Should I use the R-value or U-factor to Compare Replacement Windows? 

If you have spent any time shopping for replacement windows in Escondido, CA then you have probably seen or heard a little bit about the energy labels on these types of products. The ratings on these labels allow customers to compare products for energy efficiency head-to-head. But terms like R-value and U-value can be particularly perplexing to homeowners. If you don’t understand the difference, don’t worry. You are not alone. Here is the information you need to know about these references before you purchase replacement windows:

What is the R-Value?

R-values were originally developed to rank the thermal performance specifically on insulation. It accounts for both the thermal performance and the thickness of a certain material. And the higher the R-value, the better the insulation. And this rating system is now used to compare the thermal performance of other building materials as well, but only one specific material at a time. If you layer different materials you simply add the R-value of each individual material together. That said, this measurement is not used to measure the thermal performance of an entire system. It also only accounts for conduction. But heat can move in and out of the home in several different ways. That is where the U-factor comes in.

What is U-Value or U-Factor?

The U-value is an engineering rating. It is the inverse of the total heat resistance of an element. But it is a bit more complex. Like the R-value, it measures how much heat is lost through the given thickness of a certain material. But it also accounts for convection and radiation as well. The National Fenestration Rating Council (NFRC) uses the U-value or U-factor as the standard rating metric on windows and doors. And because this measures the rate at which a product transfers heat, lower U-values mean better insulation and help protect the building envelope.

What to do if Replacement Windows Have Both Ratings?

Some manufacturers have taken to labeling their own products or product lines with R-values. They think these ratings are a bit easier for the consumer to understand. After all, it is easy to see how an R6 material insulates better than an R4. Whereas, it can be a bit more difficult to compare a U-factor of 0.17 and 0.25. That said, it is important to keep in mind that R-values still only reference a single material, not the entire assembly. If you really want to get a good comparison of products you will want to use the U-factor along with the Solar Heat Gain Coefficient (SHGC) on energy labels. That is the best way to know exactly the type of energy performance you can expect from new windows and doors.

If you are interested in learning more about the energy labels on replacement windows in Escondido, CA stop by Pelican Replacement Windows. We can walk you through the basics of these ratings and help you find the best solutions for the local climate. That way you can feel more confident choosing your replacement windows, knowing you are getting the best possible energy performance.