Selling, renting or leasing a residential property, you must have a valid EPC prior to marketing the property by law.

Level 3 & 4 Non-Domestic Energy Assessments.
Commercial property to be sold or rented or new construction require an EPC as at 1 October 2008.

Level 3& 4 Air Conditioning Energy Assessments.
For systems with a rated output of 12kW or more the first inspection must be by 4 January 2011.