OT: Heat wave

Submitted by Purkinje on

Who else out there is soaking up as much MGoBlog as they can before the power lines inevitably start being fried by the air conditioners tonight? Before the little bit of rain we just had here in AA swept through, the heat index was 106 degrees. Now it's at 99. I can't wait until Thursday when the straight up temperature is predicted to be 99. If it's as humid as today, the heat index will be 115.

wiper

July 19th, 2011 at 10:12 PM ^

my central air is set at 70, and i still run a window unit all night on high cool 9/9 temp because i want to be able to curl up under the covers even though it's still 80 degrees outside.

no wonder i've had a cold for seemingly weeks. 

jmblue

July 18th, 2011 at 5:19 PM ^

I'm not going to begrudge anyone for running their AC when they're indoors right now - but leaving it on when you leave your home (as my neighbors do) is ridiculous.  They walk out and lock the door with the AC unit loudly cranking in the background.  You can survive a few minutes inside when you come home before it kicks in.

In reply to by somewittyname

skunk bear

July 18th, 2011 at 6:07 PM ^

Yeah, it makes sense to me that if you leave it off, you're saving energy even if you turn it back on later. Is there some way to confirm this?

somewittyname

July 18th, 2011 at 6:23 PM ^

The total energy removed in a day and the efficiency of the air conditioner. The amount of heat leak into the house is a function of the difference in temperature between inside and outside (the larger the difference the larger the leak). What this means, is that as your house heats up the heat leak into the house will be proportionally less. Therefore, from a total energy perspective you'll have to remove more heat to keep the thermostat at a lower temperature. See example below.

Say you have the thermostat set @ 70F, and the heat leak is 100 W, that means you have to constantly remove 100 W for the duration you're gone (say 5 hrs). So your AC has to remove 500 W-hr in that time period (a unit of energy). Now say you don't remove that heat during that time period, well that 100 W rate is going to drop over the 5 hrs as your house heats up, so that maybe now you only have to remove a total of 400 W-hr to get back to 70F.

Now the only thing that could negate this is efficiency. If your AC was less efficient at the higher temperature, then the two effects could cancel. However, air conditioning efficiency is based on temperature lift with the more lift required, the lower the efficiency. In other words, it actually takes more energy to remove 1W @ 70F than at 80F given a constant outside temperature of say 85F. So in fact, efficiency is also working in your favor. Case closed. And if you need another reference:

http://green.yahoo.com/blog/the_conscious_consumer/144/five-air-conditi…

TIMMMAAY

July 18th, 2011 at 6:29 PM ^

Hit with the knowledge, it seems. I was always told (I work with a lot of trades) that AC's run more efficiently if set at a constant temperature. I fail it seems...

But I will check out your link because now I'm really curious.

mgowin

July 18th, 2011 at 8:30 PM ^

I would like to see the mold in your walls. Most people forget the other side of the air conditioning equation. The envelope of most homes in humid areas require active (as opposed to passive i.e. opening a window) dehumidification. Even if you don't need the AC for the comfort factor, you probably need it to remove moisture from your house. Edit: I also live in the south now and its always 100 degrees and 99% humidity so get off my lawn.

BiSB

July 18th, 2011 at 3:52 PM ^

It's a crisp 92 in South Bend.  I tried to take the dogs for a walk... they got as far as the sidewalk before they looked at me as if to say, "yeah, fuck that, buddy," and turned around toward the door.

CRex

July 18th, 2011 at 4:59 PM ^

My malamutes both want the prime spot under the main AC vent.  However it is hot and they're way to hot to fight for it.  So they just lie there on the floor and kind of half heartedly growl at each other.  It is kind of sad.  I guess I'll have to take them down the river and let them scare the kayakers a little.  

Maizeforlife

July 18th, 2011 at 3:53 PM ^

People often forget that most of SE Michigan was once a swamp.  Honestly, I look forward to this time of year, you don't have to shovel sunshine off your car.

74polSKA

July 18th, 2011 at 3:57 PM ^

Yeah, but you can put on more clothes when it's cold.  You can't take your skin off when it's 100 degrees out (I guess you wouldn't really want to, but you get the point).  Some people can't sit in the a/c all day, or so I hear.

Hannibal.

July 18th, 2011 at 4:06 PM ^

This is why I think that the upper MIdwest has probably the worst weather in the country.  You've got nigh unbearable extremes in the winter and summer, and then a short transition period in between them that is also sometimes beset with those extremes.  I feel like the summer should be a bigger reward than it is for enduring each miserable winter.

Hannibal.

July 18th, 2011 at 4:16 PM ^

June was wonderful, but July has been pretty bad.  When it's in the upper '80s, it's still pretty unpleasant to be outside and do yardwork or go for a walk in the park.  At least for me it is.  i like to jog outside and I have to get up at 6 in the morning in July to do it. 

 

God don't remind me of 2005.  That summer was awful and it lasted until the end of September.

BlueTimesTwo

July 18th, 2011 at 7:52 PM ^

I used to laugh at people who would talk about it being a dry heat, but then I moved to Boise.  There really is a difference.  Today it was in the high 90's here and I was pretty comfortable for the most part outside.  When weather.com said that the temp was 95 here, it also said it feels like 93 (compared to Minneapolis which was 97 and it said felt like 113).  The difference in humidity shaves at least 10 degrees from the feel of the weather, and even more in the shade.  I don't miss the humidity, but I do miss Michigan football and hockey.

BlueTimesTwo

July 19th, 2011 at 1:24 PM ^

I do try to get to as many games as I can.  The stadium atmosphere is nothing like Michigan, but they are still fun games to watch.  BSU's success also makes people think about Idaho for something other than potatoes.  There is a lot more here than people think, especially if you like the outdoors.