h a l f b a k e r yQuis custodiet the custard?
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In order to get outside fresh/air, AC/heaters regularly throw out stale air and intake fresh air.
How about avoiding that and including oxygen cylinder in the room that keeps adding O2 to the room and also including a device (probably a chemical reaction device) that takes away CO2 from the room.
This
will be more energy efficient than taking outside fresh air and reconditioning it.
CO2 scrubbing
http://en.wikipedia.org/wiki/Rebreather
Used in diving [VJW, Jun 07 2011]
Grow your own fresh air
http://www.ted.com/..._own_fresh_air.html
Kamal Meattle on TED [CyberCod, Jun 07 2011]
[link]
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Stale air has more issues than just CO2 / O2 levels. Does this system use a CO2 scrubber, or are you looking for a high-pressure O2 tank? Sounds dangerous. |
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... and therefore gets a bun. [+]. |
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Lithium hydroxide cartridges ? |
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This is already implemented on submarines and spacecraft, and is therefore Widely Known To Exist. |
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[Ray] O2 tank can be kept outside house, if dengerous. |
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Better is what's called a counterflow fresh air ventilator. |
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What [rayfo] said. "Staleness" isn't usually about CO2
or O2 levels (unless you've inadvertently locked
yourself in a trunk, and which of us hasn't done that
at some point?). It's more about temperature,
humidity, and the various effluviata that machines
and people produce. |
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And, in terms of energy efficiency, preparing a tank
full of pure O2 is not a great way to begin. |
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I believe it is called "keeping plants" and somehow it refreshes the oxygen in the house on a regular basis. Not sure how it works, but thats technology for you. |
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//keeping plants// Complete myth. You need hundreds of square metres of actively growing vegetation to replace the oxygen consumed by a single person. A couple of piddly little house plants may cause a net _consumption_ of oxygen due to decomposition of the potting medium. |
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At night, plants intake O2 and release CO2. !! |
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In many air conditioned offices and supermarkets, IAQ (Indoor Air Quality, staleness) is precisely about CO2 levels and also humidity (assuming a stable temperature control algorithm. Depending on the Outside Air Condition recirculation and fresh air dampers modulate to trim first the temperature, then the CO2 level (taking priority). Temperature control in this mode is carried out via CHW and LPHW coils (or other modes. It is actually the MOST energy efficient way of doing this. |
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// Complete myth. You need hundreds of square
metres of actively growing vegetation to replace the
oxygen consumed by a single person.//
No, besides the TedTalk link, there is a undersea
observatory which generates all their oxygen with an
algae tank. I just can't seem to find a link, but I did
find some about the Navy testing the use of plants
for oxygen on Nuclear subs. |
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Plants do not produce O2 at night, and produce CO2 instead, correct ? |
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On Subs, whatever O2 is produced by plants should get consumed back by plants at night/sleeping. |
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//Plants do not produce O2 at night, and produce CO2 instead, correct ? // Correct. (But a system whose biomass is increasing or being exported produces a net amount of oxygen, as daytime photosynthesis exceeds nighttime respiration). |
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OK, obviously plants can be used to supply oxygen indoors, and by using algae the area can be reduced, but the amount needed is much more than people tend to think. |
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You also need kilowatts of light per person, which means very large windows or powerful lights, either of which would add more heat to a building than would be saved due to reduced ventilation - fine when the heat is needed, but no good if cooling is desired. |
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That Ted talk link does not suggest producing all, or most, of a building's oxygen from plants. To do that you would need something more closely resembling the Biosphere project than a conventional building. |
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For example, a reasonably active adult averages about 150 watts of metabolic energy. Sugarcane, one of the most efficient photosynthesizers, is able to fix about 0.01 of the incident light energy. You therefore need about 15 kw of light, which would consume about 40 kw of electricity or require nearly 30 m² of optimally placed windows in the tropics, to supply one person's oxygen, day and night. You could squeeze that into a large room - but that's a best case scenario, with optimally fed and watered sugarcane growing under continuous, intense artificial light, consuming (or admitting into the building) tens of times the power any reasonable air conditioning installation would normally need to transfer ... need I go on? |
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//nuclear sub// You could float the garden up with the periscope. |
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If you're at periscope depth, you could use the snorkel. |
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and if you were on a nukular sub you could brute-force the CO2 back into C + O2. |
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spider mother you are mixing metabolic energy
with O2 consumption. Most metabolic energy
comes from the conversion of sugars not 02
respiration. |
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the average human consumes about 53 L of 02 an
hour. I'm not sure what the efficiency level is, as
each breath won't perfectly convert all the 02. |
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a leaf makes about 5ml of 02/hr but I have no clue
on the areal density of leaves. |
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//And, in terms of energy efficiency, preparing a tank full of pure O2 is not a great way to begin// |
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Ok, how about not liquifying O2, but O2 stored at just above atmospheric pressure. |
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And rather than being purists, how about less than 100% pure O2, say something like 70-80%, if it gives energy efficiency. |
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Energy efficiency is actually relative in this case, and depends upon difference between inside and outside temperature. e.g. Something that is efficient, for a difference of 30 degrees , may not be effeicient for a difference of 10 degrees. |
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//mixing metabolic energy with O2 consumption// To a fairly close approximation, a plant that fixes 1 joule of energy releases the same amount of oxygen as is consumed by an organism that metabolises 1 joule of food energy. Making that assumption kept the calculations simpler. The efficiency of metabolism makes no difference; the only requirement is that the food is completely metabolised. The ratio of fats to carbohydrates, and whether the consumer is growing, make a difference, but not a very big one. |
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Within a wide range of light levels, the potential rate of photosynthesis is closely proportional to incident light flux, so there is no need to get bogged down with oxygen production of individual leaves. |
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