What is Low E Glass?

6 minutes

The humble window, a staple in architectural design for centuries, has long played a role beyond simply letting light into our homes and offering views of the outside world. As architectural and technological landscapes have shifted, the window has undergone its own metamorphosis. Its evolution reveals a fascinating interplay between form and function, style and sustainability. 

Among the leading advancements in this domain is the Low-e window. This term, “Low-E”, has steadily gained prominence in the lexicon of builders, homeowners, and environmental enthusiasts. On the surface, it might seem like yet another technical jargon in an industry already filled with them. However, its implications are both vast and vital. Understanding Low-E isn’t just about knowing what it stands for; it’s about recognizing its transformative potential for energy conservation in contemporary construction. 

In the following discussion, we’ll delve deeper into the science and significance of Low-e windows. From their origins to their increasing importance in a green home, we’ll unveil why these windows are more than just panes of glass. They’re a testament to how innovation can reshape our living spaces, making them more in tune with the environment and our modern-day needs. 

What does Low-E Glass mean?

Low-E stands for “low emissivity.” At its core, emissivity refers to a material’s ability to emit infrared energy. Low-E glass is specifically designed to minimize the amount of ultraviolet and infrared light that passes through glass without compromising the amount of visible light that is transmitted. 

Here’s a breakdown of what that means: 

  • Infrared Light: This is a form of light we feel as heat but can’t see. Low-E coatings reduce the infrared light transmission, helping to control heat transfer through windows. 
  • Ultraviolet Light: This form of light can cause fabrics and furnishings to fade. By limiting the amount of UV light that enters a space, Low-E glass helps protect your interior furnishings. 
  • Visible Light: This is the light spectrum that we can see. Low-E glass allows a majority of the visible light spectrum to pass through, ensuring spaces remain bright. 

The Low-E coatings are microscopically thin, metallic layers that are applied to the glass or suspended between two panes. This allows the window to reflect certain wavelengths of light, thereby controlling the amount and type of light and heat that passes through the window. 

In practical terms, this means that in colder climates, Low-E windows can help keep heat inside a home, reducing heating costs. Conversely, in warmer climates, they can reflect some of the sun’s heat, keeping interiors cooler and reducing cooling costs. 

What Factors are Used to Determine the Effectiveness of Glass? 

The effectiveness of glass, especially in architectural and construction contexts, is determined by a variety of factors, many of which cater to energy efficiency, safety, and aesthetic requirements. Here are some key factors used to determine the effectiveness of glass: 

  • U-Value (Thermal Transmittance): This value measures how effective a material is as an insulator. A lower U-value indicates better insulating properties. In the context of windows, it measures the rate of heat transfer and indicates how well the window insulates. 
  • Solar Heat Gain Coefficient (SHGC): This measures the fraction of incident solar radiation that passes through the window, either transmitted or absorbed and then released inward. A lower SHGC means the window transmits less solar heat. 
  • Visible Light Transmittance (VLT): This factor quantifies the amount of visible light that a pane of glass lets through. It’s given as a percentage – higher percentages mean more light is transmitted through the glass. 
  • Emissivity: As mentioned earlier, this is the measure of a material’s ability to emit infrared energy. Low-E glass has low emissivity, meaning it’s designed to reflect more infrared light, impacting heat transfer. 
  • R-Value: This measures resistance to heat flow. A higher R-value indicates better insulation properties. 
  • Acoustic Properties: Some glasses are designed to dampen sound, and their effectiveness can be gauged based on how well they reduce noise transmission. 
  • Tint and Reflectivity: The tint and reflectivity of the glass can affect its aesthetic appeal and its ability to reduce glare or heat from the sun. 
  • Air Leakage: This measures the rate at which air passes through window joints. A lower value indicates less air leakage. 
  • Edge Seals and Spacers: In double or triple-glazed windows, the type of edge seal or spacer can determine the effectiveness of the insulating gas between the panes and its longevity. 

These factors collectively help architects, builders, and homeowners choose the most appropriate type of glass for a specific purpose or climate. Properly chosen glass can significantly improve energy efficiency, reduce costs, and enhance the comfort and safety of indoor spaces. 

What are the Different Types of Low-E Coatings?

Low-E (low-emissivity) coatings enhance the energy efficiency of windows by controlling the transfer of heat and light. The type and application of Low-E coatings can be tailored to specific climate conditions and desired interior effects. There are several types of Low-E coatings, and they can be broadly categorized as follows: 

Passive Low-E Coatings (or Hard-Coat): 

  • Manufacturing Process: Created using a pyrolytic process, which involves applying the coating while the glass is still in a semi-molten state. 
  • Characteristics: This type of coating is more durable and can be exposed. It’s often referred to as “hard-coat” because of its resilient nature. 
  • Best Used: Primarily in colder climates because they allow short-wave infrared energy (from the sun) to pass through and help heat a home while retaining that heat more effectively. 

Solar Control Low-E Coatings (or Soft-Coat): 

  • Manufacturing Process: Applied in a secondary process using a Magnetron Sputter Vacuum Deposition (MSVD) method. The coating is applied in a vacuum chamber using an electrically charged gas (plasma). 
  • Characteristics: This coating, often called a “soft-coat,” is more delicate and must be sealed within the window unit. It typically has multiple layers of silver, making it a superior performer in reflecting heat. 
  • Best Used: Best suited for warmer, sunnier climates as they reflect the sun’s rays and prevent interior spaces from overheating. 

Tinted Low-E Coatings:

  • Manufacturing Process: Can be either passive or solar control coatings but have added tints.
  • Characteristics: Tinted coatings not only provide energy efficiency but also reduce glare and offer some privacy. The tints can also give windows an aesthetic appeal and are available in various colors. 
  • Best Used: In scenarios where aesthetics, glare control, or privacy are desired in addition to energy efficiency. 

Double and Triple Silver Low-E Coatings: 

  • Manufacturing Process: Similar to the soft-coat process but with multiple layers of silver. 
  • Characteristics: Each layer of silver enhances the glass’s ability to reflect radiant heat, making these coatings some of the most efficient. 
  • Best Used: In areas where maximum energy efficiency is desired. 

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Act now. Contact us today at 844-DaBella for a free consultation and let DaBella elevate your living space with the unmatched quality of Glasswing windows.