LoĒ²-240 Glass

Wherever glare is a problem, Cardinal LoĒ²-240® glass is the ideal solution. It’s a specially treated version of our finest LoĒ² glass. But LoĒ²-240 does much more than control glare. It also maintains year-round comfort. In summer, it blocks oppressive solar heat gain and maintains cool glass temperatures. Then when winter rolls around, it keeps inside glass temperatures warm. Control and year-round comfort – that’s the Cardinal advantage.

The best solar control glass under the sun.

Other tinted glass comes with glaring deficiencies. Regular tinted glass works by absorbing sunlight. The color of the glass changes with the thickness and becomes hot in the sunlight. However, LoĒ²-240 is a coating that is applied to clear glass, so that the appearance and performance are the same regardless of the glass thickness.

The science of glare control glass.

Clear glass transmits as much as 90% of the solar energy in all the regions and is ineffective at controlling glare or solar heat gain.

Bronze and gray-tinted glass absorb as much as 50% of all sunlight, but this varies with thickness. Large windows with thick glass will be dark, while small windows with thin glass will have little tint and minimal solar control. What’s more, single-pane tinted glass temperatures can exceed 100°F, leading to serious discomfort near the window.

Reflective glass products are effective in rejecting solar gain, but their shiny appearance is undesirable in most homes and buildings.

To understand how LoĒ²-240 advances the science of glare control glass, let’s review what sunlight is and how various glass products handle this energy. Within the spectrum of solar energy, there are three distinct regions:
  1. Ultraviolet (UV). UV is invisible and makes up about 3% of the total solar energy. This region of wave lengths is typically associated with fading of fabrics, paints, etc.
  2. Visible Light. This portion of the solar spectrum makes up about 45% of total solar energy.
  3. Near Infrared (NIR). NIR is approximately 52% of the solar energy and invisible to the eye.

The invisible difference: LoĒ²-240 spectrally selective glass

What makes multi-layer LoĒ²-240 different is its ability to handle each portion of the solar spectrum differently:
  • Blocks over 84% of the harmful UV radiation.
  • Absorbs 60% of the visible light, which gives the coating glare control and its soft muted blue color.
  • Reflects nearly all of the invisible solar infrared rays.
240_solar_transmition LoĒ²-240 permits visible light to shine while blocking UV and NIR light.


This graph compares the solar transmission of clear glass, bronze tinted glass and LoĒ²-240. Clear glass allows nearly all the solar energy through. Bronze glass reduces transmission by absorbing sunlight, but it’s more effective at blocking light than heat. To match the glare control of LoĒ²-240, a tinted glass would have to be 1/4” thick.

Even at this heavy thickness, the solar blockage of tinted glass doesn’t compare with LoĒ²-240. As a result, LoĒ²-240 provides effective glare control and maximum solar blockage in a softly tinted design – without the punishing discomfort of heat-absorbing glass or the visual disruption of highly reflective glass.

All season comfort.

LoĒ²-240 is more than a solar control glass. Its advanced coating design also provides an extremely low U-Factor to deliver comfort and energy savings during cold winter weather.

Year-round thermal comfort is a result of warm glass temperatures in the winter, cool glass temperatures in the summer, and the blockage of oppressive solar heat gains. Comfort comparisons for various products are shown in the chart. Note that the solar blockage for single- pane tinted glass is marginal, and the extreme temperature fluctuations can lead to serious year-round comfort problems.
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The invisible difference no matter what
the season is.

Inside Glass Temperatures
  •  
  • Single-pane, tinted
  • Double-pane, tinted
  • Double-pane, tinted & low-e
  • LoĒ² – 240 (argon fill)
  • Winter
    night
  • 15°
  • 44°
  • 53°
  • 55°
  • Summer
    day
  • 100°
  • 95°
  • 96°
  • 86°
  • Solar
    blockage
  • 27%
  • 37%
  • 42%
  • 75%


Double glazing improves the winter comfort, especially when a low emittance LoĒ² coating is used. A double-pane window with a conventional tinted glass and low-e on the #3 surface (air space side of indoor pane) improves the solar blockage, but leaves the building occupants exposed to hot glass temperatures in the summer.

LoĒ²-240 is placed on the #2 surface (air-space side of outdoor pane) and provides the best comfort through all the seasons.

The best choice for glare control is quite clear.

If you envision your home’s design benefiting from a tinted glass for glare control, LoĒ²-240 offers a great combination of aesthetic appeal along with energy performance and indoor comfort. The summary shown here gives you a comparative ranking based on a variety of glass selection criteria.
Glass Comparisons
  •  
  • Single-pane, tinted
  • Double-pane, tinted
  • Double pane, tinted & low-e
  • LoĒ² – 240
  • Light Transmission
  • Moderate
  • Moderate
  • Moderate
  • Moderate
  • Reflectance
  • Low
  • Low
  • Low
  • Low
  • Color
  • Tinted
  • Tinted
  • Tinted
  • Tinted
  • Winter
    Comfort
  • Poor
  • Moderate
  • Good
  • Good
  • Summer
    Comfort
  • Poor
  • Moderate
  • Moderate
  • Good


Glass Performance
  •  
  • Single-pane, tinted
  • Double-pane, tinted
  • Double pane, tinted & low-e
  • LoĒ² – 240
  • Visible Light
    Transmittance
  • 68%
  • 61%
  • 58%
  • 40%
  • Solar Heat Gain
    Coefficient
  • 0.73
  • 0.63
  • 0.58
  • 0.25
  • Winter U-Factor
    (Air / Argon )
  • 1.04 / –
  • 0.48 / –
  • 0.34 / 0.30
  • 0.30 / 0.26
  • UV
  • 0.38
  • 0.32
  • 0.28
  • 0.16
  • Fading
    Transmission
  • 0.58
  • 0.52
  • 0.47
  • 0.35
Definitions
Note: All values calculated using Window 6.3. (See http://windows.lbl.gov/software/default.htm and http://windows.lbl.gov/materials/optical_data/default.htm for more information on glass optical data and the Windows 6.3 program.) 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 portion of energy transmitted in a spectral region from 300 to 600 nanometers. 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.

U-Factor – This represents the heat flow rate through a window expressed in BTU/hr•ft²•°F, 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.

Cardinal actively supports and participates in the National Fenestration Rating Council (NFRC). Windows with LoĒ²-240 that are rated and certified by the NFRC can comply with Energy Star requirements in all regions of the country. Northern zone will likely require the addition of LoĒ-i89 on the 4th surface to comply with U-Factor requirements. (See https://www.energystar.gov/products/certified-products/detail/residential-windows-doors-and-skylights for more information on the Energy Star windows program.)

Controlling glare is only the beginning.

LoĒ²-240 does much more. It also maintains year-round comfort. It blocks oppressive solar heat gain in summer and maintains cool glass temperatures. Then in winter, it keeps inside glass temperatures warm.

LoĒ²-240 can be purchased in hurricane-resistant laminated glass in a variety of shapes and sizes.

More About Cardinal

Since 1962, Cardinal's mission has been to provide the highest quality glass products for residential windows throughout the world.

Today we’re the largest fabricator of sealed insulating glass units and supply over half the low-emissivity coatings used in North America. We now distribute our energy efficient and durable glass products worldwide.

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