m Ransley wrote:
Right Nick, you post numbers but cant prove anything, because foil does
nothing of real merit to R value, it is a Radiant barrier, no R value of
significance. If as you say it increases each side by R3 then R 7.2 -
1" of polyiso would come out near R 13, kind of dumb, yes, maybe you
have numbers to prove your dream.
Unlike your arrogance, your ignorance may be curable :-)
You might buy an old copy of the ASHRAE Handbook of Fundamentals and look
at the table on R-values of plane airspaces, or look into "System R-values."
Nick
Labeling and Advertising of Home Insulation (R-Value Rule) CFR 16CFR460
(From the U.S. Government Printing Office via GPO Access)
Source: 44 FR 50242, Aug. 27, 1979, unless otherwise noted.
Sec. 460.1 What this regulation does.
This regulation deals with home insulation labels, fact sheets, ads, and
other promotional materials in or affecting commerce, as "commerce" is
defined in the Federal Trade Commission Act. If you are covered by this
regulation, breaking any of its rules is an unfair and deceptive act or
practice or an unfair method of competition under section 5 of that Act. You
can be fined heavily (up to $10,000 plus an adjustment for inflation, under
Sec. 1.98 of this chapter) each time you break a rule...
460.5 R-value tests.
R-value measures resistance to heat flow. R-values given in labels, fact
sheets, ads, or other promotional materials must be based on tests done
under the methods listed below. They were designed by the American Society
of Testing and Materials (ASTM). The test methods a
All types of insulation except aluminum foil must be tested with ASTM C
177-85 (Reapproved 1993), "Standard Test Method for Steady-State Heat Flux
Measurements and Thermal Transmission Properties by Means of the
Guarded-Hot-Plate Apparatus;" ASTM C 236-89 (Reapproved 1993)...
The tests must be done at a mean temperature of 75 deg.Fahrenheit. The tests
must be done on the insulation material alone (excluding any airspace).
R-values ("thermal resistance") based upon heat flux measurements according
to ASTM C 177-85 (Reapproved 1993) or ASTM C 518-91 must be reported only
in accordance with the requirements and restrictions of ASTM C 1045-90,
"Standard Practice for Calculating Thermal Transmission Properties from
Steady-State Heat Flux Measurements."
Aluminum foil systems with more than one sheet must be tested with ASTM C
236-89 (Reapproved 1993) or ASTM C 976-90, which are incorporated by
reference in paragraph (a) of this section. The tests must be done at a mean
temperature of 75 deg.Fahrenheit, with a temperature differential of 30
deg.Fahrenheit.
Single sheet systems of aluminum foil must be tested with ASTM E408 or
another test method that provides comparable results. This tests the
emissivity of the foil--its power to radiate heat. To get the R-value for a
specific emissivity level, air space, and direction of heat flow, use the
tables in the most recent edition of the American Society of Heating,
Refrigerating, and Air-Conditioning Engineers' (ASHRAE) Handbook. You must
use the R-value shown for 50 deg.Fahrenheit, with a temperature differential
of 30 deg.Fahrenheit.
For insulation materials with foil facings, you must test the R-value of the
material alone (excluding any air spaces) under the methods listed in
paragraph (a) of this section. You can also determine the R-value of the
material in conjunction with an air space. You can use one of two methods to
do this:
You can test the system, with its air space, under ASTM C 236-89 (Reapproved
1993) or ASTM C 976-90, which are incorporated by reference in paragraph (a)
of this section. If you do this, you must follow the rules in paragraph (a)
of this section on temperature, aging and settled density.
You can add up the tested R-value of the material and the R-value of the air
space. To get the R-value for the air space, you must follow the rules in
paragraph (c) of this section.
For aluminum foil: the number of foil sheets; the number and thickness of
the air spaces; and the R-value provided by that system when the direction
of heat flow is up, down, and horizontal.
For insulation materials with foil facings, you must follow the rule that
applies to the material itself. For example, if you manufacture boardstock
with a foil facing, follow paragraph (b)(4) of this section. You can also
show the R-value of the insulation when it is installed in conjunction with
an air space. This is its "system R-value." If you do this, you must clearly
and conspicuously state the conditions under which the system R-value can be
attained.
Also see:
http://www.atlasroofing.com/download...ng_rackbro.pdf
and
http://www.reflectixinc.com/PDF/RIMA_Handbook.pdf