In the United Kingdom, all buildings housing a 'public authority' or providing regular service to the public, and of a certain size, must post a Display Energy Certificate annually. It ranks your energy efficiency from A - G, lists your carbon emissions, and identifies your energy sources - including renewables. It's quite colorful and must be prominently displayed. Can you imagine one in your museum?
Well, Seth Godin's blog post Will Energy Consumption Stay Private? talks about a similar possibility: connectedness and measurements lead to information in the public domain.
Just like Pilot Fees, expect to see Energy Carbon Certificates on a museum near you soon. Why not pre-empt it with an Energy Star label or LEED plaque instead?