http://www.thestar.com/...r-supermarket-s-roof?bn=1

Although I guess what could be grown would be somewhat limited but still..

That's a brilliant idea :)

I wonder how economical it will be, I guess we will learn soon thanks to this pioneering project.

There's a movement in the US to convert the top of sky scrapers/office complexes to a greenhouse type set up. Apparently they're trying to organize a collective that will lease space and maintain greenhouses, or something along those lines...too lazy to find the link.

I think it's a great though. It supports local agriculture, reduces transportation of produce, and (I'm guessing) probably lowers the expense of products. My only concern would be the quality level - but I guess the market would probably demand quality product.

Chicago is home to the largest amount of green roofs in the country.

greenroofs.com

This would be a bonanza in Canada, at least, because the produce is insanely over priced to begin with. The lament (even in the article) that transportation costs (50% of costs of a head of lettuce sold in NY) is overblown. Maybe 50% of wholesale price. Long haul trucking companies charge somewhere around 1.5$/mile and haul about 40,000 lbs in a load. From California to Nova Scotia, around 3,800 miles. That gives about 15c/lb once you factor in local transportation. If that is 50% of the cost then the head of lettuce costs about 10-15c. You buy it at the store for 1.50$ or more.

And that's among the cheaper produce in terms of $/lb. Look at the high value stuff - avocados (I pay 1.5$ each.... in Cali they sell for 15c. Transpo cost is about 4-5c).

I mean what supermarket in Canada would let some schmuck company setup on their rooftops when the margins on the products are so insanely high that they couldn't possibly fail to generate profit by doing the same? It's not like greenhouses on rooftops is a copyrighted idea. I'd love to see it done around where I live, except that the novelty would give them an excuse to jack up produce costs even more.

great idea

I was just in the grocery store......

And I realized that it may be a problem in Canada with currently operating stores. The roofs are built to code to hold a certain amount of snow pack but the additional weight might require a lot of adjustment (probably a lot more expensive than the greenhouses).

But the dissipating heat from within the building would be a bonus.

some of my friends who were engineers were very against sticking ontop of roofs given the history of leakage and all the other structural issues it could create (citing some actual examples including some research greenhouses on the roof of buildings at the university of alberta and the one in saskatchewan). On the other hand with some retrofitting it could be done correctly (or stick it in a parking lot) :P

In my opinion urban farming is only going to become more popular. I think we're going to start utilizing "wasted" space in cities much more in the future. Right now "our" food gets transported vast differences which will almost certainly not be economical in the future. Our current means of growing and transporting food does not seem to be very sustainable. Growing food on rooftops and in window boxes certainly seems to be something that will continue to grow.

oats - you're forgetting that the food also has to be stored prior to and after shipping (all rolled into transportation for most companies), and has to actually get TO the long haul trucking company. In many cases, it's already been transported 1-3 times by that point. I agree 50% may be a bit of an exaggeration, depending on the company, but I wouldn't be surprised at all if it was 35%-40% which is a huge jump in price.

I have to imagine that that the cost:benefit ratio of retrofitting buildings to properly house something like this has got to be pretty good after 4-5 years.

Mmmmm smog flavored veggies

What about the snow? I guess if you keep things warm enough it will melt and run off... or something... otherwise i guess you're shovelling it off?

Other than in heavy snowfall I would imagine a green house stays sufficiently warm to keep itself mostly clear.

in some places in Canada, heavy snowfall over a short period would be a very real concern. However our building codes are such that any snow caused structural collapse is exceedingly rare, even in places like Montreal or Southern ontario where one gets a lot of wet snow in a short period. Greenhouses can be built with glass that can easily withstand any sane amount of snow (plus they would probably have a slopped roof so snow would slide off).

Falling snow and ice from structures is a bigger concern :P

Some greenhouses also run warm water lines along the roof to provide a little extra assistance. We have a few year round greenhouses here in MN, and I'd guess if you can pull it off here you can pull it off just about anywhere.

Living in Wisconsin, I know that a sloped roof is insufficient for a normal roof to remain clear (and if the light doesn't penetrate the glass then the green house is not going to be sufficiently warm). I don't know how different that would be with a glass roof but I still expect that during heavy snowfalls there could be a need for manually clearing.

Who's going to work there, will the increased labor costs be off set by the saved cost of transport?

@detmer: it's a combination of slopped roofs and structural integrity.
As for the transport vs labour costs, depends on what it is I suppose. Note that the "increased labour costs" would only be the difference between the labour needed to grow the food at source vs the labour needed to grow in the green house. There is also the cost of maintaining and powering the greenhouse.
Probably fuel costs will drive this more than labour costs.

Not to mention the cost of labor saved in eliminating/minimizing transportation and logistical staff.

+ it creates local jobs -- something which should be important to local communities :)

I plan to grow stuff at my house once I get one. If I could grow a niche food on a small bit of land well enough, I'd love to sell it for supplemental income.

I want a garden so I can grow my own veggies and tomatoes for sauce.

you're in the perfect area to make it happen Jiman :)

I grow food on my balcony. I'm thinking about getting some grow lights and growing tomaters inside. And then watch as the police raid me because they think it's something other than tomatos lol:P

My parents have a fairly large garden. Even with a mid-sized house, converting the entire yard into a garden is probably only enough to feed you for part of the year (in most of Canada at any rate). Not likely one can make money from that by sellng the veggies, but you can certainly save money and get fresher stuff.