• 129 E. La Porte St.,
  • Arcadia, CA 91006-2832
  • Phone: 626-445-8712
  • Fax: 626-445-7824

Deciphering the Sticker

Manufacturers typically submit their windows to tests that follow standards set by the nonprofit National Fenestration Rating Council (NFRC). Their findings, reported on a sticker affixed to most new windows, rate several factors, each expressed as a number. The sample below shows what all the figures actually mean:

(A) U-FACTOR measures how much heat escapes from a room through the window; the lower the number (usually between 0.20 and 1.20), the better the window's insulating ability. In colder climates, look for 0.35 or lower. Warmer climates can go as high as 0.75.

(B) SOLAR HEAT GAIN COEFFICIENT (SHGC) indicates how much heat from the sun the window allows to come into a room, expressed on a scale of 0 to 1. In warmer climates, look for an SHGC lower than 0.4, which means that less than 40 percent of the sun's heat enters a room.

(C) VISIBLE LIGHT TRANSMITTANCE (VT) measures how much light passes through the window. Anything higher than 0.6 (meaning 60 percent of the light is transmitted) will appear clear to the naked eye. Numbers below 0.5 can significantly darken the view.

(D) AIR LEAKAGE (optional) essentially says how drafty a window is, measured in cubic feet of air per square foot of window. A good number is between 0.1 and 0.3, and few manufacturers report this rating unless the window falls into that range.

(E) CONDENSATION RESISTANCE (optional) shows, through a number between 1 and 100, how well a window resists forming condensation (on the inside during cold months, on the outside during a humid summer). The higher the number, the better the window is at resisting condensation.

DESIGN PRESSURE (Not shown) (optional) is a structural rating that shows how well a window can withstand pressure from wind and rain in pounds per square foot. A large window should rate at least DP-30; 40 or 50 is even better. In hurricane regions they must also have impact glass, which, like a windshield, doesn't shatter. Check codes for local requirements.


LoĒ³-366 Glass

SHGC: 0.27 / U-FACTOR: 0.24 / TDW: 0.43 / LIGHT TRANS: 66% / All stats

A new standard

Cardinal introduces LoĒ³-366 (pronounced low E cubed-366), the ultimate performance glass. It just might make all other low-E glasses obsolete. LoĒ³-366 delivers the ideal balance of solar control and high visibility. And it provides the highest levels of year-round comfort and energy savings, making it the perfect glass no matter where you live. The secret? An unprecedented triple layer of silver. This is beyond ordinary low-E glass; LoĒ³-366 sets the new standard.

Low-E times three makes the difference

Cardinal has for years worked with top-tier window manufacturers by providing energy-efficient LoĒ² glass. Now with three layers of year-round thermal protection, the benefits are exceptional.
The result: a clear coating that blocks even more solar gain than ever before, reflects heat and lets the light stream in. Notice the difference below between clear glass, regular low-E glass and new LoĒ³-366.

Energy savings all year long

The full-year benefits of LoĒ³-366 can be clearly seen. When the temperature soars in the summer, ordinary window glass just can't beat the heat. And tinted glass spoils the view. LoĒ³-366 is formulated to reject solar heat while maintaining attractive visibility. So it keeps the heat out while letting light in. As a matter of fact, LoĒ³-366 glass is our ultimate in performance and clarity among all of Cardinal's clear coated products.


What is more, LoĒ³-366 provides the ultimate in fading protection. It blocks 95% of the sun's damaging ultraviolet rays - a leading cause of fading - so your furniture, carpets, curtains and wall coverings stay beautiful for years.

During the cold weather, the insulating effect of your windows has a direct impact on how your rooms feel. The better insulated the window glass, the warmer your room will feel. In fact, the Efficient Windows Collaborative suggests that when glass surface temperature falls below 52°F, there is a risk of thermal discomfort. To maintain the best comfort during the winter, select a glass product that produces surface temperatures that will stay above this point during the coldest outdoor conditions.

According the chart below, the insulating capability of LoĒ³-366 can't be compared to any other glass product. This is a key factor in the construction of comfortable homes. Additionally, the dramatic comfort improvement in windows with warm glass surfaces means the humidity of the indoor air can be controlled and maintained properly. Proper humidity levels will improve comfort and promote a healthier living environment.

Saving money and protecting the environment

test2According to the Consumer Federation of America, the average American household spends $1,500 per year on energy costs.  But energy-efficient windows can help save a bundle.  In fact, you can reduce your energy bills by one-third by simply using low-emissivity glass.
But not only does it make financial sense, it's smart to do in view of limited global resources. Conscious consumers are increasingly making purchasing decisions based current environmental realities. By using products that reduce energy consumption, one diminishes their environmental footprint, limiting usage of fossil fuels and lowering carbon emissions.


