Can Cardinal LoE 180 be applied to both surface #2 and #3 of an IGU ?
I want to install double glazed replacement windows that have high solar heat gain and a low u value. The Cardinal product for this purpose is LoE 180 applied to surface #3. I would like to have the 180 coating applied to both surface #3 and #2 to further decrease the U value but maintain the high solar heat gain attributes of the IGU. My local Marvin window distributor told me that Marvin told him that 180 could not be used on adjacent surfaces as I am requesting. I have not spoken directly to Cardinal about this. Unless LoE 180 has anisotropic properties that are determined by the coating – glass interface I do not see any reason why it cannot be applied to both surface #3 and #2. I know that Cardinal sells double glazed IGU’s with various coatings -270, 366- on surface #2 and i81 on surface #4 to decrease the U value of the IGU but these options all have high solar heat gain ratings. Can anyone enlighten me on the feasibility of applying high SHGC LoE 180 coating to both surface #3 and #2?
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Replies
Correction to my post: The options listed with i81 on surface #4 all have low SHGC
Tim
Here is a link to all the Cardinal options and performance stats
http://www.cardinalcorp.com/technology/reference/loe-performance-stats/
Why not 180 on #2 and i81 on #4, with argon?
My guess is that 180 on #2 AND #3 is going to reduce SHGC similar to simply using 270 on #2. There's a poster Greg Smith who may come along and clear this up.
David and Garth
I am familiar with the table on the cardinal website but it only adds to my confusion. The table does not list 180 as an option on two surfaces but does list an option of 180 on surface #2 and i81 on surface #4 which makes no sense to me. LoE 180 is a high SHGC coating while i81 is an environmentally stable low SHGC coating designed specifically for the most interior surface. Using any low SHGC coating in conjunction with 180 does not make sense as a solar heat strategy and if low U value on a double glazed is the desired strategy it makes more sense to use 270 or 366 in conjunction with i81 since all are low solar heat gain.
The simplest reason for not using 180 on surface 2 and surface 3 is that the slight U value advantage isn't worth the additional cost and doesn't offset the loss of solar heat gain due to using two coatings versus one.
Also, adding to the cost and complexity, the glass would have to be heat strengthened if both surface 2 and surface 3 were coated, versus annealed glass if only surface 2 or surface 3 are coated.
To compare (Calculated using LBNL Windows 6.3 and 3mm glass with 90% argon fill):
180 surface 2 - U.260 SHGC .645
180 sur 2 & 3 - U.248 SHGC .615
180 surface 3 - U.260 SHGC .685
180 surface 2, I81 surface 4 - U.209 SHGC .588
These are glass numbers. Window performance values will vary from IGU number, of course.
As a bit of an aside, Cardinal is planning to release a new coating (currently scheduled for 1st quarter 2013?) as a follow up to I81, called I89.
I89 will have the same U value performance as I81 but with visual transmittance improvement of 81% to 89%.
Because of the VT improvement, I89 also has a significant increase in SHGC as well.
I89 on surface 3 of an IGU - U.290 SHGC .764
Current technology does not allow coatings on surface 3 and surface 4 of an IGU.
Regards
Oberon
David
You may well be right that two layers of high SHGC LoE 180 would result in a summated effect equivalent to one layer of low SHGC coating such as 270. If this is the case then 180 should never be combined with any other coating as a strategy to decrease U value on a double or triple glaze since by doing so you would negate its high solar gain effect and probably wouldn't increase U value any more than using 270 which is a less expensive coating than 180. Does anyone know what coatings are being used on Canadian fiberglass triple pane double low e high SHGC windows?
Thanks Greg, you have answered my question completely. Do you know what two coatings are being used on the Canadian high SHGC triple glazed fiberglass windows?
Tim
The last time I checked, Duxton Windows from Winnipeg, had all their IGU's made for them by Cardinal, so anything made by Cardinal should be available?...Seal quality is important as well for longevity. Cardinal made units may have an edge here...
Tim,
I'm not 100% sure of who uses what, but taken with a grain of salt since I am doing this by memory, Thermotech uses Pilkington Energy Advantage, Duxton (as Garth said) uses 180, Fibertech and Accurate Dorwin use 180, and Inline I don't remember.
Based entirely on my opinion, not any serious research, I would suggest that the three leading coatings for high solar gain performance are Energy Advantage, LoE-180, and PPG SunGate 400.
