Roofs are intentionally made to shelter man from sunlight, wind and other environmental factors beyond his manipulation. But with diminishing arable land for agriculture, roof no longer serves to comfort human. It may potentially provide appropriate space for crop production.
Also known as “living roof”, a green roof is a building roof planted partially or completely with vegetation. It is composed of a growing medium where plants are maintained and additional layers such as waterproofing, root barrier, drainage, and irrigation systems. The term “green roof” does not include roofs colored green (as with green roof tiles or roof shingles) and roofs with container gardens (where vegetation is planted on pots).
Depending on the depth of planting medium and the degree of maintenance required, green roofs are classified as intensive and extensive. The former requires considerable depth of soil, are labor-intensive, and require irrigation, drainage, and other maintenance. Intensive green roofs may grow herbs, shrubs, and small trees. On the other hand, extensive green roofs carry a light layer of vegetation (such as mosses), are lighter than intensive green roofs, require minimum maintenance, and are virtually self-sustaining.
Green roofs serve several functions. Firstly, they reduce heat and lower urban air temperature to combat island heat effects. They also reduce cooling loads on buildings from fifty to as much as ninety percent. In other words, green roofs are great thermal insulators for buildings. Furthermore, green roofs help reduce storm water run-off and filter pollutants and heavy metals from rainwater, as well as pollutants and carbon dioxide in the air. Natural habitat for wildlife can also be created on green roofs. Above all, they offer agriculture space which urban areas lack.
Green roofs are very much prevalent in many countries like Switzerland, Sweden, Germany, Iceland, United Kingdom, Canada, France, Greece, Spain, Egypt, USA, and Australia.
Imagine a community where buildings are coupled with green walls (http://scienceray.com/biology/ecology/agri-tech-green-walls/) and green roofs. People shall be harvesting crops and picking flowers right on their roof and walls. What a world it will be!See what others think about "Agri-Tech: Green Roofs."