Current adaptation theory tends to consider individual buildings or the city level, which cannot address decisions related to masterplan developments on large brownfield sites. This paper investigates the drivers for building demolition or retention and adaptation decisions at the masterplan scale. Expert interviews and three case studies are used to explore how and why decisions to demolish, or to retain and adapt, are made at this scale. The research compared three different geopolitical contexts: Cambridge in the UK; Eindhoven in the Netherlands; and Sydney in Australia. Additional factors and complexities that should be considered at the masterplan scale are identified. The theoretical underpinnings of urban development processes are used to explain these complexities in relation to four existing models and demonstrate that no one model is adequate to describe the interactions. With increasing awareness of climate change impacts, it is critical that demolition decisions on masterplan developments are reviewed in the light of retaining carbon as well as heritage.

Two key benefits of building retention and adaptation, over demolition and new build are identified in the academic literature as: the conservation of heritage, and reductions in embodied greenhouse gas emissions from construction materials. A four-year research project, including expert interviews, focus groups and three detailed case studies, developed extensive data on how these benefits are considered in decisions to demolish or retain buildings within larger urban development sites. The research found that heritage and embodied impacts are considered quite differently. Heritage is frequently a key driver towards retaining individual buildings, whilstembodied emissions are rarely key considerations. Where there are insufficient arguments based on heritage value, many buildings are therefore demolished and replaced rather than retained. To reduce the impact of construction on the environment it is crucial that we calculate the embodied as well as operational impacts of demolition decisions and retain and refurbish buildings where this is the lower carbon choice. Using heritage arguments as a basis, this paper proposes that the introduction of policy drivers for retention and against demolition, and the conversion of environmental value into economic uplift, are likely to be necessary conditions to encourage the retention of buildings for lower whole life carbon.