A liquid-to-air membrane energy exchanger comprising: a housing defining a cavity ; a plurality of liquid panels disposed in the cavity , each of which comprises: a support frame having a plurality of liquid circuits through which a liquid is configured to flow, wherein each of the plurality of liquid circuits comprises an inlet channel connected to an outlet channel through one or more flow passages ; and first and second semi-permeable membranes secured to first and second sides of the support frame ; and a plurality of air channels disposed in the cavity between adjacent pairs of the plurality of liquid panels , each of the plurality of air channels comprising a membrane support assembly configured to support the first and the second semi-permeable membranes of the adjacent pair of the liquid panels , the liquid-to-air membrane energy exchanger being configured to exchange energy between air transmitted through the plurality of air channels and the liquid transmitted through the plurality of liquid panels, and, characterised in that the plurality of liquid circuits comprises: a first plurality of flow passages (1016-1030) connected to a first inlet channel and a first outlet channel ; and a second plurality of flow passages (1016-1030) connected to a second inlet channel and a second outlet channel ; wherein the first plurality of flow passages is staggered with respect to the second plurality of flow passages. a housing defining a cavity ; a plurality of liquid panels disposed in the cavity , each of which comprises: a support frame having a plurality of liquid circuits through which a liquid is configured to flow, wherein each of the plurality of liquid circuits comprises an inlet channel connected to an outlet channel through one or more flow passages ; and first and second semi-permeable membranes secured to first and second sides of the support frame ; and a support frame having a plurality of liquid circuits through which a liquid is configured to flow, wherein each of the plurality of liquid circuits comprises an inlet channel connected to an outlet channel through one or more flow passages ; and first and second semi-permeable membranes secured to first and second sides of the support frame ; and a plurality of air channels disposed in the cavity between adjacent pairs of the plurality of liquid panels , each of the plurality of air channels comprising a membrane support assembly configured to support the first and the second semi-permeable membranes of the adjacent pair of the liquid panels , the liquid-to-air membrane energy exchanger being configured to exchange energy between air transmitted through the plurality of air channels and the liquid transmitted through the plurality of liquid panels, and, characterised in that the plurality of liquid circuits comprises: a first plurality of flow passages (1016-1030) connected to a first inlet channel and a first outlet channel ; and a second plurality of flow passages (1016-1030) connected to a second inlet channel and a second outlet channel ; a first plurality of flow passages (1016-1030) connected to a first inlet channel and a first outlet channel ; and a second plurality of flow passages (1016-1030) connected to a second inlet channel and a second outlet channel ; wherein the first plurality of flow passages is staggered with respect to the second plurality of flow passages. <EOS>