Material Use

While construction and demolition waste is generated by contractors on site, designers have a major influence on how much waste is created. By thinking carefully about which materials are specified, material sizes, construction processes, and other aspects of efficient material use, you can reduce waste and potentially save on costs and environmental harm. Sustainable design should, where possible, facilitate deconstruction (disassembly) and reuse of materials and components which will also reduce waste.

It’s worth discussing reasons for waste minimisation with your clients at an early stage, and encouraging them to become interested in good resource management.

Designing to reduce waste during construction

To minimise waste during construction:

• ensure the design allows for a logical sequence of construction
• ensure that the working drawings are clear and accurate, to minimise rework
• design to the modular sizes of sheet material such as particleboard, plasterboard and glass
• plan the plumbing, drainage and electrical services so that they are compact and have minimum runs
• specify excavated material to form landscape where possible, to avoid carting
• keep the variety of materials to a minimum
• specify that excess concrete is used on site for fill, if possible.

Specifying materials that are less wasteful

Specify materials that:

• are salvaged or recycled or have a have a significant recycled content
• are pre-finished or pre-fabricated
• can be re-used or recycled after their useful life in the building ends
• are of an appropriate durability to meet NZBC performance requirements
• are manufactured locally from local raw materials.

Designing to maximise re-use and recycling

The biggest impact on landfills comes when the building reaches the end of its useful life. Designing a home so that it can be easily remodelled may extend its useful life.

Designing for easy deconstruction will allow building components to be re-used or recycled when the building does reach the end of its life.

To make a building or its components easy to recycle or re-use when it reaches the end of its serviceable life:

• specify reversible jointing methods, e.g. bolted or screwed connections rather than welded joints in steel
• minimise use of composite materials such as coated materials and laminates, as they are generally more difficult to recycle
• not over-specifying strengths of material such as mortar or plaster
• specify materials that are easy to re-use or recycle even if they may have a higher embodied energy initially
• specify lightweight rather than heavyweight structures as they are more suited to de-construction, re-use or able to be totally relocated.

For your clients

To help your clients understand the benefits of reducing construction waste, refer them to www.smarterhomes.org.nz/construction.