I think that energy efficient upgrades are the most appealing to my market. I have been adjusting for about $100 per thermal window vs windows with storms, windows without storms maybe a little more. A company here advertises they can install thermals for $200, so I think my adjustments are justifiable.
I adjust for houses built before 1978 when title 24 of the energy act went into effect as opposed to houses built AFTER that date.......unless I have reason to believe the older homes were updated with additional insulation and dual glazed windows. Just a modest adjustment unless there is clear data to support something else.