If you’ve come across the term “SAP assessor” and aren’t quite sure what distinguishes them from an energy assessor, an EPC assessor, or anyone else with “energy” in their job title, here’s a straightforward answer: if you’re working on a new build, conversion, or significant renovation, you’ll need one at some point in the process, and this covers what the role actually involves and how to choose the right one.
In This Blog, You’ll Learn:
- What a SAP assessor does, and what “OCDEA” means
- When you actually need one
- How a SAP assessor calculates energy performance
- What to look for when choosing one
Understanding the Role of a SAP Assessor
A SAP assessor – also known as an On Construction Domestic Energy Assessor (OCDEA) – is a qualified professional who carries out Standard Assessment Procedure (SAP) calculations: the legally required method for demonstrating that new dwellings and conversions comply with energy efficiency regulations under Part L of the Building Regulations.
As an SAP Assessor, I help shape sustainable homes, reduce carbon footprints, and create a greener future – one assessment at a time. All while navigating the complexities of renewable energy systems and low-carbon heating, which don’t always align with compliance requirements and EPC expectations.
Richard Millard, Senior Sustainability Consultant at Building Energy Experts.
For the foundational question this post assumes is already answered – what a SAP calculation actually is, and whether your project needs one:
When Do You Need One?
If you’re constructing a new home, converting a building into residential use, or making significant changes to an existing dwelling, you’re required to provide SAP calculations to demonstrate compliance. A SAP assessor will:
- Model the building’s design and energy performance using approved software
- Confirm compliance with Part L before construction begins, and provide compliance reports – BREL in England, BRWL in Wales (Building Regulations England/Wales L)
- Advise on energy-efficient improvements if the initial assessment falls short
- Provide an EPC on completion
How Does the Calculation Work?
A SAP assessor uses architectural plans, insulation details, heating specifications and ventilation system information to model predicted energy performance – reviewing design specifications, running the calculation to determine energy demand, CO2 emissions and expected running costs, then advising on modifications if the property doesn’t initially meet compliance. A final compliance report and EPC follow on completion. For the full stage-by-stage breakdown of how this runs from design through to as-built, see our SAP Assessment Process post.
Choosing a Qualified SAP Assessor
SAP calculations must be carried out by an accredited professional registered with a recognised body such as Elmhurst Energy. Worth checking for:
- Experience with similar projects – new builds, conversions or extensions specifically
- Accreditation with an official SAP certification body
- Willingness to give practical energy efficiency advice beyond the minimum compliance figure
What Sets an Assessment Apart
Our SAP assessors bring a unique level of attention to detail and a client-focused approach to every project. We don’t just tick boxes – we help you optimise their building’s energy performance for long-term efficiency and comfort.
What’s Next?
Choosing the right SAP assessor early, rather than treating it as a late-stage box to tick, tends to be the difference between a design that passes comfortably and one that needs expensive last-minute changes.
Need a SAP assessor for your project? Our accredited team can talk you through what’s needed and get your assessment booked in.
Keep Informed
Get practical insights on retrofit, decarbonisation and compliance, delivered straight to your inbox.
"*" indicates required fields