What is a net zero carbon building, really?

In the last few years, we’ve seen an explosion of interest and claims around buildings being ‘net zero carbon’. But with no agreed definition in place on what that means and how it is measured, it can mean different things on different projects, causing confusion among stakeholders.

Put simply, the term ‘net zero’ refers to a state in which the greenhouse gases going into the atmosphere are balanced by removal out of the atmosphere.¹

In 2019, the UK Government committed to achieving net zero across the economy by 2050². Given the built environment is directly responsible for 25% of the UK’s carbon footprint³, understanding what net zero means in practical terms for buildings has never been more important.  

Voluntary industry guidance has gone a long way in setting the direction so far. Among the most widely adopted are the principles set out in the UK Green Building Council’s Net Zero Carbon Buildings Framework Definition, along with the Low Energy Transition Initiative’s (LETI) net zero design targets set out in its Climate Emergency Design Guide.

These have helped create a broad consensus that net zero carbon buildings must take a ‘whole life carbon’ approach, tackling both embodied carbon (primarily from construction) and operational carbon (from energy in-use). But an industry-agreed methodology for calculating, benchmarking and, importantly, verifying, net zero carbon performance remains elusive.

Until the establishment of the Net Zero Carbon Buildings Standard.

Figure 1: UKGBC’s Net Zero Carbon Buildings Framework Definition sets out principles to tackle carbon across the whole life of a building.

Setting the standard for net zero

Currently under development, the NZCB Standard is being created by experts across the built environment and will set robust performance targets for verifying that buildings are designed and delivered in line with the UK’s required rate of decarbonisation.

These targets will challenge stakeholders across the built environment to strive beyond what is currently considered achievable, to what the UK’s carbon budget demands⁴.

Just like NABERS UK is doing for the energy efficiency of offices, the NZCB Standard will reshape the industry’s understanding of a net zero carbon building: reducing ambiguity of what ‘good’ looks like, improving transparency for customers and reducing the risk of greenwashing. This could also further stimulate demand for net zero carbon buildings, helping to create a virtuous cycle.

How is Lendlease supporting?

As part of our UK Sustainability Development Standards, we require all our projects to undertake whole life carbon assessments to help them achieve a minimum LETI 2020 band ‘C’ upfront embodied carbon target (and 2030 band ‘A’ as best practice).  

So, when the NZCB Standard issued a callout for embodied carbon data to help understand the industry’s current levels of performance, we were more than happy to respond.

We provided anonymised embodied carbon data for 12 of our projects that were recently submitted for planning permission. This included a mix of residential and commercial projects, alongside key building information (e.g., RIBA Stage, floor area, modelling assumptions, etc.) to allow data to be compared across projects. 

Whilst we are progressing well on our Mission Zero journey in Europe, having reported a 53% reduction in Scope 1 and 2 emissions in our latest Mission Zero Progress Update, and are making headway to tackle our more challenging Scope 3 emissions, we can’t do this alone.

The NZCB Standard will help drive much needed consistency and clarity for the industry, ensuring that we are all pulling in the same direction. This is critical to limiting global warming to 1.5°C, avoiding the worst impacts of climate change and achieving our goal of Absolute Zero Carbon by 2040.

What’s next?

The NZCB Standard team are analysing industry data and aim to have targets set and an output ready later this year. With its release we will (hopefully) have a definitive answer to the question: What is a net zero carbon building, really?

The Lendlease Sustainability team in the UK will be staying close to the action and look forward to trialling it on our projects in the near future.

¹ University of Oxford (2023), What is Net Zero?: https://netzeroclimate.org/what-is-net-zero/

² Climate Change Committee (2023), Reaching Net Zero in the UK: https://www.theccc.org.uk/uk-action-on-climate-change/reaching-net-zero-in-the-uk/

³ UK Green Building Council (2021), Net Zero Whole Life Carbon Roadmap: A Pathway for the UK Built Environment: https://www.ukgbc.org/ukgbc-work/net-zero-whole-life-roadmap-for-the-built-environment/

⁴ Department for Business, Energy & Industrial Strategy (2021), UK enshrines new target in law to slash emissions by 78% by 2035: https://www.gov.uk/government/news/uk-enshrines-new-target-in-law-to-slash-emissions-by-78-by-2035