TEN TRENDS FOR A ZERO CARBON WORLD
04. Zero in
Over the next 30 years, an estimated 165 billion square metres of new property is expected to be built, which equates to an area roughly the size of Paris being developed every week1. Given that the sector accounts for around a third of global energy use and carbon emissions2, the way we design and construct new buildings is under scrutiny like never before.
To reach net zero by 2050, it is widely accepted that the real estate sector will need to reduce emissions by 50% by 20303. Those responsible for new development therefore face a choice: to deliver new net zero carbon buildings now or wait until forced to do so by regulations and the markets.
GLOBAL SHARE OF BUILDINGS AND CONSTRUCTION FINAL ENERGY AND EMISSIONS, 2019
All the current indications are that this decade will witness a huge transition in the way buildings are developed. The decarbonisation commitments made by some countries, cities and organisations should mean that net zero carbon new buildings will be commonplace by 2030 - and long before then in some markets. This is being driven by a huge variety of factors: building codes, government regulation, taxation and subsidies, planning requirements, occupier and investor demand, advances in building materials, increased use of technology and grid decarbonisation. Equally, longer sighted investment funds future proofing their assets against a known trajectory of tightening regulations and standards is starting to influence all areas of the market. Even shorter-term value-add investors concerned with exit price are starting to recognize that demand – and pricing – is changing in ways that create risks as well as opportunities4.
The design phase is clearly crucial in delivering a building that operates efficiently. Almost 30% of a net zero carbon building’s emissions are produced during its operation5. When designed well, the structure of a building can be optimised to capitalize on natural heating, cooling and light to reduce energy consumption – principles adopted in an architectural concept known as Passivhaus. Careful use of the right materials in buildings designed to manage solar gain and control airflows can result in operational energy savings of up to 90%6.
While much of the initial focus has been on reducing energy use and emissions during the operation of a building, emphasis is now moving towards managing and minimizing the “whole life” carbon of a development. This includes upfront embodied carbon from construction, operational emissions in-use, maintenance, lifecycle replacement and “end of life” disposal of material. Given that a large proportion of these emissions will be directly or indirectly determined at the construction stage, it is crucial that sustainability considerations are built into the process from the earliest stages of design.
Net zero carbon building definition
Net zero embodied carbon in construction is when the amount of carbon emissions associated with a building’s product manufacture and construction stages up to practical completion is zero or negative, using offsets or the net export of on-site renewable energy. A net zero carbon building in operation is highly energy efficient and powered by on-site and/or off-site renewable energy sources, with residual emissions minimised and any outstanding carbon balance effectively offset.
Source: UKGBC (2019). Net Zero Carbon Buildings: A Framework Definition.
Focus on embodied carbon
While much has been written about designing for optimal operational energy performance and emissions, embodied carbon is a less well understood issue which warrants the same level of attention and urgent action.
The carbon counter on a building begins with the materials and techniques used in its construction, which typically account for 11% of a building’s total emissions. However, as new buildings are designed to be more efficient and energy grids decarbonise, this number can rise to 40-70% of the whole life carbon of a building7. This means embodied carbon emissions from construction will, in some instances, be greater than those released during the rest of the building’s life.
Building design is clearly a key driver of the construction materials used, which is in turn a crucial determinant of embodied carbon8. Globally, concrete alone is estimated to account for 8% of total CO2 emissions9. This is partly because of the sheer volume of cement utilised around the world, but is also due to its production process which releases around 622kg of CO2 per tonne of Portland cement10. Extensive efforts are being made to significantly reduce these emissions11; there are ‘green concrete’ products already in the market, but greater commercial demand is needed to drive the development of production capacity.
Alternative materials are also growing considerably. Timber frames are an area of increasing interest, with potential carbon savings of between 14% and 31% globally if sustainable mass timber substituted concrete and steel use across the world12. The global alternative material market was estimated at $190 billion in 2020 and is forecast to grow by 74% to reach $330 billion by 203013.
WHOLE LIFE CARBON EMISSIONS BREAKDOWN, OFFICE
Speculative office building with class A fit-out in London
Encouragingly, the market is voluntarily setting best practice targets for embodied carbon through standards such as the LETI guidance14, and industry groups in the European Union15 have set roadmaps for the adoption of similar standards. In reality, widespread delivery of net zero buildings will require embodied carbon regulations to be enforced by government16. While only a limited number of places require such assessments at present17, markets and regulators are moving in this direction. A clear focus on minimising embodied carbon will pay dividends in future – by delivering buildings today that will have greater appeal in the future, and by developing the experience and expertise needed to deliver the buildings that will be seen as standard in the future.
New construction methods
While choice of materials is important, how they are transported and used in construction is also an essential piece of the puzzle. Modern methods of construction have been deployed to raise skyscrapers in weeks rather than years18. Modular construction methods using standardized materials and components significantly reduce waste and construction time19. They support modification or retrofitting of the building to accommodate future advances in construction and operation. They also make it easier to reconfigure the building while in use, extending its productive life – and to reuse or recycle materials when the building is finally deconstructed.
