I know where the losses are, the house and windows are from 1980 and there is a sunroom on the house that are just huge heat sinks. We are just waiting on funds to correct that stuff. We had some awesome shade trees but they were Ash trees and fell victim to beetles and disease so we had to have them removed so they didn’t fall on the house.
We added a radiant barrier when the roof was redone in 2016. The ceiling penetrations were all sealed and all the can lights were replaced with sealed LED fixtures.
The ac is a newer variable speed high efficiency one with new ducting that was installed 3 years ago and other than needing a minor room rebalance made a big different in our electric bill.
Its got some older fiberglass in the attic but it needs to be replaced as well since it is mildly compacted. Trees are in the plan too but that is waiting on the soil to recover a bit and the temps to drop off. Solar is a long term goal for cost and backup power but that may be a next house thing depending on how long we stay here.