Understanding U-factor and R-value
Confused about U-factor and R-value? You’re not alone. Understanding the difference between these thermal values will help to make the best decision when it comes to choosing a commercial rolling door for your customers.
According to DASMA, U-factor is poised to replace R-value and become the new industry standard. It’s a logical step, as it’s a more accurate measurement of thermal performance and is already a value that architects and specifiers are familiar with. In the end, everyone benefits, including customers and dealers, when it comes to knowing the U-factor of a product
“U-factor and R-value are often mistaken for each other, but they represent different measurements of heat transfer. Each is the opposite of the other, and they can’t be compared. Understanding the differences between the two values can help you make smarter decisions about insulation and energy efficiency.” - Nathan Janiczek, Clopay Corporation Design Engineer
How do you determine the thermal properties of garage doors?
The performance of a garage door's thermal insulation is typically characterized using two primary metrics: the "Tested Door Assembly" (U-factor) and the "Calculated Door Section" (R-value).
U-factor is determined by testing the thermal properties of an installed rolling door. This measurement encompasses the door’s entire assembly including its guides, curtain, bottom bar and perimeter seals.
R-value, on the other hand, is a calculation of the insulated materials only, meaning that you are getting the thermal property of the insulation of an individual door section, and not the full assembly.
What sets U-factor apart from other thermal ratings?
Because U-factor is determined through physical testing, like the testing available through ANSI/DASMA 105-2017, you receive a measurement that’s more accurate than other thermal performance ratings. U-factor is also nothing new for specifiers
and purchasers, since it's the current standard of gauging the thermal performance of fenestration products.This value is represented in all building codes and standards.
The R-value of a commercial door's individual section doesn’t accurately reflect its overall performance. Since it’s a calculation, you’ll find variations in the door’s components, giving you an inaccurate thermal performance measurement. Manufacturers tend to emphasize the R-value of a garage door’s most insulative component section, which doesn’t offer a precise measurement of the thermal performance of the entire installed assembly.
What’s a good U-factor for a garage door?
U-factor measures the speed of heat transferred through the door assembly. When thermal performance is improved, less heat is transferred through the assembly, resulting in a lower U-factor. So, with U-factor, lower numbers are better.
R-value calculates a material's resistance to heat transfer. When the performance of a product is improved, the resistance to heat flow increases, which results in a higher R-value.
