Audio Cities - 03/February/2020

Vancouver trailblazes on embodied carbon

The Canadian city of Vancouver is leading efforts in North America to slash emissions released in the production of building construction materials, setting itself a 40% by 2030 reduction target

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With most of its electricity coming from low carbon hydro power, the focus on reducing carbon from buildings shifted quickly to embodied carbon in Vancouver

 

AMBITIOUS In 2015, Vancouver adopted a zero emissions building plan and in 2016 a requirement that new buildings have zero or near-zero operational emissions by 2030

FREEDOM Vancouver has more room for manoeuvre than other Canadian cities since it controls its building code; most have to follow codes set by their provinces

KEY QUOTE Embodied carbon can be reduced by 40% if a building has a wood, instead of a steel and concrete, frame

 

Vancouver, Canada, recently required that embodied carbon be reduced in new buildings and major renovations by 40% by 2030 (compared with a 2018 baseline), a first in North America. The mandate includes public and private buildings. Similar goals are expected to be adopted by other forward-thinking cities in Canada and the US.

“We felt 40% was achievable and would help stretch the industry’s imagination,” says Patrick Enright, a green building engineer who heads the embodied carbon project in Vancouver, a dense metropolis on the Pacific Coast with an estimated population of more than 650,000.

The city, which is progressive in terms of climate action by Canadian standards, in 2015 adopted a zero emissions building plan and in 2016 a requirement that new buildings have zero or near-zero operational emissions by 2030. Operational emissions are those created during a building’s use, after construction and before the end of life, such as from the type of electricity used.

Since most of the electricity used in the surrounding province of British Columbia is low carbon hydro power, the focus on reducing carbon from buildings shifted to embodied carbon more quickly in Vancouver than it might have in another city. “If your operating emissions are zero, then embodied carbon is the entire pie,” says Enright.

 

 

REPORTING REQUIREMENT 

Vancouver declared a climate emergency in January 2019 and a few months later adopted its 2030 goal for embodied carbon. Since 2017, anybody seeking to change the use of a parcel of land in the city (rezoning) — including making a new or refurbished building taller — already had to calculate and report a building’s embodied carbon. Vancouver asks that lifetime assessments of embodied carbon assume a building lifespan of 60 years and while no specific method of doing so is required, nearly all projects to date have used the Athena Impact Estimator, a free Canadian-made tool.

The reporting requirement was a game-changer, says Anthony Pak, founder of the Priopta, a Vancouver consultancy that conducts environmental assessments of buildings. The expertise to help calculate embodied emissions is now well-established, he states. City officials have also learned in detail which materials represent the most carbon emissions.

The next steps on how to achieve the embodied carbon goal will be set out later in 2020. Interim goals will be established once barriers and costs have been identified, says Enright. Reductions in embodied carbon will likely be required as part of a building achieving rezoning or getting a development or building permit.

 

WOOD AND STEEL

Enright sees wood as a key player in reducing emissions. Embodied carbon can be reduced by 40% if a building has a wood instead of a steel and concrete frame, he says. Vancouver controls its building code, unlike most Canadian cites which have to follow the codes set by their provinces and which typically limit the height of timber buildings because of fire hazard.

The maximum height allowed for wood buildings in British Columbia was historically six storeys, but the province raised the limit to 12 storeys in December 2019. Vancouver plans to do the same in early 2020 and individual buildings can already apply for a waiver to the current height limit. An 18-storey mass timber building, Brock Commons, with a concrete elevator and stairwells, was completed in Vancouver in 2016. It is the world’s second tallest mostly timber building after Mjøstårnet in Norway.

An additional reduction of as much as 36% is possible if concrete is made with lower-carbon fly ash, instead of cement, or slag, says a study by the US-based National Ready Mixed Concrete Association. And there are also broader circular economy ways to reduce embodied carbon, such as reusing materials.

A study in 2019 for the city of Vancouver found embodied carbon emissions from its concrete high rise buildings could be reduced by 22-47% through innovations in concrete and design, such as taking high-emissions aluminium out of the façade. A reduction of 10-20% was found to be relatively easy, says Pak of Priopta, who conducted the study. Higher reductions might involve reducing the number of storeys of underground parking so less concrete and steel is used, changing the concrete mix or using hollow instead of solid concrete slabs.

 

TEXT Ros Davidson

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