So far so good. I would say that it does a decent job in preventing drafts. My concern was moisture buildup, as it might be preventing the little ventilation there is. At times there was condensation between the coop and the blanket, but nothing on the inside of the coop. Please understand that this blanket does not generate heat....the chickens do. If four chickens (maximum I would put in the Eglu) spend the night there, that is the equivalent of a 40 watt bulb. Temperature differences between the coop and the outside have been at best a few degrees Fahrenheit.