Dive Summary:

• Aitor Erkoreka, a researcher working in thermal engineering, has concluded that rooftop planting can produce desirable results in some cases where thermal energy in concerned.
• Erkoreka found that rooftop planting can be particularly advantageous in sunny environments, reducing cooling needs for buildings, though watering systems are important to achieve the best results.
• He claims that the amount of heat getting into buildings through rooftops can be reduced by as as much as 75%, thanks to the solar energy that plants absorb for photosynthesis and evapotranspiration.

From the article:

... "Just bearing in mind the thermal functioning of the roof, in places where it is not too hot in summer, it is not a good idea to have a green roof fitted, because it would be cheaper to have insulation that is 1 or 2 cm thicker both in the summer and in the winter. But in very sunny places where there is a great need for cooling, a green roof is recommended as it would reduce the demand for cooling considerably.​​" ...