Real estate considers embodied carbon

The real estate industry has been wrestling with its carbon footprint and how to reduce it for some time. However, until recently, the focus has been exclusively on emissions from building operations, such as lighting, heating and cooling.

But operational carbon emissions are only half the story. The construction of any building generates carbon. Making steel, glass and concrete results in carbon emissions. The transport of materials to and from a construction site and the work involved in erecting a building all involve emissions. It is estimated that 11% of total global carbon emissions come from building construction and materials.

Now the industry is beginning to look at the whole life cycle of a building to assess its emissions and it is driving changes in behaviour. Peter Epping, global head of ESG at Hines, says: “We need to be careful about which buildings we are knocking down and whether the benefit in terms of reducing operational carbon over time or other benefits are worth the embodied carbon of building new. No matter how green a building is touted to be, you still spend at least 30 years of operational carbon in its development.”

As building operations becomemore efficient, the embodied carbon in a building becomes more important. The longer a building can be preserved, the more the carbon involved in its creation can be ‘amortised’.

Billy Grayson, executive vice president, centres and initiatives, at the Urban Land Institute, says: “According to most estimates, embodied carbon accounts for as much as half of a buildings’ total carbon emissions over its lifetime. If we can develop strategies to use lower-carbon building materials and construction strategies, we can make significant progress in reducing overall emissions from the real estate sector.”

Projects that attempt to minimise embodied carbon can benefit from green building certification. Many of the major certification systems, including LEED, BREEAM and EDGE, consider embodied carbon.

Earlier this year, a pioneering low-carbon certification programme for real estate was launched in Europe, garnering support from real estate investors such as Ivanhoé Cambridge and Generali Real Estate, as well as the French BBCA association.

Like most exercises in making real estate more sustainable, measuring and assessing a building’s total carbon emissions over its projected life can help developers and investors judge its impact. A whole building life cycle analysis (WBLCA) attempts to account for all carbon sources present throughout a building’s life. Such analysis – while obviously requiring a certain amount of speculation – can give a more balanced picture of a project’s impact and might even sway decisions on whether to embark upon it.

To reduce embodied carbon, the real estate industry needs to embrace the four ‘Rs’: reduce, reuse, replace and recycle, says Grayson. Reducing the raw materials and energy used in the construction process will reduce embodied carbon. This might involve using modular construction to reduce waste and transport emissions, or producing materials on site. Of course, simply creating fewer buildings and instead refurbishing existing stock naturally reduces the use of materials.

Reuse could involve using the materials from the construction of one building for another, or they could be recycled. “Recycling all construction waste and using recycled materials for construction can also have a positive impact on reducing embodied carbon,” says Grayson. Developers are beginning to replace carbon-intensive building materials with lower- carbon or renewable materials, such as timber, lower-carbon concrete and recycled steel.

Such considerations are increasingly tipping real estate investors into refurbishing and improving existing buildings rather than demolishing them and building afresh. Grayson says: “Usually, refurbishment or repurposing of obsolete properties is better than redevelopment, from an embodied carbon perspective.”

However, refurbishment is not always the best option: it might be impossible for a building to be brought to the required specification, for example. As construction becomes lower- carbon, the balance may also swing back in favour of new buildings, especially if the building they replace can be recycled.

Using the four Rs to reduce embodied carbon should also not come at a cost; using less energy and materials in a project tends to mean lower costs. Furthermore, lower-carbon materials are often similar in cost to their standard equivalents, the ULI’s Embodied Carbon in Building Materials for Real Estate report argues. New technology is emerging to help the real estate industry reduce embodied carbon. 

Epping says: “It is very encouraging to see considerable innovation in the field of low-carbon construction, whether that is low-carbon cement, low-carbon steel or other materials.”

For example, advances in structural timber are making it a practical solution for large scale commercial buildings, even lofty skyscrapers, while solutions are emerging for concrete which are not just lower-carbon but carbon negative, as the making of the concrete involves storing carbon dioxide.

Throughout a building, the choice of materials will affect its final embodied carbon footprint. “Everything down to the choice of carpets can make a difference. And that’s why we were pushing really to getting environmental product declarations (EPDs) for everything we use in a building, so we can have a ‘carbon P&L’,” says Epping. Environmental product declarations will allow purchasers to weigh up the environmental impact of a product.

Embodied carbon could be further reduced by employing circular economy techniques. The circular economy refers to the constant reuse and recycling of materials to reduce waste, carbon emissions and pollution. This might involve reuse of buildings or the recycling of existing materials into new buildings.

Grayson says: “Circularity teaches us [that] any industry’s waste products should be a feedstock for other industries’ processes, and that we should figure out ways to reduce lifecycle environmental impacts by efficiently integrating different industries in the efficient use, reuse, and recycling of materials.

“If buildings were built from rapidly renewable materials and designed for adaptive reuse and disassembly, it would significantly reduce their life cycle greenhouse gas impact and contribute to the circular use of materials as feedstocks for future buildings and other beneficial manufacturing processes.”

Part of the challenge of reducing embodied carbon is in persuading people to consider it, how to measure it and how to reduce it. “We have seen that introducing this topic into the conversations with architects, designers and contractors means people get up to speed quite fast and act smarter. If you had mentioned this topic two years ago to anyone, they would probably just have shrugged their shoulders and looked for someone else to work with,” says Epping.

Hines has contributed to the debate by publishing an Embodied Carbon Reduction guide, which explains the topic and gives some detail on how it might be addressed by the real estate industry.

And it must be addressed, not least due to the existing and future legislation which is expected for the sector. For example, the Netherlands’ commitment to economic circularity by 2050 involves a requirement that the building sector reduce its raw materials use by 50% by 2030. Since 2013, all new buildings have been required to conduct a whole building life cycle analysis.

As noted in Sustain’s May issue, a number of new-build projects in cities across the world have been rejected, due, in part or whole, to the carbon emissions associated with their construction.

The major push factor for the real estate industry, however, is likely to be the wider implementation and higher cost of carbon taxes. Some 40 countries and more than 20 cities, states and provinces already use carbon pricing mechanisms, with more planning to implement them in the future, in order to shift the burden of climate change onto those who are responsible for it.

For example, in April, Singapore announced it would be revising its carbon tax and raising it incrementally to change behaviour. From 2024, large emitters in Singapore will have to pay S$25 (US$18) for each tonne of carbon dioxide equivalent emitted, increasing to S$45 in 2026 and 2027, and eventually to between S$50 and S$80 by 2030.

Once carbon taxation expands to more countries, developers will have a strong financial incentive to take action and reduce embodied carbon.