Membrane heat exchanger is one of the main components of green HVAC systems. Performance of a thin-membrane heat exchanger has been examined for different membrane materials. A computational fluid dynamics (CFD) approach was utilized to conduct the current study. The CFD model consisted of a single channel for hot stream and another channel for cold stream. Four membranes were investigated: 45 gsm and 60 gsm Kraft paper, modified cellulose acetate membrane and PVA/LiCl blend membrane. Obtained values of thermal effectiveness at typical HVAC system conditions showed that different membrane materials produced different thermal performance values. The amount of energy recovered from the modified cellulose acetate membrane heat exchanger was the highest. Finally, heat exchanger performance is found to be very sensitive to ambient air relative humidity variation. © 2019 by authors.