He is working on a simple and inexpensive and very energy efficient space cooling system that uses water cooled via radiation to the night sky.
Night sky roof water spray cooling system.
Water is sprayed over a flat or sloping metal panel roof at night.
The next day the cooled water is used for cooling the home s living space.
Coatings are like very thick paints that can protect the roof surface from ultra violet uv light and chemical damage.
Cooled water returns via the roof drain system to a 15 000 gallon underground tank.
Consequently they radiate heat into the sky to passively cool buildings at night.
This cool fluid is circulated through the building to absorb heat and then back to the panels to be cooled.
One of the two spray pumps circulates water through 6000 lineal feet of underfloor tubing enroute to the spray heads using the floor.
The water is then collected via a gutter system and returned the tank.
The water filled plastic bags are covered by a roof in the daytime and at night times is moved away on rollers to expose the water to the night sky.
Cooled by the night s temperature the water is funneled through roof gutters and rainwater leaders and then stored in a thermal storage tank to be used by the building s radiant cooling system with tubing located in the floor slabs and ceiling panels.
Another radiation cooling system has been the oretically and experimentally investigated by al nimr et al 1998.
A cool roof coating can benefit a building and its occupants by decreasing energy bills through the reduction of air conditioning needs.
The most common radiative coolers found on buildings are white cool roof paint coatings which have solar reflectances of up to 0 94 and a thermal emittances of up to 0 96.
The whitecap system employs the cooling of water by night sky radiation convection and evaporation of water in an open water cycle.
Surface and connected to a water pumping and filtration system.
Instead of spraying water on the roof you should apply a cool roof coating to cool your roof down.
This water is first cooled by evaporation during the spray process and then further cooled by radiation to the night sky.
David lives in castlemaine victoria australia with hot and dry summers.
If made sufficiently reflective to sunlight these materials can also achieve radiative cooling during the day.
The system works by spraying water from a water tank over the roof at night where it cools by radiation and evaporation.
The metal roof is used at night during spring autumn and acceptable summer periods to perform sensible cooling.
Various exotic night sky radiation cooling concepts have been tested in the past.
During the cooling season water is sprayed over the roof surface at night.
The water cycles through this spray cooling process until it is cooled to.
Cool roof coatings are white or special reflective pigments that reflect sunlight.
We devised an innovative night cooling system consisting of a metal roof serving as a large area low mass highly conductive radiator see figure 1.
Warm hydronic fluid from the building is pumped through flat plate solar panels at night and is cooled by radiant heat loss to the night sky.
The cold water is stored for use during the day by direct conduction to the roof whitecap r fan coils whitecap t or coils entrenched in the floor slab whitecap f.
