Evaluation of Recycling & Reuse of Building materials from Demolition: Cost feasibility and environmental impact assessment

Abstract

The processes of building construction and demolition lead to the generation of unwanted material on site. These materials are commonly referred to as construction and demolition waste.Wastes have a potential negative effect to the environment in form of pollution of land, water and air. In Sweden the total amount of wastes landfilled in 2012 which includes mining and quarrying was 82.6%. From the total generated waste in Sweden, 4.9% is C&D waste where 1.1% of this is landfilled. The recycling rate of C&D wastes in Sweden was 50% in 2010 and the vision by the Swedish environmental protection Agency is to achieve a 70% recycling rate for all generated C&D waste by 2020. Demolition of a building may be either conventional or selective in nature to attain the specified goal. In principle selective demolition should permit the recovery of a large volume of reusable and recyclable material unlike conventional demolition. It is therefore prudent to assess the environmental impact attributed to the two plans of building demolition as well as the costs involved. The environmental impact was assessed by considering a life cycle assessment perspective of building materials. The functional unit for our life cycle assessment model involved the demolition of one office building owned by Volvo Trucks Headquarters in Lundby, Gothenburg. It is an eight floor level building with a total floor area of 19,500 m2. The demolition that was done to remodel and renovate the existing office spaces generated concrete, scrap, wood and plasticmaterials. The environmental impact results for the two well defined demolition plans obtained from SimaPro software for five different environmental indicators. The difference between the two demolition plans was showing the gained environmental benefit while choosing the plan with less emissions. By opting for selective demolition the overall result for the whole building was that, Global warming and Acidification had the highest avoided impact and Ozone layer depletion had the lowest avoided impact. In unit terms and with an analysis that is independent of material volume generated, plastic material results in the greatest avoided environmental load when demolished selectively. However concrete has the least environmental avoided impact compared to plastic, wood and steel. In the case of cost estimation for each demolition plan, labour and transportation costs were considered. The result showed that the cost for selective plan was almost double that of conventional demolition plan. Overall the selective demolition plan is more environmentally friendly although it is the expensive option considering the outlined assumptions. The author also recommends to have a very clear material inventory before and after demolition to facilitate determination of materials suitable for reuse or recycle.