Report Number




Dehumidification; Energy Consumption; Air Conditioning; Moisture


This research project evaluated the energy impacts and dehumidification performance related to how ducted dehumidifiers (DHU) ducts were configured. Lab controlled testing over a variety of weather and latent loads evaluated five-different ducted DHU configurations as follows: Test 1 DHU air ducted from/to the central main body of building. Test 2 DHU air ducted from/to return side of central air conditioner (AC). Test 3 DHU air ducted from/to supply side of AC. Test 4 DHU air ducted from central main body and ducted to supply side of AC. Test 5 DHU air ducted from outdoors and indoors mixed before DHU then ducted to supply side of AC. There was insignificant difference in total space conditioning energy use or dehumidification performance between Test 1, Test 3, and Test 4. Test 5, used 8% more space conditioning energy than Test 1, which was mostly attributed to added cooling load associated with mechanical ventilation during warm humid weather. Test 2 used 3% more space conditioning energy and had poorer dehumidification. During steady operation of the central air and DHU, heat and dry air from the DHU reduced the latent performance of the central cooling system by 28%. Furthermore, the DHU evaporated moisture off of the central cooling coil at a rate of 2-3 pounds of water per hour when the AC was cycled off. This was about the average rate of the measured DHU moisture removal under actual test conditions. Test 2 was not a recommended practice.

Date Published


Local Subjects

Buildings - Air Conditioning; Buildings - Dehumidification; Buildings - Energy Consumption; Buildings - Moisture


FSEC Energy Research Center® Collection



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