A cool way to save money

When the summer heat has you sweating, it’s just nature’s way of keeping your body cool through evaporation. Of course, many of us prefer to retreat to the air-conditioned indoors — but if your home’s AC unit can’t keep up, maybe it needs to start sweating too.

Mistbox does exactly that. The smart add-on system sprays a fine mist of water droplets around a central AC unit, cooling the air near the condenser coils so they can more efficiently transfer heat from within the house to the outside air.

Smart Evaporative AC Booster: Mistbox

The system attaches to the outside of a condenser and consists of a screw-mounted control box, several mister bars that hang off the sides of the AC, and a water line that hooks up to a garden spigot.

The control box contains several sensors to detect when the AC could use an efficiency boost. First is an adjustable temperature threshold, which by default only lets the misters activate when it’s above 80 F outside. Then there’s both a noise sensor that listens for fan sounds, and an electromagnetic sensor that detects how much electricity the unit is running. These combine to determine how hard the AC is working, and when it cycles into high gear, the misters kick on.

Mistbox is powered by an internal battery that recharges from a small solar panel. It connects to a home’s Wi-Fi network for additional features like tracking electricity savings and reminding users to change the filter each year (replacements can be ordered right in the app).

Smart Evaporative AC Booster: Mistbox
Smart Evaporative AC Booster

Beta testers who are now in their third season with Mistbox say their ACs run far fewer hours and are more effective at cooling the house, saving hundreds of dollars in electricity costs each season — more than enough to offset the misters’ minimal water use. The systems also qualifies for a 30 percent Federal Green Tax Credit.

Mistbox raised more than $160,000 on Kickstarter last December, and this month began shipping to backers as well as taking general orders.

Learn more in the video below.

Related: Smart Home Retrofits, Tado Cooling, Ambi Climate


  • Solar Powered and built-in water filter
  • 802.11 b/g/n @ 2.4GHz w/ Android and Iphone apps
  • Expected savings of 20-40% on cooling costs