Water On The Roof For Cooling

The majority of time older homes do not have enough roof vents to help cool the attic in summer.

Water on the roof for cooling.

One study indicates that water use is around 100 gallons per day per 1000 sqft of roof area. Also called an evaporative cooling system a roof misting system lowers surface temperatures by spraying an extremely small amount of water across the roof allowing the water to cool the roof as it evaporates. Yes water on the roof will help cool it. These systems provide cooling by spraying the water evaporates and cools the surface.

At its lowest tech a roof misting system can be little more than a garden hose set to the mist setting and aimed across the roof. 1 gallon of water consumes 8000 btu as it evaporates. Ambient indoor temperature is approx. In the simplest form this involves placing a pond on the building roof.

This cools the roof which acts as a heat sink and absorbs heat from the interior of the building. Cooling with liquid water running off from a sprinkler is not efficient but evaporative cooling from a small amount of water like a periodic sprinkle is very efficient. As water evaporates from the pond heat is consumed. 50 radiant heat from surface radiation and 50 air temperature.

Prototype for a evaporative roof for radiant cooling cherry valley ca usa reconsidering comfort. A more refined method involves insulating the pond during the daytime to prevent solar gain. An evaporating layer of water on the roof approaches a wet bulb temperature of 12 c a typical roof reaches 60 100 c mitigating the albedo effect.