This ‘Cold Tube’ can beat the summer heat without relying on air conditioning

Many people beat the summer heat by cranking the air conditioning. However, air conditioners guzzle power and emit millions of tons of carbon dioxide every day. They are also not always good for your health – constant exposure to central A / C can increase the risks for cardiovascular germs and breathing problems.

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

They call it the Cold Tube, and they have shown that it works.

“Air conditioners work by cooling and humidifying the air around us – an expensive and not particularly environmentally friendly proposition,” explains project leader Adam Rysanek, assistant professor of environmental systems at UBC’s School of Architecture and Landscape Architecture, whose work focuses on future energy systems and green buildings. “The cold tube works by absorbing the heat that is directly emitted by radiation from a person without cooling the air that runs over their skin. This provides a significant amount of energy savings.”

The Cold Tube is a system of rectangular walls or ceiling panels that are kept cold by cold water circulating inside. Since heat naturally moves by irradiation from a hotter surface to a colder surface, when a person stands next to or below the panel, their body heat radiates to the colder panel. This causes a sensation of cooling as cold air flows over the body, even when the air temperature is quite high.

Although these types of cooling panels have been used for decades in the construction industry, what makes the Cold Tube unique is that it does not need to be combined with a deshumidification system. Just as a cold glass of lemonade would condense water on a hot summer day, cooling walls and ceilings in buildings would also condense water without first drying out the air around the panels. The researchers behind the cold tube formed an airtight, moisture-repellent membrane to enclose the cool panels to prevent condensation from forming while still being able to travel through radiation.

Cool it outside

The team built an outdoor demonstration unit in Singapore last year, inviting 55 members of the public to visit and give feedback. When the system was running, most participants reported being ‘cool’ as ‘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 fuheading the air around them, we can look at cutting up to 50 percent of the typical energy consumption of air conditioning in applied spaces,” said Eric Teitelbaum, a senior engineer at AIL Research who oversaw the demonstration project while I was working at the Singapore-ETH Center.

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

In addition to energy savings, technologies such as the Cold Tube have a great future, says project co-lead Forrest Meggers, an assistant professor at Princeton’s School of Architecture and the Andlinger Center for Energy and the Environment.

“Because the cold tube operates independently of indoor air temperature and humidity, keeping windows open during our increasingly hot summers while still feeling comfortable becomes possible,” Meggers said. “The Cold Tube can provide relief in a variety of regions, from North American homes and offices that currently rely on standard HVAC systems to emerging economies that need an upcoming cooling in the next half century.”

Keep indoor air healthy during the pandemic

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

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

The team is currently using the data collected in Singapore to update their projections of the effectiveness of the Cold Tube in indoor spaces worldwide. They plan to demonstrate a 20 commercially viable version of the technology.

The Cold Tube is described in a paper published today in the publication PNAS.