Originally published in React News.
Does it make more sense to retrofit an office building or simply build a new one? Developers are increasingly wresting with this question.
Instinct tells us that retrofitting office buildings is the best way to reduce construction carbon. Yet new builds are likely to offer the best operational savings, as their design is uncompromised by any existing building structure or fabric. However, these general truisms do not reflect the rapidly changing context of carbon savings.
There has been considerable discussion around shifting more to low-construction carbon. Until now, low-construction carbon has largely been considered a voluntary unregulated pursuit, frequently underexplored and underreported in the industry. That is, until operational and construction carbon have united under the same zero carbon banner using the UK Green Building Council’s scope definitions and heralded by the Royal Institute of British Architect’s (RIBA) 2030 Challenge targets.
Other factors also have played a part in the growing importance of reducing embodied carbon as operational emissions reduce over time: slow but steady energy saving regulations; planning influences; and the development of renewable energy on both a national scale (cleaning the grid) and site level (better performing and more affordable systems). Reports over the last decade indicate that embodied carbon for a new office building in the UK can be around 40-50 percent compared with regulated operational emissions, which could see in-use reductions of up to two-thirds based on cleaner energy supply alone.
Considering the embodied carbon in the foundations and super-structure alone can be as much as two-thirds of the total construction carbon, and tenant-controlled unregulated loads can be as much as half of operational emissions, the case for retrofitting becomes even stronger.
From an environmental perspective, we must tackle both construction and operational carbon together by combining a circular economy approach with low-energy passive design strategies and renewables. This means exploring all reuse options first and evaluating the depth of retrofit measures required to achieve the best overall carbon saving value.
Advances in modern methods of construction (such as off-site fabric assembly) and building services technology are making it more commercially viable to consider a retrofit approach, which can be offset in part by savings on reusing parts of the existing building as far as possible.
These advances also provide a means to restore and enhance the character of the existing building within the wider urban context, upholding social values and identity and averting a sense of urban degradation. Until designing for deconstruction becomes mainstream, the opportunities of reuse can be limiting. But it is a rapidly changing market in response to increasing global and national drivers to reduce carbon emissions.
When to Consider a New Build
Only when building reuse options are fully exhausted should a new build approach be considered, using passive design principles to reduce operational loads as far as possible. Construction carbon can then be reduced by favoring off-site construction with bio-based, sustainably sourced and responsibly made components that, together with a low energy design and on-site renewables, should align to RIBA 2030 targets or better.
The office of the future will likely be judged on its boldness to progress from the substandard approach epitomized by the office of the past. Converting these offices toward zero-carbon and designing out associated ill-health related aspects requires a more sensitive and responsive approach to design and construction than simply demolition and landfill.
This may seem like an onerous pursuit. However, material and program savings can be availed on the reused elements. Other advantages include minimizing needless waste, restoring urban character and improving healthy working environments. Our clients, the local community and the wider world will benefit.