The Appraisal Institute just released a new form for home appraisers that helps quantify the additional value of energy efficiency upgrades to a home.  The form is available here:
The areas of the home appraised include insulation, water efficiency, HVAC, windows, daylighting, appliances, energy rating, HERS rating, utility costs, and whether the home has had an energy audit.  This information should help appraisers attach a higher value to homes that are more energy efficient.