has been suggested in the Netherlands - and immediately scoffed at - but there are now agencies who offer the service to determine a house's energy usage and report back with recommendations.

Your thought seems to determine what is nowadays a good standard for energy usage - which opens a whole extra can of worms. It may have been suggested before, but surely sensible. I will be busy developing the spreadsheet further, looking for other material and querying other people to do likewise. If there isn't a standard yet, let's develop one.