Major advance to measure and reduce construction industry’s embodied carbon

09 May 2023

Photo by Casey Horner on Unsplash

Following months of industry consultation, the New Zealand Green Building Council (NZGBC) and sustainability firm thinkstep-anz are proud to release guidance to help the building and construction industry calculate embodied carbon accurately and reliably.

One of the major challenges in our sector’s efforts to decarbonise is the emissions associated with our products and materials. With new buildings targeting a Green Star rating now required to demonstrate at least a 10% reduction in upfront carbon, we are supporting the industry to make more sustainable choices.

Developed with industry, the newly released Embodied Carbon Calculator, calculator guide and methodology provide a robust and consistent approach for calculating upfront carbon and whole-of-life embodied carbon.

“With multiple calculators in the market, each producing different results, this guidance outlines best-practice methodology, definitions and scope to support accurate, comparable calculations. This will allow industry to compare designs across buildings accurately and tool developers to harmonise their methodology and data,” says Jeff Vickers, Technical Director at thinkstep-anz.

The Green Star NZ Embodied Carbon Methodology provides clarity on important issues, such as how to account for stored biogenic carbon (how to count the amount of carbon wood stores) and credits for recycling/reusing materials. It also provides guidance on which building elements should be included in the calculation and a database of carbon emission factors for common building products.

“Today’s release follows 18 months of engagement with the sector on embodied carbon measurement and reduction. There’s huge appetite from across the supply chain, developers, architects, and builders to tackle their climate pollution. Measuring is a vital first step, and we’re grateful to have had some of the industry’s brightest and most passionate sustainability advocates supporting this work,” says Andrew Eagles, NZGBC Chief Executive.

“Importantly, this guidance sets us up for the future. It’s been developed to align with MBIE's Building for Climate Change (BfCC) programme, and we’ve worked closely with the Green Building Council of Australia and NABERS in Australia to provide consistency on both sides of the Tasman.”

A copy of the two calculators, methodology and two guides can be found here.


Note to editors

For recent and future projects registered under the latest version of Green Star - Green Star Design & As Built NZ v1.1, teams must prove a reduction in upfront carbon of at least 10% to achieve a rating. Points are awarded based on how much upfront carbon they’ve reduced, with higher reductions rewarded with more points.

This work has involved a long period of engagement with the sector on embodied carbon measurement and reduction. A summary of feedback and how it has been dealt with particularly on the carbon calculator is provided here 

We intend all documents and the Embodied Carbon Calculator to be living documents that are updated as new emissions factors (e.g., new Environmental Product Declarations, new versions of BRANZ CO2NSTRUCT) are published.