Cooling in a warming world

The planet is warming from greenhouse gas emissions, with increases in both peak and average temperatures. Consequently, the demand for cooling will intensify, driven by climate change as well as improving economic conditions. Cooling requirements for data centers and new technologies may also call for innovative solutions. Developing a wide array of cooling strategies will be vital for human comfort and prevention of heat-induced medical emergencies. A growing number of materials and methods are being designed to improve technologies, meet the temperature needs of data centers and other facilities, and reduce harmful emissions. Vapor compression systems supply much of the residential and industrial cooling infrastructure. These systems rely on compressing gases, many of which contribute to the greenhouse effect if released into the atmosphere. Finding replacements is a priority but requires balancing trade-offs between toxicity, flammability, and lower efficiency. An alternative approach involves the use of caloric materials—i.e., solids that effectively pump heat as they are electrically, magnetically, or mechanically manipulated. A completely different cooling strategy is to use materials that regulate heat in the form of infrared radiation. Passive radiative cooling materials take advantage of an atmosphere window for infrared radiation to eject heat into space. When deployed on rooftops, these systems can potentially cool buildings by a few degrees, even in the daytime. Along the same lines, textiles may be modified so that heat can more efficiently radiate through them, allowing people to be more comfortable at higher thermostat set points. As the planet warms, keeping cool without increasing greenhouse gas emissions will be a challenge, but new materials and technologies are poised to meet this goal.