Enduring logic

It might sound obvious but if a building is to be truly sustainable, it needs to sustain: to endure both in form and in usefulness

Building design has always involved juggling a range of different requirements and coming up with the most elegant solution within the constraints of budget, site and materials. But it’s surely never been harder than it is today, when the designer’s task is complicated not only by having to constantly improve on performance and energy consumption, but also by the moving nature of many of the targets, not to mention the high stakes of getting it wrong in a shifting world that feels increasingly perilous.

To prevent catastrophic climate change, we know we have to reduce both the operational and embodied carbon associated with our buildings – though we are still in the process of developing the targets for the industry to work towards. We also know that, whatever we do, our climate will continue to become hotter and wetter, and that extreme events such as floods and storms will occur with greater frequency. Here, the science predicting the conditions that future buildings will have to withstand is more advanced.

It might sound obvious but if a building is to be truly sustainable, it needs to sustain: to endure both in form and in usefulness. We cannot know for sure what needs any of our buildings might have to fulfil in the future, but we do know that the environment will become more challenging. Overheating is a growing, measurable risk, especially for an ageing population, as is flooding.

In this issue, we explore two key technical issues that show the weight of information that specifiers must consider. We look at methods for assessing the fire performance of concrete frames on adaptive reuse projects – a strategy that is becoming more common for lowering the wholelife carbon of developments. We also outline the results of an independent life cycle carbon analysis (LCA) of two notional apartment blocks, one with a reinforced concrete structure, the other made of cross-laminated timber.

Whole-life carbon is an important measure of a building’s performance, but there is a dawning recognition that controlling peak energy loads within our buildings also has a role to play at a wider national level as we switch to more intermittent renewable sources. The study found that the concrete building’s peak space heating load was on average 25% lower. The LCA’s other striking takeaway was that, even before exhausting all opportunities for optimisation, the concrete structure was only slightly more carbonintensive than the CLT one, while also providing all the well-understood co-benefits of heavyweight, mineral-based structures, such as resilience to flooding and overheating.

The direction of travel is clear: we need to reduce carbon in our built environment significantly and quickly. But we can’t afford to do this at the expense of all the other hugely important functions that we need our buildings to perform, now and in the future – on which the evidence is equally impossible to ignore.

Elaine Toogood, head of architecture, The Concrete Centre