“It is always wise to look ahead, but difficult to look farther than you can see.”—Winston Churchill

After attending GlassBuild last week and reviewing innovations that can help improve thermal performance, I’m encouraged! The new low-E coatings and combinations of coatings, along with some new work on thin triples, advises us that we can achieve lower U-factor for the next Energy Star revision. Innovations will allow us to stay in double-glazed configurations for many window types if we can convince the U.S. Environmental Protection Agency (EPA) to slightly modify its first proposal. Currently EPA is setting a 0.22 U-factor for the Northern zone to replace the current 0.27 requirement that has been in place for six years.

In many cases the 0.22 U-factor proposal will push designers to change glazing pockets and respectively overall depths to allow triple-pane insulating glass units (IGUs). This is very concerning, since it is a major investment in every aspect of our production systems. Starting from lineals, to every tool that touches the lineals, to most of the hardware, it will be a major refit at most factories.

Of course, many of us do make triple pane options, but they are limited in volume and in very few product lines. This is witnessed by the Energy Star Most Efficient program, which requires triple glazing, having only a 1-2% share after many years.

The initial comment period has passed on the first draft from EPA and the trade associations have responded with extensive requests to modify. These letters will be public soon, as the EPA posts all responses on its website. I have also sent in a response partially copied below.

My suggestion is for your company to weigh in on this proposal considering the effects on your customers!

My selected comments to EPA are as follows.

… This note is to address concerns with the proposal to require Energy Star program changes to windows, doors, and skylights. We would like to thank you for the extensive work and analysis your team and DOE put into this proposal. The reports are the most extensive we have seen. As you know I have been heavily involved with Energy star development since the start of the program in 1998 and have been part of NFRC since 1991. Given this experience and concern for the consumers of our products I write these concerns:

  • Consumer acceptance by willingness to pay a premium is key to the program’s success. We must be most concerned about the … proposal’s key component basis of a $3.59 energy savings per month over existing energy star products. This low savings number along with the $1,265-$2,760 projected increase in window price (whole house of 23 windows) reveals a poor deal for the consumer. They must be willing to buy Energy Star products!
  • The proposal requires a triple pane for most every window in the North. This drives carbon content of windows up by … nearly 50% and is in strong conflict with EPA’s carbon reduction program. Triple panes also drive the weight of a standard window up by nearly 45 lbs. each. This will cause more (transport) carbon embodiment (along with) safety concerns for installers.
  • EPA is proposing a 23% increase in performance, which is dramatically higher than other Energy star categories under revision. This disadvantages the window, door and skylight industry.
  • The proposal’s triple pane quest also puts strain on the durability of IG products. The current low volume of triples has not given the industry enough experience with high volume sealant application, pressing and curing. The manufacturing of triples is three times more difficult with standard processes.

The recommended remedy is to modify the proposal to keep double panes in all regions and to limit U-values to 0.24 and not the 0.22 proposed. This reconsideration is critical to keeping the consumer engaged with the program and thus keeping large retailers and distributors engaged.

Keep innovating!


  1. I agree 100%
    One thing to add.
    The 30/30 criteria for the past tax credit proved to be a winner due to the fact it was for the masses,not just the elite of triple glazed windows.
    It was a success to get more homes replaced with better windows.
    At an affordable number!!

  2. In Energy Star version 7 the northern zone version 7 is not limited to a .22 u-value but rather, .22 , .23, .24, .25 and .26 with corresponding trade off in the form of SHGC.
    I am surprised for full transparency the V7 graphic isn’t included in the article, perhaps this was more of an op-ed.

  3. David, RR, and others,
    Thanks for your comments and notes. I agree the tax credit was a great boost when we needed it in the great recession. It applied to a large volume of very good performing windows and doors and lowered the payback time for these products. That is exactly the concern with Proposal 7- that the paybacks are too long due to higher costs to consumers.
    Concerning the trade-offs in the proposal 7, they are not in the range for most windows with double glazing and two layers of Low e to hit. A quick search of Hung products in the NFRC directory will show most products that hit the trade off numbers are triple glazed. See the Proposal 7 details here;

    Thanks again and keep Innovating! Ray

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