i have a 40,000 BTU "infrared" propane heater installed in a VERY airtight, insulated shop and, i can tell from experience, your advice is poor advice.
"infrared" heaters DO NOT heat the items in the room, they heat the air which in turn heat the items. i go into a nice long factual debate with you on this one if you wish.
Sorry I twisted your undies all up. If you read my post I stated that an "infrared heater pointed at you may work".
He didn't ask how to heat the whole shop, if I read the original post correctly he was asking about staying warm in a poorly insulated shop.
My experience with infrared heaters is that they will keep the object (person) they are pointed at warm. Are you saying this is incorrect?