Although the completed CRL will help to reduce Auckland’s carbon footprint, enabling more Aucklanders to get out of their cars, its construction and operation will consume significant resources.
The project aims to reduce these impacts as much as possible in order to contribute to regional and national greenhouse gas emission reduction targets.
Planned initiatives include:
- Using New Zealand’s predominately renewable electricity to replace the on-site diesel generators typically used in construction
- Changing construction techniques to reduce on-site diesel use
- Collaborating with the Energy Efficiency and Conservation Authority (EECA) to implement a fuel efficiency programme during construction
- Using locally produced bio-diesel
- Specifying high efficiency station plant and equipment
- Energy-saving motion sensors on the escalators
- Efficient heating and ventilation
- Motion and daylight sensors for station lighting
- LED street lighting
These initiatives are projected to reduce the construction carbon footprint by over 29%, and operational emissions by more than 25%.
The use of construction materials not only consumes valuable resources, but also generates greenhouse gas emissions during manufacture due to the energy used and the industrial processing involved.
Building underground tunnels and stations requires a lot of concrete and steel, both of which have significant quantities of this ‘embodied carbon’.
The CRL design team is working to minimise the use of concrete and steel whilst ensuring that the infrastructure is fit-for-purpose and long-lasting.
The team has found savings equating to almost 600 tonnes of greenhouse gas emissions on the Albert St portion of the work and over 1,200 tonnes on the Britomart portion.
One approach that has helped reduce the embodied carbon of the concrete has been the specification of fly-ash, a partial cement replacement and waste product from coal-fired power stations. This not only reduces the embodied carbon but changes the curing process of the concrete, thereby improving its performance.
Reducing water use has a range of benefits, including reducing the amount of energy needed to process and pump water to point-of-use and for the re-processing of wastewater.
One of the big uses of water during construction is washing the wheels of trucks before they leave worksites to prevent them tracking mud onto the road. In Albert Street this will be avoided by providing a traffic deck at street level, and loading trucks using a long-reach excavator, rather than driving trucks down into the excavation. This initiative is more efficient and is expected to save around three-and-a-half million litres of water; enough to supply an average Auckland household for 22 years.