The race for net zero; how construction is modernizing its materials and construction methods by 2050
With the race for the net zero goal of 2050 and the countdown to COP26 in November 2021, pressure is increasing on the construction industry to find ways to reduce its carbon footprint. Ultimately, this can lead to an urgent review of building materials and construction methods and we take a look at some recent developments below.
As one of the most versatile materials on the planet and a readily available and inexpensive product, it’s no wonder that after water, concrete is the most widely used substance on earth. Unfortunately, it comes at a high environmental price, given that cement is responsible for 7% of global carbon emissions. As a result, the cement industry is under increasing pressure to find ways to reduce its carbon footprint.
The reaction required to form the produced clinker, used to make cement, requires heat to 1450 degrees Celsius, compromising one-third of overall emissions, with the remaining two-thirds emitted during calcination. The Mineral Products Association (MPA) suggests that the use of alternative materials can reduce the carbon footprint of cement by 12% by 2050. Two main alternatives to Portland cement (CEM1) are granulated blast furnace slag (GGBS) ), which can replace up to 85% of the cement in a mixture of concrete and fly ash, which can replace 30% of CEM1. Manufacturers such as Cemfree offer concrete that uses an alternative geopolymer alkaline activator to CEM1, further reducing the carbon footprint of concrete. However, such concretes do not currently meet British standards. The main concrete manufacturers, such as Cemex with their product “Vertua”, now offer ready-to-use products with varying amounts of these alternatives. But such alternatives are not without limits. The supply of GBBS and fly ash could be an issue and importing these alternatives from more distant countries could shift the balance of environmental benefits of using these alternatives in the first place.
Another possibility for decarbonizing concrete is to use alternative fuels to heat the kiln during cement production. The MPA has set a target of reducing emissions from cement production by 16% by 2050. The MPA study, conducted in 2019, concluded that a combination of 70% biomass, 20% hydrogen and 10% electrical energy could be used to eliminate cement emissions. manufacturing. Currently, Hanson Concrete is testing biomass and hydrogen at its Ribblesdale plant in Lancashire and other manufacturers are testing hydrogen, with Cemex investing £ 18million in a new hydrogen system at its Rugby plant that will be able to operate. 100% hydrogen. There again, the supply of these alternative fuels poses a problem, the Ribblesdale plant requiring, for example, 0.3 tonnes of hydrogen per hour, and a tanker truck can only transport 0.4 tonnes. To generate enough power to produce the necessary hydrogen, it would take 60 wind turbines to provide 50% of the fuel needed in Ribblesdale.
Additionally, the cement industry views carbon capture storage (CCS) as the primary solution to the carbon emissions problem, with MPA estimating that 61% of emissions from cement manufacturing will be mitigated by this technology. In addition, there is also the possibility of using the carbon dioxide captured by this process for industrial processes and the fabrication of fuels (carbon capture, use and storage). The UK has created several low-carbon clusters to experiment with CCS technology on an industrial scale, including HyNet North West which will produce, store and distribute hydrogen and capture and store carbon as well. This new technology will take time to take hold and be commercially deployed in cement plants around the world, however, there are good reasons for CCS given the challenges of cement production and the availability of alternatives.
More efficient use of materials
It might sound obvious, but one of the best ways to reduce our carbon footprint is to use fewer materials that can lead to high carbon emissions. A UK-funded research project on decarbonizing precast concrete brought together a range of partners, including precast manufacturer Forterra, design-to-manufacture specialist Akerlof and the Department of Justice (MoJ) to examine the question. The guinea pig of the project was the construction of Wellingborough and Glen Parva prisons. The project revealed that the floor load specifications could be reduced from a slab thickness of 200mm to 160mm and that a concrete mix of 50% GGBS was found to be appropriate. These measures made it possible to reduce the carbon content of the slabs by 30%. These changes had no cost and would be ready to apply to a real project. The Department of Justice will use the low carbon products on the next slice of prisons.
In addition, saving a building from the “wrecking ball” and opting for renovation instead of complete demolition can further reduce the carbon footprint of buildings. One Triton Square would be the new benchmark for the industry to beat when it comes to low carbon retrofits. The original building was designed by Arup Associates and completed in 1998. The main objective of this project was to make it as low in carbon as possible. Several strategies have been used to implement the low carbon initiative, including opting for small improvements in many areas, which is a significant overall benefit. One of the biggest carbon savings, and something rarely done, was taking the faceplate apart, cleaning it, and putting it back in place. An additional 57% space was created by adding three more floors and reducing the atrium. Instead of adding additional columns to strengthen the structure, the original 175 columns have been reinforced. The building has all new services, with the original factory being sold where it could be reused or recycled. The renovation saved 25,000 tonnes of carbon compared to new construction, or 40,000 tonnes over the 20-year lifespan of the building. One Triton Square is said to have set a precedent for other projects.
Modern construction methods
It is not only the materials used that the industry needs to review in order to reduce the sector’s carbon footprint, but the ways in which projects are designed can also be examined. Sustainable design is a critical part of how industry can achieve net zero carbon in the built environment. Nature provides excellent opportunities for solving design problems such as rain gardens as part of sustainable drainage systems (SuDS). The urban heat island effect, whereby solar energy is absorbed by hard surfaces and subsequent re-radiation, causing high temperature in urban environments, can be combated by introducing more landscaping and planting. soft. Reducing the temperature in this way not only improves the quality of environmental spaces, but reduces the need for cooling solutions and therefore energy consumption. The UK Green Building Council (UKGBC) has linked the Nature Based Solutions Program with the Climate Adaptation Program and provides several case studies to demonstrate their co-benefits. The Ignition Project, Manchester will help strengthen Manchester’s ability to adapt to the growing impact of climate change by working with nature and using solutions such as rain gardens, street trees, rooftops and green walls. Large developers, such as the Crown Estate, are considering using nature-based solutions as part of their net zero carbon trajectories.
It is clear that the construction industry is starting to take steps towards a low carbon building environment, but with many proposals still in the testing phase, the sector still has a ways to go until these modern construction methods and materials can be deployed. at the much larger scale needed to achieve the goal of net zero. Unfortunately, these developments are likely to continue to be gradual and incremental, as industry experience suggests that new products and methods are often fertile ground for complaints. However, a positive approach to risk allocation and sharing can help manage the problems that arise from new products and methods and help ensure that the path to net zero continues at an urgent pace.