Everybody is talking about R5 windows! Late in May, the U.S. Department of Energy launched its “Highly-Insulating R-5 Windows and Low-E Storm Windows Volume Purchase Program” with an event in Washington, D.C., held at the headquarters of the National Association of Homebuilders (NAHB). The program was designed to pair manufacturers of super energy efficient windows with potential large-volume purchasers such as government agencies, builders, energy retrofitters, renovators and weatherization providers who are completing projects such as K-12 schools, local/state agencies, federal-government building projects, non-profit agencies and universities.

During 2009 I saw a considerable effort by many of my customers, usually the larger window companies who have the engineering resources and project management budgets, to put an R5 program together so that they can get on the list.

To be considered for the R-5 Volume Purchase Program, windows must achieve a maximum 0.22 U-value for operable units and 0.20 U-factor for fixed. Additionally, they must be certified to ASTM E2190 for insulating glass durability, NFRC 100/200 for U-factor/Solar Heat Gain and AAMA/WDMA/CSA 101/IS2/A440-05 for air, water and structural performance. All windows must be offered at a fixed price and provide a 20-year warranty on the glass.

As I travel from customer to customer, I am seeing that everyone is moving in a similar direction. In order to achieve R5 status, they are moving toward using triple pane IG, krypton gas, warmer edge spacer systems, multi-stack low-E coatings, and more thermally efficient framing systems. But many voice a common concern: “Jim, what components give me the most for my dollar and what workmanship improvements do I need to implement so that I can get to R5 while minimizing my risk?” I am asked.

R5 windows, of course, dictate the use of high performance components. Is my warm- edge spacer warm enough? How well does my spacer distribute stress? Is the sealant that I am using up to the task or do I need to upgrade to a dual-seal equivalent type? Will argon suffice or do I need to look into krypton? If so, will my current gas filling equipment suffice or do I need to upgrade? Also, with heavier triple pane IG units, window extrusions and hardware may need to be upgraded to support the heavier weight of a triple pane glass unit. Do I need to replace metal reinforcements with fiberglass or non-metal composite polymer materials in order to provide strength to vinyl profiles without the heat conductance that is typical with metal? Will injecting foam into my profiles help? These are all questions that have been asked and answers evaluated.

But at the same time that components are being upgraded, so must quality assurance programs! Triple-pane windows have twice the probability of failure because there are now two pane gaps vs. one. However, it only takes one cavity to fog to result in a complete unit failure. This means that workmanship practices need to go under the magnifying glass! What handling and storage practices do I have in place for sputter-coated low-e glass? Do I need to upgrade my glass cutting equipment to increase accuracy for triple pane construction? Do I need to edge delete? Is my glass washer operating at the correct temperature and drying the glass thoroughly? What is the optimum oven press temperature and how do I ensure adequate adhesion across all three panes of glass?

So the R5 Volume Purchase Program means higher component costs as well as a greater investment in quality assurance programs and possibly equipment upgrades! However, at the same time, it must all be accomplished at a fixed price, which the DOE targets at $4 per square foot. So where is the payback for the fenestration industry?

The answer resides in the title of the program itself…Volume. So, let’s all hope that this volume does indeed materialize. If so, then R5 will become R Future!

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