In order to achieve the specific window thermal insulation requirements, we can not only optimize the thermal insulation design of the profile but also adjust the glass configuration. The application of Low E coating can significantly improve the insulation performance of insulating glass. In addition, we usually choose to use argon filled insulating glass, and replace aluminum glass spacers with warm edge spacers to improve the thermal insulation performance of the entire window.
Argon VS warm edge spacer
Since replacing the improved thermal insulation performance of filling argon and using warm edge spacer in insulated glass are similar,both them can decrease the Uw by 0.1-0.2W/M2.K ,we often have to face the problem “argon” or “warm edge”.
Filling with argon gas can reduce the Ug value in the formula for calculating Uw (windows U value) below, and replacing the aluminum spacer with a warm-edge spacer will reduce the ψg value.
Calculation formula for windows thermal insulation performance
Although their function to reduce the windows U value are similar and closer, the actual impact is different. Let’s take a comprehensive look at the different effects of argon filling and the use of warm edge spacers on doors and windows.
The influence on windows U value
Take the 60 series aluminium windows that use 24mm thermal break strips, the 70 series products that use 34mm thermal break strips, and the 75 series products that use 39mm thermal break strips as examples. In the initial state,glass are insulated glass with single silver low-E coating and aluminium spacer,air space.Glass combinations are 5+12A+5Low e IGU, 5+12A+5+12A+5Low e IGU, 5+15A+5+15A+5Low e IGU.
The compare is based on AHERE windows conditions and calculated with WINDOW 6.3,THERM 6.3.
Aluminium windows used to compare the thermal insulation peformance
- Simulation resultsbased on 60 series aluminium windows( 24mm thermal break bridge strips)
| Glass Type | Glass Combination | Glass U value | Spacer Type | Windows U value |
|---|---|---|---|---|
| Air + Aluminium Spacer | 5+12A+5 LOW-E | 1.773 | Aluminium Spacer | 2.17 |
| Argon + Aluminium Spacer | 5+12AR+5 LOW-E | 1.531 | Aluminium Spacer | 2.01 |
| Air +Warm edge spacer | 5+12A+5 LOW-E | 1.773 | Warm edge spacer | 2.05 |
- Simulation resultsbased on 70 series aluminium windows( 34mm thermal break bridge strips)
| Glass Type | Glass Combination | Glass U value | Spacer Type | Windows U value |
|---|---|---|---|---|
| Air + Aluminium Spacer | 5+12A+5+12A+5 LOW-E | 1.275 | Aluminium Spacer | 1.71 |
| Argon + Aluminium Spacer | 5+12AR+5+12AR+5 LOW-E | 1.094 | Aluminium Spacer | 1.60 |
| Air +Warm edge spacer | 5+12A+5+12A+5 LOW-E | 1.275 | Warm edge spacer | 1.55 |
- Simulation resultsbased on 75 series aluminium windows( 39mm thermal break bridge strips)
| Glass Type | Glass Combination | Glass U value | Spacer Type | Windows U value |
|---|---|---|---|---|
| Air + Aluminium Spacer | 5+15A+5 +15+5LOW-E | 1.225 | Aluminium Spacer | 1.62 |
| Argon + Aluminium Spacer | 5+15AR+5 +15AR+5LOW-E | 1.080 | Aluminium Spacer | 1.52 |
| Air +Warm edge spacer | 5+15A+5 +15A+5LOW-E | 1.225 | Warm edge spacer | 1.43 |
With above tests,we got conclusions:
- For most conventional window types, choosing to fill the insulating glass with argon gas and replacing the aluminum spacers with warm-edge spacers can reduce the entire window U value by about 0.1-0.2W/m2K”.
- For double glazed unitswith 12mm spacer, the influence argon is better than using warm edge. For the triple glazed units, whether it is 12mm or 15mm spacer,warm edge spacer has much better thermal insulation performance than argon filled glass units. Especially for the 15mm,the reduction of U value is almost twice that of argon filled units.
The influence on windows&doors condensation
The condensation of doors and windows mainly depends on the temperature of the indoor surface and the indoor humidity. The higher the indoor surface temperature of doors and windows, the less likely it is to condense; the lower the indoor humidity, the less likely it is to condense.Today we will mainly talk about the temperature of the indoor surface of doors and windows.
glass condensation
For normal windows &doors with insulated glass,the lowest temperature happened on the glass edge area,while the temperature of the glass center,and aluminium frame inner surface are relatively higher,That’s the reason why glass condensation always happened on the glass edge.
Below is a simulation result based on the 60 series windows,the temperature of the windows& glass are very clear:
windows temperature difference-aluminium windows+insulated glass
The temperature at the glass edge is 0.9°C-2.7°C, and after filling the insulating glass with argon ,the temperature of the glass edge is 1.2°C-3.0°C, which is slightly higher. However, if you use Technoform warm edge spacers, the edge temperature of the glass can be increased to 4.1 ℃ -5.5 ℃, and the average temperature increase will reach about 3 ℃.
After being filled with argon, it doesn’t increase the thermal break performance of the windows&doors weakest part -glass edge , but increase the glass center that is already has the best performance,the glass edge which has high condensation risks is not increased. Therefore, for the control of door and window condensation, the effect of argon filling is not obvious.
The simulation result on 70 and 75 series aluminium windows are similar:
After using the warm edge, the thermal insulation performance of whole window is more balanced, and there is no obvious weak parts in the window. While using argon filling ,the balance of thermal insulation performance of each part of the window has been further broken. The result of argon filling is to further improve the thermal insulation performance of the central part of the glass, which has relatively good thermal insulation performance, while the edge of the glass with the weakest part has not been optimized.
The lifetime of argon gas and warm edge spacers
The argon will slowly leak over time, and this will affect the insulation performance of the insulating glass. Even if the units is well sealed, it cannot completely prevent the leakage of argon, but can only reduce the rate of argon leakage.
The warm edge spacer used has the same lifetime as the insulated glass,so we don’t have any worry about the performance decrease after years.
The price between argon gas and warm edge spacer
Argon filled insulated glass is about USD1.5/SQM higher than normal glass with air.Warm edge spacer price is about USD2/SQM higher, it depend on the warm edge spacer brands, the international brands Morn usually use are Technoform, Fenzi, Lisec and other brands.Some China manufacturers also have warm edge products but the performance is relatively poor.
Lisec insulating line -MORN-CHINA
But what we should be clear is:There’s not many methods to precisely detect the argon content,some glass manufacturers still using very lagging machines to fill the glass and cannot guarantee the actual content (usually 85-90% argon content is required).Some insulating glass production line manufacturers such as Bystronic,Lisec already has lines that can fill gas online and detect the content.
Here we recommend a machine to detect the argon content precisely.
Both argon and warm edge can increase the insulating glass thermal insulation performance,we suggest using them together, combing with high performance low-E coatings,the glass U value will be decreased to only 0.6-0.8W/M2.K.
Insulated glass manufacturer-MORN-CHINA-double glazed units
Morn is your turnkey insulated glass manufacturer and supplier in China,welcome contact us if you got any questions.
Download this article here:Argon filled insulating glass VS warm edge spacer insulating glass
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