Reuse
The inherent low maintenance and durable nature of a concrete structure, together with its resilience to fire and the impacts of climate change, mean that it can remain in use over a long period, with the potential to be repurposed and reused multiple times during its lifetime.
Refurbishing and using an existing building’s concrete structure is an effective way to reduce the upfront embodied carbon of a new development.
The durability of concrete sub- and super-structure means that they can often remain in place while other shorter-lived building elements are replaced, and often well beyond the notional 60-year service life of a building. The methodologies for establishing the suitability of a frame for reuse is well established.
Examples include:
The Standard Hotel: the concrete structure, originally built in the mid-70s as an annexe to Camden Town Hall, was repurposed, adapted and the exterior cleaned to house an upmarket 266-room hotel.
Northampton International Academy: a repurposed derelict Royal Mail sorting office, reborn into a 2,200 pupil school. Article in Concrete Futures: Remixed.
A collection of reuse case studies can be found in ‘CQ Focus: Reuse'.
Summary guidance for engineers for assessing the potential for reuse of a concrete structure can be found in the Concrete Quarterly technical article ‘Reusing structures: One step closer to a circular economy’ It is available to read in the 2022 CQ technical compendium.
Design for future reuse
Where a new structure or building is required, this should be designed to optimise future reuse, so embedding good circular economy practice. Here, the durability of concrete is an advantage.
According to the design standards for a concrete frame located internally – in other words, in an environment classed as “low exposure” – no additional measures are required to achieve a service life of over 100 years compared to 50. (See BS 8500-1, tables A4 and A5, XC1 exposure class.)
The inherent low maintenance requirements of a concrete structure, and its resilience to fire and the impacts of weather, mean that it can remain serviceable over a long period, with the potential for multiple reuses during its lifetime.
Design for disassembly and reuse
While the majority of examples of reuse of concrete construction elements remain in use on a site. Design of these structures to facilitate the removal and replacement of other shorter lived elements such as windows/ facades, internal walls etc is fairly straightforward and are more reliant on forethought than innovation for implementation.
The concrete structure can also be designed to be disassembled for reuse where required. This is currently mostly confined to temporary structures such as car parks and stadium seating. The upper tiers of the London Olympic Stadium are one such example. The durability and robustness of concrete is an advantage in this regard. Key areas of focus are fixings and standardisation of element size to avoid the need for future adaptation.
Increased environmental awareness means that, rather than throwing away, we are increasingly being advised to recycle and re-use. This ethos is also increasingly being applied to buildings. Rather than knock down and start again, the option to recycle and re-use buildings is being examined more carefully with a view to gaining time, cost and embodied CO2 savings - as it may prove more carbon efficient on a whole life basis to re-use what is already built. This philosophy can offer operational CO2 savings too as the heating and air-conditioning requirements of the refurbished buildings are reduced.
Concrete’s inherent robustness, flexibility and minimal need for additional finishes mean that concrete buildings are particularly well-suited to the ethos of reuse. They can easily be updated and future-proofed to meet the differing demands of occupiers and predicted impacts of climate change. However, should a concrete building be deemed unsuitable for retention and refurbishment, its concrete structure and reinforced steel are easily recycled.