As noted in many existing posts; man buyers are less willing to pay for energy improvements than they are to pay for more obvious "doodads", ie granite countertops. As an appraiser, I can vouch for this. One big reason is that energy improvements are not quantified. I am not an expert, so I won't pretend to know which rating is most accurate. But if MLS's were to quote an energy rating, maybe HERS, on each listing then buyers could begin to capitalize the costs to upgrade. By capitalize, I mean they can determine how much they want to pay for a given level of energy upgrade. It worked for autos and MPG. This would provide financial incentive to builders and renovators. Buyers and sellers would soon understand that not only are operating costs lowered, thus effecting ROI, but that some or all of the capital cost may be returned at the sale. An effort to get MLS to list such data would be one of the most beneficial that green organizations could accomplish.

As you suggest, I think that lack of information is the problem. If listing included even average monthly utility bills, that would be a huge step in the right direction. Buyers would be much more likely to take kind of information into account when making purchase price decisions. Lenders might be interested in taking that into account, as well.