The drive for net zero carbon in construction and real estate represents an unparalleled development in the history of green buildings. There has been a fundamental shift in how we understand carbon emissions and the evolving and expanding definition of net zero carbon exemplifies this change.
Initially, net zero carbon referred to operational emissions. The first frameworks and best practices focused on existing buildings and the emissions they produced. However, in just a few years the pendulum has swung backwards. Much more attention is now centred on the amount of carbon emissions that are generated by construction. Of all the carbon emissions a building will generate over its lifetime, about half occur before it is even occupied. The decarbonisation of the grid in the UK makes the situation for new buildings (and major refurbishments) even more difficult, since so much carbon is required in the making (and not the running) of buildings.
This newfound focus on how buildings are made – their ingredients, how far components have had to travel, how much materials have been processed – is striking, but not entirely surprising. After all, other industries have faced these issues for years. If the questions around net zero carbon sounds familiar, they ought to – the food industry has been grappling with these questions for decades.
In this article, we explore how taking a plant-based approach to buildings, both in terms of operations and components, can help you find new opportunities and de-risk what is likely to be an ever-increasing focus on the whole life cycle of buildings.
Net zero carbon: the early years
In its initial formation, net zero carbon applied primarily to the operation of buildings. To achieve net zero carbon operationally, buildings had essentially two options: 1. produce renewable energy onsite and/or 2. procure renewable energy from on an offsite provider. Without the availability of renewable energy (primarily from offsite providers) the concept of net zero carbon simply made no sense.
Like plants, the buildings of the future (if they are to be net zero) will need to rely on renewable energy for all or most of their power. As the definition of net zero continues to tighten, there is an expectation that a greater percentage of renewable energy will need to come from onsite renewables. The most available technology for achieving onsite renewable energy is photovoltaics, which have been compared to the leaves on a tree, which are also solar receptors and energy converters.
On the operations side, buildings are beginning to realise that plant-based processes will be key to longer term net zero carbon goals. Not only do plants rely on renewable energy but they also store energy that is not currently being used. The next step for net zero carbon buildings is also storage of energy from intermittent sources in batteries.
Net zero carbon expands
Almost from the beginning it was clear that the first definitions of net zero carbon were both too easy to achieve and insufficient to capture major sources of carbon emissions. The availability of offsite renewable energy meant that buildings could simply switch to a renewable supplier without making significant changes to operations, including reducing consumption. That is why later versions of net zero carbon frameworks contained energy use intensities (EUIs), which are essentially limits on how much energy the whole building can use.
More importantly, the focus on operational energy was too narrow in terms of thinking about carbon, ignoring the almost 50% of a building’s whole life carbon emissions generated by the production, transportation, and assembly of materials. Any serious discussion around net zero carbon buildings now focuses on “whole life carbon” and includes all impacts from the inception of the project to the demolition of the building.
The time span between the first net zero carbon frameworks that focused on operational energy and later formulations that included whole life carbon was less than a decade. In terms of rapid redefinition, expansion, and adoption, this is a remarkable development. But we are not done - the concept continues to evolve. That is why it is important to remember that net zero carbon, even in it most expansive definition, is still just a starting point. Net zero carbon is more than a discussion about carbon – it is the beginning of an inquiry into building ingredients and operations more generally.
What’s in the box?
Net zero carbon is now largely a question of how buildings are made. The focus on embodied carbon is really a question about ingredients and manufacturing processes, and so the sustainability lessons from other industries are both appropriate and instructive.
We know from the food world about simple and natural ingredients, the impact of transportation or “food miles,” the negatives of highly processed foods, and so on. The sustainability message for food is a clear one – natural, local, minimally handled and plant-based ingredients are better for the environment (and people).
As with food, building materials that are more local, natural, and less processed are much more likely to be lower in embodied carbon. Bio-based materials typically have lower embodied carbon, with timber around three times less than steel and over five times less than traditional concrete. Plant-based materials also sequester carbon, meaning that as they grow, they absorb carbon and store it, locking it into the material for lifespan of its use.
