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  1. #1
    Join Date
    Jun 2011
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    29

    Default Heat/AC Setting: Your Opinion

    I am sure it costs more to keep a house air conditioned at, say, 72 degrees than at 80, and it costs more to use the a/c than an attic fan on cooler days. But I've always heard different opinions about leaving the a/c off or set at a higher temp while we're at work all day and turning it on when we get home. I've been told it costs more to cool a house from 95 down to 76 than it is to leave it at 76 to begin with, because the a/c uses more energy and works harder to cool an entire house than it does to maintain a cooler temperature. We normally leave the a/c at something like 80 while we're gone and drop it a bit after we get home. In the winter we normally set the furnace at 60 if we're gone all day (and when we go to bed at night).

    What say you guys?

  2. #2
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,969

    Default Re: Heat/AC Setting: Your Opinion

    Poison,

    You certainly opened a can of worms for us. There is a long standing debate on this forum about how much of a temperature swing is good before the inefficiencies of re-heating / cooling starts to make a difference. A search of the past postings will reveal looooong debates.

    IMHO there should be no more than a 7 degree range between your away temp and your at-home temp.

    We'll see who chimes in this morning.

  3. #3
    Join Date
    Jul 2009
    Location
    Northeast
    Posts
    661

    Default Re: Heat/AC Setting: Your Opinion

    I agree with Houston

  4. #4
    Join Date
    Jun 2011
    Posts
    29

    Default Re: Heat/AC Setting: Your Opinion

    Oops! Sorry 'bout that. Evidently my search skills aren't up to snuff. If anyone would be kind enough to provide a like to an older thread I'd be content with that.

    I'd never heard of the 7 degree range, though.

    Thanks for the response. We'll see if it takes off......

  5. #5
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    6,598

    Default Re: Heat/AC Setting: Your Opinion

    The 7 degree rule is an energy saver, and since we all agree that "heat" and "cold" are relative terms, most people really don't need a wider gap in temperatures to be comfortable.

    CA code for places like RCFE (Residential Care Facility for the Elderly) doesn't require the temperature to be set at 78 no matter what. So if outside temp goes up to 110 in the summer, the state will accept 90 inside (20 degree difference will "feel" cool inside the home).

    For those who have to have 78 degrees, keeping the A/C going regardless the cost of cooling is the only way.

    For me, a relative relief from very hot is all that matters, so I keep my A/C off while I'm away, turn it on when I return home and keep my money in the bank for more important things. My wife agrees!

    On the other hand, "heating" is almost a non issue around here.

  6. #6
    Join Date
    Jun 2011
    Posts
    29

    Default Re: Heat/AC Setting: Your Opinion

    Quote Originally Posted by dj1 View Post
    The 7 degree rule is an energy saver, and since we all agree that "heat" and "cold" are relative terms, most people really don't need a wider gap in temperatures to be comfortable.

    CA code for places like RCFE (Residential Care Facility for the Elderly) doesn't require the temperature to be set at 78 no matter what. So if outside temp goes up to 110 in the summer, the state will accept 90 inside (20 degree difference will "feel" cool inside the home).

    For those who have to have 78 degrees, keeping the A/C going regardless the cost of cooling is the only way.

    For me, a relative relief from very hot is all that matters, so I keep my A/C off while I'm away, turn it on when I return home and keep my money in the bank for more important things. My wife agrees!

    On the other hand, "heating" is almost a non issue around here.
    Oddly enough, sometimes I feel colder when the temp is in the 30's or 40's than I do when it's in the 20's or teens.

  7. #7
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    6,598

    Default Re: Heat/AC Setting: Your Opinion

    Quote Originally Posted by Poison Oak View Post
    Oddly enough, sometimes I feel colder when the temp is in the 30's or 40's than I do when it's in the 20's or teens.
    It's not odd at all, cause when you hear the weather forecast, your brain is prepared to face the extreme weather or maybe you dress warmer, so you are mentally and physically more ready. That's why low 20's don't feel much worse than mid 30's.

    The same with a heat wave: 120 is bad but doesn't feel much hotter than 105, when you know it's coming.

  8. #8
    Join Date
    Jun 2007
    Location
    Keyport, NJ
    Posts
    36

    Default Re: Heat/AC Setting: Your Opinion

    I think a lot has to do with the home and the type of HVAC system you have. You would probably save more with a set back if the home was poorly insulated than you would if it was well insulated. The length of time plays a role as well.

    Systems that are more rightly sized will have longer recovery times and set backs don't make much sense in those situations. My new boiler takes a lot longer to recover from a set back than my old one. So I gave up the set back. I am still saving money vs. the older system and the house feels far warmer because the structure of the house and everything else in the room is warmer.

  9. #9
    Join Date
    Dec 2010
    Posts
    5

    Cool Re: Heat/AC Setting: Your Opinion

    I'd first go for an energy audit from a reputable company (if they reccomend upgrades over a few grand then run) Just sealing the ductwork saved my 55yo house about $100/mo or so in AZ summer.

    The savings all depends on the area you live, the shading your house has, and the effectiveness of the insulation your house has. If it holds it temperature pretty well, then lowering it in the evening could might not save you money. but where I live, it's well over 110 on a regular basis, and my house bakes in the AZ sun. So turning it up to 80 in the day give the A/C some relief when the brick walls and steel framed single pane casement windows start heating up in the afternoon. Later, when the sun goes down, I can turn it back down to 74 so I don't sleep in a sauna.

    p.s. yes I know I can upgrade my windows, but who is going to give me the +$5G's needed for that?

  10. #10
    Join Date
    May 2011
    Posts
    251

    Default Re: Heat/AC Setting: Your Opinion

    Quote Originally Posted by eline65 View Post

    p.s. yes I know I can upgrade my windows, but who is going to give me the +$5G's needed for that?

    Plus it will take you 100 years to recover that $5k... and replacement windows will likely wear out in as early as 15-20 or could last as long as 40-50 depending on quality. Not to mention that metal casements are really nice. They will last forever if cared for properly.

    For 1/4 that price you can get nearly as much improvement in insulation value with a storm window.
    1925 Two-Story Stucco Beaux Arts Neoclassical

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