About Hemcalcs
Practical energy assessment advice, grounded in building experience.
We help architects, builders, developers and homeowners with SAP calculations, U-value calculations and energy compliance advice for projects across the UK.
From the first drawings to the final assessment, our aim is to make the requirements clear and help you make informed decisions about your build.
Building experience behind every calculation
I'm Ian Kay, the assessor behind Hemcalcs. I'm an Elmhurst-accredited On Construction Domestic Energy Assessor (OCDEA), with a background in building work.
Before moving into energy assessment, I worked on site laying foundations, building walls and fitting insulation. That experience still shapes the way I look at drawings and specifications today.
A recommendation has to make sense for the building, the budget and the people doing the work. When a specification needs attention, I explain what is affecting the result and help you work through practical options.
Whether you're planning your first extension or managing a development, you should be able to understand the advice and know what to do next.
Qualified to understand the whole building
SAP assessment is our core work. Ian's wider qualifications bring an understanding of existing buildings, heat loss and the way different parts of a building work together.
Elmhurst-accredited OCDEA
On Construction Domestic Energy Assessor, accredited in 2025. This covers SAP assessments for new homes, including design and as built calculations, supporting reports and EPC lodgements.
Verify Elmhurst membership: EES/026337 (opens in a new tab)
View certificate: Ian Kay, OCDEA (PDF, opens in a new tab)-
Domestic Energy Assessment
Level 3 Certificate · 2022Assessment of existing homes, their construction and energy performance.
View certificate: Domestic Energy Assessment (PDF, opens in a new tab) -
Non Domestic Energy Assessment
ABBE Level 4 Diploma · 2023A wider grounding in building fabric, services and energy assessment.
View certificate: Non Domestic Energy Assessment (PDF, opens in a new tab) -
Surveying and Calculation of Building Heat Loss
ABBE Level 3 Certificate · 2023Understanding how heat is lost through a building and calculating heating demand.
View certificate: Surveying and Calculation of Building Heat Loss (PDF, opens in a new tab)
Practical advice for the decisions that matter
A useful assessment helps you understand your options. We take the time to look at the design, explain the results and identify the next steps.
Understand the design
We review your drawings, construction details and proposed systems. If information is missing or something needs clarifying, we explain what we need and why.
Compare useful changes
Where a specification needs adjusting, we look at the details affecting the result. We can model relevant changes so you can weigh up the options before committing to them.
Make the next step clear
You get an explanation of the results and the information needed for your next assessment stage. If the design changes, tell us so the calculations can reflect it.
Support for your project
We work from your drawings and specification on projects across the UK. Find out how we can help with your type of build.
New builds
SAP calculations and practical support for new homes, from design assessments to as built EPCs.
Explore new builds servicesConversions
Energy assessment advice for projects creating homes through a conversion or material change of use.
Explore conversions servicesExtensions
Glazing checks, U-value calculations and SAP comparisons to help assess your extension design.
Explore extensions servicesSend us your plans and tell us where you are in the project. We'll confirm the scope of work, the price and the expected turnaround before you decide to go ahead.
