What type of heating is commonly used to warm doorways in work areas?

Radiant spot heating is commonly used to warm doorways in work areas because it effectively targets specific areas rather than heating an entire space. This type of heating utilizes infrared radiation to warm objects and people directly, which can be particularly beneficial in high-traffic zones like doorways where quick heat-up times and localized warmth are desired.

The advantage of radiant spot heating lies in its efficiency; since it does not rely on heating the air in the room, it can maintain comfort in localized areas without wasting energy on the surrounding environment. This is especially useful in work areas where doors frequently open, allowing cold air to enter and where constant heating of the entire space would be inefficient.

While convection heating warms the air, it may not be fast enough to counteract drafts as quickly or effectively as radiant spot heating. Heat pumps are more appropriate for overall space heating or cooling rather than for specific areas like doorways, and while infrared heating does make use of radiant principles, radiant spot heating is more specifically designed for targeted applications like entrances in work environments.