The ‘quantum campfire’: warmth that moves with you
Conventional patio heaters provide radiant warmth within a fixed area. Targeted systems explore how that warmth could follow occupants.
A patio heater can make a cold evening more comfortable, but its warmth reaches a fixed area. The idea behind a ‘quantum campfire’ takes radiant heating a step further: tracking where people are and directing warmth towards them as they move.
For terraces, covered outdoor spaces and large interiors with few occupants, the appeal is straightforward. Heating could respond to the people using a space, concentrating its output where warmth is needed rather than spreading it across empty areas.
A ‘quantum campfire’ describes the idea of targeted infrared heating that follows people as they move. The phrase is a metaphor, rather than a scientific term or a particular product. The underlying approach combines established infrared heating with sensors, controls and steerable beams, creating something closer to a spotlight of warmth. Understanding it starts with the way a fire can warm your skin while the surrounding air remains cold.
How infrared heating warms people and objects
A fire transfers energy to its surroundings in several ways. Hot gases rise through convection, while radiation travels outwards and warms surfaces that absorb it. This is why the side of your body facing a fire can feel warm even when the air around you is cold.
Infrared heaters make use of that second process. Their emitting elements produce electromagnetic radiation beyond the red end of the visible spectrum, transferring energy to skin, clothing and other absorbing surfaces. Furniture and floors can warm up too; human skin is not the radiation’s exclusive target.
The same broad heating principle is used in infrared saunas and some heated yoga and Pilates studios, examples discussed in National Geographic’s reporting on infrared heat. These offer a familiar reference point for direct radiant warmth, although their purpose and operating conditions differ from a system designed to follow people across a room.
Conventional gas-fired patio heaters also produce infrared radiation. Their effectiveness outdoors does not depend solely on warming the air, as is sometimes claimed. A responsive system builds on established radiant heating by changing where its output is directed as occupants move.
How motion tracking can make infrared warmth follow you
A historical example comes from the Massachusetts Institute of Technology (MIT), whose Senseable City Lab presented its Local Warming installation at the Venice Architecture Biennale in 2014. It combined motorised infrared heaters with WiTrack, a wireless tracking system developed by a team led by MIT professor Dina Katabi. MIT’s Computer Science and Artificial Intelligence Laboratory describes how it supplied occupants’ positions and trajectories to a grid of heating elements near the ceiling.
Each element combined a motor, an infrared bulb, a mirror and other optics to form a focused beam. The motor changed its direction, allowing warmth to be aimed at a person a few metres away. Position updates connected the tracking system to the moving heating hardware.
Sensing and radiation perform separate jobs here. The tracker determines where someone is; the optical components shape the beam, and the motor points it towards them. The radiation itself has no ability to identify a person or choose a destination.
Together, those components extend the idea of a fixed heated zone. A conventional radiant heater serves the area within its coverage, whereas a steerable arrangement can change that coverage in response to movement.
Why radiant heating can keep people warm in cooler air
The reason this can work is that a thermostat captures only part of what determines thermal comfort. We exchange radiant energy with surrounding surfaces as well as losing or gaining heat through contact with air. Clothing and activity also influence how warm we feel.
Additional radiation from a heater can therefore make a cooler space comfortable. ASHRAE, the professional society that publishes engineering guidance on heating and cooling, explains that radiant systems can provide comfort at lower air temperatures, reducing heat losses associated with ventilation and the building envelope.
This does not mean the air remains completely unaffected. Once radiation warms a floor, wall or piece of furniture, that surface can transfer heat to adjacent air. The important difference is that the initial delivery of energy does not require heating and circulating a large volume of air first.
Placement remains important because the radiation needs a clear path to its intended target. Indoors, reflectors and mounting positions help determine where warmth lands; outdoors, the same considerations apply alongside wind, which continues to draw heat from the body even while it receives radiant energy.
Where targeted infrared heating could save energy
The most intuitive applications are places where people occupy only a small part of the available space. In describing their 2014 prototype, MIT’s researchers suggested exterior and semi-covered areas, large lobbies and industrial lofts as potential settings for responsive heating.
A terrace with only a few occupied tables illustrates the opportunity. Broad heating coverage may send energy towards empty seats and surrounding surfaces, while tracking and steering could concentrate more of the output where customers are sitting. In a large entrance hall, the relevant locations might change as people arrive, wait and leave.
The potential saving comes from reducing unnecessary coverage and operating time. Its size depends on occupancy, the equipment’s controls and the heating system being replaced; directing beams towards people does not by itself establish a particular reduction in electricity use. A lower-carbon electricity supply can further reduce emissions associated with operating an electric system.
The practical appeal is a closer relationship between comfort and presence. For a café customer, that could mean being able to move a chair without immediately leaving the warmth behind. For a building operator, it offers a way to think about heating around where people actually spend time, bringing an old experience of radiant warmth into a more responsive environment.
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