Every sleeping room below the fourth floor shall have at least one openable window or door to the outside to permit emergency exit or rescue. The emergency door or window shall be openable from the inside to provide a full, clear opening without the use of separate tools. Windows shall have a sill height of not more than 44 inches above the floor. Windows shall comply with all the following three conditions:

  • Provide not less than 5.7 (821 In2 ) square feet of clear openable area.
  • Provide a net clear opening minimum width = 20"
  • Provide a net clear minimum height = 24".

Energy Efficiency

ENERGY STAR qualified windows, doors and skylights reduce energy bills by about 7-24 percent, increase comfort, and come in a variety of shapes and sizes to achieve precisely the look you’re after.

The energy performance of all ENERGY STAR qualified windows, doors, and skylights must be independently tested and certified according to test procedures established by the National Fenestration Rating Council (NFRC).

Performance Ratings

The NFRC label can be found on all ENERGY STAR qualified windows, doors, and skylights and provides performance ratings in five categories:

  • U-Factor measures the rate of heat transfer and tells you how well the window insulates. U-factor values generally range from 0.25 to 1.25 and are measured in Btu/h·ft²·°F. The lower the U-factor, the better the window insulates.
  • Solar Heat Gain Coefficient (SHGC) measures the fraction of solar energy transmitted and tells you how well the product blocks heat caused by sunlight. SHGC is measured on a scale of 0 to 1; values typically range from 0.25 to 0.80. The lower the SHGC, the less solar heat the window transmits.
  • Visible Transmittance (VT) measures the amount of light the window lets through. VT is measured on a scale of 0 to 1; values generally range from 0.20 to 0.80. The higher the VT, the more light you see.
  • Air Leakage (AL) measures the rate at which air passes through joints in the window. AL is measured in cubic feet of air passing through one square foot of window area per minute. The lower the AL value, the less air leakage. Most industry standards and building codes require an AL of 0.3 cf·m/ft².
  • Condensation Resistance measures how well the window resists water build-up. Condensation Resistance is scored on a scale from 0 to 100. The higher the condensation resistance factor, the less build-up the window allows.

For more information on NFRC performance ratings and label, visit NFRC’s Web site.
ENERGY STAR qualification is based on U-factor and SHGC ratings only.

2016 Energy Star

Energy Star Chart

Sound Attenuation

Noise Is Measured in Decibels (dB)

  • Whispers – about 20 dB
  • Normal conversations – about 60 dB
  • City traffic – about 80 dB
  • Lawn mowers/leaf blowers – around 103 dB
  • Repeated exposure to sounds over 85 decibels is considered dangerous to hearing, and the louder the noise, the less time it takes to damage hearing

Sound Transmission Loss

Sound transmission loss is the reduction in noise level resulting from passage through an obstruction. Sound transmission class (STC) is the measure of the effectiveness of a material to attenuate sound.

The method to determine STC is conducted using two test rooms: a ''source'' room and a ''receiver'' room. The source room will contain a full-range test loudspeaker. The receiver room will contain a microphone, which is connected to sound-measuring devices. There is a nominal opening between the two rooms - usually about 9' wide by 8' high, but can vary in accordance with the standard.

The first step is to measure the sound transmitted from one room into the other through the opening. The sound is measured in decibels (dB) in 1/3-octave bands from 125 Hz to 4000 Hz.

The next step is to ''plug'' the opening with the material or partition construction. This could be a single layer of barrier (such as plywood or SheetBlok), or a complete wall with as many materials, layers, air gaps, etc. that can fit in the opening. The edges are completely sealed and sound transmission between the rooms is measured again.

The sound level from the ''after'' test is subtracted from the sound level ''before'' plugging the opening. The resulting difference is the transmission loss or ''TL.''

Doors are also often weak components of sound insulation and must be properly air sealed to minimize sound leaks. A 45mm (1-3/8") solid core wood door completely sealed with gaskets or weather stripping can achieve an STC rating of 27.

The average single glaze glass window has a STC of 25

Double or triple pane glass and storm windows can all help reduce sound transmission through windows.
Dual Glaze Insulted Glass Window has a average STC of 31
Dual Glaze Insulated Glass using different glass thickness can achieve a STC of 34
Dual Glaze Insulated Glass using different glass thickness and laminated glass can achieve a STC of  36

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