Energy Efficient Windows Low-E 366 – i89

Energy Efficient Windows Low-E 366 – i89 is a new breakthrough in window coating technology that will become more known as new energy codes are enforced.  Many window companies are gearing up to 2014-2015 new energy code requirements and the Low-E 366 – i89 combination is sure to be an important factor for those houses that have large areas of glass.


Low-E 366 – i89 : latest energy efficient glass

Rand Soellner, ArCH/NCARB, Senior Staff Architect at HOME ARCHITECTS ®, said: “Our company has always designed and specified energy efficiency levels at or above the latest Energy Codes and in fact we typically exceed Energy Star values. The Low-E 366 – i89 glass coating combination is already part of our latest specifications.  When you can design large window areas that have about the same R-value as a 1″ thick sheet of Styrofoam, that’s a win-win for the Owner and the environment.”


UPDATE: While Cardinal is capable of producing the i89 coating, unfortunately, Jeld-Wen and other window fabricators don’t make their windows available in all regions with this option.  For instance, while our firm tried to obtain this product on one of SE USA projects, local distributors were unable to find it.  SO: don’t plan on having the i89 coating. 










Energy Efficient Windows Low-E 366 – i89
Energy Efficient Windows Low-E 366 – i89 is the latest improvement to High Performance windows. The “i”= Indium, a rare chemical element with the symbol “In” and atomic # 49. This coating improves the performance of Low-E glass.
Click image above to see the Green Architects Index.

 What Soellner means by a “win-win”: specifying glass/windows/doors that provide big views, while decreasing the heat loss/gain through them = less energy consumed = lower monthly power bills for his company’s clients.  Also: less energy consumed = lower carbon footprint on our planet = lower global greenhouse emissions.  That is because, according to the EPA, the burning of coal, natural gas and oil for electricity is the largest single source of global greenhouse gas emissions (26% of all emissions).


Click here to see a video of the Low-E 366 glass compared with other glass types in terms of BTU transmission (heat gain & loss) –>  Low-E 366 Performance.


The simple BTU gain/loss test illustrated by the test above, indicates the following:

Nothing (air):                                           500 BTU gain/loss

Single pane clear glass:                          400 BTU gain/loss

Clear insulated (2 panes) glass:              300 BTU gain/loss

Low-E single coating:                              295 BTU gain/loss

Low-E 272? insulated (2 panes) glass:      45 BTU gain/loss

Low-E 366 insulated (2 panes) glass:          7 BTU gain/loss











This means that Low-E 366 insulated glass (without the i89) added benefit is more than 57 times more effective than single pane clear glass in insulative value, and 42+ times more effective than double-pane ordinary clear glass, and 6.42 times more effective than the Low-E 272 insulated glass.  This is a breakthrough in glass coating technology.

Energy Efficient Windows Low-E 366 – i89
Energy Efficient Windows Low-E 366 – i89 allows larger glass areas for housing design, while saving energy. Like having your cake and eating it too. (C) Copyright 2005-2013 Home Architect, PLLC, All Rights Reserved Worldwide.
Designed by HOME ARCHITECTS: the Falcon Cliff Lodge.
Click the image above to see the Falcon Cliff Lodge.













The i89 bumps the effectiveness even higher, especially for the U- value several notches, to exceed the highest IECC (International Energy Conservation Code) 2012 indicated values in the USA.  Click here for Cardinal Industries’ “LoE Performance Stats” chart–> LoE Performance Chart.  The line items of interest are the 3/4″ Double Pane, because that is typically what is used in windows supplying the residential construction industry, from manufacturers like Jeld-Wen, Marvin and others.  What this chart reveals (from the manufacturer of the glass) is the following:


.                      light       reflec.    UV    SHGC    U (IP)   R-value
.                      trans.

Clear/Clear:   82%      15%       0.58    0.78       0.48      2.083

LoE 272 (#2) / Clear:
.                     72%      11%        0.16    0.41       0.30      3.33

LoE 366 (#2) / Clear:
.                      65%     11%         0.05    0.27       0.29      3.44

LoE 366 (#2) /i89 (#4)
.                      63%     11%         0.05    0.27       0.23      4.37


(all values withOUT Argon: air only between the panes, as once you get above a certain altitude, perhaps 1,500’ASL+/-, the seal around the insulated glass will likely develop micro-tears, letting the Argon gas out and you will need breather tubes to equalize the pressure to help prevent fogged glass: per HOME ARCHITECTS ® Knowledge Base, confirmed by Cardinal Industries 9/2013).











The “#2” designation means that the coatings (272 or 366) are all on the #2 surface, in multiple layers.  The “2” in 272 = two coatings with a result of about 72% light transmittance.  The “3” in 366 = 3 coatings resulting in about a 66% light transmittance.  The “i89″= Indium, about 89% light transmittance (actually closer to 87% according to Cardinal).

Energy Efficient Windows Low-E 366 – i89
Energy Efficient Windows Low-E 366 – i89 allows for creative approaches like this, letting in views and light, while blocking harmful UV and conserving heat loss and gain. (C) Copyright 2005-2013 Home Architect, PLLC, All Rights Reserved Worldwide. Designed by HOME ARCHITECTS : Eagle Mountain Aerie.
Click the image above to see the Eagle Mountain Aerie project.



What is interesting is that the i89 coating (applied to the #4 side: the inboard side of the inner pane of glass) is what bumps up the “U” value, improving the glass’ ability for a higher “R” value (the reciprocal of the U).  Which means that the LoE 366/i89 glass is starting to approach the value of nearly an inch of XPS Dow Styrofoam (r=5).  That’s amazing!  Something that is nearly invisible has the thermal properties of nearly an inch of foam insulation!  We are reminded of the Star Trek IV: The Voyage Home movie in which there was “transparent aluminum.” This may not be that, but still represents an incredible innovation for glass making and for improved thermal performance in windows and doors with glass.


REASON: Owners of houses want large glass areas to allow them to enjoy the views of their property, particularly when they have acreage with long-distance view of natural features, such as mountains and lakes.  The problem is that energy regulations are increasingly demanding in terms of reducing the amount of heat gain and heat loss.  This means that if window technology did not improve, the windows would have to become smaller.  Fortunately, due to advances in window coating technology such as the Low-E 366 / i89 processes, windows can become larger while still allowing Architects to design houses that conform to and exceed energy standards, resulting in a win for the Owner and for the environment.

It is important to note that while the i89 coating is a “hardcoat”, it is on the #4 surface, which means that it is exposed to the interior of the house.  Cardinal has indicated that this coating can be scratched by razor blades and other sharp objects, so Contractors need to take precautions to protect this glass during construction: particularly during painting, because if you get paint over-spray on the glass, and try to remove it later with scrapers, you will damage the coating.  Better to protect the glass with construction paper using special painter’s tape applied to the window frames before painting the room, then remove after any paint mist has settled.  That way, there is nothing to be cleaned.


Contact for Architects specifying and detailed Low-E 366 / i89 glass in windows and doors:      1-828-269-9046 in the USA.


tags: Energy Efficient Windows Low-E 366 – i89, custom residential design, cashiers, atlanta, aspen, telluride, newnan, asheville, roanoke, hendersonville, lake toxaway, highlands, sylva, franklin



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