Sounds like a good idea to me:

Enerscore wants to be the equivalent of Walk Score, which estimates how walkable a home is relative to local services. For any address you type in, Enerscore serves up a color-coded rating, an estimate for annual energy usage, and a link to its site where you can get a breakdown for electricity, heating, and so on. The startup wants to build up its service so one of the big real estate sites, like Zillow or Trulia, will eventually incorporate it.

When we tried the demo, it was a little buggy. But Butler assures us the service will be ready when it launches fully in August. The startup makes its estimates based on public records showing construction dates, square footage, types of heating and cooling system, and so on. That means the ratings are approximations only. But one study from Chicago showed that a similar method could be accurate to within 10% of the real value.

Countries that have set up energy efficiency rating systems have found they can affect house prices fairly dramatically. One program from France, for example, showed 25% to 30% increases and decreases in home value after a color-coding program was introduced.

The challenge with this service will be accuracy. People will be upset if they get a bad score that is not accurate. If it negatively affects home prices, you may even see litigation threats. But if they can do a good job, this company’s founders could be onto something very significant for encouraging energy retrofits.