WE.2.A || Life Cycle Sustainability in Construction and Renovation of Buildings II

Wiche, Pia; Rodríguez Droguett, Bárbara; Granato, Danilo

This study was commissioned by the Chilean Housing Ministry and analyses the state of the art of methodologies for the carbon footprint (CF) of buildings to identify the challenges to create a national CF program for the sector. Four key challenges emerge from the analysis of several certification programs, design guides, databases, calculators, standards, and MRV programs worldwide. First is the adoption of standards to make results comparable. There are already standards such as the EN 15978, ISO 14067, and PCRs, which must be mainstreamed to achieve comparability. However, other standards are missing, such as the definition of the functional unit. Should the internal m2 or external m2 be used? Should m3 be used to account for higher ceilings? There’s no international consensus in the industry yet. Second is deciding if the objective is to guide low CF design or to certify low CF performance. Guiding low CF design can be based of BIM models and generic datasets as it should allow for quick and directional results during the design phase. In contrast, certifying low CF performance requires actual in situ material usage, recurring energy use, and high-quality local secondary data. This makes it more expensive and complex, as it demands joint data collection efforts from different actors, including material producers and tenants. Third is incentivizing the CF calculation during the complete life cycle of the building. This can be through penalties, such as a carbon tax, or through benefits, such as a voluntary certification scheme or advantages for public bidding. Lastly is creating a sustainable governance model which ensures CF quality, enables regular updates of the data, and has guaranteed funding, possibly by the incentive mechanism adopted. Some countries may be more advanced than others on these challenges, but none have solved them completely. A concerted effort would be best to reduce the construction sector CF globally.