In France, before buying or selling a house, you need to contract a company to do an Energy consumption diagnostic, which gives you a rating between A to F, F b

In France, before buying or selling a house, you need to contract a company to do an Energy consumption diagnostic, which gives you a rating between A to F, F being the worst. It also gives you an estimate of the amount Energy used to heat/cool your dwelling as well as the average yearly cost. Obviously, this system is not perfect but its something. Based on that you can work out if buying a cheaper and less insulated place is actually worth it or not.