Low-E Glass


What is Low-E Glass? 

Low-e glass (as low emissivity glass) is a green energy-saving building produced by multiple coating layers of metal or other compounds on the surface of the glass using a vacuum magnetron sputtering process (containing one or more layers of 10-20 nanometers thick metallic silver) material. It has lower thermal conductivity and higher visible light transmittance. Low-e glass is divided into offline low-e and online low-e. In addition to the different manufacturing processes, the two types of glass also differ greatly in emissivity. The emissivity of offline low-e glass is lower than 0.15, and the emissivity of double silver and triple silver is as low as 0.03. The emissivity of online low-e is between 0.18-0.22.

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Why You Need Green Building Material

With the development of economy and technology, more and more buildings adopt green building materials. Why are people keen to adopt green building materials? There are two forms of thermal energy in the natural environment: solar radiation and far-infrared thermal radiation. Solar radiation comes from the sun, only from outside. The far-infrared heat radiation comes from objects with temperature, both indoors and outdoors. Buildings absorb sunlight so that rising temperature and become a source of heat radiation. The wavelength of heat radiation emitted by it is much larger than the wavelength range of solar radiation.

Using green building materials, on the one hand, it can reduce the ultraviolet radiation from the sun, and on the other hand, it can play a role in heat insulation. As a glass manufacturer with deep processing technology, China Grand Glass focuses on the research and development of technical green glass and is committed to creating sustainable modern construction projects for the society. On September 28, 2020, China Grand Glass won the first batch of "China Green Product Certification" certificate for architectural glass.

As the high-quality green building material, Low-e glass has properties of heat insulation, sound insulation, UV protection and energy saving.


Why Low-E Glass Can Save Energy

On the one hand, the Low-E film can reduce the heat exchange between the glass surface and the air, reduce the heat transfer caused by the temperature difference on both sides of the glass, and reduce the heat transfer of the glass; on the other hand, the Low-E film can effectively reflect Solar radiation, so as to limit the solar radiation through the glass radiant heat, reduce the solar heat through the glass.

Buildings equipped with Low-E glass can effectively reduce the cost of indoor air-conditioning and cooling in summer and heating in winter, and also allow buildings to have good lighting performance.


Advantage of Low-E Glass

• Low heat transfer coefficient K value. Strong ability to resist temperature difference and heat transfer. Heat insulation in summer and heat preservation in winter.
• The shading coefficient Sc has a wide range, which can be applied to the needs of different regions. (Sc>5 is the traditional type, Sc≤5 is shading type)
• Good comfort performance, balanced indoor temperature
• The offline Low-E film cannot be used as a single piece. We usually produce Low-E glass for insulating glass or laminated insulating glass.

Also, Low-E glass can attenuate more than 60% of ultraviolet rays, and the lowest ultraviolet transmittance can reach 9%. Therefore, using it as a home door and window material can effectively slow down the fading of furniture. According to customer needs, Grand Glass® can produce various kinds of color, variety of optical parameter such as transmittance and shading coefficient, kinds of series and can be toughened Low-E coated glass.


What Is Different Between Low-E Glass and Solar Control Glass?

For now, the type of energy-saving glasses applied in architecture mainly include Low-E glass and solar control glass. Solar control coated glass is also known as heat reflective coated glass. Coating one or more metal or chemical compound layer on float glass using magnetron sputtering in vacuum condition produces verity of colors, light reflectance, light transmittance and absorbability for different usages. Due to the colorful appearance of sunlight control coated glass, it is mostly used for exterior decoration of buildings. Low-E coated glass is using metal materials or silver with low radiation performance, therefore, Low-E glass is better choice if you may have a higher requirements for optical parameters.


Type of Low-E Coating Insulating Glass

You may have such a question: If I put an extra Low-E film on the glass, will the energy-saving effect be better? Low-E glass from Grand Glass® can be divided into single silver Low-E glass, double silver Low-E glass, and triple silver Low-E glass. The main difference between them is the number of pure silver films, each silver film is separated by multi-layer metal films and medium films. Low-E glass could be high solar transmittance and visible light transmittance. In winter, it can not only ensure that a certain amount of solar thermal radiation enters, but also ensure that the indoor far-infrared thermal radiation is reflected in the room, thereby reducing heating energy consumption. Low-E glass is mostly used in low-latitude areas with hot summers and buildings that require better outdoor sight shielding effects. Because it has moderately visible light transmittance and low solar transmittance, it can reflect better summer heat insulation effect and outdoor sight shielding effect.

