Drive-Thru Windows

[fungineer]

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]

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.

 

[cherylh]

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?

I have this same question, and 4 years later I'm also having trouble finding a manufacturer that meets IECC requirements. Did you ever find a solution to this?

 

[Penguin87]

I hate the IECC and try to use ASHRAE and Comcheck as much as possible. It allows tradeoff methods which is what I typically pursue - add more insulation in the roof to offset other requirements. A small window that underperforms can be easily offset by a little bit of extra cheap insulation somewhere else.

A TI could be a different story, however it looks as if Ready Access provides low-E glazing options.

 

[cherylh]

I hate the IECC and try to use ASHRAE and Comcheck as much as possible. It allows tradeoff methods which is what I typically pursue - add more insulation in the roof to offset other requirements. A small window that underperforms can be easily offset by a little bit of extra cheap insulation somewhere else.

A TI could be a different story, however it looks as if Ready Access provides low-E glazing options.

I agree about Comcheck but my understanding is that you can't use that for Alterations. Ready Access does offer low-e glazing and they even list performance ratings (unlike some other manufacturers). But even with low-e glass the U-value is listed as 0.73, and the project I'm working on in MA requires 0.45

 

[Penguin87]

Question - if the code requires a certain type of product performance, which does not exist, how does one comply with the code?

 

[steveray]

Question - if the code requires a certain type of product performance, which does not exist, how does one comply with the code?

Alternative means and methods....