Moisture Removal Efficiency (MRE) is a measure of the energy efficiency of any dehumidification process. Moisture removal efficiency is the water vapor removed from the air temperature and humidity, divided by the total energy consumed by the dehumidification equipment during the same time period, including all the fan and pump energy needed to move air and fluids through the system . Water vapor removal is expressed as pounds or kilograms. Energy is usually expressed as kilowatt hours. Inlet air temperature is expressed in degrees Fahrenheit or degrees Celsius. Inlet air humidity may be expressed in several ways, most commonly in the air; the weight of water vapor in the air, compared to the weight of the air that contains it. An example of the MRE of a dehumidification system could be: 4. 4 lb / kWh @ 85 ° F, 140 gr / lb. Using the SI system of units, that same MRE would be 2.0 kg / kWh @ 30 ° C, 20.0 g / kg.

The authority for this definition of moisture removal is ANSI / AHRI Standard 920, published by the Air Conditioning, Heating and Refrigeration Institute (AHRI). AHRI is an association of equipment manufacturers. Standard 920 was developed by the group of manufacturers of AHRI that is concerned with energy efficiency of outdoor equipment (DOAS equipment). The standard provides an objective and quantitative basis for rating and comparison of dehumidification performance and energy consumption of dehumidifiers and ventilation as part of a building’s mechanical systems. Dehumidification of ventilation and makeup air consumes a great deal of energy worldwide. In all except desert and high-altitude climates, the annual dehumidification load for ventilation the annual cooling load for ventilation by a factor of 2 to 5. The issue of energy efficiency of dehumidification arises because of the requirements of energy efficiency. According to the members of AHRI’s dehumidification product section, the reason for developing Standard 920 was to provide ASHRAE with a neutral and high-quality test method for dehumidification energy efficiency. The committee’s goal has been ASHRAE include minimum dehumidification efficiency requirements in ASHRAE Standard 90.1. That standard is often used in the United States and Canada,

To provide a metric that allows an estimation of the annual dehumidification dehumidification dehumidification dehumidification systems, AHRI Standard 920 further defines a test protocol for measuring a system of integrated seasonal moisture removal efficiency. This metric is similar to the seasonal energy efficiency ratio (SEER) that is used to compare cooling energy efficiency of competing equipment. Like the SEER test methodology, AHRI Standard 920 requires that the dehumidification equipment be tested at several discrete combinations of inlet air temperature and humidity. In the 2015 edition of the standard, these test conditions are defined. The moisture removal efficiency of the equipment is measured at each of these conditions, and then the proportionality factor is applied to each MRE.

ASHRAE ASHRAE ASHRAE Standard 90.1 ASHRAE 90.1 AHRI Air Conditioning, Heating and Refrigeration Institute Dehumidifier Dehumidifier SEER Energy efficiency ratio LEED Leadership in Energy and Environmental Design