2021 RETA Breeze May-June

HELPFUL DEFINITIONS • Dry bulb temperature (°F). The temperature of the room air taken with a standard thermometer. • Relative Humidity (% RH). The percentage of water vapor (at a given dry bulb temperature) present in the air as compared to how much water vapor could be present if the same air was totally saturated. • Dew Point Temperature (°F). The temperature at which a given air-water vapor mixture will become completely saturated (i.e., 100% RH) and water vapor will start to condense. • Vapor Pressure (inches Hg). Each water molecule in a given air-water vapor mixture exerts pressure on the

surrounding environment. Vapor pressure is the measure of this pressure caused by the amount of water vapor in the air-water mixture. Moist air = higher vapor pressure; Dry air = lower vapor pressure. • Minimum Efficiency Reporting Value (MERV). A system used to rate the efficiency of an air filter. The higher the MERV, the more efficient – and more expensive – the filter will be. • Latent Heat. The amount of heat absorbed or released by a substance undergoing a change of phase (e.g., ice changing to water or water to vapor) at constant temperature and pressure. • Sensible Heat. Heat conveyed by a substance which has a greater temperature than its surroundings.

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