Argentine Scientist Designs Low-Cost Configurable Solar Roof
by Paula Alvarado, Buenos Aires 
on 01. 8.08
Our previously featured Luis Juanico, who redesigned a heater for more efficiency, has launched his latest project: a concept of economically accessible solar collector roof to manage the temperature of the house through redistribution of water.
Even though American chemist Harold Hay (link to bio) was pioneer in the use of water to collect the sun’s heat and then use it to heat homes in his Skytherm House, what the Argentine scientist has added is the water redistribution and low cost factors. “Traditional solar collectors require high investments, what I’m proposing is a roof whose cost is near to the one of a conventional roof and which can provide heating and cooling by water redistribution and therefore save energy,” says the scientist in the presentation of the project.
Picture: Luis Juanico (white shirt) and his team at his office in Bariloche, Patagonia (Rio Negro newspaper).
The roof is conformed of a water pond, and two glass isolators with an air chamber in between; and it is covered by a scrollable curtain. During winter days, the curtain is scrolled out for the roof to absorb the sun’s radiation, which gives direct heat to the house and heats the water inside the pond. Through an outlet, the hot water is stored in a tank. At night, with the curtain scrolled out the house gets isolation and at the same time, the hot stored water is sent to the heating in-floor system.
During the summer, the process is backwards: the roof remains uncovered during the night to cool the water which then will be used during the day to cool the in-floor system, while the curtain remains covering the roof to avoid the sun’s radiation.
The mentioned curtain is actually a rolling awning (not foldable) also designed by Juanico, and is configurable to be opaque, transparent and open mesh, according to the needs.
“As pioneers like Harold Hay have shown, it is possible to obtain very good results by means of configurable designs, adaptable to the environment. These two new configurable designs could help us modify the deeply rooted paradigm of the classic roof and building,” says Juanico at the end of his project presentation.
The cost of the roof is the same of a good quality roof: 100 US dollars the square meter, informs the presentation of the project.
The configurable solar roof received the first prize of the technical contest at the International BIEL Light & Building Buenos Aires congress in 2007 and will be published in the Solar Energy magazine. It is being tested at El Bolson, in Patagonia. For more information, see the PDF presentation of the project from the BIEL website or write an e-mail to Luis Juanico (juanico [at] cab [dot] cnea [dot] gov [dot] ar. ::Configurable Solar Roof Presentation
Scheme that shows the functioning of the roof on a winter day.
Graphic for the functioning on a winter night.
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Brilliant!!!
Anything that uses water pipes or tanks probably can't be used in places with prolonged subzero temperatures, without further adaptation or modifications. I grew up in Michigan and when the temperature drops down to single digits, people's pipes start freezing and bursting.
One solution is to put antifreeze into the water, but that may not be "green" enough for some.
I wonder how well this essentially flat roof layout will work in the snowbelt? Up here you have to have snow-shedding capability built into the roof. I have snow 2.5 feet deep in places. And at 44 degrees north latitude, the highest the sun gets is 22.9 degrees altitude at noon during the winter solstice, not much solar radiation is going to be absorbed. and the scrollable curtain won't survive the first snowstorm.
Good idea, but what about parts of the world where you need a pitched roof? Would it work with the more standard solar water heater systems, or would there be problems with circulation?
It looks like this will only be ultimately successful on a flat roof, though most have a significant incline...
brilliant. but you'd still need a VERY efficient house construction to take advantage of the minimal heat that would be generated by the hot water. Standard home construction would benefit little from this, as the floors and walls leak heat badly. That's not likely to happen much in today's world on a large scale. But matched with solar or the grid this could be a money saver to some.
Ah, but an excellent idea riddled with impracticalities. Inevitably, the pipes will clog with sediments as any hot/cold water piping system will. The materials for the roof will need to be changed to accommodate holding water for long periods of time. With exposure to light and sunlight, the system will inevitably build up algae; therein comes the problem of how to deal with the algae in such a system? All in all, a great step in the right direction. The devil is in the details. :)
This is a really stupid idea. And it won first place? My god, what where the others?
Ever tried to run a cooling system through a floor when there's any kind of humidity in the room?
It won't be long before you have a nice slippery film of condensation on your floor. On the other hand it could be a quick way to collect on Granny's inheritance.
I don't know if the roof will be low-cost but infloor system certainly isn't !
Sorry for the late comment publish guys! I´m outside the country and couldn´t do it earlier. Thanks for all inputs and discussion!
I helped my father-in-law research, design, and build a solar house. We ended up with an earthbearmed on the sides solar attic type design house with a front green house and railroad rock heat storage in the crawl space.
However, we seriously looked at the solar pond roof design, as cooling is more critical in Clemson S.C. than heating. We could not use the design, as it required re-enforced concrete walls to support the weight. However, some of the new techniques now in use has lowered the cost and probably would be cheap enough now.
As far as a pitched roof for a snow load, yes, you could use one but you do not need to.
This design uses an insulated cover with a reflective surface. This reflective surface, opened during the day, effectively increased the collection surface by 12-20% if at the correct angle, but also is closed at night to reflect heat back in. This cover would be closed on days it would snow, than the snow would be brushed off (use a leave blower) to remove snow from the cover so no snow would accumulate on the solar pond glazing or its insulated cover.
More and more this designed should be used where A/C is more energy consuming and costly than heating. Of course, it still heats in cold weather when you need it. I frankly feel this design is one of the best systems, as it requires few moving parts. Just an insulated reflective cover that can be pulled in place by hand (counter weights) or use a garage door opener for your motive force.
ARTHUR L. BELGE
AUGUSTA. GA