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Written 28th September 2020

Article two

Words by Mark Tillett

Smart Sustainable Solutions

The approach to delivering healthy and sustainable buildings has undergone a seismic shift over the past 20 years. And the concept of designing for the future has adapted to reflect the huge social and environmental changes in our cities, homes and communities. Now more than ever, we have become acutely aware of our responsibility as engineers to create intelligent and low-carbon structures. To achieve net zero carbon by 2050, we need buildings which are capable of changing use, and can lead long, flexible and adventurous lives without a cost on the environment.

Central to this is Long Life Loose Fit which provides a number of key flexible design principles. When first introduced in the early 70s the concept of flexibility centred around demountable, lightweight and low energy structures. With buildings changing use more frequently, the emphasis is now often placed on reducing destructive, high-carbon activities such as recoring.

To optimise the carbon cost associated with recoring we’ve developed a ‘Soft Core’ philosophy which runs through a number of our retrofit projects. Soft Core repositions the stability elements of an existing core, which are often aggressive to demolish, and places them into the architecture of the façade where they become much more efficient. Through transforming the central core, the building is better able to flex, move and grow to suit each change of use.

'As well as better buildings, the shared benefits of a Long Life Loose Fit approach mean fewer new build developments and less aggressive redevelopments, transforming our cities and public spaces with healthier buildings, less construction traffic and cleaner air.'

The benefits of adaptable structures should also be recognised through our building awards. Instead of awarding a project the year it completes, it should be assessed 10 or 20 years down the line. A lifetime achievement award which questions how adaptable a building has been and considers its post occupancy performance could largely help to underpin the value of flexible building stock.

Total Engineering

To drive meaningful change our carbon counting methods should also be questioned. As an industry we have only just begun to measure embodied carbon in a small proportion of the building process. To truly measure the carbon within a building, we need to apply a holistic approach, measuring everything from transport and temporary works to retention schemes and post occupancy evaluation.

At HTS, this is a fundamental aspect of our approach and one we have come to refer to as Total Engineering. We believe that the most successful projects are delivered through a small team working collaboratively towards a shared vision. By having one team design all the key elements from the existing buil ding, the carbon cost can be consistently measured, benchmarked and lowered at every stage.

The recently completed Standard, designed with Orms Architects, exemplifies the substantial benefits of our Total Engineering approach. Working closely with the
contractor, we designed both temporary and permanent works as a single integrated system which used smart phasing to minimise the temporary works and its hidden embodied carbon while maximising program advantages. 94% of the primary structure was retained, saving 6,000 tonnes [1]  of CO2. Based on an area gain of 1,905 m3 to 18,107 m3 resulted in an overall embodied carbon value of 121 kgco2/m2 for the building structure, well below the LETI 2030 carbon target of 201 kgco2e/m2 and the RIBA 2030 carbon target of 144 kgco2e/m2.

[1] Embodied carbon of the retained portion of the structure if it were demolished and rebuilt today

Net zero carbon

If the most sustainable building is one that already exists, then we need to question how our new generation of buildings will function in 20 or 30 years’ time, embedding sustainable principles into projects from the outset. To deliver sustainable structures, we need to demystify the process of reducing carbon, and adopt an informed process driven by research, reflection and evaluation. While there has been some excellent progress across the industry over the past 12 months, there is still a lot of work to do if we’re to achieve net zero by 2050.

To achieve true sustainability carbon measurement should be brought to the forefront of the agenda with planning authorities and made a key driver of the project brief. We need to review the classic building model of plan, build, let and sell which has little incentive for a developer to build-in future flexibility. A truly sustainable approach needs to have a commercial value to support the ethical standpoint many responsible developers want to adopt. A lifelong carbon tax with penalties for polluting processes, carbon heavy materials and additional work to the building such as strip out, plant replacement, demolition and fit-out could help to integrate sustainable principles into projects before the team put pen to paper. The solution to climate change has to be collaboration with a shared ambition; it starts with engineering and everything else must follow through.