The requirement for Homestar projects to calculate and report on their embodied emissions is being expanded to cover all standalone homes.
Homestar v5 includes a new credit (EN2: Embodied Carbon) that rewards projects taking steps to reduce greenhouse gas emissions associated with the products and materials used to construct a home. The embodied carbon content of a project is an important metric that should be considered when delivering the homes needed for a sustainable future while meeting our obligations to decarbonize the building industry.
Currently those projects targeting an 8 Homestar rating or above are required to do an assessment. From July 1st that requirement is being expanded to all standalone homes registering for 6 Homestar and above.
Projects are awarded a point towards certification for carrying out a full lifecycle assessment of the greenhouse gas emissions associated with products and materials used in the construction. Additional points are available for those that can demonstrate a reduction in the predicted cradle-to-gate and construction stage emissions. Projects can get a maximum of 5 points if they can reduce emissions below 60kg.CO2-e/m2 – in alignment with New Zealand’s residential carbon budget required to limit global warming to 1.5 C.
How to calculate embodied carbon
While other (third-party) tools may also be used to comply with the EN2 credit, BRANZ has developed the Homestar Embodied Carbon Calculator (HECC) for NZGBC, as an easy to use tool for estimating the embodied carbon content of a typical home.
We are making this tool freely and publicly available to encourage industry professionals to consider the embodied carbon content associated with their projects.
Download the Homestar Embodied Carbon Calculator
In addition projects can use third-party tools such as LCAQuick or ETool.
A full rundown of the credit, called EN2, is available in the Homestar v5 Technical Manual.