ABE 990 SEMINAR When: 1:30 PM, Friday, February 26, 2010 Where: 1A80 Engineering Speaker: Gao Zhu (M.Sc. student) Dehumidification of Greenhouses in Cold Region Topic: One major challenge greenhouse producers face is the excessively high relative humidity (RH) during cold seasons which result in fungi diseases and reduction in yield and quality. Conventional dehumidification by increasing ventilation rate is either costly because of the resultant heat loss or ineffective in spring or fall when outside RH is high. In this study, two dehumidification technologies, i.e. air to air heat exchangers and mechanical dehumidifiers, were evaluated in a Saskatchewan tomato greenhouse, and laboratory tests using chilled water condensation system, another potential dehumidification method, were conducted to investigate its dehumidification effect under different environment conditions. The three dehumidification methods were evaluated against the conventional one based on moisture removal efficiency (MRE) and the energy cost. This presentation mainly focuses on the MRE comparison of the three methods. It was concluded that dehumidifiers were the most energy efficient in heating season; heat exchanger and dehumidifiers were both functional for heating season but not desirable for cooling season due to the added heat to the greenhouse; the chilled water condensation method consumed much more energy when removed certain amount of water compared to the others, thus the least competitive.