hard coat vs soft coat

Today i will talk again about low-e layers.

Where put we this films?

As we already said, it depends on the type: hard or soft.

As first we will define the surfaces which we will refer to.
The part of the double glass windows toward the outside is called Surface #1 and #2 #3 #4 follow, with #4 as the one facing the inside of the building.
Obviously if it is triple glass we have #5 and #6

We begin defining invernal condition:

Using as coating:  
Cardinal LoE 366 : low-e soft coat 4.8 mm
Pilkington Energy AdvantageTM : low-e hard coat 4.7 mm
then:
Pilkington Optifloat Clear : clear glass 4.7 mm
Internal chamber 12 mm with a mix of Air (10%) and Argon (90%)

Analizing U in invernal regime the singles surfaces temperatures are:

We notice that with the external hard coat we have not substantial improvements but we obtain a lower value of U with an internal coating, and so with the temperature.

The soft coat do not influence U and the temperatures, which are definitively higher than the other cases. But soft coat will influence the tripler glass behaviour.

Hybrid solution with soft and hard coats:

From this data we conclude that the hybrid solution soft#2 / hard#4 seems to be the more interesting, and so the Dual Low-E of Pilkington has been developed. But even this has some weaknesses.
Which ones in the next post.