SR248 Life cycle costs and analysis of roof cladding systems (2018)

This report is on the life cycle cost (LCC) and ranking of common roof claddings used on New Zealand dwellings. Costs and rankings data is based on an Excel calculator tool created by BRANZ for common roof cladding systems used in New Zealand dwellings. The tool combines costs with sustainability impact factors (CO₂, embodied energy and recyclability) to which the user applies weights to give a total cost-sustainability score and the ability to rank selected claddings.

Costs of materials are a main concern of most builders and designers, but they are not the only consideration in the design of new housing. Apart from aesthetics, the designer and owner are often interested in the environmental impact of a product or material. This report describes a calculator tool developed to combine cost aspects with sustainability impact aspects of roof cladding materials. The analysis considers costs, CO₂ gas emissions, embodied energy of cladding material and the ability to recycle the material.

Weights for each characteristic were used in the following combinations:

• 100% LCC (sustainability factors not considered).
• 70% LCC, 10% CO₂ gas emissions, 10% embodied energy of cladding material, 10% recyclability.
• 40% LCC, 20% CO₂ gas emissions, 20% embodied energy of cladding material, 20% recyclability (an example of some green assessment schemes).