Building LCA – Options appraisal including reuse/recycling of existing construction products on site
In general, reuse and recycling of existing construction product on site is likely to mean lower environmental impacts compared with products from other sources. However, this may not always be the case. After the demolition, transport and processing of the waste into a recognised product is finished (impacts at the end of the previous life), there will often be subsequent ‘product stage’ processing impacts (impacts at the start of the next life e.g. crushing, cleaning, making good). In addition, there will typically be a need for ongoing maintenance and possible replacement during the life of the new building. Building LCA options appraisal will help to show if this amounts to a higher environmental impact than products from other sources.
Even when it seems self-evident that reuse is optimal (e.g. in-situ products with minimal ongoing maintenance and a remaining service life sufficient for the building design life – such as reused in-situ concrete substructure), options appraisal will demonstrate to the design team the environmental benefit of reuse vs. newly installed products. This is of particular relevance where the reuse will impose design constraints (e.g. structural layout, aesthetic) that the design team have accepted in order to achieve lower environmental impacts.
For these reasons, it is valid to carry out options appraisal that compares reuse or recycling of existing construction products on site with products from other sources.
Please note: For Building LCA in BREEAM, reuse does not apply to existing construction products that have been installed in preparation for a planned new building (or planned extension to a building) – even if a significant amount of time has passed. For example, substructure that has never been used to support a building cannot be considered as reused. Nor can substructure that has been used to support an existing building but, in addition, was originally designed to support a planned future extension. These elements should be included in the building LCA as if newly installed.
Please note: For Building LCA in BREEAM, there shall be no assumption of reuse of products on-site after the end of the building’s life. All impacts (A, B and C stages) must be included as per the product LCA data found in the recognised building LCA tool. Although projects that chose to remove and dispose of reusable or recyclable products will not be penalised by the resulting demolition, transport, processing and disposal (impacts which belong to the end-of-life of the previous building), reuse is still significantly incentivised by avoiding the A1 to A4 (all or in part) and stage C impacts that would result from using products from other sources.
24/01/2019 - Re-worded for clarity and additional information added (last paragraph)