For anyone looking to go beyond the requirements of building regulations, those benchmarks can still form the basis of alternative performance targets. There are other schemes and guidelines that a client, designer, specifier, or contractor might consider using to demonstrate the efforts being made on a project.
Using building regulation compliance as a benchmark for net zero
For domestic buildings, the energy efficiency requirements of building regulations are assessed via SAP calculations. The proposed building is modelled against a theoretical ‘notional’ building, the performance of which must be matched or bettered to meet the regulations.
As a compliance tool, SAP is designed to provide a certain set of outputs. The broad intention is to allow different dwellings in a variety of locations to be compared through their EPCs. Nevertheless, many within the industry use it as a design tool – and it can be used as part of a net zero strategy.
For example, by taking the target emission rate (TER) set by SAP, and then aiming to achieve a dwelling emission rate (DER) that is a 100% reduction compared to the TER, it can be demonstrated that a building can achieve net zero regulated carbon. This was the approach adopted on the Europa Way project that Darren Evans provided consultation and calculation services for.
How does the performance gap impact on net zero carbon?
Where national building regulations and SAP tend to falter is in translating the predicted performance into real-world performance. This is the performance gap that has been talked about in construction for a long time and still remains a current issue.
Having a net zero building on paper is one thing, but it is another thing entirely for the UK construction industry to achieve net zero in practice.
The actual energy use and carbon emissions of buildings can be up to 2.5 times what was estimated at design stage – and sometimes more. That figure is compared to existing levels of performance, not net zero specifications.
The introduction of Part L 2021 set out measures to try and address the performance gap, including requiring photos from site as evidence of what has been installed.
There are questions as to how effective this requirement will be, and there is little doubt that on site practice has a long way to go to deliver the levels of performance needed from buildings. None of this is to say that it cannot be done, but a wider change in culture and quality control is required.
How can voluntary standards help meet performance targets?
Where project teams want to use alternative benchmarks to go beyond building regulations, they can look to a range of non-regulatory (voluntary) standards – especially for non-domestic projects.
BREEAM is arguably the most well-known certification scheme for new buildings (especially non-domestic buildings). It takes a broad view of sustainability, with the energy performance of the building being just one area of performance. Embodied carbon is addressed by BREEAM through the Man 02 and Mat 01 criteria. At the time of writing, however, the Building Research Establishment has not developed a net zero carbon standard of its own.
By contrast, the London Energy Transformation Initiative (LETI) has produced a ‘Climate Emergency Design Guide’, which sets out operational energy targets, and targets to minimise embodied carbon, based on building type (including residential).
It gives building fabric specifications and design advice and suggests which areas of life cycle assessment should be targeted to make the biggest embodied carbon savings.
It is ‘only’ guidance, however. No formal certification exists and therefore neither does a database of buildings that can be used as case studies. Despite this, there is increasing adoption of LETI’s targets within UK construction. Anybody looking to achieve net zero operational carbon and lower embodied carbon would therefore do well to start with LETI’s publications.
Other standards include Leadership in Energy and Environmental Design (LEED), a US standard that includes LEED Zero Carbon certification. The German Green Building Council publishes the DGNB (Deutsche Gesellschaft für Nachhaltiges Bauen e.V) Climate Positive standard. And the US-based International Living Future Institute (ILFI) has a Zero Carbon certification programme.
All take a different approach to how they address operational and embodied carbon, so it is important to be aware of what is required and to ensure it aligns with a project’s goals. Several of these schemes rely on post-occupancy monitoring, with certification only awarded after the first year of the building’s use.
Most recognise that annual operational carbon can be met and exceeded, but the approaches to embodied carbon and the acceptability of carbon offsetting vary.
About the author
Darren Evans - Business leader connecting with people to treat people and planet as the precious resources they are so that we can build a better future together https://darren-evans.co.uk/