Cooling residential with rainwater
Monday, August 9, 2010 at 1:06PM One recent sweltering August we made the mistake of tent camping on St. James Island in Charleston, SC. It was one of the hottest summer experiences of my life. Evening temperatures stayed in the 90s. It was very difficult to sleep at night for a man grown accustomed to the simulated autumn environment of air-conditioned bedrooms. Relief came at about 2 - 3 a.m. every morning as thunderstorms would form over the ocean and blow inland. As the downpour passed over our campsite, I joyfully stood outside the tent in just my swimsuit. A few hours of blessed sleep came as a result of the rain shower cool-off.
Did you know that rainwater can be used to cool homes?
The simplest most elegant approach I've seen is employed on a home in Turkey where the roof was constructed as a shallow pool. Collected rainwater cascades from an upper level to a lower in a continuous loop. As you can see from the photo, this natural passive cooling system harmonizes beautifully with the landscape.
A regenerative passive cooling project funded by the German Environmental Foundation takes a slightly more complex approach. Harvested rainwater is pumped from the cistern to the roof at night. As the water runs back down the roof it is cooled by heat dissipation due to heat interchange with the atmosphere, convection and some evaporation. By the time the water cycles back through the downspouts and filter it has cooled to just below dewpoint. During the day, the heat generated by the building's cooling system is fed back into and stored in the cistern by a heat exchanger. That evening, the cycle repeats, cooling the heated water for the next day. It's essentially a geothermal system in miniature.
Sanyo is developing a system that purifies the rainwater with ozone and sprinkles it on the roof where heat is taken from the roof as the rainwater evaporates. This reduces the air conditioning load. Evaporation also helps when outdoor condenser units are sprayed with rainwater when the temperature is high, improving the cooling capacity. This stategy results in the conservation of energy.
These solutions may make you want to reconsider how much rainwater you collect. In hot areas that receive a lot of rainfall like Atlanta, it may be wise to collect and store as much rainwater as possible. That way you can add supplemental cooling to the list of uses for rainwater.
Reader Comments (3)
Amazing technology and concept.
Anthony
Excellent post! The picture of that house in Turkey is amazing.
Can this concept be used with any old rainbarrel or water storage tank? It is amazing- the things we can do with rain!
This is such an interesting blog by the way! Check out www.raintankdepot.com ... I think you will be impressed with many of our products.
hi,
i would love to get more details on the house in turky -
doesn't it get too much heat during the day when the pond is not covered?
where in turky is it? when was it built?
thanks,
lilach.