Even when you ignore the greenhouse effect related to the release of HFCs (hydrofluorocarbons), the impact of residential climate control on the environment is substantial. HVAC (Heating, Ventilation, and Air Conditioning) systems account for 6% of all residential energy use in the United States, and that results in 100 million tons of carbon dioxide being released in the atmosphere each year. That’s hardly a trivial amount, and is a big cost just to stay comfortable. That’s why engineers from the University of California San Diego have developed a wearable heating and cooling patch that can act as a personal thermostat.
Even if you live in a modestly-sized one bedroom apartment, your air conditioner is still likely cooling at least 600 square feet of space. But you’re only ever occupying a few square feet of that at any given time. That is, of course, a lot of waste — there’s no sense in cooling hundreds of square feet that aren’t being used. The idea behind this wearable device is that it cools or warms your skin directly to keep you comfortable while saving energy.
Personal climate control devices do exist, but they are generally use fans and aren’t often wearable. This device works through thermoelectric heat transfer. It’s made up of small pieces of themoelectric bismuth telluride alloys sandwiched between two layers of flexible elastomer sheets embedded with aluminum nitride powder to help with thermal conductivity. By passing current through one way, the skin is cooled. By pushing current through the other way, the skin is warmed.
It’s powered by a flexible matrix of coin cell batteries, so it’s comfortable to wear. In testing, it could maintain a set skin temperature even when the ambient temperature varied by more than 25 degrees Fahrenheit. This was done with an armband, but the technology could be expanded and integrated into clothing to form an entire vest that consumes 80 watts of power, at most. That’s orders of magnitude less than a traditional HVAC system, which saves money and ultimately helps the environment.