Earthtubes (earthtubing) are, in a word, sustainable, non-electric, passive geothermal solar heating and solar cooling systems. Earthtubing utilizes conventional, thin wall, plastic pipe to passive solar pre-heat your home's air intake. Fresh air enters a system of these pipes which are laid around the interior of your home's foundation. You can let the air draft naturally through your earthtubes for a truly sustainble, non-electric, passive geothermal system or add fans and filters to supplement the home's back-up heating and cooling system. Be careful with Earthtube details, though ... while architects are warming-up to the idea, they are making very elementary mistakes, like using large concrete (cement) pipe that is impossible to clean.
Does anyone know of a list of building materials and their relative toxicity?
travisr wrote:PVC is useless without the addition of a plethora of toxic additives
Kabir424 wrote:it would have to be a decently steep slope I would assume to overcome the ability of water to stick to a given surface.
Joel Hollingsworth wrote:
Toxicity is difficult to define in this context in a useful way.
Pharmacologists use LD50 (dose lethal to 50% of the population: Paul uses such a figure in passing without mentioning its name, as he discusses master gardener training and herbicide) as a measure of acute toxicity, but chronic toxicity has no similarly standard measure that I'm aware of (I've heard of dioxin equivalent, but that seems limited to organohalide compounds). And even LD50 is just a shorthand, about as useful in understanding toxicity as IQ tests are for understanding intelligence.
The LD50 would be much higher (indicating greater safety) for PVC than for copper or even galvanized pipe. But copper, zinc, and iron have much different effects over the long term than the additives in PVC, and of course the interaction of pipes with good drinking water (i.e., hard water) is entirely different in polymers versus metals: metals tend to interact very strongly at first, but build up layers of reaction products over time, slowing at an exponential rate, so that lead pipes that have been in use for 20 years might be safer than galvanized pipes in their first year. Polymers barely interact at all, but additives or free monomers can drift through them and into the water at a fairly constant rate.
That is good info, but it doesn't really apply here, as phthalates and similar are for softened PVC, which is the same underlying polymer but in a different universe of additives from what we're discussing. Pure PVC with no additives is actually quite useful, but the quote is correct in that such a material is too brittle for curtains or clothing or chew toys.
The stuff in pipes is actually hardened instead of softened, using mineral fillers: phthalates would be counterproductive and unnecessarily expensive. It's very much like the difference between brain-cured buckskin and traditional (hide glue-based) gesso: one common ingredient, but very different processes with very different goals.
I had thought of that but it would have to be a decently steep slope I would assume to overcome the ability of water to stick to a given surface. This would of course depend on the individual surfaces since water will probably be more likely to stick to certain types of plastic and not to certain types of glass etc.. Maybe you can treat the tubes with Rain-X and that water will just bead up and run off. Anyone know the equivalency of coefficient of friction for water on PVC pipe? There's got to be someone nerdy enough on these forums that knows this.
My best guess is that one will need to once a week have access to the tubes to pass a swab through there soaked in alcohol that will sterilize the surface and keep it free of mold. Any other ideas?
I don't have any ideas but I am questioning how "bad" mold and bacterial exposure can be from condensation. Developing countries have not or little reports of allergies but its a rampant problem in developed countries. Many scientist think it has to do with developed countries sterile environments as compared to developing countries.
I personally fear relatively new chemical exposure because we do not understand the effects it has on us as humans. Our bodies know how to deal with mold and bacteria but I doubt evolution has provided any defenses against Formaldehyde or other volatile organic compounds that are leaching or off gassing from our building materials.