Quote:
Originally Posted by Mikesolar
You are right that I (and others) am concerned with a heating dominated climate and this is why i criticize bubble wrap. We are not used to any heating equipment at all in any attic space in Canada/northern US but I realize that it is quite common in the south. I do scratch my head about its use. I also talk to a lot of heating technicians in the mid and south who are always trying to take a sub-par system (ducts in the attic) and make it better because they get a huge number of complaints with heat loss and condensation in these types of systems. We sometimes have ducts in the attic for cooling only but there is a big trade off between system efficiency and the ability to have cooling in century old hot water heated homes. To my mind, I cannot even conceive of designing a system with ducts in the attic. That said, if you inherit a system like this, you must live with it and try to find ways to make it work better.
I have no problems with radiant barriers where appropriate but the one big problem is when they are misrepresented as having an R value that they simply don't have. I have seen too many very unhappy people who relied on tarps under slabs.
I agree with the use of radiant barriers in attics but, that too, is not used in our climate much. Having it on top of batt insulation is a good idea partly because it will reduce air movement within the batt which reduces its R value a great deal. Having it below the batt, is, in my opinion useless as that air space is still needed for IR reflection.
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In the southern US, usually square footage is more expensive, typically homes don't have basements(which is where we normally put ducts and furnaces in the North), and people down there building houses don't think the public wants an air handler or furnace in a closet near the kitchen(noisy near the bedrooms or living rooms). There's more to it than that but if I had to move to the South for some reason and bought a house with ductwork in the attic, I'd seal up the attic, insulate the attic, and seal all the ductwork(so the air inside the ducts can't touch the air in the house). I'd likely remove it rather than just close it off though because insulating and sealing the attic would be easier. In the southern US I'd want the most cooling efficiency I can get and the winter isn't that cold so both of these coins add up to a mini-split setup. ..just don't forget to deal with solar gains through windows. I'd still do R60 in the attic, even down there, that way I don't have to care how hot the attic is.