Under the premise of the same light transmittance, double silver and triple silver Low-E have lower shading coefficient Sc. They can effectively prevent the penetration of solar thermal radiation, especially near-infrared thermal radiation. More importantly, the emissivity and heat transfer coefficient of double silver and triple silver Low-E is lower than single silver Low-E glass, which can further improve the thermal insulation performance of external windows, truly achieving warm in winter and cool in summer, and greatly reduces the heat exchange between indoor and outdoor environment through glass. To put it simply, Low-E glass can stay in standby state for a longer time after the indoor temperature reaches the set temperature, thus saving power consumption.

Based on the energy-saving effect, off-line Low-E glass is made into insulating glass, and the Low-E film is placed inside surface.


Grand Glass Super Energy-saving Low-E Glass

Grand Glass Super Energy-saving Low-E Glass for Passive House is a breakthrough in the field of energy-saving glass in China's buildings. It is a low-E insulating glass with ultra-low "heat transfer coefficient" (U value), with a U value as low as 0.62 W/m2K. It can fully meet the technical requirements of passive houses in Europe, Hong Kong and Macao ultra-low energy buildings. This product cleverly combines Grand Glass high-performance Low-E glass with online Low-E glass, which greatly reduces the U value of the entire insulating glass. At the same time, it can give full play to the excellent performance and rich colors of "offline low-emissivity coated glass". By choosing different color systems and models of offline low-emissivity coated glass products, it can meet the requirements of different colors, transmittance, reflectivity and shading performance.

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Moreover, Low-E glass can be processed and compounded with power-generating glass. The composite product power-generating glass can realize the conversion of light energy into electric energy while meeting the effect of light energy entering the room and heat insulating. It is an energy-saving and beautiful green building material.

Frequently Asked Questions

Q: Which surface of the insulating glass is most suitable for the Low-E film?
A: Usually Low-E film is placed inside layer of insulating glass. The insulating glass has 4 surfaces, and the numbers from outdoor to indoor are 1#, 2#, 3#, 4# surface. Low-E coated glass is the glass has several layers of metals or other chemical compounds sputtered on the surface(including one or more 10-20 nanometers thick silver layer). Silver has the lowest radiation rate in the natural world, the silver layer on the Low-E glass lower the infrared radiation rate from 0.84 to 0.15, reduce 90% of the indoor radiation heat loss, combine with IGU is the most effective way of energy saving for buildings. Grand Glass will make a suggestion and manufacture according to customer’s need. For example, in the north area where heating demand exceeds cold demand, the Low-E file layer is located on the 3rd surface. Conversely, in the southern area, the Low-E film should be located in the 2nd surface. 

Q: What are the common types of architectural glass substrates?
A: Clear glass, Low-iron glass, F green glass, crystal gray glass, European gray glass, blue glass, gray blue glass are common used in building curtain wall.

Q: Why the glass is needed to be tempered?
A: The strength of toughened glass is 3-4 times that of ordinary glass. After being broken, it becomes small particles, which can minimize the damage caused by falling or splashing after the glass is broken. Therefore, it belongs to safety glass. Tempered glass has good thermal stability, and there can be a temperature difference of 200℃ on the same piece of glass without thermal cracking.

Q: How to reduce the spontaneous explosion rate of tempered glass?
A: Homogeneous processing(known as heat soaking processing) can reduce its rate.

Q: Why homogeneous processing can reduce the spontaneous explosion rate of tempered glass?
A: Because it is to place the tempered glass in a homogenizing furnace and continue to raise the temperature to a certain temperature for several hours to promote the NiS inside the tempered glass to change phase or the expansion of hard impurities to cause the glass to break. After it gradually cools, take out the intact glass. This process is also vividly called detonation processing.