Well, this year I was going to use whole straw bales for my insulating my new 16X16 coop we are building (just a few more days!) but because of the fact that we are already about $1000 into making it the best coop ever, when I calculated the amount I needed and realized it was $400 worth, we just decided to use wood. However, something great I found at the feed store was ceramic reptile heaters. They are little black things that screw into a regular heat lamp hood, and range from 50-150 watts. This was especially great for us because we live "off the grid" and have to use a generator, battery, and solar system setup instead of using the regular power grid (we are too far into the woods for it to reach us) and we can't run too many things overnight or it will drain the batteries.