environment

Builders release ambitious zero carbon roadmap

The Green Building Council has put out an ambitious roadmap that illustrates how to make all of New Zealand's buildings and homes zero carbon, Marc Daalder reports.

Constructing and operating buildings makes up a fifth of New Zealand's carbon emissions, but the New Zealand Green Building Council wants to drop that to zero.

A landmark report from NZGBC provides the first-ever roadmap for all buildings to become zero carbon. In order to do so, major Government action and industry participation will be needed, but the council is confident that all involved will be on board with its proposals.

"I don't think they are going to say yes to it immediately, but I think they will be interested," said Andrew Eagles, CEO of the NZGBC.

"Some [companies] will go slightly slower than others, some are already not far off zero carbon. The key is Government leadership."

Construction emissions a "hidden cost"

The public doesn't often look at the construction sector as a source of emissions, focusing instead on agriculture and transport. In part, the council says, this is because of the way that emissions are traditionally portrayed, with the building emissions split up under energy and industry categories.

According to the NZGBC, 20 percent of New Zealand's domestic emissions come from building and operating buildings.

Of this, 28 percent originates from so-called embodied emissions - the carbon that is emitted as a result of the production of building materials like concrete and steel.

The vast majority of building emissions, 70 percent, are released through occupation. These include things like gas fired water heaters and the use of electricity, which is not 100 percent renewable.

The final 2 percent of emissions can be traced to water consumption over the lifetime of the building.

Building Code "below standards"

The top target for a carbon zero construction sector is New Zealand's Building Code. When compared with those of other countries, New Zealand's construction standards are among the worst for energy efficiency.

In 2017, the International Energy Agency found that "the New Zealand Building Code is below the standards required in most IEA countries with comparable climates".

NZGBC wants to see the Government progressively amend the Building Code to bring New Zealand closer to being a carbon zero building sector.

"To ensure zero carbon buildings in Aotearoa, the Government must set a 10-year trajectory to ensure new buildings are zero energy under the Building Code by 2030. We propose three updates to the Building Code in 2022, 2026 and 2030 to get there," the NZGBC report states.

By "zero energy" buildings, the council means, broadly, "those with very low levels of heating and cooling demand, and high-performance heating, hot water and lighting systems. The term zero energy is used here for simplicity. Technically this would mean the lowest energy use that is practicable based on the lowest life-cycle cost."

Fossil fuel heating a target

Amending the Building Code would be the Government's primary tool for implementing the rest of the NZGBC proposal. Chief among these is the energy used by buildings, which helps make up more than 10 percent of New Zealand's overall carbon emissions.

While the electric grid is nearing closer and closer to fully renewable, many houses rely on fossil fuel for water and space heating, increasing the amount of emissions.

"Around a third of the operational carbon emissions from New Zealand’s buildings come from fossil fuels used for space and hot water heating," the report says.

The 2026 Building Code amendment would put restrictions on fossil fuel combustion in new buildings and the 2030 amendment would ban it entirely. Major work will also have to be undertaken to replace fossil fuel combustion systems in existing buildings with low or zero carbon heat sources by 2050.

Doing so would avert one million tonnes of CO2 equivalent annually, or about 3 percent of the New Zealand's total emissions, NZGBC said. 

Building energy labels

In addition to the regulatory tool of the Building Code, the Green Building Council proposed the implementation of building energy labels. Just like the mandated energy labels on washing machines and dryers, labels would have to accompany all non-residential buildings larger than 1,000 m2 and all residential buildings.

The system would rely on NABERSNZ, a local version of Australia's building energy-consumption rating system, for commercial buildings. The Government is considering requiring NABERSNZ ratings on new Government leases, but NZGBC says this doesn't go far enough.

It wants the Government to not only require NABERSNZ ratings on new leases by 2021, but to require that ministries and agencies only sign new leases on buildings with at least a 4-star NABERSNZ rating by 2024.

The council also called on the Government to make NABERSNZ (or a residential equivalent) ratings on all non-residential larger than 1,000 m2 and all residential buildings by 2024.

Embodied carbon a tricky issue

Embodied emissions pose a special challenge for companies trying to construct zero carbon buildings. Two of the most popular building materials, steel and concrete, release large amounts of emissions when produced.

Overall, construction materials represent close to a third of the emissions released by constructing and operating a building for 60 years.

While the remaining 70 percent is released over the next several decades, the embodied emissions emerge in the first year, meaning they need particular focus as the world works to move past peak emissions. It's comparable, in some ways, to the differences between short-lived methane and long-lived carbon dioxide in the agricultural emission debate.

When possible, the NZGBC wants to see companies use carbon-neutral or carbon-negative materials like timber in place of cement or steel. When the particular properties of cement is needed, the council wants companies to consider using substitutes like fly ash, pozzolanic cement and geopolymers.

At the same time, steel and cement producers should look to reduce the carbon emitted in their manufacturing processes and builders should purchase materials from low-carbon manufacturers.

Eagles pointed to aluminium as an example: Chinese-made aluminium window dressings emit five times as much carbon as the aluminium produced by the smelter at Tiwai Point, which is powered by hydro-electric power from the Manapouri Station.

Market action also needed

In addition to carefully choosing materials and suppliers, construction sector companies should lead the way on a handful of other issues, NZGBC says. These include constructing all new buildings as zero carbon and reducing embodied emissions by 20 percent in the next five years.

Property owners can also make a difference through retrofitting their existing assets and being picky about what new buildings to add to their portfolios. The council wants owners to start certifying their buildings as zero carbon in 2020 and get them all to that state by the end of the decade.

Even tenant companies can play a role, the council says. It wants to see tenants telling their landlords next year that they'll only sign new leases for zero carbon spaces after 2025.

The Government also has power as a market player, not just a regulator. Because departments like the Ministry of Health, Ministry of Education, Department of Corrections and the NZDF use a significant percentage of New Zealand's real estate, they have real power in pushing for zero carbon buildings with their wallets.

Beginning in June 2020, the NZGBC said these agencies should "lead an all-of-government shift to verify their new buildings as sustainable and having lower embodied carbon".

Newsroom is powered by the generosity of readers like you, who support our mission to produce fearless, independent and provocative journalism.

Become a Supporter

Comments

Newsroom does not allow comments directly on this website. We invite all readers who wish to discuss a story or leave a comment to visit us on Twitter or Facebook. We also welcome your news tips and feedback via email: contact@newsroom.co.nz. Thank you.

PARTNERS