Radiant Cooling and Heating Panels

The challenge for radiant cooling has always been two-fold: (1) develop a panel that operates in humid environments without condensing water, and (2) achieve the required performance with a panel that can be sold at a price the market will accept.

     As illustrated in first illustration at the right, our solution is a radiant cooling panel that physically isolates the panel’s cold surface from direct contact with ambient air without significantly interfering with the exchange of infrared radiation (i.e., radiation emitted by a warm body).  Similar to concepts proposed as early as 1961, our panels use thin, IR-transparent membranes to create buffers of stagnant air over their cold surfaces that insulate the cold surfaces from heat exchange with ambient.  Since ambient air is neither cooled nor dehumidified, very little power is needed to keep the cold surface functioning as a low-temperature sink for thermal radiation.

     Our solution advances prior art by applying the membranes as a twin-film module that is a field serviceable, easily replaced, low-cost element—a critical patent-pending feature when the membranes are relatively fragile 50-micron films.  Furthermore, by making the cold surfaces transparent or translucent—a second patent-pending feature that turns the panel into a chilled window—our solution expands radiant cooling into many outdoor public spaces where sheltered occupants will want to view the outdoors, e.g., a parent in a park gazebo watching a child play, a person waiting for a bus, etc.

     As reported almost daily during the summer, the outdoors in large regions of the world is becoming almost unlivable.  This threat applies equally to people and animals.  The meat, dairy and egg industries are all impacted by extreme heat.  Outdoor cooling solutions are needed to protect animal welfare.  Based on discussions we have had with farmers and engineers working in these industries, a low-cost, low-power radiant cooling panel with acceptable O&M characteristics could reduce heat-related losses in these industries, losses that are now over $500 million per year globally and growing.

     Extreme heat is also a growing danger for outdoor workers.  As noted on the OSHA website, millions of U.S. workers are exposed to heat stress in their workplaces. Although illness from exposure to heat is preventable, every year, thousands become sick from occupational heat exposure that in some cases is fatal.

     Affordable radiant cooling with low power demand would impact far greater global populations than just farm animals and outdoor workers.  We anticipate applications that provide:

• essential social benefits, e.g., radiant cooled bus stops, park gazebos and other public pavilions

• enhanced worker and athlete performance, e.g.,  heat relief stations for outdoor workers; radiantly cooled benches and dugouts for athletes

• expanded use of the outdoors, e.g., actively cooled shade for patios and al fresco dining for restaurant.​

An important demonstration of the benefits provided by radiant cooling was the 2020 demonstration executed by our lead engineer in Singapore of the Cold Tube--the outdoor pavilion shown in the second and third figures on the right, whose only source of cooling was the chilled-water panels that were its walls and ceiling. 

     In the last year (2024), we designed, built and operated two fully functional prototypes of radiant cooling panels.  For the panel shown in the third figure on the left, the cold surface is a flat, water-cooled, transparent plastic heat exchanger, and for the panel shown in the fourth figure on the left, the cold surface is the flat evaporator of a solar-powered heat pump. Both of these panels used twin-wall membrane assemblies to prevent condensation on the cold plate.

    Our most recent work focuses on converting a radiant cooling panel into a low-cost commodity product.  The fourth and fifth figures on the right show both the twin membrane face and underlying evaporator for a radiant cooling/heating panel that is fabricated from a structural foam.  With this design, we dramatically reduce the cost to manufacture and the weight of our panels compared to prior construction methods.

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