This “ cold tube ” can beat the summer heat without relying on air conditioning

Many people fight the summer heat by turning on the air conditioning. However, air conditioners take power and release millions of tons of carbon dioxide per day. They’re also not always good for you – constant exposure to central air conditioning can increase the chances of germs recirculating and causing breathing problems.

There is a better alternative, according to a team of researchers from the University of British Columbia, Princeton University, University of California, Berkeley and the Singapore-ETH Center.

They call it the cold tube, and they’ve shown it to work.

“Air conditioners work by cooling and dehumidifying the air around us – an expensive proposition and not particularly environmentally friendly,” says Adam Rysanek, co-director of the project, assistant professor of environmental systems at the school of Architecture and Landscape Architecture at UBC, whose work focuses on future energy systems and green buildings. “The Cold Tube works by absorbing heat directly emitted by a person’s radiation without having to cool the air passing over their skin. This results in significant energy savings.”

The Cold Tube is a system of rectangular wall or ceiling panels that are kept cold by the ice water circulating through them. Since heat naturally moves by radiation from a warmer surface to a cooler surface, when a person stands next to or under the panel, their body heat radiates to the cooler panel. It creates a cooling sensation like cold air flowing over the body even though the air temperature is quite high.

Although these types of cooling panels have been used in the construction industry for several decades, what makes the Cold Tube unique is that it 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 the walls and ceilings of buildings would also condense the water without first drying out the air around the panels. The researchers behind the Cold Tube designed an airtight, moisture-repellent membrane to wrap around the cooled panels to prevent condensation from forming while still allowing radiation to pass through.

Refresh the exterior

The team built an outdoor demonstration unit last year in Singapore, inviting 55 members of the public to visit and provide commentary. When the system was in operation, most participants reported feeling “cool” or “comfortable” despite an average air temperature of 30 degrees Celsius (86 degrees Fahrenheit). The panels also remained dry, thanks to the special membrane.

“Because the cold tube can make people feel cool without dehumidifying the air around them, we can consider reducing the typical energy consumption of air conditioning in the affected spaces by up to 50%,” he said. said Eric Teitelbaum, senior engineer at AIL Research, who oversaw the demonstration project while working at the Singapore-ETH Center.

“This design is ready. It can obviously be used in many outdoor spaces – think outdoor summer fairs, concerts, bus stops and public markets. But the mission is to adapt the design to the spaces. interiors that would typically use central air conditioning, “he added.

Beyond energy savings, technologies like Cold Tube have a bright future, says Forrest Meggers, co-lead of the project, assistant professor at the Princeton School of Architecture and the Andlinger Center for Energy and the Environment.

“Because the cold tube works regardless of the temperature and humidity of the indoor air, it becomes possible to keep the windows open during our increasingly hot summers while still feeling comfortable,” said Meggers. “The Cold Tube can provide relief in different regions, from North American homes and offices that currently depend on standard HVAC systems, to developing economies that anticipate a significant cooling need in the next half century.”

Keeping indoor air healthy during the pandemic

There is another aspect of the Cold Tube that is particularly relevant in 2020, says Adam Rysanek.

“The COVID-19 pandemic has raised public awareness of the sensitivity of our health to the quality of the air we breathe indoors. Specifically, we know that some of the safest spaces in this ‘new normal’ are the outdoor spaces, ”said Rysanek. “As the climate changes and air conditioning becomes more of a global necessity than a luxury, we must prepare for alternatives that are not only better for the environment, but also for our health. The idea of ​​staying cool with the windows open is much more valuable today than it was six months ago. “

The team is currently using data collected in Singapore to update their projections of the effectiveness of the Cold Tube in indoor spaces around the world. They plan to demonstrate a commercially viable version of the technology by 2022.

The cold tube is described in an article published today in PNAS.