A science-based approach to setting climate targets for buildings: The case of a New Zealand detached house

Abstract

Climate change mitigation requires the construction of low-carbon buildings. The use of Life Cycle Assessment provides useful information to support eco-efficiency improvements and therefore, to reduce the climate impact of buildings. However, it does not ascertain whether a proposed design aligns with achieving the global climate target of limiting global warming to below 1.5 °C or 2 °C. This study, therefore, introduces a science-based approach for setting climate targets for individual buildings using a whole-of-life cycle perspective. It involves assigning a share of the 2 °C global carbon budget for 2018-2050 to a country, its construction sector, and finally to each life cycle stage of a building. A stock projection model is used to account for the projected growth in the number of buildings and associated climate impact in a country up to 2050. The approach was applied to define a climate target for a New Zealand new-built detached house of 198 m2 gross floor area, the most common residential building type in the country. The weighted average climate impact of three New Zealand new-built detached houses was compared with the defined climate target. The results showed that the climate impact of new-built detached housing exceeded the climate target by a factor of five. When the climate impact was compared with the climate targets at each life cycle stage, exceedances were a factor three to five higher across the different life cycle stages. The proposed approach has potential to guide designers and other interested stakeholders to operate the construction sector within planetary boundaries.