Advice needed: insulate walls or replace windows?

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  #1  
Old 05-23-11, 08:00 AM
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Advice needed: insulate walls or replace windows?

Hello,

My house was built in 1970 with 2x4 walls with R5 insulation (which I know from a kitchen remodel two years ago). It also has the original single pane aluminum frame windows (6 total). New York State is offering a free home energy audit, so I had it done since I wanted to see what improvements I should make first. It was done by a BPI certified contractor who just happens to be an insulation contractor.

The results came back that I should first insulate the walls with blown in cellulose. There is 1,184 sq ft of outside wall to do for a price of $2,012.

The next improvement to make would be to replace the windows. To my surprise, the windows are fairly tight as the blower door test revealed the overall air leakage to be 1739 CFM50, which he said was very good. Last year I got window prices from a local installer for Sunrise windows. The price to replace all 6 would be $4,800 (which I might have to do half at one time and the other half later due to budget).

So obviously insulating the walls would be cheaper, but I wanted to get some opinions on whether the walls should indeed be first and the windows second (the attic already is insulated with 2 layers of R19). Since the guy who did the energy audit is an insulation contractor, I just want to make sure he didn't stack the deck in favor of insulating the walls (though he seemed very professional and has been in business a long time).

Should I do the walls first and windows second? I can probably only afford to do one and not both this year, so which would reduce my energy usage the most and increase the comfort level in the house?

Let me know if you need any other info. All advice/opinions greatly appreciated. Thanks.

Mark
 
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  #2  
Old 05-23-11, 08:26 AM
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Go with the walls. There is far more square footage there than on the windows. You will also be increasing the R value much more with the walls. The windows won't be as much. Get another quote for the cellulose too.
 
  #3  
Old 05-23-11, 08:48 AM
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Hi Indiana,
The information you show here doesn't seem to work. A CFM of 1739 for a 1,400 sq ft home is high. He should have calculated a building tightness limit (BTL) to determine the threshold where mechanical ventilation would be required. But that isn't where one should stop. Air sealing is the first step that should be taken. It reduces energy loss and controls where moisture enters and exits the structure.

Windows are usually last and adding extra insulation to what you have is ok but low on the possible list. Adding storm windows might buy you some time.

What type of heat do you have, gas, oil, forced hot air or hot water?

What are your current heating and electric bills, per year?

Replacement windows usually go in fast so that price looks high. If you specified "new construction" then they are a bit harder depending.

Most homes your size would have a dozen windows, so are yours very large?

Basically, an energy audit can give you every little detail and all of the possible options. Unfortunately, a contractor based auditor will all too often zero in on what they do best, exactly your concern.

If you want to feed us the info, there are several auditors here who will offer advice.

Bud
 
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Old 05-23-11, 09:02 AM
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Not to hijack....but can you use blown in if there is batt insulation existing (that wasn't made clear in the post)? Wouldn't the batt prevent the cellulose from filling the area? I know it works with old loose fill or no insulation.
 
  #5  
Old 05-23-11, 10:06 AM
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My house is more like 1800 sq ft with a large family room below grade. Only one of its walls is exposed and the previous owners remodeled it fairly recently and installed new insulation. So only the upstairs level that is all above grade needs more insulation (except the 12' kitchen wall that I insulated when I remodeled it 2 years ago).

My windows are fairly small and are all sliders. Five of them are 2.5' x 5' (all in bedrooms) and the 6th is about 3' x 3' (in the kitchen). We've talked about making two of the bedroom ones taller and double hungs.

We heat with forced air heated by natural gas (we also have central air). The past 12 months I have paid $1913 for electric and gas.

I hope this helps. I'm open to all feedback. Thanks.

Mark
 
  #6  
Old 05-23-11, 11:42 AM
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Originally Posted by Gunguy45 View Post
Not to hijack....but can you use blown in if there is batt insulation existing (that wasn't made clear in the post)? Wouldn't the batt prevent the cellulose from filling the area? I know it works with old loose fill or no insulation.
I do believe that it is possible to do this. I've never seen R-5, but I assume it doesn't have much thickness to it. I think what happens is that the cellulose pushes the batt out of the way. It's much denser than fiberglass.
 
  #7  
Old 05-23-11, 12:39 PM
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I agree with drooplug on the R-5 insulation (that's barely over 1") and wonder if that isn't R-11 that they are calling a poor installation. In other words, you can't recommend the wall insulation which your company does, if it isn't bad enough to justify. I built my first home in 1970 in NJ with gas heat and the required insulation was 3.5" in the walls and 6" in the ceiling. You have to get back a few years to find the R-11 fg. R-5, I have never seen.

Mark, that explains the extra area. I was using the wall area and calculating backwards. Still, I would look for half the CFM 50 even at 1,800 sq ft and I would install a HRV (heat recovery ventilator) for a 24/7 trickle of fresh air. That lets you control where the replacement air is coming from instead of it filtering through cracks in the walls.

