In an interview, CIBSE's Head of Net Zero Policy, Julie Godefroy, sat down with CIBSE's PR & Communications Manager, Panos Balalas, to discuss the UK's new Net Zero Carbon Buildings Standard (UKNZCBS). This ambitious initiative aims to establish a unified standard for achieving net zero emissions in the built environment, responding to strong industry demand for clarity and consistency. The standard is designed to align with the UK's commitment to limiting global warming to 1.5°C and achieving carbon budgets for 2035 and 2050. CIBSE's active role, alongside eight other leading organisations, underscores the collaborative effort to address the complexities of operational energy and embodied carbon, ensuring that the new standard is both ambitious and achievable. Through their comprehensive approach, Julie Godefroy and her colleagues hope to transform how developers, architects, and stakeholders approach net zero, ultimately paving the way for a sustainable future in building design and construction.
Read Julie’s interview about UKNZCBS, below:
Julie, can you describe the main objectives of the UK's new Net Zero Carbon Buildings Standard and what it aims to achieve for the built environment?
The aim is to provide a single standard on what is required to achieve net zero. There was a very strong industry steer towards this. Industry wanted one single standard, not a range of initiatives. So that's the first, to respond to industry requests and needs. The objective is that these requirements have been developed to be aligned with the UK built environment on a trajectory to 1.5°, which means meeting our carbon budgets to 2035 and 2050, and also the associated electricity budgets.
What role does CIBSE play in the development of this new standard, and why is this initiative important for the organisation?
CIBSE has been involved from the start, we were one of the founding members of the Technical Steering Group. As Head of Net Zero Policy at CIBSE, I am on the Technical Steering Group and led the Task Group focused on operational energy. In addition, we've had a CIBSE representative on the Governance Board from the start – previously the current CIBSE President Fiona Cousins and now CIBSE’s Technical Director Anastasia Mylona.
How did CIBSE and the other eight leading organisations come together to create this standard? What was the process of collaboration like?
The collaboration built on initiatives that a few organisations had already been working on. For example, the UK GBC Net Zero framework and the roadmap, and the CIBSE-LETI net zero FAQs which were produced early 2022. These net zero FAQs were led by CIBSE and LETI but then were endorsed by a number of organisations. So there were already very active discussions among quite a few of us about the need to standardise the discussions and the requirements around net zero. The collaboration is fantastic, and we don’t know of another such significant collaboration in the field of net zero that has happened with an actual outcome like this, there are many cross-industry groups, but to have produced something so significant collaboratively is quite rare, so it's fantastic. It can mean that some things take a bit longer, to reach consensus, but the outcome really is better.
What were some of the key challenges faced during the development of the Net Zero Carbon Buildings Standard, and how were they overcome?
Obviously, there were technical challenges, if this was easy, it would already have existed. Some of the challenges was to source the right data. Both the right quantity and quality of data on operational energy and embodied carbon. We had a very big call for evidence with industry contributing to this. We also had essentially the key challenge of setting principles across a huge variety of sectors, and that's why we created all the sector groups: we had task groups by themes, i.e. operational energy, embodied carbon, top-down budgets, and this set the technical principles and overall approach, in discussion with the TSG. We then had 13 dedicated sector groups plus a heritage group, to really think in more detail about the application of these principles in their sector. For example, the task group on operational energy set the principle that ‘the limits should be in annual energy use per year’, but every sector was then asked ‘what would be the right metric in your sector, should it be kWh per square meter per year, or would another metric be more suitable in your sector?’. This combination of overarching principles and sector-specific input is one of the really important ways that we've managed to tackle challenges. I would mention another one, which is probably the one that has taken the longest because it's quite complex and we needed to test a lot of scenarios and think more deeply about it: It is how to distribute efforts across the stock and where to pitch the net zero standard compared to that. We have a model that allows us to develop scenarios for a net zero compatible UK built environment, but that is independent from the standard. A huge, important and difficult point is to decide where in that net zero trajectory we pitch the standard. Is it what on average the stock has to do? Is it the top X percent better buildings, etc? This sort of philosophical question - what sort of standard do we want it to be, was probably the biggest challenge, I would say. We have pitched it to be ambitious but achievable, and to encourage retrofit of the existing stock.
How will this new standard impact developers, architects, and other stakeholders in the building industry?
