U-Value confusion - trying to match what Vitro shows

[dave paulmeyer]

Hi all,

I am trying to reconcile manufacturers' published information vs. what I can create using the WINDOW program. Below is what I see from Vitro for Solarban70 on clear.

Below is what I see when trying to replicate with the WINDOW program. Can anyone help me with the U-Values shown above compared to the U-Factor below?

[Jonathan Spencer]

Couple of things:

1. You need to switch your units from metric to imperial

2. It looks like you defined the IG Height and Width as 25mm. This is very small and probably not what you want to do. NFRC uses a standard 1000mm x 1000mm size for COG calculations. If you change yours back to that, everything starts to make a lot more sense.

 Once you do those things, you'll get a U-Factor of ~0.285. This is close to the 0.28 that Vitro reported under "Winter Nighttime". (NFRC uses winter conditions for U-Factor calculation, so this all lines up nicely)