Simon Sturgis returns to questions of how to achieve low-carbon architecture with nine key steps to involve in a climate-aware approach to architecture
What does driving down whole life carbon mean for architecture and the design of buildings as we approach the middle of the 21st century and the deadline for net zero?
Mark Carney, when he was governor of the Bank of England, said: 'We can’t get to net zero by flipping a green switch. We need to rewire our entire economy.'
This is not something that can be solved with an impressive BREEAM rating, or meeting energy targets; what this means is a comprehensive overhaul in the way buildings are designed. To achieve truly low carbon buildings, we will have to re-examine everything from the earliest design stages, including the overall shape, structural efficiency, envelope, materiality, energy use, durability, life cycle, end of life and so on. Nothing will be left unchanged. This is therefore an exciting time for architects as the opportunities for architectural innovation are multiple. We are at the threshold of the greatest change in architecture since the birth of the modern movement 100 years ago.
The climate crisis means that the planet is on course to increase temperatures by 3° centigrade, or more, by the end of this century. This will lead to the extinction of whole nations – such as the Maldives, for example – and coastal flooding to low lying areas globally – parts of Florida and East Anglia for instance – and other devasting consequences. To divert from this course requires behavioural change by all of us. The built environment is responsible for some 43% of global emissions so architects’ actions can directly mitigate climate change, or, alternatively, make it even worse. Architects need to act.
In my previous RIBA Journal articles I discussed the practicalities of whole life carbon assessment and how to do it with reference to the RICS WLCA second edition. I also covered the benefits, the business case and general assessment guidance for making low carbon buildings. We of course bring change through calculation, but we also need to develop a ‘carbon intuition’ to help us to make good, low carbon design decisions without the need for detailed assessments at every step.
This will evolve, with practice, such that we develop an understanding of how to look holistically at every design issue from the carbon and resource efficiency perspective. We need to be able to understand the impacts of our design choices not just at practical completion (PC), but well into the future. We need to know how our buildings will perform over many decades, how they can be managed and maintained, and eventually how they can be reused, adapted, dismantled and repurposed. PC is no longer the cut off in terms of our responsibilities.
Reuse of existing buildings via retrofit or refurbishment is a fundamental part of reducing both carbon emissions and the use of new resources. The Circular Economy, as in recycling (good) repurposing (better) and reuse (best), of materials and buildings will be a central part of the net zero economy. But Westminster City Council, with the proposed New Policy 43, is already in the process of enacting planning requirements that will have a clear presumption against demolition and in favour of retrofit/refurbishment. This policy is ground-breaking in the detail and will require meeting very stringent LETI Whole Life Carbon targets, which for a new building will have to be less or similar to a retrofit option. This approach will mean that within Westminster architects and design teams will be forced to ‘rewire their entire design approach’ (apologies to Mark Carney). Westminster Council is already getting a lot of interest from other local authorities, both in the UK and elsewhere, and so we can expect these sorts of conditions to be increasingly prevalent.
Low carbon focus, step by step
We still need new buildings, and today this particularly applies to housing. So, what are the key issues that architects must focus on to ensure they are making inherently low carbon choices, that will deliver good results with lower wholelife carbon?
Assessment Whole life carbon assessments should be started at the outset of the project as the greatest carbon impacts are set in stone at the earliest strategic design stages.
Existing buildings When the site already includes buildings, the first action should be to examine how best to reuse them. This is the easiest way to minimise carbon emissions and optimise resource efficiency. It is also the most circular approach to such a site. Westminster City Council, with its proposed New Policy 43, is already getting a lot of interest from other local authorities, both in the UK and elsewhere, and so we can expect these sorts of conditions to be increasingly prevalent.
Shape The overall efficiency of the shape of a proposed new building, sometimes referred to as wall to floor ratio, is a key early determinate of overall carbon and resource efficiency. Complex external shapes require more material and offer more surface with which to gain or lose heat. Compact, efficient shapes are inherently more carbon efficient.
Structure The nature and materiality of structure is a huge influence. Buckminster Fuller famously asked: 'How much does your building weigh Mr Foster?' – a prescient point that is arguably still valid. The lowest carbon structure may be to do with materials, or it may be to do with how efficiently you use the materials chosen. How elements are disassembled can be as important as what they are made of.
Envelope Fundamental issues when designing the envelope are balancing low carbon construction with long life/durability, and high quality environmental performance. A key issue is glazing. Double glazed units are a notoriously weak point in a facade as they don’t last more than about 30 years. This leads to replacements not just of glazing but also framing. All-glass facades are therefore a major problem. The maintenance and replacement of elements needs to be thought through from the outset.
Energy use The new RICS WLCA Standard enables KWh to be translated into kgCO2e. This is crucial as energy use can be designed to optimum efficiency as part of a carbon cost/benefit equation in conjunction with the facade design. Operational and embodied emissions trade off against each other to optimise both. This may seem a technical point but is a revolutionary principle that will change the way we design facades.
Interiors Life expectancy and the process of how aging and wear-and-tear are handled are fundamental issues to resolve. The choice between selecting materials that age well vs the need for regular redecoration is a balance of choices. We can now assess the comparative lifetime carbon costs of materials that can age well without maintenance against those that require regular refinishing.
Materials Many regularly used materials can be perceived to be either low or high carbon. This is usually an oversimplification. There are no default guaranteed low carbon options. Timber is often cited as the solution, but designers need to understand the disposal emissions costs as well as the sequestration benefits. In addition, an increase in timber use from the current 4-5% of construction materials to say 25% would have a disastrous impact on global forestry. From the carbon perspective, the optimum material for a task is the one that has the lowest environmental impact over its entire life cycle. The global supply chain is already innovating to adapt the existing, and to produce new products to meet today’s requirements.
Reuse, repurposing, recycling, and circularity Reusing materials in the next best thing to reusing entire buildings, provided this can be done efficiently. We should also be designing for future circularity, so that our buildings can be maintained and reused with minimum future waste or energy use.
The above pointers give a small window into design thinking for lower carbon outcomes, and will change the nature and expression of architecture. Climate mitigation will be the driver of a new and exciting architecture.
Simon Sturgis is an architect and founder of Targeting Zero