regulate changes in the external environment, be it hot or cold, then you're going to use less energy either heating or cooling the inside of your house. Bricks are really good as a material if you want to build sustainably because they are long lasting, both in terms of performance and aesthetics.
For architects and developers, Stephanie says that the key to designing for net-zero is thinking about the building’s life span and purpose of that building when you choose construction materials.
“If you really want to maximise the benefits of brick you need to be thinking long-term. We want customers to use brick in buildings that will be used for more than 100 years.
“In conversations about materials, I always ask how long their building is expected to last, and unfortunately a lot of architects don’t know, which makes their decision-making process really difficult. The best thing you can do is consider the life span of the building, how it might be used in the future, and design for flexibility and adaptability which will minimise resource consumption over the long term. That will have a positive impact on the whole life carbon impact of the building too.
“If you’re going to have a building with a really long life span then I would argue that it's okay to allow the higher upfront carbon associated with producing bricks, so that you get the durability and the low maintenance benefits.”
Can you recycle bricks?
Of course, when you think about the life span of a building and its materials, it’s crucial to not forget the end of life phase and how that affects carbon emissions. Wienerberger’s efforts to decarbonise do not stop once construction is finished; the company is also looking at recycling and re-use.
“In generic scenarios that we modelled, around 90% of brick construction waste could be recycled, usually down-cycled as aggregate, but that is still preventing virgin material being used for things like infrastructure projects, so there is value in that. Only 10% would go to landfill, but there's obviously more we can do to improve that.
“In addition, making bricks easily reusable will be a strand of work for us in the future. At the moment, mortar is so good at sticking bricks together that it can be quite difficult to remove, but if you do have the time and the resources then you can split bricks out into individual units and reuse them. If you're going to do that we recommend putting the bricks through durability tests, just to make sure that they are fit for reuse. We’d like to see more reuse in the future, because ultimately it will reduce resource consumption.”
