Operating buildings sustainably is a granular endeavour. Britomart gathers detailed monthly data on energy and water use, and monitors refrigerant losses and waste volumes in order to refine and reduce our resource use.


Britomart precinct’s Toitū Carbonreduce plan includes a commitment to a 5 percent reduction in total emissions by 2026, to be achieved through a wide range of undertakings, from monitoring building air temperatures to increasing energy efficiency, decreasing waste and investigating solar power for some buildings. In the 2022/2023 year, Britomart group’s total greenhouse gas emissions were 721.66 tonnes of CO2e (carbon dioxide equivalent emissions). This represents a 40 percent reduction in emissions from the previous year.

In the 2022/2023 year, Britomart group’s total greenhouse gas emissions were 721.66 tonnes of CO2e (carbon dioxide equivalent emissions). This represents a 40 percent reduction in emissions from the previous year.

Our emissions are reported in the following categories:

Direct emissions In the last year, our direct emissions reduced by 42.5 percent overall, going from 774.32 tCO2e in 2021/22 to 445.01 tCO2e in 2022/23. This was attributable to: Fewer refrigerant leaks (refrigerant has an extremely high emissions intensity). More accurate reporting of the quantity of refrigerant lost from leaks – previously this had been over-reported by suppliers. Most refrigerant leaks in the precinct have been coming from three buildings – the East Building, the Charter Customs Building and the Excelsior Stanbeth Building. The East and Charter Customs Buildings are easily the largest in the precinct, and can be expected to generate the highest number of leaks. For the Excelsior Stanbeth Building, the leaks are due to ongoing issues and faults related to the age of the plant. Engineering consultancy NDY has been engaged to redesign the air conditioning system in Excelsior Stanbeth with a view to replacing it when the building is refurbished. The smaller buildings’ refrigerants leaks are an expected part of building operation and maintenance is ongoing. Leaks can be caused by something as small as a nut becoming loose on an air-conditioning unit.

Indirect emissions from imported energy Emissions from the use of electricity also showed a notable reduction of 40 percent, going from 381.79 tCO2e in Year 3 to 229.07 tCO2e in Year 4. The reasons for the decreased use of electricity included: More people working from home so some office spaces were not as frequently in use. Temporary closures of some businesses for refits. Improvements to the air conditioning systems within the East Building (the single largest electricity user) which improved efficiency. Fairy lights were replaced with more energy-efficient versions. The Britomart Saturday Markets operated at a smaller scale over a very wet winter.

Indirect emissions from products This category relates to transmission losses – such as leaks or heat loss – as gas and electricity is transmitted to each building.

Indirect emissions from transport This relates to emissions from car or air travel. In the 2020-2022 years, this category was very low due to travel restrictions. In the past year, this has increased, as expected, from virtually zero to 12.51 tCO2e.

Ongoing activities Weekly technical meetings are held to collaborate on ideas for reducing overall utilities consumption across Britomart. Monitoring of building temperatures via our Building Management System is ongoing.


Since we published our last Sustainability Report, there have been some changes in the way that Toitū Envirocare, the agency that issues our greenhouse emissions accreditation, makes its calculations.

The first change occurred in August 2022. The Ministry for the Environment decided that a change in methodology was needed for calculating the electricity emissions factor in Toitū emissions assessments. This change was retrospectively applied to all emissions assessments, and affected all Toitū-rated organisations that have electricity as part of their emissions total. Depending on how large a factor electricity is for each organisation, this change could affect overall emissions totals slightly or substantially. For Britomart, this had a moderate effect, as electricity use accounts for a reasonable portion of our emissions. All of Britomart’s emissions totals have been revised, dating back to our first assessment in 2019. The second change was in August 2023, and will be applied to future emissions calculations. This applied to the emissions factor relating to petrol and diesel. Emissions factors change over time for a variety of reasons – such as vehicles becoming more fuel-efficient, the country using more thermal generation in one year compared to another, etc. As Britomart has no vehicle fleet, this change will have little effect on our overall totals.


NABERSNZ (National Australian Building Energy Ratings System New Zealand) is a system for rating the energy efficiency of buildings. At Britomart, five buildings currently hold NABERSNZ ratings.

Prior to 2022/3, Britomart used an external consulting company to manage our NABERSNZ assessments. This company collated data related to the energy efficiency of the rated buildings at Britomart using schematics and data from our energy suppliers and building management systems. As NABERSNZ-accredited assessors, they managed our annual NABERSNZ submission. For our 2023/4 NABERSNZ rating, we changed to a new NABERSNZaccredited assessor, who does regular site visits and provides quarterly reports and advice at meetings alongside managing the NABERSNZ assessment. This more frequent monitoring and data collection gave us a much deeper understanding of the limitations of our existing metering systems. We could recognise gaps where the data was insufficient to provide a fair assessment of the division between energy used by tenants and energy used in the common areas in the building (which we are responsible for as landlords). This means that two buildings needed to change from Base Building ratings to Whole Building ratings, which assess energy efficiency in both tenant and common spaces. This requires including additional factors in calculating the energy efficiency of these buildings, such as the number of people working on-site. The type of business operating from the building can affect the ratings – for example, a building housing co-working spaces that have few permanent workers on-site will typically achieve a lower score than an office with a larger group of permanent workers. These variables are now included in our data.

What's changed with our NABERSNZ ratings

Australis Nathan 2022 rating Base Building 5 Star (NZ-leading) 2023 rating Whole Building 4 Star (Excellent) We intend to return this building to a Base Building rating by adding additional metering to enable us to do so.

Excelsior Stanbeth 2022 rating Base Building 6 Star (Aspirational) 2023 rating Whole Building 4 Star (Excellent) We would like to return this building to a Base Building rating and are scoping the feasibility of installing additional metering. Due to the building’s unsuitability for solar panels and the small floor area of the building, which results in a higher kWh/m2 heat loss per year than larger floor-plate buildings, we’ve been advised that even after returning to a Base Building rating, it would be unlikely to achieve a 6-star rating in the future.

Altranz Quay 2022 rating Whole Building 5.5 (NZ Leading) 2023 rating Whole Building 5.5 (NZ Leading) Although there was no change in this building’s rating, this was also identified by our assessor as benefiting from additional metering. We are currently scoping the feasibility of installing additional meters, enabling it to be rated as a base building.

NEXT / Learn why good data is important to energy efficiency ratings in our interview with NABERSNZ-accredited assessor Dave Annable