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RE: [hreg] Re: Radiant Heat Shield

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  • Mike Ewert
    The foil or paint under the rafters works because the emissivity is low; even though the foil itself gets hot, it doesn t radiate much heat. My AC guy said
    Message 1 of 11 , Feb 9, 2003
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      The foil  or paint under the rafters works because the emissivity is low; even though the foil itself gets hot, it doesn't radiate much heat.  My AC guy said he used the paint in his metal building shop and really noticed a difference.
      -----Original Message-----
      From: mark r. johnson <mrj53@...> [mailto:mrj53@...]
      Sent: Thursday, February 06, 2003 1:39 PM
      To: hreg@yahoogroups.com
      Subject: [hreg] Re: Radiant Heat Shield

      Chris, what I have clearly been hearing is these methods work. The one
      that seems most unlikely to you, attaching this foil-like material to
      the underside of the roof decking, is to the best of my knowledge the
      most effective method for adding to an existing home. Of course if you
      are building new construction, or re-roofing and can consider
      replacing the decking, you probably would find it better to buy the
      kind of
      roof decking that has the foil underside.

      Evidently the shiny side must face an air space for it to work. The
      downside of laying the barrier horizontally on existing attic
      insulation, is that it works fine the first day, but it soon will get
      dusty and become less effective.

      Usually we assume asphalt shingles when we talk about radiant
      barriers. If you happen to have a different roof material, we ought to
      stop and reconsider. I have read that tile roofs have advantages which
      lessen the effectiveness of radiant barriers and attic ventilation.
      Probably metal roofs as well.

      It is my understanding that spray-on radiant barrier paint cannot be
      as reflective as foil stapled to roof rafters or on decking material,
      but its ease of use may be attractive for retro-fit jobs. Tom Tynan
      endorses spray-on radiant barrier paint on the underside of your roof
      decking:
      http://tomsangle.com/docs/Radiant.pdf
      So far as I can tell, Tom agrees that foil based roof decking is
      superior for new construction. I believe stapling foil type material
      to the rafters, will provide superior performance but it might be so
      much extra labor that costs outweigh the benefits.

      You might find the following article from the Florida Solar Energy
      Center (FSEC) interesting. All that I have seen from FSEC appears high
      quality practical research, in my opinion:
      http://www.fsec.ucf.edu/bldg/pubs/pf337/

      I must say that I am a total amateur and am merely passing along
      things I have been taught which sound right. Am thinking about putting
      up foil type radiant barrier in my house but have not done the project
      yet. Am somewhat thinking about retro-fitting "skin venting" to our
      exterior walls but first must find someone with professional
      credentials who will endorse such a project. If anyone finds fault
      with what I have said, it will be to everybody's benefit to correct
      me.

      Thanks and good luck -- Mark J.





      --- In hreg@yahoogroups.com, "Roxanne Boyer" <rox1@a...> wrote:
      > I am looking for ways to reduce the cooling energy costs of my home.
      I have heard about radiant heat barriers in the form of:
      > 1) Exterior coatings (put on the paint or shingles) that reflect
      solar radiation.
      > 2) Foils that are applied to the underside of the roofing board -
      either sprayed or stapped in sheets - that reflect infared radiation.
      > 3) Foils that cover the attic floor on top of the insulation that
      also reflect infared radiation.
      >
      > Does anyone have any experience with these applications?  Do they
      work?  How much does it cost to have them installed?
      >
      > Theoretically the radiant barrier on the exterior of the roof and
      the radiant barrier on the attic floor should work.  I don't see how
      the foil/spray on the bottom of the roof could work.
      >
      > Chris Boyer
      > "Conservation is a great alternative fuel."


      Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
    • Robert Bruce Warburton
      I found a web site from a Danish group similar to the HREG, but concentrating on windpower. The Danes make the greatest use of windpower as far as I have read.
      Message 2 of 11 , Feb 9, 2003
      • 0 Attachment
        I found a web site from a Danish group similar to the HREG, but concentrating on windpower. The Danes make the greatest use of windpower as far as I have read. Mike what have you heard about the Russian shuttle Buran? No one is mentioning the Buran which had just one launch.

