AC with some windows open?

[tuixiu]

How much money does it waste to run the air conditioner with downstairs windows open, just for a half hour per day? I know, I know there are a million variables that make this question too hard to just answer with that, and yes I know it sounds like a really stupid idea.

Problem is right now in Arizona every day is beautiful, it's truly why we all moved here. So in the morning I go around to all the windows in our townhome and open them up to enjoy the fresh air, sounds of outside, get a breeze etc. it's something I love. I work from home.

Unfortunately by right around now (5:00 pmish) it's a bit hot in here, I assume from the sun heating up the house. So I usually run turn the AC on just to get us over the hump, it'll bring the temperature down to a nice level within 20-30 minutes and with the sun lower we're good for the evening. Problem is I'm too lazy to walk around and shut every window in the house, usually just do the windows upstairs.

My wife says this wastes tons of money, I'm thinking how much could it possibly be wasting for 20-30 minutes in a townhome with level-payment electric bill of only $120/month.

So if you had to take a wild-ass guess what would you think? Am I wasting $10 per month? $40? If it's under $30 then no you couldn't pay me a dollar to walk around and cycle the windows.

 

[RunningBum]

My guess is under $10. If the A/C is shutting off not long after it gets to that comfortable level, you're probably wasting very little.

Security might be a better reason to close the lower level windows.

 

[ERD50]

Probably not so much. You need to find the power draw in watts of your A/C and fan ( if this is the central air system). And your KWHr electricity cost ( ~ $0.11 national average). Then, watts divided by 1000 (to get KW), multiply by your KWHr charge rate, and divide by 2 (for one half an hour).

Or read your meter before/after.

As a super-rough ballpark figure, our A/C unit is on 40Amp breaker, and they normally don't exceed 80% of that rating, so say 32A draw. Times ~ 230 V =7360 watts; so 7.36 KWatts; times $0.11 = .8096; divide by two for 1/2 hour ~ 41 cents.

Our fan is 3/4 HP so maybe another KW for that 46 cents. Ballpark.

edit - those are per day; so 30 * .46 for a month ~ $13.80.

-ERD50

 

[MasterBlaster]

TiuXiu:

Careful !

If you run the A/C too long with the windows open you'll turn the desert into the Artic. Instead of sand dunes and cattle heads you'll have glaciers and polar bears.

 

[Koolau]

I live in Hawaii so the outside nearly always looks inviting and in many residential settings, AC isn't needed anytime. But when I go to stores and restaurants, it's not uncommon to have AC going with windows/doors open. We have one of the highest electric rates (roughly $.24/KWH right now and I've paid $.30 in the last oil "crisis"). So business don't seem to think the extra energy is much of an issue. I'm guessing for your half hour, it's not much of an issue either. Still, I couldn't do it. When I lived in the midwest, I "prided" myself in carefully managing my AC costs by strategically opening windows in the cool of the evening and then closing them when outside air temps approached inside air temps the next morning. There were summers I used the AC less than 2 weeks and was still quite comfortable. Still, it took a fair amount of effort and a lot of commitment to run around the house opening and closing windows. It was worth it to me and I'm convinced it saved considerable money as I compared bills to neighbors and ours was never half what theirs was. Still, in your case, I wouldn't worry about it until it's starts getting hot outside for more than half an hour per day.

A good problem to have, I would submit!

 

[W2R]

In Arizona? Where summer temperatures are routinely way over 100F? My guess would be that your wife is correct - - you are wasting a lot of money especially as summer draws near.

If airing out the house with the A/C off while it is still cooler early in the morning, then closing the windows and using the A/C is good enough for everyone else, then it is probably good enough even for you. If not, then it seems to me that Arizona is not a good place for you to be living.

 

[ERD50]

In Arizona? Where summer temperatures are routinely way over 100F? My guess would be that your wife is correct - - you are wasting a lot of money especially as summer draws near.

If you read the OP, you'll see he is talking about running the A/C for 20 minutes a day under these conditions, just enough to take off the built up heat. That is only going to cost ~ $13 a month if he does it 30 days a month. And that is the total cost to run the A/C for that time, closing the downstairs windows would only knock off a fraction of that. I'm having trouble seeing how that relates to a lot of money, esp considering the effort involved to save it. Heat rises, cold sinks. As long as it is hotter upstairs than down, I doubt it even has all that much effect.

I'm big on energy conservation myself, but I can see why someone would not want to bother running downstairs to close a bunch of windows on 30 occasions to save maybe a couple bucks that month. The wear and tear on the windows might even exceed that cost - one worn out/broken bracket, or knock over a plant in the process, and it just isn't worth it to many.

I got the impression that once summer kicks in, and the A/C is on for long periods, that the poster would close the windows. He was specific about the 20-30 minutes once per day.

-ERD50

 

[tuixiu]

Thanks for kind replies/advice, and yeah ERD50 nailed it no way I'd attempt this in the summer.

This problem presents itself only in October, November, March, and April.

Today I'm making dried tuna "wind style" with a fan, so I'm quite sure the entire neighborhood is unhappy that my windows are open.

 

[FUEGO]

Today I'm making dried tuna "wind style" with a fan, so I'm quite sure the entire neighborhood is unhappy that my windows are open.

This little tidbit goes a long way in explaining why you like the windows open a lot!

 

[Koolau]

Thanks for kind replies/advice, and yeah ERD50 nailed it no way I'd attempt this in the summer.

This problem presents itself only in October, November, March, and April.

Today I'm making dried tuna "wind style" with a fan, so I'm quite sure the entire neighborhood is unhappy that my windows are open.

Call it dried "ahi" and no one will complain!

 

[tuixiu]

The tuna relates to this thread:

http://www.early-retirement.org/forums/f27/jerky-45427.html

Except my newer refined technique for added safety is to air dry until seems like jerky then go oven on 170 for awhile to further assault any wayward bacterial threats.

I've learned I can't go oven right off or it cooks the outside too much compared to inside, but air first to dry out does the trick.