Design for deconstruction
Reusing and recycling construction products and materials have a significant contribution to make to achieving sustainable development. To optimise the reuse and recycling rates of construction products it is important that consideration is given to designing buildings and structures to facilitate their future deconstruction.
The construction industry is the largest consumer of resources in the UK using some 450 million tonnes of materials each year. Similarly for waste, the construction industry is the worst performing sector generating around 90 million tonnes of construction and demolition waste annually. By reusing and recycling construction and demolition waste, resource consumption and waste disposal are reduced.
Already vehicles and electrical and electronic goods are the subject of end-of-life directives that require dismantling, recovery and recycling of a large proportion of their constituent parts. It is highly likely that, in the future, buildings will be the subject of similar legislation.
Steel is 100% recyclable and can be recycled again and again with current technology, without any degradation in terms of properties or performance.
Unlike many other construction materials, the intrinsic economic value of scrap steel ensures that it is efficiently recovered from the waste stream and either reused or recycled. By using steel therefore the designer can be confident that in the future, the steel he uses today will be recycled into new products that are able meet future needs.
The recovery rate of steel construction products from UK demolition sites is currently 94% with 10% being reused and 84% recycled.
Steel offers the opportunity to design buildings that can be easily dismantled and their components reused or recycled at the end of the building’s life.
Steps that the designer can take to maximise the value of deconstructing steel buildings include:
- using bolted connections to allow the structure to be dismantled during deconstruction
- ensure that columns and main beams are accessible to allow for inspection should the structural capacity of the frame need to be assessed before deconstruction
- ensure that the steel is kept dry and free of corrosion
- identify the origin and properties of the component for example by bar-coding or e-tagging and keep an inventory of products.
Reuse of steel construction products offers even greater environmental advantage than recycling. Already some industries, such as the agricultural sector, commonly reuse steel structures and cladding components.
Many steel construction products and components are highly re-usable. Steel products that are already commonly reused include
- piles (sheet and bearing piles)
- structural members including hollow sections
- light gauge product such as purlins and rails.
Steps that the designer can take to maximise the opportunity for reusing structural steel include:
- use bolted connections in preference to welded joints
- use standard connection details including bolt sizes and the spacing of holes
- ensure easy and permanent access to connections
- where feasible, try to ensure that the steel is free from coatings or coverings that will prevent visual assessment of the condition of the steel; for example, fire engineering approach adopted may enable fire protection to be eliminated
- minimise the use of fixings to structural steel elements that require welding, drilling holes, or fixing with Hilti nails; use clamped fittings where possible
- use long-span beams as they are more likely to allow flexibility of use and to be reusable by cutting the beam to a new length.
Modular construction systems can offer the greatest opportunities for reuse. Modules or pods can be deconstructed from the building and refurbished and reused on the same or an alternative building.
