1. Basic Requirements for EPC

Must have a roof and walls.
Uses energy for heating, mechanical ventilation, or air-conditioning to condition the indoor climate.

2. Services Conditioning Indoor Climate

Heating, mechanical ventilation, or air-conditioning are considered essential.
Hot water provision and electric lighting do not contribute to conditioning and thus do not require an EPC.

3. Requirement Trigger

If a building is expected to have heating, mechanical ventilation, or air conditioning installed, it needs an EPC based on assumed fit-out as per Part L of Building Regulations.

4. Scope of Building

Can encompass the entire building or part of it.
Part of a building designed or altered for separate use qualifies if it has:

Separate access.

Separate provision or control of heating and ventilation.

5. Non-Dwelling Considerations:

Even if some facilities (like kitchen and toilet facilities) are shared, a part of a non-dwelling building can be considered separate for EPC requirements.
Examples include units in shopping centers or floors in office buildings.

These points outline when a building requires an Energy Performance Certificate (EPC) based on its structure, energy use for indoor climate control, and design for separate use or occupation.

https://assets.publishing.service.gov.uk/media/5a82114d40f0b62305b924df/A_guide_to_energy_performance_certificates_for_the_construction_sale_and_let_of_non-dwellings.pdf

EPC requirements