I recently ran some numbers using Windows 6.3 (not in anyway related to this thread - just a coincidence), for comparisons between those three coatings and the new I89 for both U value and SHGC. I found the results to be very interesting.
And lets see if I can get these to line up...
All numbers are based on using 3mm glass and 90% argon fill.
Dual pane calculated using 1/2" airspace and triple pane using 7/16" airspaces.
dual pane IGU
surface............ SHGC.... U value
...... 3
clear glass....... 0.778.... .463
I 89................. 0.749 .... .305
EnerAdv.......... 0.734 .... .295
SG400............ 0.691 .... .277
LoE180........... 0.687 .... .277
triple pane IGU
surface ...... surface
...... 3............. 5........... SHGC .... U value
clr glass ... clr glass....... 0.702 ... .294
I 89.............................. 0.675 ... .213
EnerAdv........................ 0.666 ... .216
SG400........................... 0.629 ... .206
LoE180.......................... 0.627 ... .196
.................... I 89............ 0.666 ... .208
.................... EnerAdv...... 0.658 ... .211
.................... SG400........ 0.623 ... .200
.................... LoE180....... 0.615 ... .189
I 89.............. I 89............ 0.649 ... .162
EnerAdv..... EnerAdv........ 0.631 ... .165
I 89.............. LoE180....... 0.615 ... .149
LoE180......... I 89............ 0.609 ... .151
SG400.......... SG400........ 0.588 ... .152
LoE180......... LoE180....... 0.585 ... .140
Again, these numbers were calculated simply for my own curiousity and they don't represent any sort of product endorsement or in any way are intended to suggest or represent any of the glass companies internal data.
Greg
I find the entire situation with low e coatings very confusing and my local window retailers do not add much clarification. I am looking at Marvin windows so I am restricted to 180 if I want high SHGC. I did a little tabulation using your Win 6.3 calculations and contrasted those to data off of the Cardinal web site. I used the Cardinal data for 1-1/8 triple pane with argon to compare to your data. I have no idea how Cardinal calculates their specs and also do not know how Win 6.3 does its simulations.
¾ inch Double pane
Calculation Surface SHGC U factor
Cardinal #3 180 0.69 0.26
Cardinal #2 180 #4 i81 0.59 0.21
Your Win 6.3 #3 180 0.687 0.277
Your Win 6.3 #3 I89 0.749 0.305
1 -1/8 inch triple pane
Cardinal #2 180 #5 180 0.56 0.15
Cardinal #2 180 #4 180 #6 i81 0.50 0.13
Your Win 6.3 #3 180 #5 180 0.585 0.14
Your Win 6.3 #3 I89 #5 I89 0.649 0.162
Your Win 6.3 #3 180 #5 I89 0.609 0.151
I few points cross my mind:
It does not seem to make sense to mix 180 with i81 from a high solar heat gain standpoint or for using two layers of 180 from the same standpoint for that matter although U factor certainly is decreased with two layers of 180. The new I89 product, not currently available, seems to make sense from a high solar heat gain standpoint but at the expense of raising U factor. There are tradeoffs in all of this and price should be included to make a valid decision. My best currently available option for the best compromise of high SHGC and low U factor is probably triple glaze with 180 on surfaces #2 and #5. Your simulations with coating on surface #3 does not appear to be currently offered by Cardinal. A double layer of the new I89 certainly has promise from a high SHGC standpoint if your info is accurate and it actually comes to market. I also find it a bit disconcerting that Cardinal is already switching from i81 to I89 before i81 ever had much consumer usage. Can the new I89 be placed on the most interior surface of an IGU?
Tim,
I agree that mixing 180 and I81 doesn't make much sense.
In a dual pane, if you want 180 on surface 3, then it isn't even possible.
If you want maximum solar gain in a dual pane then always place the coating on surface 3. In a triple pane get the coating on surface 3 and surface 5 - or just surface 3.
There should be no problem in getting as coating on surface 3, but if it's a triple, the center glass will need to be heat strengthened.
The I89 will raise the U value a little bit versus 180, but the gain in SHGC should offset the slight loss in U value in a properly designed and orientated home.
I89, like I81, is intended to be a surface 4 coating to improve U value in dual pane windows. The fact that it has the impressive SHGC numbers is a side benefit, so it will be interesting to see how it is marketed.