Construction waste, often referred to as construction and demolition waste (CDW), consists of the materials used in construction and packaging. The largest constituent of CDW is so-called inert material (e.g. soil, sand, gravel, crushed concrete). However, timber, tiles, metals, and plastics also play considerable roles in the mix. A commonly overlooked aspect, despite its significant contribution to CDW, is inert material.
Emissions from waste within the boundary of the construction site are defined as greenhouse gas emissions from the production and handling of materials before and after they become waste (CEN 2011). The production of waste on the construction site adds to the total transport of building materials.
The total amount of waste generated, how it is handled, and total emissions need to be clarified and require further analysis. This is part of the recommendations made in Chapter 3 - Assessment of Environmental Impacts.
Traditionally waste management was considered a way to dispose of waste economically and without too much harm to the environment. This has changed and there is now considerable interest in finding ways to minimise waste generation and maximise reuse and recycling. Both circular economy frameworks and European waste hierarchy principles are based on waste prevention and that no waste should enter disposal solutions such as landfills (Zhang et al. 2022).
Emissions can be reduced by preventing waste by minimising excess material or reusing and recycling the material so that it does not become waste.
5.1. Construction methods for waste prevention
Preventing waste from being produced in the first place should be the objective in all phases of the construction of a building. Waste reduction should be taken into account in planning and design to provide the scope for proactive and cost-effective solutions. Reactive waste prevention on the construction site is more difficult and typically limited to the reuse and recycling of unused materials.
More knowledge is needed about how the design of buildings affects the generation of waste during construction. Prefabricated building elements are one example of a construction method that reduces cut-offs and therefore waste (Mamo Fufa, Venås, and Kjendseth Wiik 2021). In the same vein as prefabrication, using standard factory dimensions for elements and products can also reduce cut-offs. Many other design choices, with similar quality and cost (or lower cost), can influence the quantity of production waste.
5.2 Material reuse and recycling
Although construction waste cannot be eliminated, its environmental impact can still be reduced. As discussed before, decisions made during the planning and design phases have a considerable influence on the construction site. The design of buildings should facilitate the cost-effective reuse and recycling of construction waste.
Construction site material management can greatly reduce waste and ensure that as much as possible is reused and recycled. The careful sorting of waste is becoming standard practice on Nordic construction sites. Material management is improving, which is reducing the amount of damaged materials. Nevertheless, there is still room for improvement considering the amount of waste from construction and the diversity of this material. While management at the construction site can be improved, such as by limiting excessive ordering, procuring the right dimensions of materials and proper waste sorting, design can also help and there may be regulatory barriers that need to be removed.