What is Low E glass?
Low E glass (Low emissivity glass) is a coated glass with a film composed of multiple layers of metal or other compounds on the surface. The coating layer has a high transmission of visible light and a high reflection of mid-and far-infrared. Comparing with ordinary glass, the Low E glass has an excellent heat insulation effect and good light transmittance.
How low emissivity glass works?
The glass itself is inherently highly radiating heat. Therefore, to improve thermal control, low emissivity film coatings are applied to the glass.
The Low-E coating reduces the emission of radiant infrared energy, so it tends to keep the heat on the origin side of the glass while letting visible light pass through.
In other words, the heat from the room stays indoors (the warmer side) in winter. Summer heat does not radiate from the outside, thus keeping the inside cool.
What’s the benefit of Low E glass?
Energy Saving & Cost Saving
Low emissivity glass has a directional blocking of heat penetration, keeping the heat on the original side. In the cold zone, it can reduce heat loss indoor and maintain the indoor temperature. In tropical or subtropical regions, it can reduce the heat transmitted by outdoor sunlight to reduce air conditioning load.
How many types of low emissivity glass?
Classified by the manufacturing process, there are soft coat types and hard coat types. Classified by the functional layers, there are single-silver, double-silver, triple-silver, as well as quad-silver. Regarding the light transmittance capacity, there is high light transmittance >70%, medium-light transmittance 50-70%, low light transmittance <50%. Therefore, different light transmittance glass will be select for different climate areas. Other classifications of different characteristics include shading coefficient (Sc) and heat transfer coefficient (U).
Low E glass application in the different climate areas
High latitude and cold climate
These areas have long winters, shallow winter temperatures, short daylight hours, and weak light intensity.
Firstly, the high-transmittance low emissivity glass can make maximum use of natural light due to its excellent light transmittance. Secondly, the indoor temperature is higher than outdoors, and the far-infrared heat radiation mainly comes indoors. Therefore, the low emissivity glass can reflect it indoors to keep the indoor heat from leaking.
Hot summer and warm winter area
These areas heat up quickly in summer, and the demand for heating in winter is lower than that of high-latitude regions. In addition, Double-silver or triple-silver low-emissivity glass can prevent outside heat from entering the room, reducing the energy consumption for air conditioning and cooling.
The outdoor temperature is higher than indoors, and the far-infrared heat radiation mainly comes from the outdoors. Low emissivity glass can reflect the mid-and-fort-infrared rays in the sunlight, allowing only visible light to pass through, turning the sunlight into a cold light source and preventing heat from entering the room. Thus, it can achieve the purpose of energy-saving and also meet the lighting needs of the room.
Hot summer and cold winter area
This area has four distinct seasons, significant temperature differences between winter and summer, and more variable climatic conditions. So we can use low-transmittance sun-shading low emissivity glass.
In summer, it can reduce the light transmittance of the glass and prevent outdoor heat radiation from entering the room. While in the winter, the light transmittance is relatively low, but it can meet everyday lighting needs. At the same time, it prevents indoor heating and other heat from passing outside. So it is necessary to consider heat dissipation in summer and keep warm in winter. Using suitable low-emissivity glass can find a balance between summer and winter.