The only 100% prevention of frostbite is to not expose the birds to sub freezing temps, frostbite won't happen if the temps are above freezing, but there are some preventative measure that can help and provide good results, especially in cold weather tolerant breeds...
With proper ventilation that keeps the humidity low (below 60%) you can prevent frostbite in mild to moderate freezing temps aka above about 0°F... High humidity drastically increases frostbite at these mild/moderate temps even at very mild freezing temps like 32°F frostbite can happen if the humidity is high... As the temps continue to fall into the sever freezing temps (F° negative numbers) the humidity also needs to continue to fall, aiming for below 40% humidity is a good reference point... But, as the temps continue to fall into the double digit negative F°, and one is attempting to use humidity to hold frostbite at bay, your success rate will start to fail as humidity plays less and less of a role at these extreme temps, and even with low humidity you run the risk of frostbite on any exposed skin just due to sheer cold...
If you have cold intolerant birds, sick birds, injured birds, or elderly birds that can drastically reduce the protection offered by lowering the humidity, and IMO the reality is SAFE heating might be a better choice...