I dug around looking for info on the montebello. There are specs about efficiency in the product information (AFU number or something like that) if thats the type of efficiency you mean. If you mean as a window to the great outdoors as you plan to use, its wind tested but again to find the document that gives the results you have to do a bit of digging. My understanding is tho it passes a minimum rating for air infiltration as a window. I wouldn't expect energy star type of performance however.

Heres a link for a PDF that seemingly is intended for Lennox dealers, I found it gave the most specific information regarding air tightness testing. Hope it helps, sorry didn't see this sooner..don't frequent the fireplaces section much.

I have spec'd this unit myself but I can't speak to personal use and probably won't be able to until next winter (spring completion)

Here is a link that might be useful: Montebello See Through Launch kit document

This post was edited by niteshadepromises on Sun, Jan 12, 14 at 6:15

niteshadepromises, Did you end up getting the Montebello See Through as an indoor/outdoor application?

How do you like it? We are putting an indoor/outdoor fireplace in our new build. Thanks for your feedback, or anyone else that has real life experience with an indoor/outdoor gas fireplace.