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  • Writer's pictureKaren Fletcher

The Net Zero Carbon Buildings Standard

The SectorScope reports on new approach to measuring and optimising embodied and operational carbon in buildings.

At the CIBSE National Conference 2023 in London a group of experts set out the progress towards establishing a Net Zero Carbon Buildings Standard.

Chaired by CIBSE Vice President David Cooper this seminar outlined an undertaking that demonstrates what can be achieved when the industry works together. It has been driven forward by hundreds of expert volunteers including engineers, architects and sector experts.

Katie Clemence-Jackson, Sustainability Associate QODA outlined the main objectives for the Standard. These are to establish a common understanding of what we mean by a ‘net zero carbon’ building, and to create a rule book for assessing carbon in new and existing buildings across a range of sectors.

Notably, she also highlighted that this will not be an ISO or British Standard, nor certification method, so it will be available without a paywall. It’s intended to be developed collaboratively by the construction industry (and its clients) with continuous updates based on technical input.

The NZC Standard focuses solely on whole-life carbon in buildings, so other social and environmental issues are not covered. The reason is that areas such as biodiversity, occupant wellbeing and others are addressed in other existing standards.

The Standard aims to be as broad as possible, covering a range of typologies by tapping into the know-how of sector experts.

At this stage, the leading team identifies the following key property types that the Standard will eventually cover:




Warehouses / Logistics





Higher education

Sport and leisure

Commercial residential

Culture and entertainment

Science and technology

The targets for building embodied and operational carbon will be science-based and aligned with UK carbon budgets (the 1.5oC pathway). Another crucial point about this standard is that it is not constrained by or tied to government policy (although it could be adopted in future)/

It is based on outcomes, which means focusing on metered data, although embodied carbon can be modelled for calculation purposes.

Clara Bagenall George, Associate at Introba and one of the founders of the Low Energy Transformation Initiative, offered further detail on the targets for the Standard are being set.

The targets and limits for carbon are based on existing guidance and recommendations already published by construction and property organisations.

The RICS methodology and the Built Environment Carbon Database are key to the target-setting. These will form the basis for applying the Standard and act as a repository for shared performance data that will also support further developments of the Standard.

The Standard’s carbon targets will, therefore, be top-down and bottom-up. Top-down means that the targets reflect the UK’s carbon budgets, set by the Climate Change Committee. Bottom-up means considering what levels of building performance in each sector can be achieved today – and tomorrow.

Will Arnold, representing the Institute of Structural Engineers, explained how bottom-up carbon performance measures will work. Currently, the group is exploring several key questions that can help set these carbon measures across different sectors: “We are asking what levels of building carbon performance are achievable today and tomorrow.”

The group has been collecting metered data and information on best practice to develop benchmarking for today and into the future as our Carbon Budgets tighten. One of the aims of this Standard is to be driven by industry and to be practical to deliver.

This means that some issues are still being addressed, such as how to allow refrigerants in HVAC systems. Mr Arnold noted that some consideration was being given to placing limits on the GWP of refrigerants (rather than amounts) and requiring leak detection for all systems. Another question is the use of renewables on-site. While this is desirable, it must be done in a way that does not add to the overall embodied carbon of a project. These issues will be clarified in the final Standard.

CIBSE’s Head of Net Zero, Julie Godefroy offered insights into the Standard’s approach to operational carbon. She noted that there is plenty of data available to the technical teams in this area (as it’s easier to access than data on embodied carbon). However, this poses its own challenges.

“For each sector, we have developed sub-sectors and performance metrics,” she explained. “We are taking a different approach to benchmarking for each sector.”

Again, the focus is on what is currently achievable in the best-performing buildings today and asking what that might look like in the near future. Again, the technical teams working on the Standard are tackling some of the detailed issues, for example, how it will account for buildings on heat networks.

Currently, technical groups working on the standard are creating a tool that will set the targets for projects (using the top-down and bottom-up approaches), and that is undergoing testing. We can expect to see a beta test version of the Standard in Spring 2024.

One important final point made by Katie Clemence-Jackson is that the Governance Board for the Standard want a tool that is “trusted by investors and tied to green finance”. This means that it will be a trustworthy measure that can be used to make investment decisions.


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