Sustainability assessment of refurbishment vs. new constructions by means of LCA and durability-based estimations of buildings lifespans: A new approach

摘要

A common practice in Life Cycle Assessment (LCA) of buildings is to consider a default value for their lifespans. However, statistical data show longer lifespans and it is proved that the higher they are the lower the environmental impacts. Therefore, the common practice of considering a default value for lifespans in buildings LCA involves a high risk of programmed obsolescence in the building sector. This paper addresses a new approach to estimate buildings lifespans based on their structures durability. We use a comparative case study of refurbishment vs. new construction to illustrate its use. The lifespans of the refurbished and the new buildings are estimated by applying degradation models of reinforced concrete structures. Two thermal performance levels are evaluated: standard and passive, in both alternatives, the refurbished and the new building. Comparisons are also made with other approaches to determine buildings lifespans based on default value and statistical data. Results show that a new building can have a lifespan more than six times longer than a refurbished one. A strong dependence of LCA results on the lifespan is revealed. Its value can alter the order of preference of the solutions when comparing alternatives and therefore default value approaches are unadvisable. There is in our case study a 11% potential of environmental improvement for new buildings behaviour by changing current practices and extending buildings' lifespan up to their physical limit.