An assessment takes anywhere from 25 minutes to 1 hour for a domestic EPC and a couple of hours to a couple of days for a Commercial EPC depending upon the size of the commercial property.
Factors such as the size of the property, it’s age and general access to it, will have an influence on the time.
Generally, an energy assessment won’t cause much inconvenience but, it’s important that the energy assessor can get access to any loft space and heating appliances (e.g. a boiler).
An internal and external inspection of the property is also required for a certificate.