Low-E glass is window glass with a microscopically thin, invisible metal coating that reflects heat. Low-E stands for low emissivity. The coating bounces infrared heat back toward its source while letting visible light through, so your home stays cooler in summer and warmer in winter without looking tinted. In a Texas home, it is the single most important feature in the glass.
Window quotes come with a stack of numbers and acronyms. Here is what each rating means and how to tell which Low-E glass package performs in Texas heat.
Measures how well the window prevents heat transfer. Lower numbers mean better insulation performance.
Indicates how much solar heat passes through the glass. Lower values help reduce summer heat buildup.
Shows how much natural light enters your home. Higher numbers mean brighter interiors.
A microscopically thin metallic layer applied to the glass that reflects heat while allowing natural light to pass through. It keeps interiors cooler in summer and warmer in winter without darkening your home, the single most important upgrade in modern window glass.
Modern Low-E windows are double pane: two glass panes sealed together with argon gas between them. The Low-E coating sits on an inside glass surface, where it is protected from weather and wear.
Argon gas is sealed between the panes of a double pane window to slow heat movement more effectively than air. It improves insulation performance without affecting clarity, and it is standard in every Cardinal LoĒ package we install.
It reflects heat instead of absorbing it. Low-E glass uses ultra-thin layers of silver to control heat transfer. In summer, the coating reflects the sun’s infrared heat back outside. In winter, it reflects interior warmth back into the room. Paired with argon gas between the panes, it reduces strain on your HVAC system and keeps rooms comfortable year-round in Plano homes and across the Dallas area.
It blocks the rays that fade your floors. The Cardinal Low-E packages we install block 95 to 99 percent of UV rays, compared with about 42 percent for clear double-pane glass.
| Glass Type | U-Factor | SHGC | Visible Light | UV Block |
|---|---|---|---|---|
| Clear Glass (No Low-E) | 0.48 | 0.78 | 82% | 42% |
| LoĒ³-340 | 0.25 | 0.18 | 39% | 98% |
| LoĒ³-366 | 0.24 | 0.27 | 65% | 95% |
| Quad LoĒ-452+ | 0.24 | 0.22 | 52% | 99% |
| LoĒ³-366 + LoĒ-i89 | 0.20 | 0.27 | 63% | 95% |
The difference shows up in the SHGC column. Clear double-pane glass lets in 78 percent of the sun’s heat. Cardinal LoĒ³-366 lets in 27 percent while still passing 65 percent of visible light, so rooms stay bright without the heat.
Values are Cardinal’s published center-of-glass figures for dual-pane glass with argon fill (clear glass shown with air fill). Certified by the NFRC. Browse the official database.
Every Texas home has different sun exposure, room layouts and comfort needs. Cardinal LoĒ packages let us match the right glass to each side of your home. Here is how each option performs.
Not sure which package fits your home?
We walk you through every option during your in-home consultation.
LoĒ-i89 is a clear coating applied to the room-side surface of the glass. Paired with LoĒ³-366, it lowers a dual-pane window’s U-factor from 0.24 to 0.20 for stronger insulation.
Why add it: it reflects interior heat back into the home in winter without reducing visible light, which makes it a strong upgrade for homeowners focused on maximum insulation.
Engineered for strong south and west sun exposure. It blocks the most solar heat of the packages we offer, cuts glare, and protects flooring and furnishings from UV damage.
Where it fits: west-facing rooms and large windows that take direct afternoon sun. It has a visible tint and lets in 39 percent of visible light, so we use it where heat control matters more than brightness.
The most versatile glass package for Dallas-area homes. It delivers strong summer heat control while keeping views clear and neutral with comfortable daylight.
Where it fits: most east, west and south exposures. It blocks 73 percent of the sun’s heat and 95 percent of UV rays with no heavy tint.
Designed for homeowners who want stronger heat control than LoĒ³-366 with more natural light than LoĒ³-340. Its four silver layers block 99 percent of UV rays to reduce interior fading.
Where it fits: large window walls and homes with heavy sun exposure. Pair it with LoĒ-i89 to lower the U-factor from 0.24 to 0.20 for stronger year-round insulation.
Optional upgrades to enhance your Low-E glass package, including self-cleaning coatings, sound reduction and decorative privacy options.
An advanced coating activated by sunlight that helps rainwater rinse away dirt and mineral buildup, keeping your windows cleaner with less maintenance.
Engineered with offset glass thickness and acoustic layers to help reduce outside noise while adding strength and security.
Add privacy or style while keeping your home bright. Perfect for baths, entryways, and sidelites.
Two often-overlooked details that affect how your windows arrive and how they perform long-term: the Endur IG spacer between the panes and the Preserve film that protects the glass on its way to your home.
Engineered to reduce heat transfer around the perimeter of the glass where most energy loss occurs.
• Reduces edge condensation
• Improves overall insulation performance
• Helps extend seal life
• Supports long-term durability
A factory-applied protective layer that shields glass during shipping and installation, ensuring your windows look pristine on day one.
• Protects against scratches and debris
• Removed cleanly after installation
• Helps deliver a spotless final result
• Reinforces installation quality
Low-E glass reflects infrared heat to keep homes cooler in summer and warmer in winter. It filters out UV rays that cause fading while maintaining natural daylight and clear views.
ENERGY STAR estimates that replacing poor-performing windows with certified models lowers household energy bills by an average of up to 13 percent, and savings vary by climate and home. In Texas, most of the gain comes from blocking summer heat. Our FGIA-certified installation makes sure the insulation value you pay for performs in real conditions.
Not with the right package. Coatings like Cardinal LoĒ³-366 and Quad LoĒ-452+ look clear and neutral with no heavy tint or mirror effect. LoĒ³-340 is noticeably darker, which is why we reserve it for windows that take the hardest sun.
Yes. The Cardinal packages we install block 95 to 99 percent of UV rays, compared with about 42 percent for clear double-pane glass. That protects floors, rugs and furniture from fading.
Recent projects showcasing professionally installed, energy-efficient windows in a variety of home styles and settings.
Our certified team is here to help you choose the right glass for every window in your home, with honest answers every step of the way. Clear Guidance. No Pressure.
