C-Therm sensors work just like your fingertips – they add a small amount of heat when they touch something, and instantly measure how much of that heat is reflected back.Even when the two items are identical in temperature, the metal feels colder. Why? Wood is not a good conductor of heat, so it is slow to absorb the heat from your hand. Metal has higher thermal effusivity, so the heat from your hand flows into the metal quickly – creating the sensation of it feeling cold.