Dematerialisation

Reducing the amount of material required for construction is a key focus for reducing embodied carbon and supporting a more circular economy. This includes reuse of existing resources, more efficient use of resources through structural design and material specification and reduce waste in manufacture, construction and in use.

Concrete and masonry construction offers a range of opportunities to achieve material savings both within the structure and beyond. Significant improvements in the material efficiency of the frame can be achieved through reducing design loads, reducing spans and selecting the most efficient structural system for the design criteria. Beyond improving material use in the structure, concrete offers the opportunity to make further material savings throughout the building. Exposing concrete frames can avoid additional cost and carbon associated with ceilings and wall and floor finishes, as well as improving use of its inherent thermal mass.

Below is a list of key considerations and resources for designers and specifiers in developing material-efficient design solutions.

Resource-efficient structural solutions

• A wide range of concrete frame options enables designers to improve material efficiency, e.g. using post-tensioned concrete or ribbed or waffle slabs, which requires less material to support the same loads and achieve the same spans. Material efficient designs can lead to reduced foundation loads and further savings in the substructure. Refer to the Concrete Compass on Material Efficiency for more information and links to resources.
• Concept V5 - Concept is a free conceptual design tool which enables designers to quickly compare embodied carbon, cost and construction time for a wide range of concrete frame options. It is intended to be used for selecting the most appropriate scheme for a concrete frame building, and to give initial member sizes.
• Concrete is a non-combustible material and its inherent fire resistance means concrete structures generally do not require additional fire protection. In concrete structures, fire resistance requirements are typically met by achieving minimum element sizes, such as slab depths or column dimensions, and through reinforcement detailing. This removes time, cost and carbon in construction.

Resource-efficient manufacture and construction

• Concrete typically contains recycled materials and by-products from other industries that reduce the amount of virgin materials required. Research is ongoing to expand the materials that can be used within concrete mixes.
• Concrete is manufactured using efficient, low-waste processes. Ready-mixed concrete is made to order, with manufacturers providing tools to estimating quantities and also take back diversion schemes to reduce waste on-site. The combination of just-in-time delivery and factory controlled offsite manufacture reduces site waste through use of precast products.
• A study on wastage rates provides guidance on current wastage rates associated with common forms of concrete construction.

Designing for dematerialisation in use

• Concrete can be designed to offer a wide range of finishes and it is not uncommon to expose the surfaces of concrete frames. Over the life of the building, exposing the surface of structural concrete reduces the resources associated with the replacement and maintenance of less robust finishes.
• Unlike other materials, concrete does not need any coatings or paint to protect it against deterioration and typically requires little maintenance. Concrete is, by its nature, very robust, and can be designed to withstand explosions, accidental damage and vandalism.
• Exposed soffits and fair-faced concrete reduce the need for internal finishes, whilst optimising the benefits of thermal mass. The thermal mass of concrete helps stabilise internal temperatures and provides the opportunity to reduce the energy use associated with mechanical cooling. Other potential benefits of thermal mass include reduced peak load demand for heating and reduction in overheating risk.
• Design for Longevity: Concrete is highly durable, with internal concrete frames able to achieve a 100 year design life with no additional cover or concrete mix requirements when compared to a typical 50 year design life The long service life and robustness of concrete facilitate the reuse of existing concrete frames, extending a building’s life still further.
• Future, as well as current, environmental conditions are essential considerations in the design development of new buildings to ensure their sustainability as well as the safety and comfort of occupants. Concrete frames offer the potential to provide resilience to both flooding and overheating and thus enable adaptation for climate change, facilitating the long term service life of the structure and its use and reuse.