Almost half a tonne of upfront embodied carbon can be saved for every square metre retained from an existing commercial office, when compared to an equivalent new-build project, according to Slattery’s new embodied carbon report.
Embodied carbon is the greenhouse gas emissions generated during the manufacture, construction, maintenance and demolition of buildings. The report said it accounts for 35-45 per cent of a standard building’s lifecycle carbon emissions.
According to the report, retaining a structure and envelope – the substructure, upper floors, columns, external walls, roof, stairs and internal structural walls – allows for the preservation of nearly three quarters, or 74 per cent, of a building’s upfront embodied carbon.
Slattery Carbon Planning Director Tom Dean said historically the discussion around sustainability and net zero has focused on operational carbon.
“The operational carbon is everything you run the building with,” he said.
“About 45 per cent of it is the embodied carbon, which has everything to do with the materials. And until a couple years ago, that was not reported on and measured for any project.
“It’s about half the equation that we’re ignoring.
“The most sustainable building is the building that’s already there.”
Mr Dean said measuring and understanding a building’s embodied carbon can be an attractive proposition to tenants who have ESG reporting requirements themselves.
The highest intensity of embodied carbon is typically in heavy materials, such as concrete and steel, Mr Dean said. He said the proportion of carbon intensity in these items can be a bigger proportion to the cost of the project.
He also said while measurements of embodied carbon are not the be all end all to keeping an asset, it is an important part of the sustainability equation that is becoming more relevant.
The report provided an example in which Slattery was engaged by The GPT Group to provide carbon planning on the refurbishment of buildings known as the ‘Gothic Bank Complex’ at the corner of Queen Street and Collins Street in Melbourne’s CBD.
This included three 19th century neo-gothic architectural landmarks and a 1990s office tower.
By refurbishing the corner of Queen Street and Collins Street, the quantity of carbon intensive materials was reduced, leading to a significant saving of more than 22,000 tonnes of greenhouse gas emissions.
This saving is equivalent to removing 4,800 fossil-fuel powered cars from our roads for 12 months, or the annual carbon footprint of 1,100 standard homes.
NABERS, the National Australian Built Environment Rating System, is currently developing a framework to measure, benchmark and certify embodied carbon emissions.
Mr Dean said there is alot that can be done on the embodied carbon front in fitouts.
The report said when the decision is made to retrofit, refurbish and fit out an existing building, embodied carbon intensive building elements are generally preserved and the embodied carbon emissions associated with these works eliminated.