Application of Absolute Sustainability Assessment to New Zealand Residential Dwellings

One approach to supporting the implementation of sustainable activities by industry sectors is the use of climate targets. Such climate targets have potential to be used in design and rating tools for buildings and to support government regulation for the building and construction sector. In this study, the climate targets for New Zealand residential dwellings were calculated based on assigning the global carbon budget (for limiting temperature increase to 1.5 or 2.0 °C during 2018-2050) to three building typologies: detached, medium-density housing and apartments. These budgets were assigned to the pre-existing and new-built dwellings using building stock projections for the nominated period. Separately, the climate impact of new-built dwellings in each of the three residential typologies were assessed using Life Cycle Assessment methodology. For New Zealand residential buildings, new-built dwellings exceed their 1.5 °C climate targets by a factor of 6.7, 6.8 and 10.9 for detached, medium-density housing, and apartments respectively. For the 2.0 °C climate target, these factors are 4.8, 4.8 and 7.7 for detached, medium-density housing, and apartments respectively. The results show that about two-thirds of the climate impact of residential dwellings for the period 2018-2050 is associated with preexisting dwellings rather than new-builds. The operational energy used for space heating, water heating, lighting and plug loads makes the biggest contribution to the climate impact for all typologies of pre-built residential dwellings. For new-built residential dwellings, both the operational energy and the construction materials/products contribute most of the climate impact.