Green Star Buildings Carbon Reduction Requirements
Green Star Buildings Carbon Reduction Strategy
Reducing carbon emissions from buildings is essential to meeting Aotearoa’s climate goals. The built environment contributes around 15% of the country’s total emissions, making it a critical area for action. To support this, Green Star Buildings has introduced a Carbon Reduction strategy that provides a clear pathway for further emissions reductions. This strategy helps the sector take measurable steps toward meeting the targets of the Paris Agreement and accelerating the transition to a low-carbon future.
If you’ve done a deep dive of the Green Star Buildings Submission Guideline, you may have noticed this diagram. But what does it really mean?
We know that every kilogram of CO2 we emit is directly related to how much our atmosphere warms. That means we can calculate a carbon budget; the total amount of carbon we can still emit to keep warming below 1.5°C as per the Paris Agreement. This total budget can then be divided between countries and different industries to attribute a share to individual buildings. This is how we arrived at the required reduction percentages that must be met by all 6 Star Green Star buildings. Over time, the remaining budget decreases, so any new buildings are subject to increasingly stricter targets.
What does this mean for your project?
The minimum requirements that your project must achieve are related to the type of building and the targeted Star Rating. For example, an office building targeting a 4 Star rating, must demonstrate at least a 10% upfront carbon reduction if registering before May 2026, and 15% if registering after this date. Similar staged reductions in operational energy are also required as shown below.
Energy Use Targets:
| Rating | Before May 2026 | After May 2026 |
| 4 Star | 10% | 10% |
| 5 Star | 25% | 35% |
| 6 Star | 53% | 53% |
Upfront Carbon Targets:
| Rating | Before May 2026 | After May 2026 | ||
| Building Type | Office | Other | Office | Other |
| 4 Star | 10% | 10% | 15% | 15% |
| 5 Star | 20% | 20% | 31% | 26% |
| 6 Star | 31% | 26% | 45% | 38% |
Additional requirements
In addition to the above, two other requirements are included.
The Credit Achievement of the Other Carbon Emissions credit is related to refrigerants. Depending on the type and quantity of refrigerants used, they can be a major contributor to global warming if leaked into the atmosphere. Limiting these emissions is currently only mandatory for 6 Star projects, but will include 5 Star projects as of May 2026.
The Exceptional Performance threshold for this credit involves purchasing offsets for any emissions that have not been eliminated. This becomes mandatory for 6 Star projects, therefore allowing the building to claim being net zero ready. Note that as the electricity grid does not currently use 100% renewable energy, there are still emissions associated with that electricity use, which will decrease over time as the grid further decarbonises.
Grid Resilience is the final credit impacted by this step change. This relates to reducing electricity consumption during those times when overall demand is at its highest, which is a key aspect of decarbonising our grid as it reduces the need for new power generation infrastructure.
Locking in existing thresholds before 1 May 2026
The above changes may have significant implications for any project targeting Green Star. Therefore, if you want to lock in the 2024 thresholds for your project, you must submit an EOI by 1 May 2026. You will then have until the end of May 2026 to finalise the registration by signing the forms and paying the invoice. Any projects registering after this must meet the new targets.
Want to learn more about embodied carbon, including helpful resources?
To find out more about embodied carbon, including NZGBC guides, methodologies, databases, calculators and more, head over to the embodied carbon page of our site.