Air conditioners guzzle power and spew out millions of tons of carbon dioxide daily and they are not always healthy — constant exposure to central A/C can increase risks of recirculating germs and cause breathing problems. Air conditioners work by cooling down and dehumidifying the air — an expensive and not particularly environmentally friendly proposition. To address these problems, researchers developed the Cold Tube, which works by absorbing the heat directly emitted by radiation from a person without having to cool the air passing over their skin. This achieves a significant amount of energy savings.
The Cold Tube is a system of rectangular wall or ceiling panels kept cold by chilled water circulating within them. Since heat naturally moves by radiation from a hotter surface to a colder surface, when a person stands beside or under the panel, their body heat radiates towards the colder panel. This creates a sensation of cooling like cold air flowing over the body even if the air temperature is quite high.
Although these types of cooling panels have been used in the building industry for several decades, Cold Tube does not need to be combined with a dehumidification system. Just as a cold glass of lemonade would condense water on a hot summer day, cooling down walls and ceilings in buildings would also condense water without first drying out the air around the panels. The researchers devised an airtight, humidity-repelling membrane to encase the chilled panels to prevent condensation from forming while still allowing radiation to travel through. In an outdoor demonstration unit, most participants reported feeling “cool” or “comfortable,” despite an average air temperature of 86 °F. The panels also stayed dry due to the special membrane.
Because the Cold Tube can make people feel cool without dehumidifying the air around them, the Cold Tube uses only 50 percent of typical air conditioning energy consumption in applicable spaces. Beyond the energy savings, technologies like the Cold Tube — which works independently of indoor air temperature and humidity — enable windows to be kept open in increasingly hot summers while still feeling comfortable. In addition, the Cold Tube can offer relief in different regions, from North American homes and offices that currently rely on standard HVAC systems, to developing economies that foresee significant need for cooling.