|
|
|
Age R-Values
What do R-Values Mean?
The term R-value is the most popular term used to measure various insulating materials.
Unfortunately, what is printed on the bag or on the material itself often gives a poor representation of
how the product performs in the field. In order to better understand how insulating products work it is
important to understand what R-values measure. R-value is the measurement of resistance of heat
flow through a particular product. The higher the R-value, the greater the products resistance to heat
transfer.
Here are a number of other terms used when describing a products energy rating.
Thermal Mass: Thermal mass such as logs or concrete slow the transfer of heat but do not
reduce heat transfer. This is why most basements are insulated before they are finished.
Advertised R-Value: This is the manufacturers stated R-value for the product as it is tested.
This R-value is often never achieved in real world applications. Example: Many builders are moving
towards framing with 2x6 material in order to gain a higher R-value. Unfortunately R-19 batt type
insulation needs a space of 6-1/2" in order to achieve it's stated R-value. A 2x6 is only 5-1/2" thick.
When the R-19 insulation is installed it must be compressed thereby reducing it's stated R-value to
16. Likewise, doubling up on fiberglass batts will not increase their overall R-value, in fact it lowers
it significantly.
Thermal Breaks: Thermal breaks occur when a conductive material is placed in a wall and
comes in contact with the two outer skins of the wall. An example of a thermal break is the studs in a
typical frame wall. It is important to note that metal studs "conduct" cold much more effectively
than wood.
Whole Wall R Value: Whole wall R-value is the measure of a wall system as it appears on the
house. This would include the measure of heat loss due to window openings, electrical boxes and
studs. The whole house R-value is the best measurement for a products performance in a home
application. Example: When fiberglass batts are used in a typical stud wall the combined R-values of
the 2xs material and the batt insulation must be used to determine the correct R-value. Test have
shown the actual whole house R-values for 2x4 walls with R-13 batts to be R-10 and for 2x6 walls with
R-19 to be R-13.8. This is hardly what one would consider to be "R-VALUE".
When choosing methods to insulate your home, the products with the greatest return on investment
are those products with little or no thermal breaks, have a high resistance to heat transfer and can be
installed in a manner that conforms to there true R rating. Thermocore consistently perform to it's
stated R-value when used in home construction giving you the greatest value for your money and the
highest return on your investment.
Special Note
It has become more popular to frame homes with 2x6's rather than 2x4's to increase R value. The
fact is that the true R value for a wall framed with 2x6's never reaches the intended R value of 19. It
is in fact R 13.69 a reduction in R value of 28%. The same problems occur with 2x4 construction. The
intended R value is intended to be 13 but in fact it is truly R 9.58 a loss of 27%. This phenomena does
NOT occur with Thermocore Panel Systems. The R value is in fact it's stated value. The question is:
where is the true value in R value? Clearly the answer is panels Data Source: Oakridge
National Laboratories
|
|
|
|
|
|
|
|
|
Site Designed By:
|
|