Looking for a roll up door? When selecting the best one for your needs, there are a few factors you need to keep in mind, including the “who, what, where, when, why, and how” of the door.
While the questions above are standard ones you may ask yourself when choosing a roll up door, one people may tend to forget is if the door also needs a certain level of thermal resistance.
Thermal resistance is not something that often comes to mind when people select their roll-up doors. While it may not be at the top of the list, it should be taken into consideration. If you don’t take thermal resistance and air leakage into account, they can drastically reduce the energy performance of your commercial garage door and garage door insulation, especially when closed. R-Value and U-Factor are two terms to know when talking about thermal resistance.
R-Value is usually seen as a straightforward measurement in regards to thermal resistance. However, R-Value is sometimes misunderstood. The technical definition of R-Value is “the inverse of the time rate of heat flow through a body from one of its bounding surfaces to the other surface for a unit temperature difference between the two surfaces, under steady state conditions, per unit area.”
While not exactly the most helpful definition for those of us who aren’t extremely technical, this definition encapsulates R-Value. Luckily for you, we’ve translated this into plain English: the R-Value is the capacity of an insulating material to resist heat flow. The higher the R-Value on a roll up door, the greater insulation power it has.
People often think that R-Value is the only thing they need to take into account when determining an insulated coiling door’s energy efficiency. This is not the case.
While R-Value can accurately measure how effective wall insulation is, it isn’t the greatest for figuring out how well insulated a product with multiple components is. So when you see an R-Value for insulation on a garage door, this really only refers to the slat cavity’s resistance to heat transfer. It’s like putting a thick pair of wool gloves on to protect your hands while wearing a tank top and shorts in the bitter cold.
The insulation (a thick, wool glove) is great for your hand, but leaving roll-up door guides, head and hood out of the equation (with improper seals) is just like not caring for any other parts of your body in 10⁰.
Imagine the amount of “air leakage” you’d feel in this scenario, and it sums up what this means for a roll-up door in a similar situation: the R-Value is null and void. R-Value is a calculated, but not tested measurement. This means that a roll-up door isn’t tested as a whole or a complete assembly. Other important items left out of the measurement of R-Value are the seal around the door guides, head and hood.
U-Factor measures the rate of heat transfer, and is appropriately applied to the thermal efficiency of windows which, similar to garage door insulation, are assemblies comprised of multiple components.
Where R-Value is only calculated, U-Factor is tested. The tested value in U-Factor is one of heat transfer via conduction and radiation, making it a better energy performance indicator than R-Value.
Along with being independently tested, U-Factor also tests the entire door assembly unlike the calculations done for R-Value, which only include a single component. Whereas a high R-Value is good news, in the case of U-Factor, the lower the number, the better. U-Factor is an overall better measure of your commercial garage door and its insulation because it takes everything into account.For more information on insulated roll up doors and the most energy efficient commercial doors in the industry, contact us today. We can help explain the benefits and assist you with solving any complex problem with our rolling door solutions.
Cookson continues to lead in innovations in roll up door, security gate and closure products. To inquire how Cookson’s experts and customer service can help you with your next roll up door project, call 1-800-294-4358