Is there less useage of furnace and a/c if I have a radiant barrier sprayed on the underside of the roof. Is this method
for real or not worth the cost?
Don't know about sprayed on
My house has 2 attics. I put a paper/foil radiant barrier on one. It is consistently 10-15 degrees cooler than the attic without a radiant barier.
In heavy cooling climates yes.
If you live in the appropriate climate, I believe there has been proof that radiant barrier (RB) can typically save 8-12% on your cooling bill. The Florida Solar Energy Center is the best place I can point to, which will affirm the truth of this:
The above link is titled "Radiant Barriers: A Question and Answer Primer (FSEC-EN-15)". Sometimes the FSEC website has problems, so you may need to be patient or use Google to find other good research.
There are unscrupulous companies selling RB "chips" and claiming much higher savings. I hope you will recognize the more grandiose claims as being deceptive advertising. I do believe the better RB paints are 80% as effective as the foil type. Couple that with lower labor costs and that may be the way to go.
I have recently installed foil type RB in my S.Texas house and find the attic is much cooler. Am trying to verify the energy savings but with weather and energy prices changing so much, that's a real problem to prove and measure savings in a single house. I do believe it's going to be about 10% though.
Hope this helps -- Pstu
anyone out there with specific experience with the sprayed on type? I'm also considering this option living here in DFW.
I read up on the links given and also did a search on RB here. Now I'm really confused. Seems there is a lot of conflicting views. Even read one link that stated RB stapled to the rafters would make the attic hotter?? I just want to know about real results. Anybody have any they want to share? Seems like it would help. I checked my attic temp today around 5 p.m., it was 123F, outside was 99F. If I could get a 10-15 degree drop that would be great.
My own attic has foil type stapled to the rafters. It now runs maybe 10 degrees hotter than outdoors. The attic FEELS distinctly less hot, I have been reading my electric meter and so far the 10% cooling savings seems plausible. For best results you want to have good attic ventilation also, from most of the stuff I read.
>>Even read one link that stated RB stapled to the rafters would make the attic hotter??
I have read some false information from some vendors, slandering their competitors. Objective info is better obtained from universities and non-commercial sources. Florida Solar Energy Center has post-graduate scientists who seem to be doing a good job, asking the right questions and trying to get correct answers.
Hope this helps -- Pstu
Though there are conflicting claims from vendors, I believe that properly applied foil barrier or aluminum paints will lower attic temps.
For me the real key is can you do this as a DIY project. If so, the cost is well worth the long term gain.
Recently, in our area, West Texas, a vendor visited our city, provided dinner for potential customers, promised savings which might have been a little high but real, BUT then bid jobs at 15-20 times what this could have been done DIY.
Wish I could post pricing as you would be stunned.
That's what I'm looking for. Real tests from real people, not labs or vendors. That one vendor was pushing their RB chips. They also stated ridge vents were totally ineffective. OK why do so many people have them? I do have ridge vents soffit vent and gable vents on each end of my house with a gable fan on one end to aid airflow. Wondering how much it(fan) really helps. May conduct my own test if temps stay the same. Ptsu, what part of the country are you in?
I am also located in the DFW area and I have seen , both types used, as I spend alot of time in attics.
I would say that the V-Radiant Barrier foil works well if attic has some venting to extract the thermal load out.
The paint type I have only seen (1) home in Flower Mound with it and it was in spring , maybe 80* outdoor and attic was not warm at all.
I would research some company's around the DFW area and maybe; ask an energy Consulant about the savings.
'Life begins with the journey each day'
Radiant barriers - if applied correctly - provide the very best energy savings per sqft. For a 5,000 sqft roof it only cost me $500 for the barrier. My framers installed the foil on top of the roof trusses for another $200. Assuming a 10% savings you could easily payback the investment in 1-2 years. It is amazing how cool the house is with all this heat but no inside insulation
Here is a link of what it looks like inside my house (without insulation)
One of the negatives from installing radiant barriers is supposed to be less life from the shingles or whatever roof covering has been applied.
I have yet to see any long term studies verifying if this is true.
I live in DFW, and I was on Sherwin Williams site looking at their RB paint. Seriously considering it.
Installs, Changeouts, & Heat Stroke.....not necessarily in that order