A system (500; 100) for dehumidifying an enclosed space, the system (500; 100) comprising: a supply plenum (702; 602; 102) configured to direct return air from the enclosed space through the supply plenum (702; 602; 102) from a return air inlet to a supply air outlet; a scavenger plenum (704; 604; 104) configured to direct outdoor air through the scavenger plenum (704; 604; 104) from an outdoor air inlet to an exhaust air outlet; a dehumidification liquid-to-air membrane energy exchanger, LAMEE , arranged in the supply plenum (702; 602; 102) and configured to selectively remove water vapor from the return air using a desiccant, the dehumidification LAMEE (323; 313) comprising a first desiccant flow path separated from an air flow path by a membrane, the dehumidification LAMEE (323; 313) configured to selectively circulate the desiccant through the first desiccant flow path and remove water from the return air in the air flow path; a regeneration unit arranged in the scavenger plenum (704; 604; 104) and configured to selectively concentrate a dilute desiccant from the dehumidification LAMEE (323; 313) using the outdoor air passing through the regeneration unit ; and a heat recovery system (500; 100; 128) configured to heat the outdoor air in the scavenger plenum (704; 604; 104), wherein the system (500; 100) is configured to operate in a wet mode in which the dehumidification LAMEE (323; 313) and regeneration unit are operational and a dry mode in which the dehumidification LAMEE (323; 313) and regeneration unit are off or bypassed, and selection of the mode depends on outdoor air conditions, and wherein the heat recovery system (500; 100; 128) uses either exhaust scavenger air or exhaust return air as a heat source, depending on the selected mode. a supply plenum (702; 602; 102) configured to direct return air from the enclosed space through the supply plenum (702; 602; 102) from a return air inlet to a supply air outlet; a scavenger plenum (704; 604; 104) configured to direct outdoor air through the scavenger plenum (704; 604; 104) from an outdoor air inlet to an exhaust air outlet; a dehumidification liquid-to-air membrane energy exchanger, LAMEE , arranged in the supply plenum (702; 602; 102) and configured to selectively remove water vapor from the return air using a desiccant, the dehumidification LAMEE (323; 313) comprising a first desiccant flow path separated from an air flow path by a membrane, the dehumidification LAMEE (323; 313) configured to selectively circulate the desiccant through the first desiccant flow path and remove water from the return air in the air flow path; a regeneration unit arranged in the scavenger plenum (704; 604; 104) and configured to selectively concentrate a dilute desiccant from the dehumidification LAMEE (323; 313) using the outdoor air passing through the regeneration unit ; and a heat recovery system (500; 100; 128) configured to heat the outdoor air in the scavenger plenum (704; 604; 104), wherein the system (500; 100) is configured to operate in a wet mode in which the dehumidification LAMEE (323; 313) and regeneration unit are operational and a dry mode in which the dehumidification LAMEE (323; 313) and regeneration unit are off or bypassed, and selection of the mode depends on outdoor air conditions, and wherein the heat recovery system (500; 100; 128) uses either exhaust scavenger air or exhaust return air as a heat source, depending on the selected mode. <EOS>