ways -options to heat multiple igloo's outdoor

creger.robert said:

fire marshall wont allow propane heaters in igloo here

Oh great. Well, he or she might have a point. However, let us consider your predicament, then. You want to heat up an outdoor igloo. That means you need a heat source, and preferably a radiant one so you are heating your patrons, not the great out of doors. That means you either have fire (or catalytic heat from fuel) or electricity. Your fire marshal will not allow fire or catalytic heat.

Or will he or she allow fire? Would he or she permit a small fire pit in each igloo? Might be worth an enquiry, as logic is not necessarily a strong point...something like this: https://www.amazon.com/BALI-OUTDOORS-Propane-Rectangular-Tabletop/dp/B07JFSKSSF/ref=asc_df_B07JFSKSSF?tag=bingshoppinga-20&linkCode=df0&hvadid=80058245652742&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4583657822603837&psc=1?

Otherwise... looks like electric radiant is what you're stuck with.