Earth Tubes to Cool Roof
Bill Greene| Posted inEnergy Efficiency and Durabilityon
I know there is some debate about the benefit of earth tubes, such as air quality issues and cost/savings. If the trenching for the tubes was already a “sunk cost”, would it make any sense (or cause any problems) to run the tubes up the exterior wall (or inside the exterior wall) and into the roof soffit in order to vent the roof with cooler air? To extend the idea further, would this help the efficiency of roof mounted PV panels (or laminate PV) by keeping the PV panels cooler?
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Replies
Bill,
Would it make any sense? No. Would it cause any problems? Maybe.
Ventilation is a very ineffective way to cool roof sheathing or roofing, as Bill Rose's research has shown. If you want to keep your roofing or roof sheathing cool, the most effective approach is to choose white roofing (or one of the newer cool roof products in a variety of colors).
Introducing air from an earth tube into an attic might cause problems if the earth tube ever has standing water -- yes, that has happened -- because in that you case you would be introducing humid air into your attic.
The most effective way to keep a roof-mounted PV array cool is to maintain an air space between the underside of the PV modules and the roofing.