Single, Double, Triple Silver Low-E Glass Performance Difference

The low-emissivity coating is applied on the glass surface purpose is to reduce the emissivity and maintain good light transmittance to meet the requirements of natural lighting.

At the same time, it limits the penetration of infrared heat radiation, reaching better the thermal insulation performance.

Low-E coated glass is being used as an environmentally friendly and energy-saving high-performance building material, which is widely used in construction, automobiles. In modern buildings, the energy-saving and ornamental requirements of curtain wall glass are getting higher and higher.

For areas with different climatic conditions, it is particularly important to choose suitable curtain wall glass.

Sometimes in order to meet the design requirements, a combination of body tinted glass and Low-E coating is selected.

This article will be based on the performance of single silver, double silver, and triple silver LOW-E coating on different glass substrates, and an analysis of how glass substrate affects coating performance.

Parameter to evaluate glass thermal performance

Evaluating the heat transferred through the glass consists of two parts,
1. one is the heat energy transmitted through solar radiation, and the 2. other is the heat energy transferred by the environmental temperature difference and long-wave infrared radiation on both sides of the glass.

Usually, we use the SC-shading coefficient and U value to measure it.

The smaller the Sc, the smaller the solar energy entering the room.
U value is the heat transfer coefficient, which reflects the heat transfer characteristics of glass and reflects the heat preservation performance of glass.
Under the same environmental conditions, the lower the U value, the less heat transfer through the glass, and the better the heat preservation performance of the glass.

Besides that, LSG ( light to solar heat gain) is another parameter showing the glass performance, higher LSG means,under the same light transmittance condition, lower solar energy transmitted the glass.

Object: heat conduction, heat convection, and thermal radiation

Below tests are based on ASHRAE Summer condition:

1. Different glass substrate performance

1.1 Whether it’s clear, low iron, or tinted glass, the same glass surface emissivity decides the same U value.

1.2 While color darkness decides different SC values, darker glass blocks more solar energy, SC value is also lower.

To achieve better energy-saving effects, it is necessary to coat low-E film on glass, here we

Calculate performance based on 6 low-E+12A+6 Clear Glass

Single silver lowE insulated glass

Low-transmittance single silver is coated on different substrates, conclusion is below:

U value basically does not change with the change of the substrate.
F green glass has the highest selection coefficient, followed by clear and low iron glass but light transmittance of green glass is nearly 18% lower

Based on low light transmittance ford blue and Euro grey glass, coated glass is also the lowest and the lowest LSG, which is not suitable for large area curtain walls.

The same result happened to middle and high light transmittance single silver coatings, see below tables.

When single silver with different transmittance is coated on different glass substrates, the IGU LSG selectivity coefficients are different.

Double silver lowE insulated glass

Let’s analyze double silver low-E again.

Below are our conclusion:

Apply double silver low-E coating on low iron glass can get the best light transmittance and the best LSG.

Insulated glass U value won’t be affected by the glass substrate.

Compared with single silver low-E, double one has better LSG. But applied on low light transmittance body tinted glass, SC won’t decrease significantly which will lose its energy advantage.

Triple silver low-E coatings have the same conclusion.

Applied with the same low-E coatings, the different substrates will have different light and heat characteristics.

Low iron glass exhibits higher transmittance and selectivity in double silver and triple silver coatings, as well as excellent energy-saving properties.

8 triple silver low-E+12AR+8C+12AR+13.52 project

Although green glass has higher LSG in some IGU systems, its visible light transmittance is lower. However, dark color body tints are not suitable for large-area curtain walls due to their low transmittance.

In practical applications, we found that the curtain wall using ultra-white glass not only has excellent energy-saving properties but also has a good appearance effect.

If no special requirements for glass curtain wall colors t, it’s suggested to use a glass combination of low iron glass with Low-E coatings to have better energy-saving characteristics and an ideal appearance.

In Southeast Asian and Middle East countries, customers prefer using a glass combination of grey glass and low-E coatings, even though overall light transmittance can be controlled below 25%, but solar coefficient is not good as expected.

Eliterglass is able to manufacture, supply deliver to worldwide all kinds of high-performance energy-saving glass, including double and triple silver low-E coatings glass, warm edge space glass, triple insulated glass units, etc.

Category: Insulated glass