A project was carried out to develop selection guidelines for enthalpy residential air-to-air heat exchangers. A review of ventilation requirements, appropriate indoor humdity levels, moisture sources, and enthalpy exchanger characteristics was undertaken. Models for humdity storage, window condensation, and moisture recovery were developed and inserted into a commercially available hourly energy analysis computer program. Simulations of three house sizes with various ventilation systems and rates, and various moisture generation rates were carried out for three geographic locations. Guidelines for the application of enthalpy residential air-to-air heat exchangers were developed.