Glass Glossary

Low-E (LoĒ) Glass


Last Updated: November 23, 2023

Low-E, or low-emissivity, glass refers to a type of energy-efficient glass designed to prevent heat from escaping or entering a building, thereby enhancing thermal comfort and reducing energy costs. The “emissivity” of a material indicates its ability to emit infrared energy. Low-E glass has a microscopically thin, transparent coating—usually made of metallic or metallic oxide layers—that reflects long-wave infrared energy, or heat.

Low-E is a generic term to apply to any company’s low emissivity products. However, LoĒ™, LoĒ²®, LoĒ³®, and Quad LoĒ™ are Cardinal trademarks and refer to Cardinal’s version of low-E coatings.

Key features of Low-E glass:

Thermal Efficiency: Low-E glass reflects the interior temperatures back inside, keeping rooms warmer in the winter and cooler in the summer.

UV Protection: The special coatings on Low-E glass block significant amounts of harmful UV rays, which can fade fabrics, furnishings, and cause skin damage.

Reduced Glare: Some types of Low-E glass coatings can help reduce the amount of visible light that comes through the glass, decreasing potential glare and increasing comfort.

Versatility: Depending on its design and intended use, Low-E glass can either increase solar gain (beneficial in colder climates to reduce heating needs) or decrease it (ideal for warmer climates to reduce cooling needs).

Benefits of using Low-E glass:

Energy Savings: Homes and buildings equipped with Low-E glass windows and doors can achieve significant energy savings, as they reduce the need for heating and air conditioning.

Comfort: Low-E glass helps maintain a consistent indoor temperature, eliminating cold drafts or overly warm spots, enhancing overall comfort.

Environmental Impact: By reducing energy consumption, Low-E glass can contribute to reduced greenhouse gas emissions.

Two primary types of Low-E coatings:

Soft Coat (or Sputtered): Applied in multiple layers under vacuum conditions, soft coat silver-based Low-E offers the most superior performance characteristics and works inside a sealed insulating glass unit. Cardinal’s regular LoĒ products are applied to the #2, #3 and #5 surface of IG units

Cardinal’s LoĒ-i89, LoĒ-Di89 are indium-based and are capable of being applied to surface #4 of a dual pane and surface #6 of a triple pane insulating units, offering even better performance. Indium-based coatings are very smooth, durable, and easy to clean. They are designed to be exposed to the room-side of the insulating units. Cardinal’s Neat+™ coating is smooth and applied in a patented process inside the vacuum sputter coater and helps keep glass cleaner longer, is anti-static, and works with UV light from the sun to loosen bonds with dirt to assist in cleaning the glass.

Hard Coat (or Pyrolytic): This coating is integrated during the float glass manufacturing process, with its application occurring at elevated temperatures. This makes the coating an intrinsic part of the glass surface. Cardinal’s HydroClear™ serves as a prime example of hard-coated glass products. These coatings are permanently positioned on the #1, #4, or #6 surfaces, boasting scratch resistance equivalent to standard glass.

Key features of Low-E glass:

Thermal Efficiency: Low-E glass reflects the interior temperatures back inside, keeping rooms warmer in the winter and cooler in the summer.

UV Protection: The special coatings on Low-E glass block significant amounts of harmful UV rays, which can fade fabrics, furnishings, and cause skin damage.

Reduced Glare: Some types of Low-E glass coatings can help reduce the amount of visible light that comes through the glass, decreasing potential glare and increasing comfort.

Versatility: Depending on its design and intended use, Low-E glass can either increase solar gain (beneficial in colder climates to reduce heating needs) or decrease it (ideal for warmer climates to reduce cooling needs).

Benefits of using Low-E glass:

Energy Savings: Homes and buildings equipped with Low-E glass windows and doors can achieve significant energy savings, as they reduce the need for heating and air conditioning.

Comfort: Low-E glass helps maintain a consistent indoor temperature, eliminating cold drafts or overly warm spots, enhancing overall comfort.

Environmental Impact: By reducing energy consumption, Low-E glass can contribute to reduced greenhouse gas emissions.

Two primary types of Low-E coatings:

Soft Coat (or Sputtered): Applied in multiple layers under vacuum conditions, soft coat silver-based Low-E offers the most superior performance characteristics and works inside a sealed insulating glass unit. Cardinal’s regular LoĒ products are applied to the #2, #3 and #5 surface of IG units

Cardinal’s LoĒ-i89, LoĒ-Di89 are indium-based and are capable of being applied to surface #4 of a dual pane and surface #6 of a triple pane insulating units, offering even better performance. Indium-based coatings are very smooth, durable, and easy to clean. They are designed to be exposed to the room-side of the insulating units. Cardinal’s Neat+™ coating is smooth and applied in a patented process inside the vacuum sputter coater and helps keep glass cleaner longer, is anti-static, and works with UV light from the sun to loosen bonds with dirt to assist in cleaning the glass.

Hard Coat (or Pyrolytic): This coating is integrated during the float glass manufacturing process, with its application occurring at elevated temperatures. This makes the coating an intrinsic part of the glass surface. Cardinal’s HydroClear™ serves as a prime example of hard-coated glass products. These coatings are permanently positioned on the #1, #4, or #6 surfaces, boasting scratch resistance equivalent to standard glass.