Help...Energy efficiency... attic and what not..

Discussion in 'The BS Topic' started by Toy71Camaro, Jul 2, 2013.

  1. Toy71Camaro

    Toy71Camaro Veteran Member

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    Apr 28, 2007
    Central Valley, CA
    Ace's thread about the new AC unit, and Todd's comment about Radiant Attic Barriers got me thinking..

    We just bought a house back in Jan. 2050 sq/ft single level home in the central valley (California). With recent temps this week tipping 105-110 our AC unit (which, is fairly new, but, runs constantly to even attempt to keep up with the temp of the house). Its tough just to bring it down a couple degrees (ie from 82 down to 80). So without replacing the entire unit (couple grand I dont have), Todd's comment about Radiant attic barriers caught my attention.

    So I'm basically looking for some opinions on what I should do.. Our central duct work is all in the attic, which is flippin hot of course all summer. the Radiant barrier looks to cost around .14 sq/ft for a decent branded one (ie. not some paper thin crap). I get a .10 rebate from local power company (woohoo!). Any reasons i shouldnt do this? I'd think it would cut down on the use of the AC in multiple ways (keeps house cooler with attic being cooler, and the duct work isnt exposed to that extra heat, even though the ducts are insulated). Would be roughly $500 (including shipping) to do it (i'd install myself, seems pretty simple, just tedious), and should get about 2/3 of that cost refunded back to me.

    Also, what about whole house fans? anyone have any good recommendations on one? looks like i need about 3x my houses sq/ft in CFM per what i read. So roughly a 6,000 CFM unit. Direct drive or belt? (I'm leaning towards belt). Our evenings generally (except in this heat wave) cool off in the low 60's during the summer and we regularly leave the house open at night. So I'm leaning towards this (plus, i get a $75 rebate on that too). But they range from a $125 window mount option to $1000 and higher end units. I want best bang for buck that i'll get "back" quickest. lol. (and that will last).

    Thought about also a gable fan or two.. havent totally decided on that one yet. with the barrier it might not be all that important as there are ridge cap vents plus gable vents (3 or 4, counting the opening into the garage).

    Not sure how much energy savings would be. Not sure how I'd be able to calculate it, but it seems like it would be a smart move in the long term. Thoughts? suggestions? other options?
     
    Last edited: Jul 2, 2013
  2. Earlsfat

    Earlsfat Veteran Member Lifetime Gold Member

    1,504
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    Jun 14, 2006
    Whut?
    Any heat you can get out of your attic is good. Radiant barrier (I assume you're referrring to the double foil faced bubble wrap stuff) is supposed to be the best stuff around for attics.

    Whole house fans.... they work well here in PA, not sure about where you are. Here it's real hilly and you'll usually find a whole house fan where there fan can draw in cool(er) air from the basement levels. If you live near a lot of hot pavement, etc, a whole house fan isn't going to help much b/c it won't be able to suck in cooler air from the bottom and blow the hot air out the top. Lots of shade trees around and nearby lower ground helps alot.

    IMHO - Do the radiant barrier, if you don't have ridge vents you need a gable vent, powered ones with a thermosat and shutters work well and help keep critters out, etc. Insulate the ever loving snot out of the exterior walls and the attic floor, not sure if the radiant barrier on the attic floor does anything or not, but if you can find it cheap enough... I'd say duit. That and windows. If you don't have thermal panes in your windows, contacta local glass company and see what they charge to replace the panes. Mine were about $100 installed a piece to do low-e glass.


    That's all I got.
     
  3. Marks71BB

    Marks71BB Veteran Member Lifetime Gold Member

    I just installed a whole house fan a week and a half ago. works great but wont do much for you in an air conditioned house, gable vents would help a lot in cooling off the attic and thus lessening the load on the a/c unit due to losses in the duct work.

    eta: yeah, the whole house fan would work great if you are in the habit of keeping the house opened up in the evenings and not running the a/c. ( i incidentally skipped over the third paragraph the first time I read yer post)
     
    Last edited: Jul 2, 2013
  4. Toy71Camaro

    Toy71Camaro Veteran Member

    518
    0
    Apr 28, 2007
    Central Valley, CA
    Mark,

    Which whole house fan did you go with?

    with the average evening/night temps here (example), we keep the house open about 90% of the time in the warmer months. (ie. from April to oct). So thats where i think the whole house fan would be a good choice. I think it would even lessen the load on the AC during the day by getting the inside temp cooler (it roughly stays about 7-10 degrees cooler in the house than outside on average, at night with the house open). So bringing that overall inside temp down should lessen the load on the AC.

    thats my "thought process" anyhow. LOL.

