[JohnBooty]

Good point. Not sure what area they're talking about. I didn't get into the exact math because no matter how you slice it it's kind of absurd. Here are some more objective numbers I found. I don't know how reliable the sources are.

One common estimate for humans seems to be 1kg of CO2 exhaled per day.

A single bird's nest fern is estimated to absorb about 0.0002677kg of CO2 per day.

So about 3,700 bird's next ferns in your house for each human being should even things out. Regardless of exact numbers this seems consistent with everything I've ever read over the years, that indoor plants are nice but the amount needed to really reduce CO2 is impractical.

[6510]

say you cover 1/3 with ventilation and 1/3 by not being home for 1/3 of the day. It still wont be a small greenhouse with [say] 1200 plants but say 3 floors of 25x16 definitely seems doable. How much artificial light to keep them going?

[JohnBooty]

I'm not sure how practical that is, but I'd certainly love to live in such a place. =)

[6510]

I visited a guy one time who decorated his 5 room flat with the biggest possible plants one could fit in each room (with a few spots to keep them alive). The 14x4.5 meter living room was a 2 seat sofa, a small table with drawers, a tv attached to the wall, very thick wooden floor with big cracks all over and 5 enormous plants in pots the size of bath tubs. No amount of money could have improved it.