The steady-state performance of a run-around membrane energy exchanger (RAMEE) for a wide range of outdoor air conditions is presented here. The RAMEE is numerically simulated and the sensible and latent effectiveness values corresponding to the maximum total energy effectiveness for different outdoor air conditions are presented. The effectiveness values are shown to be very dependent on outdoor conditions which results in some effectiveness values exceeding 100% or being less than 0% for several of the outdoor air conditions investigated. The heat and moisture transfers are shown to influence the latent and sensible performances of the RAMEE, respectively. (C) 2011 Elsevier Ltd. All rights reserved.