Rapid urbanization and industrialization in the 20th and 21st centuries have contributed significantly to climate change. The floor space of global construction is predicted to double over the coming decades, and currently, investment in green, sustainable construction is severely lacking.
Buildings, both in the construction and operational phases of their lifecycles, account for nearly 40% of global carbon emissions, according to the World Economic Forum. Emissions hit an all-time high in 2019, presenting significant challenges for achieving the aims of international climate accords such as the Paris Agreement.
Contributing factors to buildings emissions include the use of traditional diesel and petrol engine vehicles, equipment, and plant during construction, the production of carbon-intensive concrete, and fossil fuels for heating and energy during the operational phase of a building’s lifecycle.
Rising global temperatures and changing climate patterns are also helping to drive the increase in carbon emissions in cities and the construction sector as air conditioners are deployed in increasing numbers in the summer months of locales with traditionally milder weather. These need electricity to function.
Taken together, alongside predictions of nearly seven in ten people globally living in cities and urban areas by 2050, the picture is one of potentially disastrous global temperature rise and increasingly complicated challenges in the construction sector to mitigate the worst effects of climate change.
Employing Renewable Energy During the Build Phase
Phasing out fossil fuels during the construction phase presents significant opportunities for reducing the overall carbon emissions of urban areas. Embodied carbon accounts for 75% of a building’s total lifetime emissions and 11% of global carbon emissions overall.
Around 14 billion cubic meters of concrete were produced globally in 2021, with this figure set to increase due to rapid urbanization and increased infrastructure. Concrete production alone accounts for around 7-8% of global carbon emissions.
In addition, manufacturing several other materials such as steel, glass, and plastic used in buildings is carbon intensive. Furthermore, conventional plant equipment runs on diesel and petrol. In order to drastically reduce embedded emissions, innovative green approaches during the build phase are essential.
Several countries are now seeking to rapidly decarbonize the construction of buildings by employing renewable energy. In Scandinavia, cities like Helsinki, Copenhagen, and Oslo are increasingly phasing out ICE construction plants in favor of electric vehicles and machinery.
As well as providing significant carbon emission reductions, electrical plant machinery is quieter and vastly less noise and air pollution in the local area, making cities more pleasant places to live.
A pilot project in Oslo reported savings of 92,500 kg of CO2 and 35,000 liters of diesel. Scaling this up to a global scale would have a profound impact on the construction sector’s sustainability. Whilst the project could not achieve 100% carbon emissions reductions, the results are highly promising.
The City of Oslo is aiming to achieve zero emissions in its construction sector by 2030. In the US, the Department of Energy and other federal agencies aim to identify renewable green technologies to reduce the sector’s climate impact. Significant funding has been earmarked in several nations towards these aims.
The UK cement industry has also announced a roadmap to achieve net zero carbon and beyond with the right investment and policies. Positive emissions reduction factors identified in reports over the past few years include decarbonizing the energy grid, biomass fuels, and decarbonizing transport.
Utilizing Renewable Energy to Provide Power for Buildings
Whilst utilizing renewable energy to decarbonize construction materials and sites will provide key solutions, current buildings need to become more energy efficient and move away from using fossil fuels for heating and power.
Growing electricity demands, such as for space cooling, residential appliances, and heating, provide key opportunities for decarbonization by switching energy grids from fossil fuels to renewables. Both off-site and on-site renewables should be used.
Solar panels are fast becoming a ubiquitous site in urban areas on commercial and domestic rooftops, car ports, and infrastructural elements. Global retailers such as IKEA are heavily concentrating on on-site solar power generation for their commercial footprint.
Retrofitting existing buildings and infrastructure with renewable energy is becoming a key area in the built environment’s move toward a greener future. In Bath in the UK, for instance, the thermal springs from the Roman Baths have been harnessed to provide an innovative eco-heating system for Bath Abbey.
In Copenhagen, a clean waste-to-energy incinerator can provide electricity and heat for 150,000 households. Compared to the old plant used by the city, this project saves over 107,000 tonnes of carbon dioxide emissions.
A major project in San Francisco, which received an aware from the American Institute of Architect’s Committee on the Environment, renovated and expanded the Lick-Wilmerding High School, focusing on reducing the building’s carbon emissions and improving its environmental footprint.
Zero energy design, which preserves the school’s historic fabric, was central to the project’s aims. Roof areas were optimized for solar PVs with the aim of a 21kBtu reduction in energy usage intensity. The design was completed in 2017 at a cost of just over $31 million.
Whilst several key challenges still exist with improving the sustainability of the construction sector, strides have been taken in recent years to fully decarbonize materials manufacture, site operations, and post-build emissions.
With a total contribution of nearly 40% of total global carbon emissions, the construction industry is a key target of climate change policies. The uptake of renewable energy solutions in the sector will significantly help global temperature rises remain below the key figure of 2oC laid out in international agreements.