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Modeling shows green roofs can cool cities and save energy
(techxplore.com)
This is a most excellent place for technology news and articles.
Interesting that they note that the installation and upkeep are expensive. I wonder if they've factored the upkeep into the energy expenditure. Flat roofing is far worse than a pitched room for needing replacement etc.
Basically, it sounds good, but the research needs to consider the full lifecycle of these projects.
It also takes a toll on the sunlight below.
I still somewhat like the idea, but maybe it should be some carcasses above the actual roofs, so that roof maintenance would be easier (maintenance of these gardens as well, I think).
And no trees, just grass, moss, plants like wild grapes.
In that case maybe it won't have to be flat roofing.
8% reduction in peak AC usage would be huge. I don't have a good feel for numbers like that but I'd imagine it would take a lot of maintenance and roof replacements not not make a saving given that kind of energy reduction.
It would be nice if they could estimate some uncertainties and show where the break even is between energy reduction and upkeep energy expenditure.
Perhaps terraced rooftops with drainage pipes under the soil so excess water can still drain into a gutter system to storm water collection.