In Ireland, a Building Energy Rating (BER) certificate is generally required before a home is advertised for sale or rent, and the rating must appear in the listing. New dwellings normally need a BER before occupation, although limited exemptions can apply to certain buildings, such as protected structures or temporary buildings. A registered SEAI BER assessor calculates the rating using the property’s construction, insulation, heating, ventilation and other energy features, so the result cannot be guaranteed in advance. Certificates are generally valid for up to 10 years unless significant changes affect the building; check SEAI’s official guidance for your circumstances.