Material Use

In most instances, New Zealand house construction uses a mixture of heavy and light construction – with a heavy concrete slab on ground  and lightweight framed construction above.

Heavyweight construction

Heavyweight construction:

• usually has higher total embodied energy
• may be used as exposed thermal mass to provide heating in cool weather and cooling in warm weather
• is most suitable where the local climate has large day-night temperature differences and significant heating and cooling requirements
• is less responsive to outdoor temperature changes
• requires more substantial footing systems and causes greater site impact and disturbance
• is less sustainable when proposed for sites distant from the point of supply (due to the weight or bulk and cost of transport)
• raw materials are often quarried, with high impact on the landscape
• may require heavy lifting equipment on site
• may require temporary supporting structures during construction (which may increase waste)
• is generally considered highly durable
• is low maintenance
• may involve kiln baking e.g. of bricks.

Lightweight construction

Lightweight construction:

• typically has lower total embodied energy
• has lower total life cycle energy use, where the day-night temperature range is low
• is more responsive to outdoor temperature changes
• generally has lower transport costs because it is lighter
• can have low or high environmental impact during extraction and processing/manufacture depending on the source and type of the material e.g. sustainably sourced timber has a low impact but unsustainably sourced timber or metal has a high impact
• can be easily handled off and on site without the need for heavy machinery
• is higher maintenance
• can be less durable.

For your clients

To help your clients understand the pros and cons of different construction systems, refer them to www.smarterhomes.org.nz/construction.