When you run your dishwasher, the option to allow it to dry the dishes with forced hot air can save you the time and effort of wiping excess water from the dishes after air-drying. It can be convenient to push the "heated drying" cycle button when you start the machine. Air-drying your dishes instead can reduce your energy consumption and end the dishwasher cycle in a shorter time.
A dishwasher employs an electric heating element to create intensely heated air that it pumps through the dishwasher throughout the heated drying cycle. The small exhaust fan built into the top of the dishwasher door pulls the moisture from inside the machine and forces it out through the vents. The air-dry cycle eliminates the forced hot air and cycles room-temperature air through the dishwasher for the length of the cycle.
The heated drying cycle uses at least 15 percent more energy than air-drying. The increased energy usage increases your electric expenses over time. Air-drying reduces the energy consumption by eliminating the heating element from the process. The exhaust fan uses minimal energy compared to the draw of the heating element to produce the temperatures necessary for heated drying. The time involved to dry your dishes on an air-dry cycle is likely greater than a heated drying, depending on your climate. Humid environments will extend air-drying time.
Your dishes may dry quicker with heated drying compared to air drying, because the heat evaporates any residual water. Air drying may result in water spots or hazy film on the dishes as a result of water evaporating slowly and leaving residue behind. Drying the dishes by hand with a clean, soft towel can help eliminate the unsightly spots from air drying if you want to reduce your home energy use by eliminating the heated drying cycle.
As of 2011, all new dishwasher models include a no-heat or air-dry cycle along with the heated drying option. On some models, this is an "energy-saver" mode. If your older model dishwasher does not include this option, opening the dishwasher door slightly after the wash cycle completes can provide the same results.