What a planted roof does
Growing food in the city rather than shipping it in changes several things at once. Each of these is a mechanism, not a slogan — here is how each one actually works.
The effects
- Distance
- Food grown on a roof in this city travels streets, not borders. Almost all of the fuel, refrigeration and time that conventional produce spends in transit is simply not spent.
- Water
- A recirculating system reuses its water instead of losing it to the ground and the air. What a plant does not drink returns to the system.
- Heat
- A bare roof absorbs sun and radiates it back. A planted one shades the surface and cools the air above it as the plants release water, which eases the heat that builds up in a city through summer.
- Biodiversity
- Roofs are gravel, asphalt and concrete. Planting them adds green surface to a city that has very little of it outside its parks, and gives insects somewhere to be.
- Air
- Growing plants take up carbon dioxide as they build themselves. It is a small contribution per roof, and it happens in the middle of the city rather than far from it.
- Packaging
- Produce is packed in sustainable materials, at the place it was picked, once.