Hmm, well, I always love a good discussion. It would be my uneducated opinion that evaporative cooling would exceed radiant heat gain in MOST cases. I would say at 10% relative humidity and a 30mph wind, I would take evaporative as the winner everytime. 90% relative humidity and no wind would probably tip the scales the other way.

The variables are so great I'm not sure how it could be tested in a real pool. I will soon contact my engineer friend who deals with these issues daily and post back if he offers something interesting.

Dave S.