Raising our game

By something of a coincidence, there’s a lot of flying concrete in this issue.

At LSE’s new Marshall Building, at Folkestone’s new skatepark, and at the reinvented council building on the north bank of the Seine, each structure has effectively been jacked up to create large, open, multi-use public areas at ground level. Or perhaps it’s not a coincidence: offering welcoming, sheltered spaces is a very good way for architects to add to the social value of their projects, especially as cities become more crowded and temperatures rise.

In their own way, each of these buildings adds to the public amenity in their particular location, and each pushes the boundaries of what concrete can do. That’s one of the joys of this material: it is endlessly versatile, and it has constantly evolved to meet society’s changing needs over its history. The combination of designers’ creativity, manufacturers’ ingenuity and concrete’s inherent performance characteristics mean that it can be almost anything that it is needed to be.

One of society’s most pressing needs is for sustainable, low-carbon building materials that can keep people safe and comfortable in a hotter, wetter, stormier climate. This is reflected in two hugely important changes to the Building Regulations: Part L has been tightened up again as part of a drive for a net-zero built environment by 2050; while the new Part O addresses the risks of overheating in highly insulated new homes during warmer summers.

It is increasingly common for designers to request lower carbon concrete in their specification, using GGBS and fly ash as part of the cementitious content, and the next edition of BS 8500 is expected to expand the range of permitted lower-carbon blends significantly, with more use of powdered limestone. But even before these, and other new lower carbon mixes, become more widely available, there is a lot we can do right now to reduce the carbon of our buildings, without compromising on performance, and while ensuring they deliver the maximum possible value for communities.

We need to keep asking how much better we can do through structural engineering to improve material efficiency – by challenging loading, span and frame selection, for example – to drive down embodied carbon, and take advantage of all the tools that are already at our disposal. Advanced modelling can support this process: Jodrell Bank observatory’s new pavilion is the largest reinforced concrete dome in the UK with a diameter of 76m, but a thickness of just 200mm, an incredible feat of structural engineering aided by a complex material behaviour analysis.

We live in challenging times, and the challenge to us all now is to look beyond current expectations and norms and to keep pushing the boundaries. There’s always more we can do – and necessity is the mother of invention.

Elaine Toogood, Director, Architecture and Sustainable Design, The Concrete Centre