An improved method and apparatus for indirect evaporative cooling of a fluid stream to substantially its dew point temperature. Plate heat exchanger has perforations 11 and channels 3, 4 and 5 for gas or a low temperature for liquids on a dry side and wet side. Fluid streams 1 flow across the dry side 9, transferring heat to the plate. Gas stream 2 flows across the dry side and through perforations to channels 5 on wet side 10, which it then cools by evaporative cooling as well as conductive and radiative transfer of heat from plate. A wicking material provides wetting of wet side. In other embodiments, a desiccant wheel may be used to dehumidify the gas, air streams may be recirculated, feeder wicks 13 and a pump may be used to bring water from a water reservoir, and fans may be used to either force or induce a draft. The wicking material may be cellulose, organic fibers, organic based fibers, polyester, polypropylene, carbon-based fibers, silicon based fibers, fiberglass, or combinations of them. The device may be operated in winter months to scavenge heat from exhaust gases of a space and thus pre-heat fresh air, while simultaneously humidifying the fresh air.