Air flowing over cold surfaces is an age-old concept that’s making a big comeback due to the increased attention being paid to carbon emissions and electrical grid demands. The ancient Persians used specially designed wind catcher towers, many of which can still be seen today in parts of the Middle East and North Africa. Air funnels down to interior spaces through precisely designed openings and canals and sometimes across pools of cold subterranean water and then back up. Some water pools can even produce sheets of ice on their surface. The warm air rises and exits through another tower or opening, aided by the pressure within the building. Although there are variations to the commercial processes available today, the principals behind ice cooling remain relatively straightforward.