LOW-E glass, also known as low-emissivity glass, is a type of glass that has been coated with a low-radiation material. This coating is designed to reduce the amount of heat that is transferred through the glass, making it an ideal choice for energy-efficient buildings. In this article, we will explore the characteristics of LOW-E glass, its functional differences from heat-reflecting glass, and the main types of mature coated glass processes.
Characteristics of LOW-E Glass
LOW-E glass offers several key characteristics that make it a popular choice for modern buildings. These include:
High Infrared Reflectivity: LOW-E glass has the ability to directly reflect far infrared thermal radiation, making it an effective barrier against heat transfer.
Low Surface Emissivity: The surface emissivity (E) of LOW-E glass is low, which means that it has a reduced ability to absorb external energy. This results in less heat energy being radiated through the glass.
Controlled Solar Energy Transmission: The shading coefficient (Sc) of LOW-E glass can be adjusted to control the amount of solar energy that is transmitted through the glass. This allows for customization based on the specific needs of different regions.
Reflective Properties of LOW-E Film
The reflective properties of LOW-E glass are achieved through the use of a LOW-E film layer that is plated with a silver coating. Silver has the ability to reflect more than 98% of far infrared thermal radiation, effectively acting as a barrier to heat transfer. This reflective quality is similar to how a mirror reflects light, allowing the LOW-E glass to reflect heat directly.
Functional Differences from Heat-Reflecting Glass:
While both LOW-E glass and heat-reflecting glass are designed to limit the transfer of heat through windows, they achieve this goal through different means. Heat-reflecting glass reduces the shading factor of the glass, which limits the direct radiation of the sun into a room. This can help to reduce the need for air conditioning and save energy.
On the other hand, LOW-E glass limits far-infrared heat radiation through the glass by reducing the U-value of the glass. This helps to minimize convection conduction heat through the glass. Additionally, the shading coefficient (Sc) of LOW-E glass has a wide adjustment range, allowing for effective control of direct solar radiation energy entering a room.
Main Types of Coated Glass Processes
There are two main types of mature coated glass processes:
1. Hard Coated (Online Coating): This type of coated glass is manufactured in the float glass production line. While it offers a single variety and has poor thermal reflection, it does have the advantage of being able to be hot bent, and it has a lower manufacturing cost.
-Advantages:
Since Low E glass doesn't need to be sealed into an insulated glass unit, its durability offers the possibility for added accessories (e.g.) blinds in between the panes
This is a more inexpensive option since there are less layers needing to be applied (compared to a "soft coat").
-Disadvantages:
U-values are typically higher as the glass isn't as energy efficient as a Low E soft coat. (still energy efficient nonetheless!)
Typically yields a higher solar heat gain coefficient, allowing more infrared and ultraviolet light to pass through the glass (compared to a soft coat Low E window)
Soft coated (Vacuum Magnetron Sputtering Coating with Off-line Coating): Coated glass produced using this process offers a wide range of varieties and excellent thermal reflection performance. It has obvious energy-saving characteristics but does not support hot bending processing.
-Advantages:
When compared to a hard coat, soft coats tend to have more optical clarity. (hard coats can come off as a bit "hazier")
Provides ultra low emissivity, creating optimum u-values.
Can provide up to 70% less UV transmission compared to standard clear glazing.
-Disadvantages:
The Low E coating is very fragile, so extreme care and special gloves must be used when handling this type of glass.
More difficult to temper due to its heat reflection properties.
Can be more expensive with the added layers of silver and extra fragility
More questions, please feel free to contact Tracy@miggoglass.com or WhatsApp: +86 153 1423 0350
