Sometimes the most impressive products at Greenbuild are the most innocuous and boring looking things; last year I thought the best of show was Agriboard, a SIP made from straw. This year I spent some time trying to figure out this ridge vent for a standard shingled roof with tubes running through it, thinking that there wasn't much surface area on it and it isn't going to do much. Then I realized that all of the heat in an attic runs through the ridge vent and this thing turns your entire roof into a solar collector.
As much as 25% of the energy consumed in a house goes to making hot water, and as we have shown before, it costs a tenth as much to generate a watt of power from the sun to heat water as it does to make electricity, so it makes a lot of sense to do this first. The Greenward solar ridge vent may tilt the economics even more, since you already own about 90% of the system- the roof of the house.
As the sun beats down on those dark grey shingles, the heat rises and flows out through the ridge vent around PEX plastic tubes, heating an ethylene glycol and water mixture that is pumped down to a heat exchanger, preheating the water before it gets to the water heater. The existing hot water heater only fires up when needed.
This is one of those crazy clever ideas, replacing a four thousand dollar solar collector that people don't like putting on their roofs with a completely invisible one, taking wasted energy that we actually design our roofs to get rid of and putting it to good use. There is a bit of technology in the basement that is common to all solar hot water systems, but the basic collector is as simple and clever as you can get. The company claims:
With an average attic temperature of 120 degrees F. the Greenward™ Ridge Vent can reduce your energy consumption by just over 12 million BTU's a year and reduce your CO2 emissions by just over 1,400 pounds annually.
I often scoff at those who say that technology will save us, and then I see a simple, clever device like this that could knock out a big chunk of our energy consumption, and nobody could even tell. That's good old American ingenuity.
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