[Equest-users] Radiant barrier in walls

[Aaron Powers]

Since DOE-2 uses the weight factor method for loads, you don't have access
to the inside emissivity of surfaces directly.  You do have access to the
INSIDE-FILM-RES, which is the combined radiative and convective resistance.
 Table 12 in the Volume 2: Dictionary DOE2.2 documentation gives a guide
for what to use based on your material.  For example, if your barrier has
an emissivity of 0.05, they suggest you use a film resistance of 1.70.
 Keep in mind that when the weight factors are calculated (one time
calculation), DOE-2 assumes an emissivity of 0.9 for all surfaces which you
cannot change.  This means that your increased film resistance will have no
effect on internal loads radiating to the wall, only on the energy coming
through the wall via conduction.  This should give you a good order of
magnitude estimate, but it will tend to be conservative.  As Joe said,
there's probably also a way to equate the effect to a resistance layer.  I
believe this is what the wizard does if you select radiant barrier for a
roof.

Aaron
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20130403/60b0695f/attachment-0001.htm>