Told you there’d be more on this later. I did a little research into what it takes to build a green roof. A lot, it turns out. First, you need to collect a ton of data for the specific rooftop you will be planting. Temperature, rainfall, weather conditions, air quality: All of this must be measured, preferably for a complete year in order to understand seasonal averages. That’s the boring part. Plus, with so much climate change, how can anything have an average anymore? The IPCC just reported that weather anomalies (see: Polar Vortex, drought in the West, etc.) are going to continue due to climate change. Data is still important, but perhaps its relevance is waning in today’s rapidly weirding environment. But, I digress.
Once the data is collected, the right combination of grasses, shrubs and ground cover can be selected. If you’re planning to use the space for agriculture, this is also the time to explore the types of plants you want to use. A design will be created based on aesthetic and space constraints. Then, concrete will be poured over the roof and given time to dry. This should be done at the end of the rainy season and allowed to set throughout the dry season so that any cracks or leaks can be repaired before planting. You definitely don’t want to plant the roof and then realize there’s a leak!
Then, comes the planting. See graphic below for layering details:
Assuming your green roof is rain-fed (which is the whole point), minimal maintenance is needed. You just wait for it to grow! Benefits include better insulation/cooling in the summer, a drastic decrease in rainwater runoff, the potential for water harvesting (the plants filter out any pollutants), and the possibility of growing your own vegetables. Start-up costs are relatively low, it just takes time.
Has anyone tried to start a program that builds these in the Middle East? Or, for that matter, in Central or South Asia? How revolutionary would that be?
DC GreenWorks (local to me)
Med-O-Med (where culture and environmentalism meet. Focused on the Mediterranean, based in Spain)
EPIC Green Solutions (working to start the green roof movement in the Middle East)