Air conditioner suck up a lot of energy in hotter months by dumping heat from inside buildings to the outside, ironically heating up neighbouring locations. A Stanford research team developed a more efficient cooling system for AC by pre-cooling water that circulates through the machine. It cools water during the night by essentially beaming the eat out into space, which surprisingly uses less energy than current solutions.
For the new fluid-cooling system, the researchers made radiative panels that were each one-third of a square meter in area; they attached the panels to an aluminum heat exchanger plate with copper pipes embedded in it. The setup was enclosed in an acrylic box covered with a plastic sheet.
The team tested it on a rootop on the Stanford campus. Over three days of testing, they found that water temperatures went down by between 3- and 5 °C. The only electricity it requires is what’s needed to pump water through the copper pipes. Water that flowed more slowly was cooled more.