What are SAP calculations and when are they required?

SAP calculations assess the predicted energy performance of a dwelling. They are commonly required for new-build homes, conversions and certain extensions to demonstrate Part L compliance.

What is needed for an on-construction EPC?

The final SAP or SBEM model must reflect the completed building, supported by confirmed construction specifications, test results and commissioning evidence.

What does an Energy Statement include?

An Energy Statement normally describes planning policy, the proposed energy strategy, demand-reduction measures, low-carbon systems, renewable energy and the resulting carbon improvement.

CONVERSIONS & CHANGE OF USE

SAP calculations for conversions
built around what is retained.

Practical SAP assessments for buildings converted into homes, including flats, HMOs and commercial-to-residential projects.

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Model the existing building accurately

Conversions rarely begin with a blank sheet. We establish the retained walls, roofs, floors, openings and services, then model the proposed dwellings against the requirements that apply to the actual scope of work.

Resolve constraints through the model

Limited floor build-up, retained façades, head-height restrictions and existing openings can make standard details impractical. We quantify the effect of each constraint and test realistic improvements elsewhere in the design.

Design stage through to EPC

The initial SAP identifies the route to compliance. At completion, the model is updated using final specifications, air-test results and installation evidence so the as-built reports and EPCs can be produced.

RELEVANT PROJECT EXPERIENCE

Similar buildings.
Practical outcomes.

Selected anonymised examples showing how the assessment supported design, compliance or completion.

London conversion

Existing building converted into seven flats

Seven dwellings were assessed using the retained construction and proposed upgrades, with common assumptions coordinated across the development.

A consistent design-stage compliance package was prepared for the full conversion.

Three-flat project

As-built evidence brought together for completion

Final construction and services information was reconciled across three flats before the completion models were issued.

The completed dwellings achieved EPC ratings of 67, 74 and 68.

COMMON QUESTIONS

Clear answers.
No guesswork.

01Are retained elements treated differently?+

Yes. The applicable treatment depends on the element, its condition and the work proposed. We identify what must be evidenced and where upgrades are required.

02Can you assess a shop or office conversion?+

Yes. We regularly assess commercial-to-residential changes of use and projects divided into multiple flats.

03What if the existing construction is unknown?+

We can begin with the available evidence, but final U-values may require drawings, photographs, records or an appropriate site investigation.

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