In a former post I touted the benefit of painting city rooftops white… to help reflect heat and keep energy costs down (especially in the summertime).
But how about one better? What about *green* rooftops? What a fascinating and inspired way to use city space. It seems that green rooftops have an at least three-fold benefit over traditional roofs: they allow space for organic plant life (thereby reducing carbon emissions), they absorb excess water (thereby reducing rain water run-off which can cause overflow in urban sewer systems), and of course provide energy-savings (by providing added building insulation and cooling effects, especially in the city, where the abundance of concrete creates that ‘heat island effect’).
AND – one last benefit – you could even farm your own food up there!
Since we as a people are expanding in population and continue to take up farmable land with our abodes, why not shift the farms up on top of the buildings? No brainer! I saw a post today about the Eagle Street Rooftop Farm in Greenpoint, Brooklyn. It’s an organic farm built on top of an empty warehouse. Check out their site… they just introduced bees into their roof garden, which is not just awesome but probably very necessary, given that bees have been dying a bunch in the past few years and we need them of course to pollinate our plants so they can continue to grow and feed us. (Scary New Yorker article about this here, if you wanna read it. But alert: be prepared for fear!)
On further research, I discovered a company that provides a relatively turn-key rooftop garden solution: Sky Vegetables. They have a (somewhat glitchy) interactive piece on their website that models a rooftop greenhouse, and the related systems needed to support it: compost bins, rain water collection, even a wind turbine. Their site says they can build on urban rooftops of 10k square feet or more; but based on their website, they seem to be more focused on urban agriculture side of things, and don’t much discuss the architectural needs to create or retrofit such a roof (especially in an older city, like New York, where we have lots of new construction but even MORE older buildings, where green roofs would probably make the most impact).
The architects that worked on the Eagle Street Rooftop Garden are called Goode Green, but their website doesn’t talk about the architectural aspects of this type of project either (they posted some beautiful pictures though!). Thing is: it seems like it must be hard to create a green roof, let alone one that can sustain actual farming and plant life. The weight of such a roof must be staggering, making architectural support and structural soundness imperative. Based on limited web-based details, the cost of creating a green roof from scratch, or of retrofitting a building to support one, is higher than a traditional roof. All roofs need adequate waterproofing, but green roofs need root barriers too… additionally, some roofs (depending on the vegetation) will require ongoing maintenance, which can be costly. One can safely say that a rooftop farm would need *constant* maintenance!
That being said, a positive ROI (return on investment) seems like a totally expected result for a rooftop farm. Reduced energy costs, the fact that the greenery on the roof can actually protect and thereby extend the waterproofing lifespan, AND the fact that you could grow your own food up there if you wanted? Triple-winner.
So why don’t more buildings in NYC do this? I guess if you’re a landlord, there’s no incentive. Better to let your building fall into complete disrepair and continue to collect exorbitant rents… why invest in a roof? Sure, tax breaks exist, but the initial outlay of money upfront must make the long-term benefits and the tax breaks seem too far off into the distance to make them worthwhile.
I’ll ask my landlord what he thinks of this and will post his response in a follow-up!
