Construction industry called on to reduce carbon emissions

Photo: ODT files
Photo: ODT files
Sustainable building advocates want the construction industry to be given a clear signal to reduce its carbon emissions.

Stats New Zealand said emissions from the construction sector jumped 66 percent in the decade to 2017.

The sector is already looking to adapt, but some said it would need help to justify the investment.

Creating cement is inherently carbon intensive, with a chemical reaction decarbonising limestone.

Fletcher Building runs the country's largest cement manufacturer, Golden Bay Cement, which creates 700,000 tonnes of carbon in a year.

"Nearly 70 percent of the carbon emitted is actually from the process of converting the limestone into actual cement rock or clinker," the chief executive of its concrete division Ian Jones said.

"So we can work hard on the other 30 percent which is from energy, typically the coal use, but we've also got to work on how do we actually reduce the amount of cement that we use."

Golden Bay Cement reduced energy emissions by 50,000 tonnes by replacing some of its coal fuel with waste wood chips in 2004, and is in the process of using old tires as another alternative.

"The key challenges are that we need to make a technical change to a product that the market has been used to using for years," Ian Jones said.

Researching alternatives to cement that could provide the same concrete properties is already under way.

"If we could blend in 20 percent of alternative material that had a zero carbon footprint or close to it we could reduce the emissions in New Zealand by 20 percent. So we need to get the technical product right, we need to get the economics of that investment right, and we need to make sure that the market will actually take that alternative product.

"Better environmental credentials is something people like and want but actually the reality of paying any more for that is probably not there yet, but that will move over time."

Last year a report estimated buildings contribute 20 percent of the country's carbon footprint through their life cycle.

The author of that report and technical director of consultancy company, Thinkstep Australasia Jeff Vickers, said it was hard to change a lot of the key materials like cement and steel.

"When it comes to that side of it there needs to be some certainty from the manufacturers' perspective that by changing a process people are going to be willing to pay for those improved materials, low carbon materials."

But with people already complaining of high building costs he said it would take collaboration between manufacturers, consumers, and the government to help the industry justify investing.

"It might be for example the government saying 'for all public buildings, whether that's schools or hospitals or anything we're doing, we are going to say that we will purchase materials with this set of criteria.' Then through their large role as a procurer of materials and building products they could then help to lead change," Jeff Vickers said.

The government's framework to meeting its climate change targets is going through parliament.

Public submissions on the government's Zero Carbon Bill closed earlier this week, and the Green Building Council said it was an opportunity for the industry.

"What we really need to see is out of that to have a really clear remit to also go at buildings and homes as well," its chief executive Andrew Eagles said.

As part of the law the government would establish an independent Climate Change Commission to advise and hold them accountable.

"We're calling for one of the commissioners to have a built environment background and knowledge in this area."

Andrew Eagles said the industry would be receptive if there were clear targets and the government needed to commit to build to sustainable standards.

"The second thing the government could do is start to include things like embodied carbon and energy efficiency in the Building Code for future regulation. That's a pipeline, they could be signalling that for sometime in the future, but that enables the industry to invest to drive change."

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