Green roof evaluation: A holistic ‘long life, loose fit, low energy’ approach

Date of this Version


Document Type

Journal Article

Publication Details

Published version

Langston, C. (2015). Green roof evaluation: A holistic ‘long life, loose fit, low energy’ approach. Construction Economics and Building, 15(4), 76-94.

Access the journal

2015 HERDC submission

Construction Economics and Building 2015. © 2015 Craig Langston.

Distribution License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.




Green roofs have potential to improve the social and environmental performance of detached housing in Australia, yet often they are overlooked due to prohibitive capital cost and a range of other perceptions that are difficult to quantify. A classic evaluation problem is invoked that must balance short and long term benefits. Using two distinct designs of the same floor area, green roof and traditional housing prototypes are analysed to determine the relative ‘breakeven’ point when long-term benefits become feasible. It is discovered that green roofs are unlikely to be viable in their own right, but when coupled with an overall design strategy of long life (durability), loose fit (adaptability) and low energy (sustainability) they can deliver least cost (affordability) over time as well as unlock valuable social and environmental rewards. This outcome can be realised within 25% of a home’s expected design life of at least one hundred years. The results demonstrate that residential green roofs, when integrated as part of a holistic approach, can be both individually and collectively justified on key economic, social and environmental criteria, and are therefore able to claim a valuable contribution towards wider sustainable development goals.



This document has been peer reviewed.