        Mike Ewert wrote:

         The foil  or paint under the rafters works because the emissivity is low; even though the foil itself gets hot, it doesn't radiate much heat.  My AC guy said he used the paint in his metal building shop and really noticed a difference.
        -----Original Message-----
        From: mark r. johnson <mrj53@...> [mailto:mrj53@...]
        Sent: Thursday, February 06, 2003 1:39 PM
        To: hreg@yahoogroups.com
        Subject: [hreg] Re: Radiant Heat Shield
         
        Chris, what I have clearly been hearing is these methods work. The one
        that seems most unlikely to you, attaching this foil-like material to
        the underside of the roof decking, is to the best of my knowledge the
        most effective method for adding to an existing home. Of course if you
        are building new construction, or re-roofing and can consider
        replacing the decking, you probably would find it better to buy the
        kind of
        roof decking that has the foil underside.

        Evidently the shiny side must face an air space for it to work. The
        downside of laying the barrier horizontally on existing attic
        insulation, is that it works fine the first day, but it soon will get
        dusty and become less effective.

        Usually we assume asphalt shingles when we talk about radiant
        barriers. If you happen to have a different roof material, we ought to
        stop and reconsider. I have read that tile roofs have advantages which
        lessen the effectiveness of radiant barriers and attic ventilation.
        Probably metal roofs as well.

        It is my understanding that spray-on radiant barrier paint cannot be
        as reflective as foil stapled to roof rafters or on decking material,
        but its ease of use may be attractive for retro-fit jobs. Tom Tynan
        endorses spray-on radiant barrier paint on the underside of your roof
        decking:
        http://tomsangle.com/docs/Radiant.pdf
        So far as I can tell, Tom agrees that foil based roof decking is
        superior for new construction. I believe stapling foil type material
        to the rafters, will provide superior performance but it might be so
        much extra labor that costs outweigh the benefits.

        You might find the following article from the Florida Solar Energy
        Center (FSEC) interesting. All that I have seen from FSEC appears high
        quality practical research, in my opinion:
        http://www.fsec.ucf.edu/bldg/pubs/pf337/

        I must say that I am a total amateur and am merely passing along
        things I have been taught which sound right. Am thinking about putting
        up foil type radiant barrier in my house but have not done the project
        yet. Am somewhat thinking about retro-fitting "skin venting" to our
        exterior walls but first must find someone with professional
        credentials who will endorse such a project. If anyone finds fault
        with what I have said, it will be to everybody's benefit to correct
        me.

        Thanks and good luck -- Mark J.
         
         
         
         

        --- In hreg@yahoogroups.com, "Roxanne Boyer" <rox1@a...> wrote:
        > I am looking for ways to reduce the cooling energy costs of my home.
        I have heard about radiant heat barriers in the form of:
        > 1) Exterior coatings (put on the paint or shingles) that reflect
        solar radiation.
        > 2) Foils that are applied to the underside of the roofing board -
        either sprayed or stapped in sheets - that reflect infared radiation.
        > 3) Foils that cover the attic floor on top of the insulation that
        also reflect infared radiation.
        >
        > Does anyone have any experience with these applications?  Do they
        work?  How much does it cost to have them installed?
        >
        > Theoretically the radiant barrier on the exterior of the roof and
        the radiant barrier on the attic floor should work.  I don't see how
        the foil/spray on the bottom of the roof could work.
        >
        > Chris Boyer
        > "Conservation is a great alternative fuel."
         

        Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.


        Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

      • Mike Ewert
        http://liftoff.msfc.nasa.gov/rsa/buran.html ... From: Robert Bruce Warburton [mailto:warbur2@ev1.net] Sent: Sunday, February 09, 2003 5:16 PM To:
        Message 3 of 11 , Feb 9, 2003
        • 0 Attachment
          -----Original Message-----
          From: Robert Bruce Warburton [mailto:warbur2@...]
          Sent: Sunday, February 09, 2003 5:16 PM
          To: hreg@yahoogroups.com
          Subject: Re: [hreg] Re: Radiant Heat Shield

          I found a web site from a Danish group similar to the HREG, but concentrating on windpower. The Danes make the greatest use of windpower as far as I have read. Mike what have you heard about the Russian shuttle Buran? No one is mentioning the Buran which had just one launch.

          Mike Ewert wrote:

           The foil  or paint under the rafters works because the emissivity is low; even though the foil itself gets hot, it doesn't radiate much heat.  My AC guy said he used the paint in his metal building shop and really noticed a difference.
          -----Original Message-----
          From: mark r. johnson <mrj53@...> [mailto:mrj53@...]
          Sent: Thursday, February 06, 2003 1:39 PM
          To: hreg@yahoogroups.com
          Subject: [hreg] Re: Radiant Heat Shield
           
          Chris, what I have clearly been hearing is these methods work. The one
          that seems most unlikely to you, attaching this foil-like material to
          the underside of the roof decking, is to the best of my knowledge the
          most effective method for adding to an existing home. Of course if you
          are building new construction, or re-roofing and can consider
          replacing the decking, you probably would find it better to buy the
          kind of
          roof decking that has the foil underside.

          Evidently the shiny side must face an air space for it to work. The
          downside of laying the barrier horizontally on existing attic
          insulation, is that it works fine the first day, but it soon will get
          dusty and become less effective.

          Usually we assume asphalt shingles when we talk about radiant
          barriers. If you happen to have a different roof material, we ought to
          stop and reconsider. I have read that tile roofs have advantages which
          lessen the effectiveness of radiant barriers and attic ventilation.
          Probably metal roofs as well.

          It is my understanding that spray-on radiant barrier paint cannot be
          as reflective as foil stapled to roof rafters or on decking material,
          but its ease of use may be attractive for retro-fit jobs. Tom Tynan
          endorses spray-on radiant barrier paint on the underside of your roof
          decking:
          http://tomsangle.com/docs/Radiant.pdf
          So far as I can tell, Tom agrees that foil based roof decking is
          superior for new construction. I believe stapling foil type material
          to the rafters, will provide superior performance but it might be so
          much extra labor that costs outweigh the benefits.

          You might find the following article from the Florida Solar Energy
          Center (FSEC) interesting. All that I have seen from FSEC appears high
          quality practical research, in my opinion:
          http://www.fsec.ucf.edu/bldg/pubs/pf337/

          I must say that I am a total amateur and am merely passing along
          things I have been taught which sound right. Am thinking about putting
          up foil type radiant barrier in my house but have not done the project
          yet. Am somewhat thinking about retro-fitting "skin venting" to our
          exterior walls but first must find someone with professional
          credentials who will endorse such a project. If anyone finds fault
          with what I have said, it will be to everybody's benefit to correct
          me.

          Thanks and good luck -- Mark J.
           
           
           
           

          --- In hreg@yahoogroups.com, "Roxanne Boyer" <rox1@a...> wrote:
          > I am looking for ways to reduce the cooling energy costs of my home.
          I have heard about radiant heat barriers in the form of:
          > 1) Exterior coatings (put on the paint or shingles) that reflect
          solar radiation.
          > 2) Foils that are applied to the underside of the roofing board -
          either sprayed or stapped in sheets - that reflect infared radiation.
          > 3) Foils that cover the attic floor on top of the insulation that
          also reflect infared radiation.
          >
          > Does anyone have any experience with these applications?  Do they
          work?  How much does it cost to have them installed?
          >
          > Theoretically the radiant barrier on the exterior of the roof and
          the radiant barrier on the attic floor should work.  I don't see how
          the foil/spray on the bottom of the roof could work.
          >
          > Chris Boyer
          > "Conservation is a great alternative fuel."
           

          Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.


          Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.


          Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
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