Vacuum glazing VS Double glazing

Insulating glass，especially double glass units dominates the windows&doors market. But with the development of vacuum insulating glass in recent years. Vacuum insulating glass has shown superior performance far beyond double glazing. What are the advantages of vacuum glazing compared with double glazing?

1. Table of Contents

   VIG has much better thermal performance

Double glazing,or insulating glass,contains 3 types heat transfer types: Radiation,convection and conduction.

Because of the existing of the air convection inside the insulating glass,which make it difficult to bring IGU U value down even though more and more technology were developed..Warm edge spacer,argon filled IGU,triple and even quad silver low-E coating.etc

To suit customers higher thermal insulation performance requirement, triple glazing and even quad glazing were used to achieve the best possible U value,till now the best U value achieved for triple glazing is 0.6W/M2.K.The cost is thick and heavy glass,as well as that of hardware,windows frame etc.

Vacuum insulating glass,because of the high degree vacuum space between glass,which eliminate the heat convection inside the glass,the heat can been transferred through the micro glass pillars,and taking advantage of dual silver low-E coating,even if the 8.3mm VIG can achieve 0.47W/M2.K U value.

Below table shows the thermal performance compare between VIG and IGU.

Glass	Thickness	LT %	U value	SHGC
5+0.3v+5 double silver low-E	10.3MM	69%	0.47	0.57
5LE +16AR+5LE+16AR+5	47MM	55%	0.60	0.32

Learn about structure difference between VIG & IGU

2. VIG is lighter and thinner.

Vacuum insulating glass is 8.3 mm thick and weighs 20 kg/m²,U value is 0.47W/M2.K.

While IGU can only achieve lowest 0.6W/M2.K ,and glass combination is 4-16AR-4-16AR-4,weight 30kgs/m2.k and total thickness 42mm.

Compared with insulating glass, vacuum insulating glass can significantly reduce the cost of building load-bearing and frame materials,as well as the hardware load-bearing.

In addition, vacuum insulating glass is ideal for renovation of old buildings. No need to replace the window frame, just replace the glass or add inner layer to complete the renovation easily.

Learn more:Vacuum  insulating  glass  helps  in  windows  Restoration

3. VIG can be horizontal installed in glass roof or Skylight

The insulating glass are usually filled with gas,whether it’s air or argon. When installed horizontally, its U-value rises due to the increase in gas convection. In contrast, vacuum insulated glass contains no air between the glass sheets. The U-value remains the same regardless of the mounting position.

Learn more:How the glass U value been affected by the installation angle?

4. VIG can be applied in different altitude areas

Insulating glass manufactured at low altitudes expands when transported to high altitudes. However, vacuum insulating glass does not leave air between the glass, and there will be no expansion problem when installed at a high place. In fact, vacuum insulating glass experiences less pressure difference at higher altitudes and therefore less stress. This results in higher security.

Another benefits is,VIG panel is flat and avoid visual distortion when been applied in facade.Because VIG require high flatness ,and vacuum space also ensures no expansion or contraction and avoid

Learn more:Vacuum  glazed  windows  in  Plateau  area

5.VIG  has  superior  anti-condensation  performance

Condensation refers to the phenomenon in which condensed water droplets form on the surface of an object when the temperature of the object lower than the dew point.

Since the edges of the vacuum insulating glass are all sealed, the vacuum chamber eliminates the possibility of condensation and keeps the interior glass surface temperature above the dew point. For example,when indoor temperature is 18°C and relative humidity is 60%, the dew points of the inner surface of insulating glass and vacuum insulating glass are -8°C and -36°C, respectively. It makes vacuum insulating glass more suitable for applications in extreme cold weather areas.

 

The insulating glass may retain water vapor in the cavity that cannot be removed, causing negative effects in actual use. In contrast, vacuum insulating glass does not suffer from such problems due to its vacuum chamber.

Learn more:How vacuum glass prevent window condensation

6.VIG has superior soundproof performance against low&middle frequency noise

Generally speaking, urban noise includes living noise, traffic noise, occupational noise and construction noise, mainly in the range of low frequency (200Hz~300Hz) and medium frequency (500Hz~1000Hz). The weighted noise reduction index of vacuum insulating glass is 36dB. The sound is mainly transmitted through the spacer.

The IGU weighted noise reduction is 29dB, and the sound is transmitted through the air. This shows that vacuum insulated glass is very suitable for buildings in the city center or near the street.

Learn more:Vacuum insulating glass soundproof performance

7.VIG lifetime is much longer than insulating glass

Insulating glass usually adopts a double sealing structure of metal partitions. The inner sealant is made of butyl rubber and the outer layer is covered with silicone or polysulfide sealant. These materials age easily. In contrast, most vacuum insulating glass is sealed with solder glass and can last longer. Generally speaking, the average service life of insulating glass is about 15 years, while vacuum insulating glass can be used for more than 25 years.

Learn more: Vacuum glass lifetime

With above analysis,the main factors causing difference between IGU and VIG are the air inside glass and the glass structure.Now tempered vacuum insulating glass offers good safety performance and can be widely used in glass windows,doors,and glass facade.

Unfortunately,VIG is not perfect product,as it’s relatively new energy saving glass product,still facing many challenges.

Shortages of Vacuum Glazing

1.High price.

The high VIG price is not only related to the low production efficiency,heavy investment,but also related to the materials used in VIG.

HaanGlas VIG main sealing materials contain silver,which is quite expensive.For other manufacturers who still have to print the glass board with silk screen process,which means every sizes has unique screen plate,which affect overall price increased.

Generally VIG price is 3-5 times that of normal double glazing.

2.Low impact resistance.

We have to admit that even though many VIG manufacturers have got SGCC certificate,or passed EN12600 requirement on impact resistance.

But we have to say that the comform only means that glass fragments comform the standard requirement after breakging.

Because of the existance of micrio pillars which has high stress on glass surface,VIG overall impact resistance is far from monolithic tempered glass.

When applying VIG in glass facade,it’s recommended to use hybrid VIG and use VIG as interior panel to have better impact resistance.

Above video shows our VIG breakage and fragments.

3.Poor edge thermal conductivity.

Even though VIG center U value reach 0.4-0.6W/M2.K,but VIG edge conductivity is very high.

The coatings at glass edge are removed,and metal materials has similar conductivity as aluminium spacer bar that used in IGU.

The big difference between center and glass edge will also cause high breakage ratio.

When applying in new constructions,it’s still recommended to use hybrid VIG to decrease the edge thermal conductivity.

 

HaanGlas is your turnkey vacuum glazing supplier and manufacturer,kindly contact us for your next great building.