Advanced features on evaporative coolers recently introduced to the market include variable air volume control. Some units use variable-speed drives, or two-speed or electrically commutated motors for smaller units, to control the space temperature to the desired setpoint. Lower air velocity increases heat transfer effectiveness and significantly reduces system fan power.
An advanced feature not commonly available on evaporative coolers would include the use of sensors to monitor system performance. Temperature and humidity measurements would allow for an estimate of system effectiveness. Static pressure gauges that measure pressure drop across the media can also be used to determine when maintenance of the media is required.
Due to the higher air temperatures than traditional air conditioning systems, much more air must be used to provide the necessary cooling. As it is generally 100% outside air, provisions must be made for venting the air to the outside without requiring the opening of windows. With residential applications, vents installed in the ceiling (known as an “up duct”) are designed to open when the home is positively pressurized. Sufficient attic ventilation must be provided to then exhaust the ventilation air to the outside.
Evaporative cooling systems have a number of benefits. They use only a fraction of the energy of typical compressor-based cooling systems. Highly-efficient evaporative cooling systems can reduce energy use by 70%. (The actual savings will vary with the type of evaporative system and the climate.) For dry climates, where evaporative cooling can meet the entire load, they dramatically reduce peak-demand. When evaporative cooling is used with supplemental DX cooling it can reduce the DX cooling required. Moreover, since they use 100% outside air for cooling, the right evaporative cooling system can improve indoor air quality.
Content Source: Energy Design Resources e-News April 2010