What do you think of the .32 U-factor requirement being considered for the Northernmost zone in the 2009 Energy Star criteria?

John G. Swanson
January 30, 2008

The Talk, Page 2...

Survey Results for 01/30/2008:

What do you think of the .32 U-factor requirement being considered for the Northernmost zone in the 2009 Energy Star criteria?

It should be more stringent.


It's reasonable, even with a low SHGC.


It should be less stringent.


It's reasonable, if SHGC is higher.


As we continue discussions about the new criteria proposed for the Energy Star windows program, last week we asked about the .32 U-factor, the higher number in the range currently under consideration within the Department of Energy for the Northern climate zones of the U.S.

About 80 percent of respondents say the required U-factor for the Northern climate zone should be lower than .32. A little over 15 percent think it’s reasonable, including a handful of voters who say it depends on the SHGC requirements. Less than 5 percent said it was too stringent.

That’s a big switch from the previous week’s poll, when we asked about the lowest U-factor number DOE said it was considering for its new Energy Star criteria. Ninety percent of the respondents said. a .30 U-factor requirement would be too stringent.

Does that mean there’s consensus among our readers that the new U-factor requirement for an Energy Star label in the North is .31? Personally, I’m a bit skeptical that there’s that much agreement on the subject within the industry. We have no way of seeing where votes in our polls come from, so I can’t rule out the possibility that some one out there voted more than once. Perhaps someone inspired by all the campaigning that’s taking place these days organized voters in our poll.

I certainly don’t have an answer, however. As I stated last week, I don’t envy DOE in having to make this type of decision. It’s easy to say we want to see upgraded energy performance, but picking a specific number is tough. I will say I do think DOE is listening to the industry. While they can’t be expected to come up with a number that will make everyone happy, I do think they’re making a good faith effort to understand all the concerns.

And I think the industry is making a good faith effort to improve energy performance. There are just a lot of complications. Just how complicated all this can be is seen in an email I received from one Colorado dealer. “Our cities are working on increasing the performance with Boulder leading the way at what I think will be a 0.29. Vail and Aspen are looking at similar with most of the rest looking at 0.30 – 0.32. These numbers represent a real challenge, because nearly every manufacturer that serves the market cannot use gas fills in the airspace to achieve those numbers. This is making them look at other ways to get the values. Some have looked at triple pane, and a few are looking at coatings on more than one surface. The best option would be to glaze at this altitude but we’ll see where that goes,” he notes.

Although the high altitudes create unique conditions, his email illustrates the challenges currently out there to get U-factors lower. Of course, his email also makes clear that many state and local officials are already setting very aggressive numbers in their energy codes—one of the reasons DOE cites for making Energy Star standards more stringent.

“DOE has to set a bar a bit higher than the norm, as their philosophy is to push the envelope,” another manufacturer suggests. “I would look at it as their mandate.” Still, he notes, a more holistic approach to rating and improving energy performance might be better. “What I would like to see is a greater use of energy modeling of the whole structure. Then the gentleman who puts in big windows could weigh his options.” This manufacturer than lists a number of questions a “whole-house” approach might provide better answers to than a few particular performance numbers on the window itself.

One additional note. With all the talk on U-factors and even potential SHGC numbers in the Energy Star Northern climate zones, I hadn’t heard much discussion about what the new numbers might mean in other parts of the country. Speaking at WDMA’s meeting last week, Richard Karney, program manager for the Energy Star windows program, noted the same thing. DOE has received virtually no feedback on its proposed changes in criteria for the Southern climate zones.

One Houston-based manufacturer contacted me to note that his company is looking to push at least its own SHGC numbers lower. “We produce high end vinyl windows, distribute from Texas through Alabama, are currently at a .27 SHGC, and making strides to get below a .20,” he reports. He’s cautious about how stringent the requirements be, however, suggesting there’s likely to be industry resistance if the criteria become too stringent.


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