New Zealand does not currently have any tools available based on comprehensive, independently verified, life cycle assessment of building materials and systems. However, aspects of life cycle assessment are used in the following tools.

Embodied energy

Victoria University’s Centre for Building Performance Research in 2003 calculated the embodied energy and carbon dioxide emissions for approximately 60 New Zealand-specific building materials.

A ‘cradle to the factory gate’ analysis is used – i.e. the impacts associated with making the product are considered, but not the impacts of getting it to the site, using it on site and disposing of it after the end of its useful life. Some key values are shown in the table.

A list of New Zealand embodied energy coefficients is available for download here.

This information captures some key environmental concerns (including resource use and climate change-related indicators). However, it doesn’t differentiate between renewable and non-renewable energy forms and it doesn’t provide any information on other environmental impacts – such as ozone depletion, human toxicity and eco-toxicity.

Most figures for embodied energy are quoted in MJ/Kg. When comparing the embodied energy of different materials, designers must take account of:

• the mass of the material used in the building. For example, aluminium has a much higher embodied energy figure than concrete but significantly less (in Kg) aluminium is used than concrete
• the units of embodied energy being quoted (most are in MJ/Kg but also used are GJ/m², GJ/tonne, MJ/m³ and MJ/m²
• the product-specific manufacturing process, the location of that manufacturing relative to the point of use
• what the embodied energy figure quoted covers. A number of quoted figures will include transport of materials to building site, maintenance, energy used during construction/installation and disposal/reuse/recycling of demolition materials at the end of the building’s life (which the Victoria University’s Centre for Building Performance Research figures quoted above do not make an allowance for).

Factors that affect the total embodied energy can include:

• the efficiency and specific process used in a material's production
• the effort required to extract raw material and dispose of waste by-products
• the mode of transport used to move materials and components – transport of large volumes by ship is relatively low in energy usage while land transport of a heavy material is high
• material weight and volume
• the energy cost involved with recycling or disposal.

Case study

The embodied energy of the major components of the exemplar house (195 m² , 1½ stories) would be made up of:

  

BRANZ life cycle wall cladding tool

The BRANZ life cycle wall cladding tool examines 16 common lightweight New Zealand wall claddings, enabling the user to perform easy and fast comparisons. Four key issues are examined – carbon dioxide emissions, embodied energy, recyclability, and life cycle costs.

The tool can be downloaded as an Excel program. Users can accept the default settings or apply their own personal weightings to each environmental issue. Users can also select as many or as few of the four issues as they want. Although limited by the materials available for comparison, it is useful for comparative key environmental performance.

Environmental Choice NZ