[phgn]

Well, what does "energetic output" mean? If I understand the core point of the article correctly, radiant heat only heats the surface of objects not the air, so it will require less heat for the same effect. I don't how to put a number on this.

I think the energy.gov article you mentioned primarily talks about heat leaking outside:

> An AFUE of 90% means that 90% of the energy in the fuel becomes heat for the home and the other 10% escapes up the chimney and elsewhere.