We very much hope it will have a positive impact because it gives clarity. It has been developed by people from across the supply chain in the widest sense. We've engaged with stakeholders such as investors and developers through to people on the ground, designers, builders, etc. So hopefully it is very positive because it gives a trajectory for current projects and it also gives a trajectory for projects that might start in 5 or 20 years, allowing organisations to plan ahead. We really hope it will be overwhelmingly positive although there is no doubt that there will be challenges. Net zero is not going to be easy, but our approach is informed by bottom up analysis of what buildings can achieve. So, we believe that the requirements that we have in place are achievable today - and we know that some buildings achieve them today. You often see that with the best projects, the buildings that perform the best, they haven't done one particular thing that is very unusual. What is unusual is they have applied the range of best practise recommendations, and I don't mean all the best kit and all the best equipment, I mean they have spent time talking about the brief with their clients, they have spent time doing energy performance modelling, they have looked at embodied carbon from an early stage etc. This means, the design and construction processes would probably be different for some clients and projects who want to achieve the standard, thinking much more about performance outcomes from the start, as opposed to thinking about theoretical design targets and practical completion rather than real outcomes in use.
What kind of changes or improvements do you anticipate in the industry’s approach to achieving net zero carbon buildings as a result of this standard?
What is really important in the standard is the top down, bottom-up approach to be net zero aligned, but also that the standard is achieved based on actual performance. I think this is revolutionary. We at CIBSE have been promoting it for a long time. Our awards require this but very few incentives are in place in industry and in regulations for actual delivered performance, so this is transformative.
What are some of the key metrics and performance targets included in the standard? How will these metrics help ensure that buildings meet net zero carbon requirements?
The standard defines a set of metrics for net zero whole life carbon. This means we cover operational carbon and embodied carbon. Within this, for embodied carbon we have limits in upfront carbon at the moment – that’s the carbon up to the time when the building is operational for the first time through retrofits or construction, and we require reporting of in-use embodied carbon i.e. that which is spent in repair, maintenance etc, during the building use. At the moment we don't have limits for this in-use embodied carbon, but we expect we will in the future. And finally, within embodied carbon, we also have limits on the impact of refrigerants: a limit on the GWP of refrigerants and for systems above a certain size we require reporting on leakage. On operational carbon, our limits are not in carbon because the grid is decarbonising, so it would become meaningless very soon, but we can't assume that we don't need to worry about it and the grid will decarbonise regardless. We need to remain within the electricity budget, and that's a really important angle in the standard, which means our limits on the operational side are in operational energy use and obviously, limits on fossil fuels i.e. no use of fossil fuels on site except a very limited list of exemptions such as emergency use. There are then additional conditions, for example, in the case of heating and cooling networks, to put these networks on a trajectory to decarbonise. And looking ahead, as demand management will be more important, at the moment we require the reporting of peak demand in winter and summer, and in the future, it may be that we introduce some requirements related to this. Finally, because space heating and cooling are important for decarbonisation and very influenced by designers, we are putting limits on energy use for space seating; at the moment this is just for just a few sectors, with a view that this could be expanded to other sectors, to existing buildings, and to space cooling in the future.
All of these requirements are what we think constitutes whole life carbon requirements. I think it provides a framework for what projects need to think about. Even projects that are not targeting compliance with the Standard can use this set of metrics to benchmark their projects, benchmark their performance. My hope is for this to become more and more referenced even beyond the application of the Standard. If someone is making claims on a decarbonisation trajectory of their stock, where do they sit on our scale against this whole set of metrics?
And finally, we have an additional route where projects may decide, in addition to meeting all these requirements, to purchase carbon offsets, covering their residual carbon emissions. You can meet the standard without carbon offsets, and even if you have carbon offsets, you still have to meet all the requirements.
How do you foresee the Net Zero Carbon Buildings Standard evolving over time? Are there any plans for updates or additional phases in its development?
I’ve explained in the previous point how some of the requirements may evolve, for example to limit in-use embodied carbon or peak demand. In addition, we've already announced that we are working on two quite important developments. One is to allow what we call delineation: at the moment the pilot version only considers whole buildings. We know that in some sectors there's a strong demand from the market to allow recognition of separate responsibilities e.g. landlord versus tenants, so we are working on that, for example in offices, retail and logistics and warehouses. The other development is to work on equivalence schemes, for example schemes like NABERS or PassivHaus which are already offering certification, and which cover some of the elements addressed by our standard - reduction of energy use, especially. What we want is to be able to recognise some of these schemes so that if you are already certified, for example, against NABERS, you could automatically say ‘I am meeting this NABERS rating, therefore I already meet this part of the net zero Standard and don't need to prove it all over again’. You would still need to meet everything else but at least there wouldn't be a doubling up of efforts, paperwork and verification.
What does it mean personally to you, as Head of Net Zero Policy at CIBSE, to be involved in such a significant initiative?
It is probably one of the most significant projects that I will ever work on. I think that for all of us on the Technical Steering Group, it is something that in 10 years, if we are asked to say what were the most important projects we worked on, that will be one of them. Whether or not it has the impact that we hope it will have, it's a huge amount of work, it's a huge amount of people that we got to work with and to see hundreds if not thousands of people across the industry who wanted it to happen, and who are so excited it's there, that's quite important.
Download the Standard at https://www.nzcbuildings.co.uk/