I imagine that would be pretty difficult to do in a chicken coop. These are barns made out of corrugated steel and generally aren’t even remotely air tight. You will, ultimately, need about 10x the nitrogen you would otherwise need, and that’s if it even works.
So a special coop would need to be built for this purpose.
Chicken farmers are some of the poorest farmers in the country. They generally don’t have the means to build a special kill shed to humanely euthanize their flock. They barely have the means to keep up with Tyson and Perdue’s ridiculous bullshit.
So, while I agree, heat stroke is a fucking awful way to kill these animals, the issue isn’t just “there’s a humane method bro, just build a kill house bro”
The issue is, we are paying FAR too little for chicken, and most meat, honestly.