Low Emissivity (Low E)

Definition:

Low emissivity (Low-E) refers to a microscopically thin, transparent coating applied to glass surfaces to minimize the amount of infrared and ultraviolet light that passes through without compromising the amount of visible light transmitted. This coating reflects heat back to its source, helping to keep interiors warm in winter and cool in summer. Low-E coatings are commonly used in energy-efficient windows to enhance insulation and reduce energy costs.

Short Description:

Low-E coatings are ultra-thin metallic layers applied to glass that reflect heat and block ultraviolet light, improving a window’s insulating properties and energy efficiency.

Why It’s Important:

Incorporating Low-E coatings in windows significantly enhances a building’s energy efficiency by reducing heat transfer. This leads to lower heating and cooling costs, improved indoor comfort, and protection of interior furnishings from fading due to ultraviolet light exposure. By reflecting interior heat back into the room during winter and reducing solar heat gain in summer, Low-E windows maintain more consistent indoor temperatures year-round.

Other Things to Consider:

•Types of Low-E Coatings: There are primarily two types:

•Passive Low-E Coatings: Designed to maximize solar heat gain, beneficial in colder climates to reduce heating costs.

•Solar Control Low-E Coatings: Formulated to limit solar heat gain, ideal for warmer climates to minimize cooling expenses.

•Application Methods: Low-E coatings can be applied using:

•Hard Coat (Pyrolytic): Applied during the glass manufacturing process, resulting in a durable coating suitable for single-pane applications.

•Soft Coat (Sputtered): Applied after the glass is formed, offering superior performance but requiring sealing within insulated glass units to protect against environmental exposure.

•Impact on Visible Light: While Low-E coatings are designed to reflect infrared and ultraviolet light, they allow most visible light to pass through. However, some coatings may slightly alter the tint of the glass, which can affect aesthetics and daylighting.

•Compatibility with Glazing Systems: Low-E coatings are most effective when incorporated into double or triple-glazed window systems, often with inert gas fills like argon or krypton, to further enhance thermal performance.

By selecting the appropriate type of Low-E coating based on climate and building design, homeowners and builders can achieve optimal energy efficiency and indoor comfort.