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R&A Contracting - Energy Value ratings commercial roofing

This post is part of four-part series exploring energy efficiency values in insulation, such as K-Value, C-Value, R-Value, and U-Value.

How is U-Value measured? What’s the difference between U-Value and K-Value, C-Value, or even R-Value?

This series of articles concludes with examining the purpose and metrics of U-Value. Unlike R-Value, K-Value, and C-Value, which are more defined by construction and energy-efficiency, U-Value is more defined by engineering parameters. We can dive into the scientific calculations of U-Value and how it functions in relation to engineering qualifiers. The more effective way of communicating how U-Value is measured is through a simple illustration.

Let’s take a basic residential wall built by 2″x4″ studs that are vertically spaced the standard 16″ apart from center to center. The interior may have a thick plastic vapor barrier between the studs and a typical 3/8″-thick gypsum board. We can ignore the energy value of the doors and windows as well as the K-Value of the plastic film vapor barrier for the sake of simplicity. The exterior material and any additional insulation placed between the outside face of the wall and the exterior material can be calculated into the U-Value. And this is where it gets complicated, but don’t worry, this math can be easier than you might expect.

The U-Value is the total calculated value of all the building materials in that given wall:

  • K-Value of the gypsum boards, wall studs, interior and exterior insulation, exterior material, and any additional siding;
  • And, the C-Value of the interior vapor barrier and any additional vapor barrier, if relevant.

What’s U-Value?

U-Value measures thermal transmittance as defined by ASTM International:

“Transmittance, thermal, n: the heat transmission in unit time through unit area of a material construction and the boundary air films, induced by unit temperature difference between the environments on each side.” (ASTM International C168)

The collective energy barrier provided by that single wall in our illustration is what constitutes the U-Value. In truth, entire volumes of books have been created based solely on the calculation, nuances, and variances of U-Value in energy efficiency. Without being too simplistic, we see the U-Value as the collective energy capabilities of an entire construction entity, such as a wall, a building, or even a commercial roof.

If you’d like to learn more about how a highly efficient commercial roof can transform your energy costs, call our R&A Contracting team today.

I’d be an idiot if I did not take this opportunity to communicate to you how much we appreciate the way in which you conduct business and take care of our facility. In my experience you, and your team, are at the top of the list of all the roofing companies I’ve dealt with over the years. Thank you!

Jim Lowry - Bissinger's Handcrafted Chocolatier

Eric and crew were really nice to have around. They were courteous, careful and caused little if any disruption. Their work looks good too! To be honest… a good experience with a product that I initially had misgivings about. I’m a convert because of Bubba, Sam and Eric. Thank you.

Jim Lowry - Bissinger's Handcrafted Chocolatier

“I want to thank the crew at R&A for a job well done on our very leaky roof at the shop. It is certainly nice to have the drips and rivers gone from the shop when it is raining. I also wanted you to know how much we appreciated that the guys were able to stay out of our way and allowed us to do business as usual without any problems or interruptions. The roof looks great and the clean-up after the job made it so we couldn’t even tell you’d been here. Thanks for doing what you do so well!”

Jay Moore, President of Safe Way Tire and Auto Center

“My wife and I were on vacation when water pipes burst in our house. We got a hold of Craig and the R&A crew was able to start evacuating the water immediately. The best part was that they were able to start work before we even returned home. It was a very fast turnaround considering the extensive amount of water damage.”

Will from Dardenne Prairie, MO

“Craig and Mike came out in a timely fashion when we needed the work done. They did a reliable and quality job.”

Jerry from SLR Properties

“Craig helped us out tremendously with the insurance process. Timely and very professional.”

Lindell from Greater Missouri Builders (GMB)

“We purchased a house and there was some damage to the roof. Very impressed with the thoroughness of Mike’s inspection. Very comfortable with their explanation of what needed to be fixed. Most impressive was the way they protected our landscaping. Really liked the way they treated me as a valued customer, even though it was only a small project.”

Ross from Troy, MO

“I use R&A Contracting when my commercial roofs receive storm damage. They work on our behalf through every step of the insurance claim process. They perform all of the work and complete the insurance process, making our roofs better than they were before the storm.”

Director of Facilities for a large Property Management Company

“The team at R & A Contracting responded immediately when notified of our water disaster. They removed water-damaged materials and property quickly and restored our home even before the final settlement from our insurance company. They minimized how long our family had to live in a hotel and got us back to normal as fast as possible.”

Will from O'Fallon, MO