The pressure for the construction industry to embrace processes and materials that reduce GHG emissions is having an effect. However, there’s a tendency to look at the carbon impact of new projects or existing buildings solely from the operational energy perspective, rather than carbon’s impact throughout the building’s entire lifespan. That’s why experts like Marco Abdallah, head of engineering with the German-based consultancy Drees and Sommer, are calling for an increased understanding of lifecycle carbon assessments.
During a recent panel discussion featuring architects, builders and environmental specialists, Abdallah explained the embodied carbons associated with a project are heavily loaded at the front and back-end over the lifespan of a structure. The front end is, of course, the construction phase itself, while the back end is the demolition of the building several decades later. However, because operational carbon consequences are experienced day-to-day through energy usage — representing up to 60 per cent of the carbons created over the lifespan of a building — they tend to dominate discussions.
Government policies that focus on improving the operational performance of buildings through various and specific tax incentives also have a distorting effect, says Jerry Tate, partner with U.K. architects Tate Harmer .
“Everything is geared toward operational carbon. If there was balanced pressure between embodied and operational, there would be a more balanced outcome.”
That’s important given the commitments made by many governments to move to zero carbon for construction by 2050.
However, defining what it actually means to be net zero carbon requires a better understanding of the carbon’s massive embodied contribution over a building’s lifespan.
This draws focus to project planning, not just in terms of the building’s form and resultant operational energy use, but to the entire execution of the project from its conception at the design stage.
Simon Wyatt, partner with international engineering consultancy Cundall, would like to see more attention paid to this. Specifically, he favours the industry working towards actual carbon reductions during the planning process, and not merely offsets.
“We need to have clear targets for reducing the construction impacts and operational energy use.”
Wyatt’s company has developed a seven-part framework that it has used on projects around the world.
“We’ve been looking at energy reduction strategies such as the purchase of power that phases out fossil fuels. We also have established challenging, science-based targets which are absolute reduction targets, so we are not just offsetting but reducing our impact.”
Wyatt says the United Kingdom has been a leader in terms of developing a net zero carbon standard that could be adopted on a global basis as a consistent benchmark.
“This involves reducing construction impacts, reducing operational energy, increasing the use of renewable energy where possible, and offsetting any remaining carbon emissions. All of this needs to be publicly disclosed.”
Achieving actual carbon reductions during the construction process as well as through operations is a goal shared by the World Green Building Council (WGBC).
Victoria Kate Burrows, director of the WGBC’s Advancing Net Zero initiative, offers the council’s definition of net zero embodiment:
“A net zero embodied carbon building (new or renovated) or infrastructure assets is highly resource efficient with upfront carbon minimized to the greatest extent possible and all remaining embodied carbon reduced, or as a last resort, offset in order to achieve net zero across the lifecycle.”
Definitions and absolute targets for both operational and embodied carbon reductions are important if real progress is to be made in addressing the carbons created by the construction industry.
As Tate points out, it will then be possible to outline these to building owners and developers. He admits it’s not possible to force them to undertake this strategy, but feels designers have a responsibility to explain what can and should be done to reduce all carbon inputs.
“They may say, ‘That’s not what I really want to do.’ But they might do some of it, and that’s a win.”
John Bleasby is a Coldwater, Ont.-based freelance writer. Send comments and Inside Innovation column ideas to firstname.lastname@example.org.