Here's a link to my coop construction thread(s) where I discuss building the Chicken McMansion. https://www.backyardchickens.com/forum/viewtopic.php?id=283812 In the past month there have been 2 serious chicken coop fires in my area because of people using inappropriate heating in their backyard or garage coops. In both cases, infrared heating lamps were involved that set the bedding on fire. I've been looking at additional heating for my coop and decided I would put up a thread discussing how I am going about providing my girls additional heat without burning the coop down. In many cases, additional heating can make the difference between having a dry clean coop and a wet smelly mess. If the coop stays above freezing it gives the moisture that the chickens exhale and excrete a chance to evaporate. If the temperature stays warm enough, the ammonia chickens excrete will evaporate too, so there can be real benefits to keeping the coop warm, or at least, warmer than it would otherwise be. If you have reviewed my construction threads, you are aware that my coop is double walled and insulated with 1/1/2" of styrofoam. It has large windows that I can close tightly, or prop open as needed. I also have a number of 4" diameter soffit vents installed to ensure that even if the windows are closed for extremely inclement weather, there is still some air turnover. I do not close the door to the coop itself, because I secure the covered run instead. I do have a rag door over the opening to cut down on some of the drafts, but the door usually stays open. If really bad weather threatens, I have a door insert I can slide down to close the girls in. The coop is sufficient by itself without additional heating as long as the weather does not get too extreme. I have a remote thermometer in the coop that reads out in the living room. By themselves, our six hens usually keep the coop 6-7 degrees warmer than the outside temp with just their body heat. But before Thanksgiving, we had a cold snap here that dropped the temperatures down into the teens overnight, and although the girls stayed warm enough and dry, that thermal shock was enough that they all started holding their eggs. Production dropped off from 4.8 eggs a day to 1 egg on the 24th, and has barely averaged over 3 eggs a day since. Today is warmer and everyone laid today, but the lesson is that sometimes some additional heat is necessary. So my goal here is not to just try and keep the girls warmer, but to see if I can quantify this project by keeping their egg production up as well. If a chicken has to devote most of it's metabolism to keeping itself warm, it will devote less energy to making eggs and can stop laying all together. I should note here that I also have the coop wired, and I put the inside coop light on along with the run light around 4:00 in the afternoon until I close the girls in after 6:00. At 6:00 AM, I put the lights back on and turn them off after sunrise. (Yes, I have a timer for when I am not home, but I prefer doing it manually when I am). So! Here are some calculations and some definitions. A BTU (British Thermal Unit) is a measure of the heat required to raise the temperature of 1 pound of water by 1 degree F. It is used to calculate how much energy is needed to heat a volume of air in an enclosed room. There are different criteria that can affect the calculation, such as insulation, and the BTU calculator at Heatershop.com adjusts for these things automatically. For the purposes of heating a chicken coop, it is more than adequate. My coop is 20 square feet (5x4) with a slanted roof that averages about 4.5'. Multiply that out and it shows that the coop contains 90 cubic feet of volume. It is insulated but not that well; so in the BTU calculator I selected "Poor" insulation. I Googled a number of sources and found that a 4.5 pound brown-egg laying hen with an average body temperature of between 102 and 103 degrees F. puts off approximately 45 BTUs per Hour. With six layers on the roost, that means we have 270 BTUs an hour of heat in the coop already. I do not want to overheat, and I only want the heat on if it gets particularly cold. After a bit of research I have decided to use a flat panel heater inside the coop. I found a selection of heaters at http://www.shopthecoop.com/ and based on the above calculations, I have ordered their 150 Watt flat panel radiant heater. http://www.shopthecoop.com/mm5/merc...Code=STC&Product_Code=AIndus&Category_Code=He This heater puts out a gentle 150 watts/hour of heat without concentrating it on one spot. It's not too hot for the hens to touch it either. It's very safe and if properly installed can never be a fire hazard. 150 Watts is equal to approximately 512 BTUs per hour. The heater is controlled with a thermostatic plug that the same company sells: http://www.shopthecoop.com/mm5/merc...tore_Code=STC&Product_Code=E&Category_Code=He I like this because it turns on at 35 degrees and turns off at 45 degrees. The only time it will kick on is if the temperature in the coop heads toward freezing, and will kick back off at a reasonable temp without overheating. Using the calculations from above, and adding an additional 150 Watts or 512 BTU/Hr of heat, that would create a total of 783 BTUs/hour and per the BTU calculator would raise 90 cubic feet of air 6.53 degrees Farenheit. Now those calculations are based on my coop, and are approximate results under ideal conditions. In reality, the radiant heater will not heat the whole coop evenly, and the constant turnover of air that is always taking place will of course waste some of the heat. But to compensate, I plan to mount the heater on the inside of the coop cleanout door, which is directly below and behind the roost. It will be up away from the litter, and it mounts with velcro so you can remove it and clean it when needed. I think the girls will probably be fighting over who gets to sit in the middle.... One important consideration will be shielding the wiring from curious pecking, and I'll find some proper conduit to take care of that, and to place the thermostat at the proper height. I'll see what the manufacturer's instructions are once everything arrives. I will update this thread with my usual string of construction pictures as well. I hope that this gives some of you home coop designers an idea about how to proceed when trying to figure out how to heat the coop without burning down the house. That "red light" or infrared heat lamp is way too much and is a serious fire hazard. Many more chickens die from too much heat than from not enough, so do some figuring and calculate how much heat your coop really needs. Cheers, and thanks for reading this!