Radiant Heat Floors

After yesterdays storm it's pretty nice today.  Party sunny and 39 outside, so I have my heat turned down.  Normally I wear slippers all the time, but when I was changing I realized the floor in my closet was really COLD.  So I went and got out my handy dandy new toy, an infrared thermometer and checked floor temps around the house.  At the back of my closet it's 58.  In the back hallway it's down to 56.  Rather chilly on my bare feet.  But along the front of the house, where the sun is shining on the floor, it runs 80 to 84.  That's a very nice heat gain that warms up the thermal mass of the concrete.