With forced hot air, if those ducts have not been sealed with duct mastic or other proper material (not duct tape), then they are leaking like mad. Did they do a Duct Blaster test on the system. Same principle as the blower door test, just a smaller blower and it tests the system only. New energy code requirements require the separate test, not just some pressure measurements of the ducts while the blower door test is running. Duct sealing may save a bunch.

They also should have looked at your return ducts to be sure they are large enough and well placed so as not to be forcing your heat outside and pulling replacement air back in.

Some quick numbers. Walls with some insulation will be less than 20% of your total energy loss. Since only half of the walls need improvement we are down to 10% and because we can only reduce the heat loss through the walls, not eliminate it, at best the added wall insulation will produce less that a 5% total reduction. I suspect less. 5% of $1,913 is $95 per year. That is a simple payback of 21 years. It still helps, but the savings won't knock you off of your feet.

I am of course drawing on experience and not your actual numbers, but those actual numbers are what you paid for and calculations like this are what he should be able to provide. Every option can be considered by itself or in conjunction with any others and help you develop a weatherization plan that fits your needs.

Sealing those air ducts along with some extra insulation will also help with the ac, especially if there are any ducts in the attic.

The 1970 gas furnace, did they make any suggestions for it?

Did they use an Infrared camera and provide pictures and locations for air sealing?

Bud
 
  #8  
Old 05-23-11, 01:54 PM
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I know the walls are R5 as I was the one that did the kitchen remodel and tore all of it out myself. It was Owens pink fiberglass with brown paper on one side and clearly was labeled R5.

None of my ducts are visible except for a little bit by the furnace. The main trunk line on the garage ceiling is sheetrocked over and then plastered (bedrooms are above the garage so I assume it's code). So however they were sealed in 1970 when the house was built is how they are today. I agree sealing them probably would be helpful but there's no access, and I don't feel like tearing down the garage ceiling, sealing them, and then patching the ceiling. There are no ducts in the attic. And the furnace was replaced in mid 1990s with a high efficiency model. I believe it's labeled 90%.

Infrared camera was not used as he said the outside and inside temp were too close for it to be useful.
 
  #9  
Old 05-23-11, 02:31 PM
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You got me on the R-5, doesn't match anything I have come across. I will check other sources for my own curiosity, but I would assume it is was around 1 1/4" thick. If so, then blowing in cellulose beside it should be possible. Even so, going from R-5 to R-13 will still only reduce the heat loss through those walls by about 50%, which pretty much follows my math example. So a long payback.

The windows are aluminum and that conducts heat like mad, so pursue that option or adding storms. I can do a similar math example for whatever you select for new windows if needed. I will add a link that illustrates air sealing all over the house so you you can check for other options.

http://www.efficiencyvermont.com/ste...ide_062507.pdf

Good luck with the improvements, here if you need us.
Bud
 
  #10  
Old 05-23-11, 06:29 PM
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Maybe that R-5 was meant for duct work.
 
  #11  
Old 06-02-11, 06:31 PM
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Hey there, Mark!

I think there's a way you can easily have the best of both worlds here.

1. Insulate your walls with blown-in (closed-cell) insulation. By using closed-cell insulation, you'll also insulate the house for added energy efficiency.

2. Install window insulation panels. These will add a double airspace to your existing windows and can be done as a DIY job at, roughly, $100-$200/window. This would solve your energy efficiency problems at a pretty good price. They make the windows up to three times more energy efficient.



The value of replacing windows for increased energy efficiency is extremely overrated, in my opinion. It's one of the most expensive energy upgrades available, and no matter how great your windows will be, they'll always be the weak point in your home's insulation. Air sealing the home is by far the best way to save energy, and you'll be able to make improvements on that with the wall insulation.
 

Last edited by Shadeladie; 06-03-11 at 08:24 AM. Reason: Link removed.
  #12  
Old 06-20-11, 09:12 AM
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i find the original post interesting because my auditor was an insulator and told me it's not worth insulating my walls. he did confirm tons of leaking thru all the outlets and switches and just said to buy the insulators at home depot. I guess he didnt want my money lol

he DID recommend adding insulation in the attic and gave me a quote but i blew it in myself and saved a bunch of money and had fun in the process.

i'm glad to see you got a new heating unit, i noticed a 300 gallon decrease the year after i installed a new boiler.

i have 3 remaining single aluminum windows like you have..you can literally feel the breeze in winter, one moved an interior door a bit one day, scared me lol. 6 windows for 4800 seems high but it may be your area...in 2005 i had a 13 ft x 5 ft , a rather large dining room window, and 2 other windows done for 5500 and just last year i asked the same guy how mjuch for my spare room and he said 550 each and he's very expensive...maybe your small dimensions make a difference, i'm not sure.

i know someone that just had 2 approx 3x4 windows done by lowes and he did a pretty good job, the windows seem decent for the money and it was only 550 i think

we went to another local place and they wanted 900 for ONE of those windows..insanity..shop around!
 
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