My bathroom is tucked into the southwest corner of my house, nestled against two exterior walls. I hadn't really considered the significance of exterior walls until I became a homeowner and had to ponder the placement of plumbing to avoid frozen pipes. Exterior walls increase exposure to the elements. In a sweet old home facing a nearly record cold winter, that equals a very cold bathroom. Well, it would have, were it not for the radiant heat underneath my aluminum tiles.
According to the Department of Energy, radiant floor heating is "more efficient than baseboard heating and usually more efficient than forced-air heating because no energy is lost through ducts." Radiant heat usually involves the use of electric mats or a series of pipes that circulate heated water. My house wouldn't easily allow for a liquid system, but it's great for new construction. Ian's incredible builder, Dustin, installed a Suntouch mat just under my aluminum tile flooring.
Electricity isn't cheap, so I have the mat programmed (using the programmable thermostat seen here) to warm up just before I wake. The floor is charged during off-peak hours and then stays warm for most of the day. Because I am not heating my floor during the times when electricity rates are at their peak, I save on energy costs while enjoying an indulgently warm bathroom.