On achieving net zero carbon verification for operational energy

By Suzanne Goulder

19 October 2021

Feilden Fowles' studio has recently been verified as net zero carbon for operational energy under the UKGBC framework. Having undertaken the verification assessment, we’re proud to have contributed to this great achievement, an important milestone towards their commitment to the RIBA 2030 Climate Challenge targets.

We audited Feilden Fowles Architects’ report Feilden Fowles Studio UKGBC Net Zero Carbon Buildings Report” to show that they had achieved net zero carbon for operational energy related emissions for the period April 2019 to March 2020 in line with UKGBC’s Net Zero Carbon Buildings Framework.

The audit and report writing were carried out by myself, Engineer at Max Fordham, and my colleague Hareth Pochee, Principal Engineer at Max Fordham. We verified Feilden Fowles’ report against the requirements set out in the documents published by the UKGBC at the time of writing in March 2021, to provide assurance on sources and methods used to determine net zero carbon. 

The UKGBC Net Zero Carbon Buildings Framework was introduced in 2019 and sets out definitions and principles relating to net zero carbon (NZC) buildings for both construction (embodied emissions) and operational energy related emissions. Since its publication in 2019, the UKGBC has published additional documents, which further develop and, in some cases, superseded information contained within the original framework document. The relevant documents were therefore as follows:


“Net Zero Carbon – Operational Energy” is defined by the UKGBC as follows:

“When the amount of carbon emissions associated with the building’s operational energy on an annual basis is zero or negative. A net zero carbon building is highly energy efficient and powered from on-site and/or off-site renewable energy sources, with any remaining carbon balance offset.”

In their new guidance published in 2021, UKGBC set out requirements for achieving NZC for operational energy. The requirements had to be demonstrated by Feilden Fowles in their report, by ensuring that all the information required in the UKGBC minimum reporting template was provided.

Here's what had to be demonstrated for verification:

1.       Reduce operational energy use

UKGBC NZC targets for offices was published in 2020. This document sets out energy performance targets that offices should aim to achieve. The UKGBC are planning to release energy use intensity targets for other building archetypes soon, which are likely to be similar to RIBA 2030 and LETI Climate Emergency targets.

NZC can be claimed under the following circumstances:

  • The building does not meet the interim energy performance targets specified above, however has an action plan to achieve them. Feilden Fowles' studio was very close to meeting the interim energy performance target for 2020-25 and they have a plan to redevelop the building in the next year.
  • The building achieves or exceeds the interim energy performance targets

2.       Increase renewable energy supply

This step aims to encourage buildings to phase out fossil fuel usage completely. This could be done by producing your own renewable electricity, or purchasing renewable electricity. At the moment, Ofgem only recognises three UK suppliers as providing "high quality green tariffs" - Ecotricity, Good Energy and Green Energy. On auditing we found that Feilden Fowles already has a 100% electric building powered by energy from one of these suppliers!

3.        Offsetting

Any remaining gas or non-renewable electricity must be offset with a UKGBC recognised offsetting scheme. Given the 100% renewable energy procurement, Feilden Fowles' didn't need to procure any offsetting, however they have decided to voluntarily procure and re-wild a plot of brownfield land with woodland to help sequester carbon on a long-term basis.

4.       Public disclosure

All buildings achieving NZC for operational energy must publicly disclose information with third-party verification using the UKGBC’s minimum reporting template. This disclosure includes total energy consumption, annual CO2e emissions and carbon offsetting approach taken.

Why it’s important

With this year's updates to UKGBC documentation, it has become more challenging to achieve NZC for operational energy status. The new UKGBC levels of performance document places more emphasis on ensuring the energy performance targets are met and fossil fuels are phased out; and that offsetting is used as a last resort. If there is no trajectory plan to meet UKGBC energy performance targets or phase out fossil fuels, NZC cannot be claimed.

We think that Feilden Fowles’ studio could be one of the first projects to have achieved UKGBC NZC for operational energy status using the current UKGBC methods. To achieve this, they’ve ensured their studio is highly energy efficient and uses 100% renewable electricity (under a high-quality green tariff) and have an action plan for future building improvements which involves relocating and redeveloping the building.

What this audit really highlighted to me are the challenging energy use intensity targets that have to be met to achieve NZC. This, to me, has really emphasised the importance of the reducing energy usage and considering the efficiency of building fabric during design.  


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