Evaporative air coolers, also known as swamp coolers, differ from air conditioners in that they use water to cool air. Most effective in dry climates, evaporative coolers make your indoor space pleasant by circulating cool, humid air. They cost significantly less to install and operate than central air systems, although they produce much less cooling power. Portable evaporative coolers come in a range of sizes to fit a variety of spaces. They’re lightweight and require only water and electricity to function, which means you can put them to use in your home or office with ease.