If

The most favourite toy is the one that all the children want - even if my 3 year old hasn't played with a toy for weeks the minute he sees his little brother playing with it he wants to play with it as well.

The same affect could work on EPCs - if 10% of buyers/renters started to look at EPCs and then negotiated on price due to the EPC or bought/rented a property with a good "grade" then the EPC would become a marketing asset.

If a good result on the EPC was a saleable part of a property then prices would be adjusted with the more energy efficient properties priced higher than those that are not so energy efficient.

If a property was worth more if it was energy efficient then more people would make alterations to their properties so that they were energy efficient - more insulation, better boiler, TRVs on the radiators, solar panels etc.

It could be a very benefical knock on effect.

There are alot of ifs involved with the thoughts above but if it happened it would be a fantastic result for the environment, energy efficiency, saving money and the global community as a whole.