Saving £100 on your SAP calculations means little if the resulting specification costs you thousands more to build.
A cheap SAP calculation for your new build can be good value. But comparing the fee alone tells you very little about the work behind it. The useful question is whether your assessor has allowed enough time to understand the project, check the details and help you make sensible decisions.
Are you buying a calculation or help with the design?
SAP software produces the result. The assessor decides how to model your home, checks the information and explains what the result means.
That involves more than measuring drawings and selecting a heating system. It means investigating specifications that are unclear, finding the right product data and checking that the assumptions reflect what you intend to build.
A very low fee leaves less room for that work. If the next assessment is booked immediately afterwards, how much time is available to investigate your junction details or compare alternative specifications?
You do not necessarily need the most expensive assessor. You need to know what attention your project will receive.
The details can change the result
‘Air source heat pump’ is not a complete specification. Neither is ‘MVHR’. The selected equipment, its performance data and the way it will be installed can affect the calculation.
A thorough assessor will make reasonable efforts to identify the actual models and use the correct product data. That might mean checking the manufacturer’s information, searching the product database or asking your installer for clarification.
The Product Characteristics Database includes heat pump records with specific model and installation conditions. Those details matter when choosing the entry for an assessment.
Defaults have a place where the relevant information is unavailable. They should not become a shortcut when the product has already been selected and suitable data can be found.
The same attention belongs in the fabric assessment:
- Does the insulation match the performance and thickness you plan to install?
- Do the thermal bridging values apply to your junction details?
- Is the airtightness target realistic for the proposed construction and ventilation?
- Are the window and door figures based on the products you are buying?
A model built around vague assumptions can send the design team looking for improvements the project may not need.
A pass is not always the end of the conversation
If the design passes with a particularly expensive specification, it is worth asking whether all of it is needed to achieve the intended result.
There may be scope to change an insulation product, adjust a thickness or reconsider a system without losing compliance. Equally, a feature might be there for comfort, acoustics or another design reason. A useful assessment helps you understand the choices.
That does not mean reducing everything to the bare minimum. It means knowing where your money is making a difference.
If the SAP fails, what is the best use of your budget?
‘Add more insulation’ is not much help on its own.
Your assessor should explain which target is failing and investigate practical ways to address it. A fabric energy efficiency shortfall needs a different response from an emissions shortfall. Solar panels, for example, do not solve a failing fabric energy efficiency result.
Comparing options is where the assessment becomes useful. Better junction details, changes to the glazing, improved airtightness, heating choices or additional renewables can have very different costs and effects.
The aim should be to identify improvements that offer good value for your particular design, rather than handing over a failure report and leaving you to guess. Our guide to fabric energy efficiency failures explains that distinction in more detail.
Check the whole quote, not just the headline fee
Before comparing two SAP quotes, check:
- The stage: Design SAP, As Built SAP, or both?
- The documents: which reports, certificates and U-value calculations are included for your project?
- Advice: will the assessor explain the result and discuss improvements?
- Revisions: what changes are included, and when would another fee apply?
- Completion: what will the later assessment and EPC cost?
Our SAP calculation prices show the assessment fees and the reduced As Built follow-up fee when we completed your Design SAP. Comparing the full scope is more useful than comparing two starting prices.
Good value comes from a useful assessment
At Hemcalcs, advice and reasonable revisions are included. We review the details, explain the result and help you find practical changes where they are needed.
For a new home, you can see what our new build SAP service includes and book online. If you have an existing assessment you are concerned about, or a project that needs discussing first, send us your plans for a quote.
