I don't have any heat right now, but have been looking at diesel powered radiant heaters they just look like they would do a good job, but they are kind of pricey.
I worked in a shop with the gas overhead radiant tube heaters, they work great, the only thing that was annoying was the noise from the stainless steel reflectors forever expanding and contracting every time it warmed up and cooled down, it was really annoying.
