As Mom always says, there's no reason to pay to heat or cool the outside. The Thermal Leak Detector from Black & Decker spots energy leaks in her home. She just shines the light on a wall, sets the reference temperature, and then moves around the house, focusing on areas she thinks may be a problem. If the temperature changes by 1, 5, or 10 degrees, the light will change to red or blue to indicate a hot or cold spot. An included bonus booklet shows her ways to seal and insulate her home.
About $50, Black & Decker