A BER is an objective scale of comparison for the energy performance of a building ranging from A1 to G. It is rather like the A to G rating for a household electrical appliance like your fridge. A-rated homes are the most energy efficient and G the least efficient. From 1st January 2009 all homes being offered for sale or rent must have a BER Cert. There is a maximum fine of up to €5,000.00 for not having a BER Cert when required.