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Drive-Thru Windows

fungineer

Registered User
Joined
Feb 12, 2021
Messages
17
Location
Wauwatosa, WI
Our firm does handles a few clients in that use Drive-thru or Quick-serve windows. Typically most of our clients like the "Ready Access" brand for various reasons. However, the specific brand doesn't matter here.

How are you able to find a window that passes the IECC code? For our WI projects, which use 2015 IECC, the Operable fenestrations required a U-factor of 0.43 for our climate zone. Unless I treat the Drive-through as an "entrance" (U max = 0.77) It's really hard to find any suppliers that can meet that u-factor. I know CA requires air curtians, but that's a secondary provision.

Particularly when updating an existing building, where using prescriptive values makes sense (or a balanced method - such as Comcheck), rather than a whole-building analysis this becomes very problematic. Any thoughts, or am I missing something?
 

Jamie Holmes

Registered User
Joined
Mar 7, 2018
Messages
16
Location
Oregon
I'm not an expert, but I have taken these type of windows in sections and get them to pass COM-check as well as the California requirements without the air curtain. In COM-check, the fixed window portion most closely resembles a storefront constructed glazing and the operable portion, which is usually a small portion is >50% glazed door. Select non-swinging for operation. I haven't had any of the multiple states I deal with balk at it.
 
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