WFO - outdoor, loosing heat

Hello everyone !

Before i start i would like to say that i'm not professional baker. I work as a chef (time to time at wfo bakery and baking every day at home for family).

I'm planning to build a WFO at my garage but i don't have mch space to fit there big oven. I thought maybe i could build the oven outside and load breads from the garage as i tried to show you on the picture.

So here comes my question. Because is east Europe winter is really cold. Have you got any idea how quick heat can be lost and what solution is the best to prevent this. I will say the winter can be between -20C to - 30C max.

At this point guys, your opinion will be crucial for me.

Thanks a lot !