From the days of having an open hearth in the center of a hut with a hole in the roof for ventilation to modern HVAC systems, humans have been finding ways to stay warm at home for thousands of years.
Understanding three kinds of heat transfer and why they matter for your home will help homeowners optimize home energy efficiency and maintain a comfortable living environment.
Conduction: Heat Travels Through a Solid
Conduction refers to heat traveling through a solid material. In the context of your home, conduction happens when heat moves through walls or floors. For instance, on a hot day, the sun heats up the exterior walls of your home. This heat then conducts through the wall materials into your home, raising the indoor temperature. Similarly, during winter, the heat inside your home can conduct through the walls and escape to the colder outside environment. Insulation reduces conductive heat transfer.
Convection: Heat Travels Through Air or Water
Convection involves heat traveling through a fluid, such as air or water. In your home, convection happens when warm air rises towards the ceiling, displacing the cooler air, which then descends. This process creates a cycle of air movement, distributing heat throughout the room.
Convection, as it turns out, is the ideal heat transfer for roasting marshmallows: rather than charring them by contact with a flame, patiently waiting for the heated air next to and around the fire to gently brown them is the way to go!
Radiation: Heat Travels via Electromagnetic Waves
Radiation involves heat traveling as invisible light (electromagnetic waves). When you feel the warmth of the sun on your skin, you’re feeling radiant heat. This type of heat transfer does not require a medium like solids or fluids.
For example, the heat from hot water pipes radiates outward, warming a room (that’s why they call it radiant heat). A fireplace or an efficient fireplace insert radiates heat outward, warming the surrounding area; the air warmed by radiant heat then spreads that heat via convection.
What About Induction?
You’ve probably heard about induction stoves and cooktops as a new, energy-efficient, and more environmentally friendly way of cooking. Induction, however, isn’t a form of heat transfer at all. Instead, induction causes the surrounding magnetic field to heat up an object. Unlike conduction, induction doesn’t require physical contact between the conductor and the object it heats.
The flow of electricity from a coil underneath a glass induction cooktop generates a magnetic field. That magnetic field causes a magnetic cookpot to generate its own electric current. The heat from that current then passes into the food in the pot. If a magnet doesn’t stick firmly to the bottom of your cookpot (as with aluminum or nonmagnetic stainless steel), the pot won’t work on an induction stove.
Understanding the three kinds of heat transfer can help you manage your home’s temperature effectively and efficiently. Whether you have gas forced air heat, radiant hot water heat, or a wood-burning stove or fireplace, you’ll know how heat moves in your home, helping you to identify ways to conserve energy while staying comfortable.
