Engineering the Natural World, Jack Scarr
Word by Jack Scarr, innovation + research engineer
Written in support of World Green Building Week 2021
The natural world has inspired architects and engineers in the forms they choose for hundreds of years, from Da Vinci’s depictions of the human body and Christopher Wren’s Theory of Natural Beauty to the bubble-like biomes of the Eden Project and the winged curves at Sydney’s Opera House.
With the parameters of sustainable design constantly shifting and evolving, how can we learn from natural systems to approach design more holistically and create a more resilient built environment?
In 1991 Suzanne Simard, an ecologist from British Columbia grew 80 seedlings from three different tree species: birch, fir and cedar. She had hypothesised that the birch and fir trees would share resources between each other, while the cedar would have a symbiotic relationship with other species. The birch seedlings were injected with carbon-14, a radioactive isotope, whilst the fir and cedar were covered with shade cloths to prohibit photosynthesis. The radioactive isotope was traced through to the fir tree confirming Suzanne’s hypothesis that the two species would have a dynamic flow of resources between them.
It was previously thought a forest was a competing environment, but research has shown that the flow of resources between trees promotes the growth of seedlings, creating a more diverse and resilient ecosystem; a compelling basis to apply to the design of our built environment.
Designed from nature
Natural systems have already influenced the design of our built environment in several ways. A decentralised energy network, often referred to as a district heating network, emulates the sharing of resources within a forest. Excess heat from buildings within the district is captured using a combined heat and power unit, which is then fed into the surrounding buildings to support their energy needs. Lessons can be learned from this dynamic flow of energy to catalyse other ideas in which we can create a sharing-built environment.
The shift to sustainable transport solutions provides another good example of how local communities have been enabled through a better connection to the surrounding built environment. A road is a conduit through a local community offering little positive benefit, whilst leaving numerous negative externalities. With the provision of cycle lanes and landscaped pedestrian walkways, footfall in the local area is increased supporting businesses and provides more travel options to the community. Greater resilience is achieved when a community has a stronger connection to the built environment around them. HTS associate civil engineer Alex O'Hare recently summarised his thoughts on the topic in an article, on our site here.
There is scope to look at Sustainable Drainage Systems (SuDS) design from a more holistic approach. Each site has its advantages and limitations. On a site with a high capacity for SuDS implementation, there could be the potential to look beyond the needs of the site to provide runoff to other developments in the area that may be more restricted in their capacity to incorporate SuDS. Local authorities could incentivise developers to provide this added capacity, imitating the mother tree of a forest, to facilitate a wider resilience to the area.
Structures are static in their nature, but can be dynamic throughout their lifetime, a resource we should not underutilise. An adaptable structure can respond to the changing needs of communities and cities across the globe, alleviating the need for environmentally damaging construction. In our current climate emergency, adding excess material to facilitate an undefined adaptability is not a solution we should be settling on; as critic John Ruskin famously stated ‘when we build, let us think that we build forever’
To increase the adaptability of our structures we are undertaking dynamic testing of the HTS office, and several structures designed by HTS to gain a more thorough understanding of timber behaviour and expand our knowledge of how we can enable the repurposing of a structure.
It should be remembered that in a decarbonising economy, one tonne of material produced now will emit more carbon emissions than it ever will in the future. There are opportunities to assess and monitor the performance of the structures we design to facilitate adaptability, creating a dynamic and responsive web of resources.
Long Life, Loose Fit
Research has highlighted the vast gap between the design and the actual loading (weight) experienced by the structure from people and furniture over the lifetime. If the loading of a structure, whilst in use, was monitored it could indicate the increased occupancy the structure would be able to withstand. If we scale this up from one floor to multiple floors, it could provide a basis to understand that strengthening, a typically carbon intensive process, wouldn’t be required to the vertical elements if a small proportion of floors required a change of use, saving cost and carbon. Designing for disassembly will not only enable the circular economy but provides adaptability to our structures. With a second-hand marketplace for structural materials, there would be potential to strengthen a building through material reuse eliminating the need for significant upfront carbon costs. As part of HTS+ we are researching how we can make structures demountable to guide our designs into this circular and sharing economy.
Often the case on retrofit projects is that the foundations restrict the repurposing potential of a building. By installing distributed fibre optic sensor cables within piles, engineers could assess the structural performance over a pile’s lifetime to determine whether additional capacity could be justified. Build nothing is at the top of the net-zero design hierarchy but this does not have to equate to doing nothing. Understanding how our structures are performing will provide the adaptability, allowing them to be responsive to the changing needs of the built environment and the local community.
No Building is an Island
Being more attuned to the natural strengths and weaknesses of each development will help to understand how each can support the other. Trees within a forest don’t act in isolation and nor should the structures within our built environment. Planning conditions of new developments, around susceptible areas, could enable the shared use of spaces in times of extreme events. Developments should be encouraged to be responsive to the needs of the community and feed into the built environment web instead of acting in isolation. Providing agency to architects and engineers will allow them to respond to these demands, emboldened by the power of data and technology. Connecting our built environment together will provide resilience to the people within it and create a flourishing ecosystem.