Low-E glass has become increasingly popular in recent years, and related topics frequently appear in basic architecture exams. This article explains the energy-saving principles of Low-E glass and related exam questions.
What is Low-E glass?
Low-E glass, short for low-emissivity coated glass, refers to coated glass products that exhibit low absorption, low secondary outward radiation, and nearly complete reflection of far-infrared radiation within the 1.0 to 40μm wavelength range. This effectively blocks far-infrared radiant heat transfer.
What are the commonly used products in the construction market?
Currently, most Low-E glass products are available in double-glazed or triple-glazed configurations, typically with an inert gas filling between them to further enhance performance. For example, "6-light-transmittance Low-E tempered glass + 12Ar + 6-tempered glass" means a 6mm thick Low-E tempered glass on the outside, a 12mm thick argon-filled middle, and a 6mm thick tempered glass on the inside.
How does Low-E glass function in summer and winter? In winter, indoor temperatures are higher than outdoor temperatures. Far-infrared heat radiation primarily originates from indoors. Low-E glass reflects this radiation back into the room, preventing heat from escaping. Low-E glass still allows some of the solar radiation from outdoors to enter the room. This energy is absorbed by indoor objects and converted back into far-infrared heat radiation, which is retained indoors.
In summer, outdoor temperatures are higher than indoor temperatures. Far-infrared heat radiation primarily originates from outside. Low-E glass reflects this radiation, preventing heat from entering the room. For solar radiation from outdoors, Low-E glass with a low shading coefficient can be selected to limit its entry into the room, thereby reducing costs.
Three Important Parameters?
1.1 K Value
The heat transfer coefficient (K) is the amount of heat transferred per unit area per unit time under stable heat transfer conditions, with an air temperature difference of 1 degree (K or °C) across the building envelope. It is expressed in watts per square meter (W/m2·K).
1.2 Shading Coefficient (Sc)
The shading coefficient is defined relative to 3mm clear glass. It compares the total solar energy transmittance of other glass types to the total solar energy transmittance of 3mm clear glass. The lower the shading coefficient, the less solar heat energy enters the room.
1.3 Solar Heat Gain Coefficient (SHGC)
Also known as the heat gain factor or g-value, it refers to the ratio of the amount of solar energy entering a room through window glass to the amount of solar heat entering through an unglazed opening of the same size under the same solar radiation conditions.
Shenyang Aolid Glass Co., Ltd. is equipped with advanced equipment such as the Southtech Double-Chamber Convection Glass Tempering Furnace, the Bochi Glass Film Removal Line, the Hanjiang Insulating Glass Production Line, the Shandong Hengdi Gas-filling Insulating Glass Line. High standards are met in key glass processes such as tempering, coating, hollow glass filling, and sealing. Furthermore,our company has obtained ISO9001 quality management system certification and strictly adheres to multiple national standards in production. Through the coordinated use of equipment, processes, and certifications, Low-E glass truly achieves the perfect balance of energy conservation, safety, and comfort, providing reliable support for building energy conservation.