    As for the attic, i'm thinking there is two problems:
    1. Not enough soffit vents from what im reading (and what ive seen). Thus not getting adequate ventilation.
    2. the radiated heat from the roof increasing the temp very high, and radiating into the house as well as the duct work for the AC.

    With the cost of the radiant barrier after all its rebates being foughly $150-$200, I should be able to get a decent ROI in a couple years (ie. if its only saving me 5-10%). But who knows, maybe it could make it more efficient and save more. Coupled with all 3 items above (fan, soffit vents, barrier) we *might* make a decent dent in the monthly bill and extend the live of the A/C unit. (and be a tad more comfortable in the cooler house!)
     
  5. High Country Z

    High Country Z Veteran Member

    You need to vent as much of the soffit as you can, ridge vents or gable vents won't cool the attic much without vented soffits.
     
  6. Toy71Camaro

    Toy71Camaro Veteran Member

    518
    0
    Apr 28, 2007
    Central Valley, CA
    That's what I'm learning as I'm researching... I need the same sq/ft of vent in the "upper" attic (ie. ridge/gable) vents as in the lower attic levels (soffits). Which, i'm almost positive thats not going to be my case. When the P.O. had the roof put in, they put in a bunch of small ridge vents. and there are very few soffit vent openings at (I used them to run my security cameras lol). So likely whats happening is its not creating the proper vacuum effect to suck the cooler air from the lower soffits and likely sucking the hot air from the gables instead. No bueno.
     
  7. Toy71Camaro

    Toy71Camaro Veteran Member

    518
    0
    Apr 28, 2007
    Central Valley, CA
    Actually, I'm using the wrong term... Mine arent actually Ridge cap vents, but like these vents:

    [​IMG]

    And from what i read, you may need to actual seal off the gables to get proper flow after installing something like this.
     
  8. High Country Z

    High Country Z Veteran Member

    I've been working on my attic this year, so far I've opened up about 50% of my soffits, it's made a huge difference in the attic temp and the house itself doesn't get as warm, I'm shooting for about 75% of vented soffits, also adding an additional layer of insulation to the attic floor, it's definitely making a big difference.
     
  9. Smokin'Joe

    Smokin'Joe Veteran Member Lifetime Gold Member

    588
    17
    Aug 14, 2008
    Texas
    Interesting topic about the radiant barrier, I just had 12" of insulation added to the 6" I already had and really have no idea if it really did any good or not. - I put a min/max thermometer in the attic and have recorded 124 degreees up there on a 98 degree day. - I only have 3 small turbines on a 2600sf house, so I'll be adding more soon. -

    My perception on the radiant barrier is that although it will reduce the attic temperatures, it may also shortens the life of the asphalt shingles due to the extreme temperature duress that it puts them thru. -

    I would think that proper ventilation would keep attic temps similar to what the radiant barrier provides with out the byproduct of shortening the life of the shingles.


    Thoughts from experts ?


    Thanks !

    --
     
  10. Marks71BB

    Marks71BB Veteran Member Lifetime Gold Member

    This one and it works GREAT! Belt drive is quieter that DD. It woops up a breeze through the house and will slam bedroom doors shut :D
    [​IMG]

    click the pic for details.

    Just wait till you see what Ive been working on yesterday and today....I have to run to the hardware store real soon then I'll post pics with some details. My preliminary testing this afternoon proves promising... Its 102+ outside now and inside is 87 right now. Hose was open all night but the temps never got below 75 overnight so it was like 77 this morning when I closed up the house. I disabled my a/c system several years ago, it was costing me a fortune and try as my kids tried we could not cool off the whole mountain side.
     

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