Much misleading information is published about air conditioners being more efficient and an energy savings over using a swamp cooler. An air conditioner typically does have a higher efficiency rated motor and compressor to save as much energy as possible. The motors are more efficient than the ones commonly used in swamp coolers. However, we really have to look deeper to understand what the true energy difference is between the two.
Swamp coolers, sometimes called evaporator coolers, take advantage of ambient energy (heat) in order to work. As water pass through the cooler it evaporates, which means it changes phases from a liquid to a gas. This requires energy in order to make the phase change and the energy in this case is coming from heat in the surrounding air. This process makes the air cooler and that is the basic principle behind a evaporator cooler.
Air conditioning units use a compressor to compress refrigerants. What happens is you have a certain amount of energy (heat) in one ounce of liquid, you then compress that down into a smaller area. The liquid still has the same amount of energy, it’s just in a tighter space, making it hotter. It then flows the liquid through a radiator to cool it down, losing all the energy. Once done it uncompress, with the less energy for its mass, it is now cooler than ambient temperature. It sends the cool liquid through a heat exchanger in your central blower and the cool air blows into your home.
Lets breakdown the energy usage of each one. A standard air conditioning unit uses 4400 watts to operate its fan and compressor, plus you also have to add the central blower adding another 600 watts, for a grand total of 5000 watts. The swamp cooler has a motor and a small water pump. The motor is similar in size to that of your central blower of 600 watts and the small pump is less than 100 watts, for a grand total of 700 watts.
Swamp cooler typically require to be ran more than air conditioning units to achieve the same temperature, however, even while running more the energy savings with a swamp cooler can be significant. Swamp coolers do require a little bit more work on your part than an air conditioner and can only be ran in low humidly hot areas, such as, the mid-western states.