Enhanced Winter
Performance Glass

Maximum Heat Control
for Winter

LoĒ-i89™ is our energy-saving 4th surface coated glass. It offers excellent visible light transmittance and low reflectance. Yet it delivers a center-of-glass U-factor of just 0.20 when coupled with our LoĒ³ or LoĒ² glass and argon fill in a 2-pane unit.

Even without argon and with or without capillary tubes, the unit still delivers a U-factor of just 0.23 – perfect for high altitudes.

When regular LoĒ coated windows include room-side LoĒ-i89, more windows can meet the strict ENERGY STAR 7.0 requirements.

What’s more, LoĒ-i89 is easy to clean. It’s as scratch resistant as regular annealed glass. And there’s no haze to mar the view. That’s LoĒ-i89, our enhanced winter performance glass.

Double-pane windows become
triple-pane performers.

With LoĒ-i89, you have more options. There’s less need to go to triple-pane windows to meet the various energy-saving guidelines. No need to invest in redesigning your windows and altering your manufacturing processes either. A double-pane IG unit with LoĒ-i89 can meet the guidelines for most climate zones.

LoĒ-i89 is sputtered onto the indoor lite, the #4 surface, thus reflecting escaping heat back into the room and lowering U-factors.

Coupled with our LoĒ² or LoĒ³ glass and argon fill, this double-pane unit delivers performance much better than clear triple-pane – a center of glass U-factor of just 0.20 compared to 0.37 with clear triple-pane.

To surpass the U-factor performance of our LoĒ-i89 double-pane unit, you would need to go to a triple-pane unit with a low-E coating in each gap. But for maximum thermal control, a triple-pane IG with LoĒ-i89 on the #6 surface provides unmatched performance.

Heat is reflected, not lost.

Clear Glass

The advantages are
more than clear.

In addition to providing maximum energy efficiency in a double-pane unit, LoĒ-i89 offers several other customer-pleasing benefits.

Its surface is smooth and scratch resistant, making it easier to remove label residue and clean. And perhaps most importantly, there’s no haze to mar the view.

Rather than absorbing internal heat, LoĒ-i89 reflects it back into the room, making your living space feel warmer and more comfortable.

Naturally, Endur IG units with LoĒ-i89 live up to the Cardinal reputation for long-range durability, delivering the industry’s lowest failure rate – only 0.20% over 20 years.

Give homeowners another reason to love LoĒ-i89 units – include Neat+® naturally clean glass on the outside. Your windows stay cleaner longer and clean easier. Finally, protect your windows in transit as well as on the job site with Preserve® protective film.

LoĒ-i89 and Interior Condensation
If the humidity in a home is too high, condensation can occur along the bottom edge of the glass, around the glass periphery, or sometimes on the complete indoor glass surface. Insulating glass units with a LoĒ coating and a warm edge spacer like Endur greatly reduce the risk of condensation. While LoĒ-i89 reflects interior heat back into the room, the room-side pane of glass will be cooler than the same glass construction that does not include LoĒ-i89.
During winter conditions there is a higher probability of room-side glass condensation. This is dependent on the outdoor ambient temperature, indoor room temperature, and the relative humidity (RH) in the room. The U.S. ENERGY STAR program recommends a relative humidity (RH) of 30-40% in colder climates. In such circumstances, LoĒ-i89 paired with LoĒ3-366 or LoĒ-180 coatings maintains glass temperatures high enough to resist indoor condensation.

Warmer Glass Reduces Condensation Occurrence

ENERGY STAR recommended range for colder climates during heating season
ENERGY STAR recommended range for colder climates during heating season
  • Glass Temperature

    % RH where condensation

    • 30%
    • 40%
  • 56.2°



  • 47.7°

    LoĒ³-366 + i89


  • 55.2°



  • 46.4°

    LoĒ-180 + i89


Glass Performance

2 Pane 3/4” with LoĒ-i89

Visible Light
Fade Transmission
U-Factor :
  • IP
  • SI

3 pane 7/8” with LoĒ-i89

Visible Light
Fade Transmission
U-Factor :
  • IP
  • SI

All values calculated using Window 7.8. Emittance of ordinary (pyrolitic) low-E is 0.16.

Solar Heat Gain Coefficient – (SHGC):
The amount of solar radiation that enters a building as heat. The lower the number, the better the glazing is at preventing solar gain.

Fading Transmission:
The UV Transmittance is determined as an average for wavelengths 300 -380 nm. ISO is the weighted average for wavelengths 300 – 700 nm (based on CIE 89/3). This region includes all of the ultraviolet energy and part of the visible spectrum, and will give the best representation of relative fading rates. The lower the number, the better the glass is for reducing fading potential of carpets and interior furnishings.

This represents the heat flow rate through a window expressed in IP (BTU/hr·ft²·°F) and SI (W/m2K), using winter night weather conditions of 0°F outside and 70°F inside. The smaller the number, the better the window system is at reducing heat loss.

More information on the ENERGY STAR windows program.

LoĒ-i89: a new
low for window U-factors.

LoĒ-i89 on the 4th surface of your windows allows you to get near triple-pane performance in a double-pane unit and meet the toughest energy guidelines as well. Finally, LoĒ-i89 can be purchased in tempered or laminated glass and in a variety of shapes and sizes.

To learn more about LoĒ-i89 and other Cardinal glass products, ask your contractor, builder, or architect.

Additional Resources