In general, reuse of existing construction products on site is likely to mean lower environmental impacts compared with removal and installation of new construction products. However, this may not always be the case. There may be a need for processing (e.g. cleaning, sorting, cutting, making good, reinstallation), particularly if the products are not reused in-situ. In addition, for all reused products there will often 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 these factors amount to a higher environmental impact than removal and replacement with new alternative products.
When it is 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 the reuse vs. new (or part new) installations. 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 of existing construction products with removal and replacement options.
Please note: 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.