In 2024 Structural Engineer, Kishan Seger, co-authored an article to help clarify the benefit and criteria of Greenstar and Homestar rating tools for structural engineers within the SESOC Journal, published in September, Volume 37 No. 2. These rating tools play a vital role in promoting sustainability in the built environment by providing a comprehensive and credible assessment of a building's environmental performance.

Green Star and Homestar are sustainability assessment tools managed by the New Zealand Green Building Council (NZGBC). Green Star is used for commercial buildings, while Homestar is designed for residential buildings. Both systems evaluate various sustainability criteria, awarding points based on performance in categories such as energy efficiency, water usage, indoor environmental quality, and materials selection.

Early planning and coordination among the design team, including structural engineers, to meet the requirements of these rating systems is critical. This may require additional documentation and adjustments to standard practices to achieve the desired sustainability ratings.

It provides a valuable resource for structural engineers and other professionals involved in green building projects. It demystifies the Green Star and Homestar rating systems, making them more accessible and understandable, and underscores the importance of sustainability in the built environment.

Relevant credits for structural engineers in the Green Star Rating System:

• Climate Change Risk Assessment & Plan (2 points): this credit aims to identify and mitigate risks due to climate change, with parts of it being mandatory.
• Earthquake Resilience (1 point): this credit rewards projects that exceed standard approaches to seismic resilience.
• Indoor Pollutants (2 points): this credit limits on volatile organic compounds in paints and sealants, and formaldehyde in engineered wood products.
• Life Cycle Impacts (11 points): Mandatory reductions in upfront carbon emissions, with strategies to achieve these reductions discussed in conjunction with Lifecycle Assessment (LCA) Practitioner.
• Responsible Building Materials (3 points): Points awarded for sourcing materials from responsible suppliers, such as FSC-certified.
• Product Transparency and Sustainability (3 points): A non-mandatory credit that determines the "Product Sustainability Value".
• Onsite Renewable Energy (1 point): Incorporating onsite solar and other electricity generation methods.

Relevant credits for structural engineers in the Homestar Rating System:

• Energy Use & Winter Comfort: Assessed against benchmark numbers for energy use, largely determined by the thermal rating of the building envelope.
• Moisture Control: Mandatory minimums for thermal bridging details in floors, walls, and roofs.
• Healthy Materials: Managing the amount of volatile organic compounds in the interior environment through eco-labels or performance testing.
• Renewable Energy: Typically achieved by rooftop solar photovoltaics, with considerations for additional load and support structure.
• Embodied Carbon: Mandatory whole-life embodied carbon assessment, with points for meeting different threshold values of upfront carbon intensity
• Sustainable Materials: Achieved through re-used materials, eco-labels, EPDs or product stewardship certification.

Preformance combines Green Star and Homestar certification capabilities with practical construction experience to provide the best sustainability and project outcomes.