I don't have a bearded dragon yet but I figured I might as well prepare for the worst thing that could happen in its enclosure, the heat light going out in the middle of winter. I don't know how well grout with sand added for traction would hold onto the heat. I have an infrared temperature gun already. I mean, sand can get very hot but how long does it stay hot? And what about the grout? I mean, if they don't hold onto heat well, then if the heat light goes out in the middle of winter, I would be the warmest thing around for my eventual bearded dragon. But I have no idea how much skin temperature differs from body temperature in the warmest areas(chest and abdomen). So anyway, what should I do if the heat light goes out in the middle of winter(besides get a new bulb) to keep my eventual bearded dragon from getting ill from low temperature?