There is a reason why timber is at the very core of all low carbon building discussions - it sequesters carbon naturally, grows renewably, requires a minimum of energy-intensive manufacturing, is available almost everywhere and is reusable. As with renewable energy, it is nearly impossible to talk about net zero carbon without the adoption of timber - our recent mass timber forum series unpacked opportunities for building with timber, challenged the barriers currently being faced by the industry and debated what the future could be for these products.
But it is not just timber. Bamboo, hemp, fungi, and even agricultural waste are gaining credibility as low carbon, low impact building material substitutes and can be used in a variety of applications. Cork can be used as flooring, rigid insulation, and external cladding. Hemp can used be used for robust cladding panels and roofing tiles. Straw’s properties enable it to be used as insulation or as part of prefabricated external wall systems.
It is not the case that plant-based materials can do everything that more manufactured materials can. For example, it is more difficult to build tall buildings without concrete and steel, although not impossible. On the other hand, it may be that plant-based materials begin to help shape the direction of design.
Good for the environment, good for you
While net zero carbon is a top concern among many occupiers, it is not the only consideration. Buildings that promote health and wellbeing are also sought after. Here, too, a plant-based approach offers insights into buildings that simultaneously promote lower carbon outcomes and deliver healthy environments.
It works for both plant-based products and processes. The use of simple, natural low carbon components such as timber and plant-based paints, finishes, textiles have both physical and mental benefits in terms of promoting cleaner and calming environments. The benefits of these are numerous – fewer chemicals and off-gassing, improved air quality, noise reduction, etc. Because people prefer natural environments there are also conducive to producing less stressful, more welcoming spaces.[1]
Likewise, approaching building functions using a plant-based mindset can simultaneously lower carbon while increasing healthy building credentials. The appropriate use of sunlight and shading, natural ventilation, using materials that reduce toxins and clean the air and creating open spaces (with fewer materials) are all things that a plant-based approach advocates and which lead to lower carbon, healthier buildings.
Other “net zero” concepts
In terms of following plant-like processes, net zero carbon buildings are still primarily at the early stages. But we are already beginning to see buildings that sequester CO2 in a way like plants, and other buildings that filter the air for pollutants using passive solutions.
It is not likely to end there. Plants store water and then release when needed – effectively becoming net zero water. Plants biodegrade without harm and can be recycled back into nature without additional energy – in a nutshell, net zero waste. Now, the industry focus is on net zero carbon, but it is generally agreed that water and waste are the next areas to be developed as part of ESG. Following the operational principles of plants is a good bet as the net zero agenda and what that encompasses widens.
Conclusion
Whether it refers to the operation of buildings or their construction, a plant-based approach is a useful framework for addressing net zero carbon goals. Plants run on renewable energy, they store intermittent energy for when it is needed, and they sequester carbon that is in the environment. This is the road ahead for buildings.
Plants are renewable sources of material, regenerative and not extractive. This is not only less carbon intensive but also much more sustainable longer term. Plants have the capacity to be used with minimal processing and are widely reusable and recyclable with a minimum input of energy. In terms of a circular economy and limiting whole life carbon emissions, it is difficult to beat the example set by plants.
To be sure there are impediments to the widespread adoption of plant materials and a plant-based approach. The state of the market is young, regulation can discourage their use (although this is changing), and a willingness to change practices can be strong barriers. But at a time when net zero carbon is forcing a reconsideration of buildings on an unprecedented scale, these impediments may not seem so large.
Other industries facing questions about provenance, manufacturing, environmental impacts, and health benefits have moved in the direction of plant-based alternatives as an answer. There is much opportunity for the construction and real estate industries to successfully follow this example.
Our work in this area
At G&T, we understand the emerging importance of using biophilic materials and processes in our projects, leading on cutting-edge examples such as the Black and White Building and Hardman Square Pavilion. If you’d like advice on how a plant-based approach could help with your next project, get in touch with one of our experts today.
References
[1] For a comprehensive assessment of the green and healthy benefits of these types of materials, please this landmark report by the World Green Building Council.
