A. Definitely. Planet Symphony collated the results of diverse studies to establish that Greening of Roofs can eventually translate to attracting Rain. The Science is quite simple and well known: Transpiration boosts up humidity and greenery attracts moisture from nearby water bodies to land causing precipitation. Studies have also shown that non-green areas repel moisture. Roof Greening reduces temperatures and health-hazardous air pollution, decreases dependency on Air-Conditioners in some areas thereby bringing down both energy bills and warming caused by Air Cons. In the larger context, it regulates micro weather patterns and mitigates or prevents the damages caused by extreme weather due to global warming.
A. In the macro context of a given region over time, yes. Which is why it is imperative for citizens to take this up by at least covering 50-60% of their roofs with greenery. Of course, a number of other factors like wind patterns are involved but transformational roof-greening improves probabilities of regulating local weather.
A: Yes, substantially, according to EPA, USA which cites studies to declare: "Green roof temperatures can be 30–40°F lower than those of conventional roofs and can reduce city-wide ambient temperatures by up to 5°F."
A. There are numerous ways to prevent both including water proof mats, grow bags instead of pots with coco-peats mixed in them to hold water longer.
A. Water is never wasted on plants, it is only invested. Nevertheless, drip irrigation or using grey water that would otherwise be wasted can save millions of liters of water too. Choice of plants apt for local conditions is also vital.
A. The economic savings on energy, health and water can be enormous even with low investment
A. Water is never lost (to outer space) due to transpiration; it always comes back as rain.
Most water used on plants in several countries are not fresh but recycled water which would otherwise run off into sewers. Thus, plants convert “dirty” water into pure rain. Clearly, we don’t “lose” water because of plants. We only gain. It is also very important to not think about this at the level of individual catchments but look at the macro picture and analyse the relationships between different areas of a region in terms of the cross-country or continental transport of water vapour. So greening has only advantages for all of us in the big picture.
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