I will say one thing about my power bill. If I were having to use the upstairs unit, constantly, my bill would be double what it is, probably. I have been pleasantly surprised this summer that our bills have been as low as they are, but I know it is because when the children aren't here, I'm not cooling those 3 upstairs bedrooms. It makes a huge difference. All that changes, starting Sunday, when Helen will be back home for an indefinite period of time. It will be SO worth it, though, to have her back here!!!!