Having my cake and air conditioning it, too
Here at our office, we like to leave the windows open in the morning and have the a/c in the afternoon. The problem is, this building is about 2500 sq feet, and half of that is upstairs.
We have new a/c units upstairs and down, and the one upstairs simply isn’t cutting it. My guess was we really needed better insulation in the attic, but the a/c guy said no. Leave the a/c running 24-7. Don’t adjust it for the weekend, don’t adjust for nights when you’re not there, and definitely don’t leave the windows open in the morning because the air conditioner can’t do it. And instead of poor insulation upstairs, our ultimate problem is the heat rising from below, so it’s extra important to keep the a/c on down there.
I’m definitely no a/c guy, but I thought our main problems are that it won’t keep it cool in the afternoon no matter what and it’s very hot in my office even while the thermostat thinks it’s done its job.
I guess we’ll try it their way for a week and see if we can’t convince them they’re wrong. I really want to be able to have the windows open on nice mornings. I hope they’re at least half wrong.
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7 Responses to “Having my cake and air conditioning it, too”
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You’re letting all the humidity in when you open the windows, so your a/c has to work twice as hard to pull the moisture out of the air in order to cool it. I think the guy is right.
Like I said, I want to have my cake and eat it, too.
I wonder how much you save/cost by having no a/c running for most of the time, though?
You’ll have a nice little utility bill based on that advice too! I had a new HVAC unit installed at my house two months ago. I turn it up when I’m not there and turn it down at night, when I need it most to sleep. I don’t open windows much, but I would if I were home more often–I have complete shade on all sides of the house.
Some questions I’m wondering are:
1. What kind of window coverings do you have to cut down on heat intrusion?
2. Are windows insulated?
3. What orientation does your office have in relation to the sun in the afternoon?
A new unit should be able to remove humidity that’s brought in when windows are open for a few hours. Two new units should definitely do the job. Heat doesn’t rise from downstairs when downstairs is being cooled by its own unit. If it were always off downstairs, I can see that happening.
Leaving AC blasting at all hours will treat a symptom, not solve the problem. It’ll also wear out a unit faster.
IMO.
EDIT: There are a number of commercial applications you can use to help with the windows.
Additionally, when my office was downstairs in the building and opened directly onto the sidewalk, I routinely propped both doors open in the spring. Once the doors were closed, the unit took just a few minutes to cool down. Then again, I have a 172,000-square-foot building, so I have HVAC guys in quarterly to do maintenance. The units are in top shape.
I have nice, thick blinds on the sunshine sides of the house, and old wood windows with storm windows, too. And my office gets the sun in the morning, so it’s hot in the morning and never cools down all day!
It’s true that not only would it treat a symptom, it would also cover up the problem, if there is one, so you wouldn’t know it existed except on your power bills.
OK, so the windows are fine. Sounds like something’s going on in the attic. If you have the unit turned off in the morning, there’s only so much you can do if you’re upstairs–it’s just going to be warmer than downstairs. However, I do NOT think the solution is 24/7 heavy-duty usage. I have the 8th, 9th, and 10th floors of my building set to 71 during business hours and it goes up to 76 in the evenings and on weekends. It’s always pleasant up here too.
It just occurred to me that I should’ve titled this post “hot air rises.”
I am an A/C guy. How many tons do you have for your building? A ton is 12,000 btu. look at your units and the model number should give you some clue. ie XX24xx is a two ton unit. xx36xx is a 3 ton unit,, etc. now the “rule of thumb” is about 350 to 400 sq/ft per ton. so 2500 sq ft = about 7.5 tons of cooling.