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Hi everyone,

I am using OpenStudio and the object WindowMaterial:SimpleGlazingSystem

I have calculated the overall U value with WINDOW 7.7. Do i need to enter the U value with air films in that object or should I enter the U value without the air films ?

According to the EngineeringReference the U value includes the film but when i look at the Report: Zone Component Load Summary at the section Fenestration Conduction in Estimated Heating Peak Load Components the value is lower than expected by around 20%, when the values for infiltration and exterior wall conduction are closed to what expected.

I have noticed that the value in Fenestration Conduction varies with the wind speed value in the design day so i guess the issue comes from the air films. Or is there something else ?

Thanks for your help

Hi everyone,

I am using OpenStudio and the object WindowMaterial:SimpleGlazingSystem

I have calculated the overall U value with WINDOW 7.7. Do i need to enter the U value with air films in that object or should I enter the U value without the air films ?

According to the EngineeringReference the U value includes the film but when i look at the Report: Zone Component Load Summary at the section Fenestration Conduction in Estimated Heating Peak Load Components the value is lower than expected by around 20%, when the values for infiltration and exterior wall conduction are closed to what expected.

I have noticed that the value in Fenestration Conduction varies with the wind speed value in the design day so i guess the issue comes from the air films. Or is there something else ?

Thanks for your help