Are tubular skylights / Solatubes thermal chimneys in a house?
My house design has a long E-W axis in order to exploit Southern exposure and this creates a middle of the house, mostly hallways/foyer, which have no window exposure.
A solotube piping some natural lights into these dark areas would be terrific, but what I don’t want to create is an attic with r-80 coverage and have most of the heat in the conditioned space bee-lining for the “weak spot” under the solatubes and then race up these chimneys.
Are there any energy efficiency tricks in the grab bag of methods used by Green builders to bring light into dark areas of the house?
Any skylights which can transit through an attic and open up to a 2nd floor living space or extend further and open into a first floor space?
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Has anyone used the Parans system? This solutions seems ideal. Sunlight receivers mounted on the roof and light transmitted through fiber optic cables to a number of rooms. The only envelope penetrations are for the cables.
So, how expensive is this system?
Alex,
All skylights represent a thermal bridge through your roof system -- especially in a house with R-80 attic insulation. If you want to keep your heat in, don't install any skylights (whether rectangular or tubular).
One thing to consider about using skylights for daylighting in homes: remember that skylights make more sense in offices and schools (buildings that are mostly occupied during the day) than in homes (which are buildings that are mostly occupied at night).
The Parans system you mention starts at about $10,000. If there is any payback for this system, it must stretch for centuries.
For more information on the Parans system, see Fiber Optics for Daylighting.
For more information on skylights of all kinds, see GBA Encyclopedia: Skylights.