Cool Roof Market

Evaporative cooling is a “once-through” cooling process. It involves passing water over pads located in a big box up on the roof. In that big box is also a big fan that blows “fresh” air past those water-laden pads and then into ducts in the roofspace. Humidified and therefore cooled air enters living spaces through ceiling vents. Windows and/or doors must be left open when the evap is running so that the sometimes damp-feeling air can extract heat from the house and then leave the house altogether. On the other hand, refrigerative cooing is a “closed” process. With this, one keeps windows and doors closed and allows the airconditioner to collect heat into its circulating refrigerant fluid which, pumped by an electrically powered compressor, flows to the “outside unit” where heat is rejected outdoors. Refrigeration devices are referred to as “heat pumps” because, in the example of space cooling, they pump heat from inside a house to outside. In this closed process, no...