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NZ’s built environment isn’t as green as once thought

Auckland, New Zealand
Auckland, New Zealand

New Zealand green building leaders are calling for urgent action on building efficiency, following new analysis that has revealed the built environment is responsible for about 20 per cent of all national greenhouse gas emissions, a figure up to 10 times previous estimates.

Other studies have claimed the sector’s emissions are responsible for anywhere between two and five per cent of total emissions. The five per cent figure, which was included in last month’s NZ Productivity Commission Low Emissions Economy draft report, is based only on the operational emissions of buildings.

The thinkstep figure takes into account emissions associated with construction, as well as the products consumed within buildings and emissions associated with building products that are either imported or exported.

Of the about 20 per cent of the national gross carbon footprint attributable to the built environment, 8.6 per cent of emissions come from energy use, 8.7 per cent from building products, 2.1 per cent from imported emissions (the majority of which are services such as insurance) and 0.5 per cent from building and garden waste.

The report used an international methodology that has also been implemented by organisations such as the European Commission, Danish government, the US National Bureau of Economic Research and NZ’s Motu Economic and Public Policy Research. It allocates emissions to a sector at the point of consumption, rather than production, and considers the entire lifecycle of buildings, including the extraction of raw materials, material production, electricity and energy use, and the treatment of construction waste.

The NZ Green Building Council has backed the study, and said the results indicated the government should be increasing resources and efforts to reduce emissions from buildings.

NZGBC chief executive Andrew Eagles told The Fifth Estate the report’s findings should be a “real wake up call for people to think more deeply about materials”.

The findings are also a real shot in the arm for suppliers of materials with lower embodied carbon, such as engineered timber products, he said.

The report found that just over six per cent of NZ’s gross carbon footprint came from the production/construction phase of the built environment – 2.6 per cent from steel, 1.6 per cent from aluminium, 1.9 per cent from cement and other non-metallic minerals such as aggregates, and 0.1 per cent from other sources.

Wood products were excluded as their emissions cannot be easily separated from pulp and paper, and their maximum possible emissions contribution is only 0.5 per cent of the national total.

How about mandating green tools?

Mr Eagles said there was value in tools such as Green Star for reducing the sector’s embodied carbon pollution contribution.

“Embodied carbon is considered under Green Star – but it is not considered under the building code,” he said.

There are, however, some moves underway to see green tools used more broadly to achieve lower carbon outcomes.

“We are in discussions with the government about it using Green Star when doing a fitout for a new building or for an existing building,” Mr Eagles said.

There is also a “lot of interest” from district health boards and universities in applying the tools to their projects.

In addition, the government is considering the use of the NZGBC’s HomeStar tool for the KiwiBuild program, which will see 100,000 homes built to address the NZ housing crisis.

Mr Eagles said there were currently about 20,000 homes going through the HomeStar rating process and it was being led by the private sector.

Overall, the outcomes of greater uptake of the green toolkit would be lower embodied energy buildings, lower operational energy emissions and improved human wellbeing.

Another shift underway in relation to operational energy is there are now more substantial discussions happening around the mandating of NZ NABERS, Mr Eagles said.

The conversation has shifted from discussing the possibility to a more detailed examination of what mechanisms would need to be in place, he said.

Ultimately, to progress to a lower carbon built environment, the embodied carbon and carbon from consumption need to be measured properly and considered, Mr Eagles said.

“It also raises a question about construction waste, and how it can be used rather than chucked in landfill.”

Construction waste footprint not included

The footprint of construction waste was not included in the thinkstep report as the authors said the amount of carbon emitted from materials in landfill was low due to the inert nature of most construction waste.

Mr Eagles said this was part of the challenge of addressing its carbon contribution – the lack of a figure in terms of the embodied emissions it represents.

He said the Productivity Commission did mention both embodied carbon in buildings and in construction waste as important in its report, but also stated it could not calculate the emissions involved.

Mr Eagles said having a figure for the embodied carbon of construction waste would help the industry clearly see the impact of throwing materials away.

Jeff Vickers, technical director of thinkstep in Australasia and lead author of the report, said embodied emissions were increasingly being provided by building product manufacturers through environmental product declarations.

“Buildings and infrastructure are some of the longest-lived parts of our society, so it is crucial that we act now to reduce their contribution to climate change pollution – both through reducing emissions from energy used during the building’s life and through reducing the emissions embodied in the building products that we choose,” Mr Vickers said.

The report highlighted the areas in which NZ organisations and households could have the greatest influence on climate change through their purchasing decisions.

The consumption-oriented view does not replace the production-oriented view used in reports such as the Productivity Commission’s, as this view is mandatory for reporting at an international level.

“However, if the production-oriented view is used alone, it allows nations to shift production offshore to meet their national targets. Shifting the burden will not help us to tackle climate change; instead, we should take responsibility for the emissions we are responsible for,” the authors stated.

“Given that climate change is a shared problem, it seems logical that both producers and consumers need to be part of the solution.”

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