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Design guidance for the climate emergency

30 January 2020

The RIBA declared a Climate Emergency in June 2019. That year, it also launched the 2030 Climate Challenge, urging chartered practices to commit to a target of net zero carbon emissions for all new buildings and major refurbishments by 2030.

To help practices understand the targets in terms of operational energy, embodied carbon and water use, the RIBA has produced guidance which explains the different targets and clarifying what net zero really means in practice.

Two new, valuable documents were published this week and made free to download by the London Energy Transformation Initiative (LETI). These documents provide detailed suggestions and targets that will be helpful - not only to architects, but engineers, policy makers and clients too. One is LETI’s Climate Emergency Design Guide; the other is their supplementary Embodied Carbon Primer.

“We wanted to define what ‘good’ looks like, in terms of zero carbon emissions of buildings,” explains Clara Bagenal-George, LETI’s founder and an engineer at Elementa. “The Design Guide shows ways to reach the targets.”

She is keen to point out the urgency of the 2030 goal. It means that, in practice, all buildings being designed in the UK need to be net zero carbon by 2025. It follows that at least 10% of buildings being designed need to be net zero now, in 2020.

Fortunately, the Climate Emergency Design Guide offers detailed guidance to practices as to how to achieve this. It establishes five areas to address for a net zero carbon outcome: operational energy, embodied carbon, the future of heat, demand response, and data disclosure.

One of the Design Guide’s many strengths is that it focuses on four building archetypes: small scale residential, medium and large-scale residential, commercial offices, and schools. One of the appendices breaks down suggested actions by their RIBA stage.

Architects can turn to the page on ‘small scale housing’, for instance, and quickly inform themselves of targets for a building’s operational energy by feature or activity. These include a ‘window areas guide’, broken down by percentage of wall area they should cover, be they facing north, east, south or west.

While the 2030 net-zero targets are a challenge, there is an increasing amount of knowledge being shared to enable practices to meet them: © LETI.

Similarly, targets are provided for efficiency measures such as air tightness, thermal bridging, G-value of glass and MVHR (mechanical ventilation heat recovery). Fabric U-values are suggested for walls, floor, roof, exposed ceilings or floors and doors. An overall target is given to reduce overall energy consumption to 35 kilowatt hours per square metre per year, and to reduce space heating demand to 15.

On the same page, the typical embodied energy of small-scale housing is explained via clear and precise pie charts: superstructure and substructure being responsible for the most carbon. Similar detailed, accessible information is provided, both for operational energy and embodied carbon, for the other three building typologies.

Bagenal-George points out that unrealistic expectations for savings in operational energy is shunted on services engineers: architects need to be factoring the building’s in-use energy into their designs. “With operational energy, the most an engineer can do is divide it by three,” she states. “Form and design; how many windows there are, and where are they placed, plus what the thermal mass is: these are critical. This is a design responsibility.”

The guide recognises that its ambitions can only realistically be achieved with co-operation across the built environment industry and with regulatory change. “Regulation and policy must be implemented quickly so that the minimum standards are set to deliver net zero,” it urges.

It also points out that 'the most aspirational designer can be limited by a client with a narrow strategic vision, and the most aspirational client can be limited by design teams unskilled in delivering net zero carbon'.


Tucked away in the LETI’s Embodied Carbon Primer are appendices that will be very helpful in this regard. One is entitled ‘How to talk to your client’ and it sets out cost and quality benefits of zero-carbon builds, anticipating and answering concerns that architects may be familiar with.

Its neighbouring ‘Material guides’ explain the carbon costs of common materials such as bricks, concrete, glass, timber and steel, providing case studies and links to further resources. The document is worth downloading for these alone: they are an invaluable primer.

Architects may well be apprehensive at the perhaps steep learning curve that designing for net zero targets entails. However, as Bagenal-George points out, architects are well-practised when it comes to experimenting with new materials and finding alternative solutions.

“The knowledge will either be in-house or developed via a relationship with consultants,” she states. “But I hope that eventually we will not need sustainability experts: we will become obsolete! The more knowledge we can all share, the easier the transition will be.”

Thanks to Clara Bagenal-George, Founder, LETI.

Text by Neal Morris. This is a Professional Feature edited by the RIBA Practice team. Send us your feedback and ideas

RIBA Core Curriculum Topic: Sustainable architecture.

As part of the flexible RIBA CPD programme, Professional Features count as microlearning. See further information on the updated RIBA CPD Core Curriculum and on fulfilling your CPD requirements as an RIBA Chartered Member.

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