I put a 16x8x1.5 piece of styrofoam (R6) firmly against the wall of my un-insulated chicken coop. What you are looking at below are photos from a thermal imaging camera. You may say that R6 is not enough, however a high grade house window is close to R4. Insulation just doesn't do anything with the necessary venting. In the first photo Sp4 is where the styrofoam is at (you can barely see the outline), Sp2 is just right of the styrofoam, 0.1°F (1/10th°) difference. Sp3 is the run door. If this is not obvious, this is the chicken door, you can see the heat seeping out, there are no seals on the door. Just to the right is the people door, which has a seal. You can see there is a small leak toward the top of the photo. Here is a couple of my chickens, look how well their feathers insulate their body.