Leave the A/C on during the summer?

Leave the AC off when you're not there. Just make sure the wine stays in a fridge.

Agreed, leave it off. But aren't there shades you could lower too? It sounds like there is an excess of incoming heat for your system to remove even when you're there. You might also look at adding transparent window films on the exterior of the glass, which can reject infrared wavelengths without messing up your view.

Our practice is to set the AC to 77 degrees when we leave any property during the summer. I started this with a house in Florida that I used only a few weeks out of the year; then continued it with houses in Washington, DC. Both climates have high humidity, and I was told that leaving AC on was good practice for keeping out potential mold. Consistent with this practice, when we left New York Apartment for the month of August, I did the same thing. Imagine my horror to return to the apartment in early September to find that the wood floors had buckled to the point that it was difficult to open the front door. The building is fairly new construction (completed 2007 I think), but this had not occurred in the unit before. We now have a "good landlord" who is taking all the appropriate steps and investigating, making insurance claim, giving us opportunity to inspect, etc. We feel terrible because investigation so far suggests that floor was not properly laid, but that this construction defect would not have ever been a problem had AC in the unit remained at some level below 77. Accordingly, we feel responsible, even though we are not likely responsible under the terms of the lease. Hardwood floors are a strong preference for us, and we have never had a problem with them in humid climates where we have left AC at 77, but then again, we have never lived in new highrise construction in NYC. Has anyone else experienced anything like this?

NYCNovice, you're not responsible, and you've already gone above and beyond. And wood floors -- properly stored prior to installation and properly installed -- can take high humidity and temperatures. They're designed to expand and contract as needed -- IF done right. Sadly, that's frequently not the case these days.

In Florida, people often set their HVAC to dehumidify, but that's mostly for carpet and ducting and the like. I'm surprised it's needed in DC, frankly.

AH - I think you are right about DC because one summer the unit that cools top floor of current house went down while we were away; we came back to very hot top floor (98 degrees!), but wood floors were fine, no mold etc. Re our NYC condo rental, I feel terrible for the owner because he now has to deal with expense of repairing the floor plus trying to get sponsor to make good on the faulty construction. Real estate attorney acquaintance said that with new condo developments these days, it is not a question of "if" owners will sue sponsor over either construction or offering plan, but "when" because there is always something, even with the best developers. In any event, further investigation may reveal leak in pipes below the floor which insurance may cover, but what a bummer for owner. For us it is a drag to navigate the bumpy floors, but I feel worse for condo owner.

Thanks all for the responses. Uptown_joe, we have put the UV film on the windows, and it definitely makes a big difference. We also lower the shades where we have them, although several of the biggest plates of glass don't have any shades. Novice, controlling humidity is definitely one of the benefits of A/C, although it's not much of an issue usually out East. Thanks again for the input.

If your floors "only" show problems at 78 degrees, that is a problem with the floors.