Low E vs. Low E Squared

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Denardus
Posts: 11
Joined: Mon May 23, 2005 3:34 pm
Location: Atlanta, GA

Low E vs. Low E Squared

#1 Post by Denardus »

Hello all, I searched some previous post and found some info on the topic, but am still unsure of what would be better for may area. I live in the Atlanta area. I have had two window reps come out so far. One recommends the soft coat Low E squared ang gave what seemed to be a good explination of why. Another rep said there really is not a good enough benefit for the Low E Squared vs. Standard soft coat Low E, also mentioned that Low E squared works against itself and usually the seals will go bad within five years.

If you can help with a more laymans terms description of std low e vs. the low e squared, and shed any light on seal problems with the squared version I would be most happy.

Thank you,

Denardus

Dan
Posts: 38
Joined: Fri Oct 08, 2004 7:04 am
Location: Was Ohio now Alaska

#2 Post by Dan »

We are in the process of having windows tested for NFRC. The windows with just a single pane of soft coat Low-E tested a U-Value of .34. The same window with double soft coat Low-E was a .33. When tested with grids between the glass the numbers were the same. BTW, the same window with clear glass and no Low-E tested .47.

IMHO, going with double Low-E is a WASTE of money.

Denardus
Posts: 11
Joined: Mon May 23, 2005 3:34 pm
Location: Atlanta, GA

#3 Post by Denardus »

Thank you Dan,

Denardus

Cheryl (Fenessa)
Posts: 32
Joined: Wed Oct 27, 2004 3:05 pm
Location: California

#4 Post by Cheryl (Fenessa) »

U-values primarily address heat loss during the winter months, but if you also have summertime "cooling costs" (fans/AC) then Loe2 is the way to go. It not only blocks radiant heat loss during the winter, but also radiant heat gain in the summer. Traditional Low-E (not Loe2) does not have the same summertime impact. Energy costs vary throughout the country - this is why the Energy Star Program requirements vary regionally.

Dan
Posts: 38
Joined: Fri Oct 08, 2004 7:04 am
Location: Was Ohio now Alaska

#5 Post by Dan »

I dug deeper in the test reports and there is better protection for solor heat gain when using dual layers of Low-E glass (Soft Coat Dual Layer Low-E). On our window tests a window with clear insulated glass had a SHGC (Solar Heat Gain) of .61. The same window with insulated glass made with one piece of clear and one piece of Low-E has a SHGC of .31. That window with triple glazing made with one layer of clear and 2 layers of Low-E has a SHGC of .25.

In my opinion there doesn't seem to be much of an improvement with the addition of another piece of Low-E glass. You have an improvement of .30 using a single piece of Low-E and the second layer only nets a gain of .06. Even in Florida, to meet Energy Star levels you only need a SHGC of .40.

Adding that third piece of glass increases the weight of the sashes in windows. This can make it more difficult for a lot of people to easily tilt their windows in for cleaning. It also puts more stress on the balance system in the window.

FenEx
Posts: 553
Joined: Thu Oct 07, 2004 11:18 am
Location: Illinois

reply

#6 Post by FenEx »

I would disagree with "some" previous information posted. U-factors measure heat transmittance.... which includes transfer in or out. Any coating of Low-E or multiple coatings affect the transfer of radiant heat in both directions. In mulitple-pane insulated units, it can be more effective regionally on specific panes and surfaces but the coatings themselves are non-specific in direction by nature and design. Simply put... Low-E coatings reflect heat back towards it's source... wherever it comes from. "Cooling" or "AC" is the removal of heat.. nothing more in the world of physics or in your home. If you help control it's ability to enter or leave your home... you help control your energy bills and overall comfort.

SHGC is only a part of the heat transfer... U-factors apply 24/7... radiant heat as well as ambient and convection. The performance difference from a single pane with storm or a dbl/pane window to an average dbl-pane w/low-e/argon can be close to equal to the difference of the latter to a triple/dbl-lowE/Krypton. Does half-way matter and not the other half of the journey? It's all BTU loss or gain.

FenEx

Oberon
Posts: 280
Joined: Thu Oct 07, 2004 10:25 am
Location: East of the Mississippi

LowE

#7 Post by Oberon »

Denardus,

First, the salesman who told you that LowE squared "works against itself" would have to provide a much better "explanation" than that. His comment is ludicrous and meaningless.
Second, seal failure in five years using LowE squared versus standard LowE? Again, his comment is totally without merit and pretty much meaningless.

Dan,

Based on your two posts I get the impression that you are confusing triple pane construction with LowE coating on two lites to LowE squared.
The working part of a LowE coating is silver. "Standard" LowE has one coat of silver in the coating. LowE squared has two layers of silver.
As noted, the additional layer of silver in the coating does not have an overwhelming affect on U value, but it does have a very significant affect on SHGC.

