Last week, Michelle Kaufmann Designs released a white paper on "nutrition labels for homes":

Green homes are in demand. Buying a green home, however, can be a mystifying, exasperating process. With all the various green home labels and certifications available, buyers want for a way to compare the sustainability of one for-sale home to another. Applying a universal sustainability label to homes, just as we apply nutrition labels to food, would answer this need and further encourage the growth of the green housing market...

By coincidence, we just read an article in Green Building Elements that suggests France already has a good start. The article covers the EvolutiV house by designer Olgga Architectes:

The media in France AND the architecture firm who designed the house feel compelled to advertise efficiency in terms of a single number that is easy to understand and can be used to compare this home to others one might choose. I’ve rarely if ever seen that in discussion of US prefab options (or other green homes) - outside of a LEED rating, we’re often left to guess exactly how eco-friendly that home is. We’d love to see this become more widespread in the US - information is power, and simple, objective numbers like this can help us separate the truly eco-friendly from innovative designs that are green in name (or advertising) only.