Trombe Wall Variation

Q: Was watching a "green" show that had a Trombe wall and started thinking that if properly modified, a design might include little niches where you could plant sun tolerant plants. This could serve two purposes. The plants might help absorb heat and they would probably help clean indoor air. Are there any serious problems with my thinking? I can see that proper watering and maintenance might present a problem, but not insurmountable.

A: That Wiki looks very suspect to me. It states "The principal mechanism of heat transfer in multilayer glazing is thermal radiation from warm surfaces to cooler surfaces" That is rarely true, unless the gap is evacuated, eg a Thermos flask. As I understand it radiant heat transfer between two surfaces at around ambient temperature is quite a bit smaller than the conductive loss through the best commercial glazing. Radiant loss to *space* (effectively a very cold surface) from glazing or any other surface can be quite significant, but depends on the atmospheric humidity and the solid-angle of view of the sky from the window. Basically only on a very cold clear night with a good view of the sky. If you compare the published r-value of high-performance glazing to that of plain glass, the improvement is in the order of at best tens of percent, not hundreds. I'm familiar with it, I've read manufacturer's spec sheets, I understand how it works, its uses and abuses. I disagree with the statement I quoted as unwarranted on the basis of physics. The statement actually has nothing to do with coated glass, it is supposed to be a statement of the problem that glass addresses.

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