Life cycle assessment of the Waitakere NOW Home

David Drysdale, Barbara Nebel.

This report provides an assessment of the environmental impacts of the Waitakere NOW Home using Life Cycle Assessment (LCA). All life cycle stages from material manufacturing through to the end of life of the house are included. The inputs in the life cycles of the Waitakere NOW Home were modelled using New Zealand data and international data.

The operational stage of the Waitakere NOW Home was the most dominant stage in terms of global warming potential, embodied energy, and acidification potential of the life cycle, accounting for between 65-76% of the total impact. The foundation system in the Waitakere NOW Home accounted for the greatest proportion of the eutrophication and global warming potential of the building. This was largely due to the large mass of concrete which accounted for
a high proportion of the mass of both the foundations and the Waitakere NOW Home.

The original NOW Home design was compared to four alternative NOW Home designs, and the original NOW Home had the lowest overall life cycle impact for energy consumption and global warming potential. The difference between the life cycle global warming potential between Auckland and Wellington for all the NOW Home designs was large and this was due to the operational impact, which increased by 120% (suspended timber floor) to 183% (actual
NOW Home) between the regions.