What is the difference between Standard R-value and Effective Rvalue?


Standard R-value is the traditional way to measure how well a given insulation material can prevent or
resist heat transfer through its membrane when tested in a lab. Essentially, a scientists holds a heat
source on one side of the material and measures how much of that heat passes through or transfers to
the other side. “Effective” R-value, on the other hand, attempts to measure how that translates to real
world situations.
Your home or office environment is a complex “system” that is exposed to various sources of heat/cold
and cold, both externally (ex: hot sun/cold rain) and internally (ex: hot oven). The technical terms used
to identify these hot/cold sources or temperature effects are Conduction, Convection, Radiation and air
infiltration/circulation. As a result of this dynamic system with many real world variables, the “effective”
R-value is often different than the standard R-value.
In short, effective R-Value is a more modern and realistic way to measure insulation value. It
takes into consideration all types of heat/cold transfer that occurs in real world conditions.
It could be argued that effective R-value is more accurate and more important because most people
aren’t interested in a generic lab result so much as they are in the net effect the material will have on
the comfort of their home and, let’s be honest, the comfort of their bank account.
The bottom line is that spray foam offers the absolute highest effective R-value of all insulation products
on the market today – up to 4x that of traditional materials!
The effective R-value of spray foam translates to real world savings for you!