
World's largest urban farm to open on a Paris rooftop - galfarragem
https://www.theguardian.com/cities/2019/aug/13/worlds-largest-urban-farm-to-open-on-a-paris-rooftop
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lm28469
Wouldn't the plants/fruit/veggies suck up pollutants ? I'm not sure I'd eat
anything that grew in contact with Paris air. Last time I went there my throat
and nose itched from the pollution, it never happened to me before, not even
in LA.

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jklepatch
??? I never felt pollution like you described, having lived 23 years in Paris.
You might be extremely sensitive to pollution. And I am especially surprised
that you claim LA is less polluted, considering that public transportation is
much less developed there.

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lm28469
I assume the ocean wind + wide streets of LA makes it easier.

After morning/evening rush hours Paris tiny streets are a death trap to me. I
was born and raised in a small mountain town though, my body isn't made for
Paris.

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Kuinox
I checked right now and the LA Air Quality index is at 60 meanwhile 44
currently at paris.

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Retric
That’s just one snapshot. In terms of motor vehicle exhaust:

NO2 in Paris is 5 right now, but it was 151 a few days ago.
[https://aqicn.org/city/paris/](https://aqicn.org/city/paris/)

NO2 in LA is 4 right now and peaked at 25 over the same time period.
[http://aqicn.org/city/losangeles/los-angeles-north-main-
stre...](http://aqicn.org/city/losangeles/los-angeles-north-main-street/)

PS: Condescending all air quality into a single number is still useful, but
does represent the subjective experience of different areas as well.

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Kuinox
As an ashmatic, the best indicator for me is the fine particules(particules
fines in french), emitted by the combustion vehicules. NO2 in Paris was 151 a
few days ago, but only on one of the probes.

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dependsontheq
What exactly is an urban farm?

Does it have to be on buildings? This is an area near my hometown, it has good
public transport (the next Metro stop is a bit of a walk but you could take
the light rail)
[https://www.google.de/maps/@49.4845803,11.0337896,15z/data=!...](https://www.google.de/maps/@49.4845803,11.0337896,15z/data=!3m1!1e3)

These are all greenhouses and vegetable gardens.

This is Westland “Food Valley” it’s between Den Haag and Rotterdam ...
[https://www.google.de/maps/place/Westland,+Niederlande/@51.9...](https://www.google.de/maps/place/Westland,+Niederlande/@51.9984626,4.2186115,11z/data=!4m2!3m1!1s0x47c5b7d4aa3838df:0x31ee3d1de87f506e?hl=de-
de&gl=de)

Is this an urban farm? Is there any advantage to growing vegetables on a roof
instead of next door?

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trophycase
I think the benefit of rooftop gardens is taking what is essentially "wasted"
space (where I live most rooftops go completely unused) and repurposing it
into something productive.

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yostrovs
Having attempted growing vegetables on the rooftop of a 6 story building, I
discovered that preparing and cleaning the roof is incredibly energy
intensive. You have to bring soil from some soil farm to the city and then
onto the roof of a building where you have special beds setup and a way for
runoff to be cleaned and processed. Water, nutrients, tools, everything else
has to be brought up there. Dust blown off the beds when it gets a bit dry
flies all over the city. It also gets too hot up there because the roofs are
super hot, so you need more water. Then the birds, squirrels who are actually
able to climb as high as necessary, neighbors who live below the roof, and
other problems creep up that were totally unexpected. Good luck to many others
who will try the same and find out this on their own.

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peller
It sounds like they're using aeroponics where possible. Of course that still
requires energy, but much less so than growing in soil. There's also much less
overall water use, because it's essentially a closed loop system with minimal
evaporation.

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hodder
“Our guiding principle with all our farms is to help foster environmental and
economic resilience in tomorrow’s cities,” says Hardy, who expects the farm to
start making a profit within its first year. “If we can create a model that is
commercially viable, rather than having to rely on goodwill and subsidies,
that will help urban farms to become sustainable in their own right.”

It will be interesting to see if this succeeds economically.

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dirtyid
I'm not sure if the amount of extra engineering and costs involved to support
low rise rooftop farming is better than the opportunity cost of slapping on a
bunch of solar panels. This might be a viable model for Paris due to severe
zoning height restrictions, but when I think urban farms that solves big
problems, I think of high density vertical farms.

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ivanhoe
How much extra weight are roofs typically built to hold? Is it safe to load
them like this considering the extra weight of soil and water that soil can
capture, and say a layer of snow over all of that in winter?

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brohee
They say they are doing aeroponics, so soil is replaced by much lighter
plumbing...

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nerdponx
How much weight does the roof have to hold to support all that?