Cheryl is absolutely correct in saying that LowE squared will be worth very significant savings in the summer months. That additional coating of silver will block a very large amount of IR when the sun is trying to heat up the inside of your home. A single-silver LowE will not do nearly as well.

The softcoat LowE manufacturers will promote "standard" LowE for cold climates where a person might want to take advantage of solar heat gain, but they will also promote LowE squared for areas of the country that have significant solar heat gain issues. In a hot sunny climate, LowE squared works very well to lower energy costs and can even be so effective that a homeowner can actually downsize their airconditioner requirement.

Energy cost savings between LowE squared and dual pane windows quite readily exceed 30% and savings even up as high as 50% have been noted in monitored testing. This is based on actual field testing, and actual measurements, not theoretical numbers.

Finally, LowE squared is actually a "brand name" of the dual-silver LowE coating prduced by Cardinal. PPG Solarban 60 and Guardian Performance Plus II are also dual-silver softcoat LowE products.
LowE squared is used somewhat for all dual-silver softcoat LowE products simply because Cardinal introduced the dual silver LowE and does have the lion's share of the residential LowE market.

Dan
Posts: 38
Joined: Fri Oct 08, 2004 7:04 am
Location: Was Ohio now Alaska

#8 Post by Dan »

Oberon,

I am not confused! The Low-E used in the window tests is soft coat Low-E that has dual layers of silver in the coating. The window I was using as a comparison was tested as follows:

1) Unit with double insulated glass with clear on both sides.
2) Unit with double insulated glass with clear on one side and Low-E on the other.
3) Unit with triple glass with clear on one side, Low-E in the middle and Low-E on the inside.

What the test showed to me was that the addition of another layer of Low-E glass did little in thermal performance. Now that I look at the results, the triple glazed unit didn't test much better than a regular double glazed unit. Before you jump all over this realize that the glass in the windows being tested are 3/4" units. I would assume that an IG with 1" could test better but our windows use 3/4".

Oberon
Posts: 280
Joined: Thu Oct 07, 2004 10:25 am
Location: East of the Mississippi

confusion

#9 Post by Oberon »

No problem Dan, just an interesting discussion. We have debates and disagreements all the time here, but I think we all try to keep them friendly and professional.

Per your last post, I still think we are not entirely communicating in the same language.

The original question involved the difference between LowE and LowE squared. A triple pane IGU with LowE on two lites does not mean LowE squared. LowE squared is simply Cardinal's brand name for their version of dual-silver. Whose coating are you using, btw? Just a simple curiousity question.

What you are describing (per your post) as the test uints is a dual pane with LowE squared and a triple pane unit with LowE squared. The triple pane having LowE squared on two lites. While we can debate the relative merits of dual pane versus triple pane windows, the inclusion of two lites with LowE coating is not the definition of LowE squared...which is what I am seeing referred to in your posts. If I am confused by what you are saying, or if I am incorrect interpreting what you said, then please accept that it is unintentional and certainly not intended as a slight in any way.

For whatever it is worth, I have talked with a good many industry folks in the past, especially sales and marketing folks, who also have the impression that LowE squared refers to having a window with two lites coated compared with a single coated lite. Sometimes they think that LowE squared in a dual pane refers to both lites having the coating - one on surface 2 and one on surface 3. It is not an uncommon misperception.

Another, less common (as I have seen it anyway) misconception is that LowE squared is simply adding a layer of LowE over another Layer of LowE. That is also not true although it is closer to how the coating is applied. LowE and LowE squared are applied in slightly different processes having to do with the number of overall metallic layers within the coatings. It is quite involved actually and rather interesting in a "nerdy" sort of way.

Denardus
Posts: 11
Joined: Mon May 23, 2005 3:34 pm
Location: Atlanta, GA

THANK YOU!!!!!!!!!!!!!!

#10 Post by Denardus »

All, I just got back into town and was able to check the board. Thanks for all of the feed back, this helps us out with the Low E question.

Will be trying to visit showrooms this week to look at full size windows and narrow things down farther.

Thanks again,

Denardus

willimusk
Posts: 6
Joined: Sun May 29, 2005 9:52 am

#11 Post by willimusk »

Oberon (or anyone else), do you know whether the Andersen 400 series uses Low E or LowE2? Their literature calls it "Low E with High Performance Coating," but I can't tell whether that means Low E2. They get their glass from Cardinal, and Cardinal offers LowE2, so one would think Andersen glass would be Low E2, but the lit doesn't say so explicitly.

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