The phrase “deconstruction” also signals an important change in mindset. At present, the equivalent of 40% of the raw material weight that goes into buildings goes to waste during the construction and demolition phases of a building’s life. The industry is transitioning from the current linear thinking, where buildings are demolished and material disposed of, towards “circular economy”20 models where materials are re-entered into another building’s lifecycle. If more widely adopted, such circular models could reduce whole life carbon emissions by 35% to 40% across the G721.
The role of technology
Modern construction methods rely heavily on computer modelling to develop designs, assess structural integrity and communicate plans. However, utilising computer modelling to its full potential across the whole of the construction process could add further value. For example, creating plans using algorithms and artificial intelligence helps optimise workflows and material delivery and minimises waste even before ground is broken on-site.
Models originally developed to support design and construction can play a critical role in the later life of the building. ‘Digital twinning’ involves establishing a digital record of every aspect of the building, the state of its materials and its operational performance. The data for the building record – including the original plans, digital models and material specifications – is ideally collected from the design phase and maintained throughout the life of the building.
When combined with accurate data on actual performance in use, the model can be applied to identify and address any variation between the designed energy efficiency and the operational reality – known as the ‘performance gap’. Given that typical non-domestic buildings exceed their designed energy usage by 3.8 times22,23, anything that helps diagnose and rectify such inefficiency makes a material contribution towards reducing emissions. Such models can also play a crucial role facilitating maintenance, upgrading and modifications throughout the building’s life, and helping with reuse and recycling during eventual decommissioning.
Research and development into new building materials and construction techniques is being combined with innovative thinking around building operation, management, and re-use. Although there is a long way to go in green construction, there is a solid foundation emerging on which to build a better future.
1https://b80d7a04-1c28-45e2-b904-e0715cface93.filesusr.com/ugd/252d09_8ceffcbcafdb43cf8a19ab9af5073b92.pdf 2https://globalabc.org/sites/default/files/inline-files/2020%20Buildings%20GSR_FULL%20REPORT.pdf 3https://www.wbcsd.org/contentwbc/download/12446/185553/1 4See Dollars and sense 5RIBA (2021). Built for the Environment. https://www.architecture.com/knowledge-and-resources/resources-landing-page/built-for-the-environment-report 6https://www.passivhaustrust.org.uk/what_is_passivhaus.php 7RIBA (2021). Built for the Environment. https://www.architecture.com/knowledge-and-resources/resources-landing-page/built-for-the-environment-report 8https://www.wbcsd.org/contentwbc/download/12446/185553/1 9https://www.chathamhouse.org/2018/06/making-concrete-change-innovation-low-carbon-cement-and-concrete-0/executive-summary 10https://www.imperial.ac.uk/news/221654/best-ways-carbon-emissions-from-cement/ 11Fennell, P.S., Davis, S.J. & Mohammed, A. (2021). Decarbonizing cement production. Joule, volume 5(6). https://www.sciencedirect.com/science/article/abs/pii/S2542435121001975?dgcid=author 12https://www.tandfonline.com/doi/full/10.1080/10549811.2013.839386 13Allied Market Research (2021). Alternative Building Materials Market by Material (Bamboo, Recycled Plastic, Wood and Others), End User (Residential and Non-residential) and Application (Construction, Furniture & Flooring): Global Opportunity Analysis and Industry Forecast, 2021–2030. https://www.reportlinker.com/p06126723/Alternative-Building-Materials-Market-by-Material-End-User-and-Application-Global-Opportunity-Analysis-and-Industry-Forecast-.html?utm_source=GNW 14https://www.leti.london/ecp 15https://www.worldgbc.org/sites/default/files/WorldGBC_Bringing_Embodied_Carbon_Upfront.pdf 16https://ec.europa.eu/energy/eu-buildings-factsheets-topics-tree/embodied-energy_en 17https://www.theplanner.co.uk/opinion/the-new-london-plan-the-city%E2%80%99s-road-to-net-zero 18https://www.theguardian.com/world/2015/apr/30/chinese-construction-firm-erects-57-storey-skyscraper-in-19-days 19https://www.modular.org/marketing/documents/DesigningoutWaste.pdf 20https://ellenmacarthurfoundation.org/ 21Hertwich, E., Lifset, R., Pauliuk, S. & Heeren, N. (2020). Resource Efficiency and Climate Change: Material Efficiency Strategies for a Low-Carbon Future. A report of the International Resource Panel. United Nations Environment Programme, Nairobi, Kenya. IRP. https://www.resourcepanel.org/reports/resource-efficiency-and-climatechange 22https://www.gov.uk/government/publications/low-carbon-buildings-best-practices-and-what-to-avoid 23https://www.mdpi.com/2071-1050/9/8/1345/htm