ENEA: a green rooftop to help regulate microclimate
The absorption of up to 50% of rainfall, by regulating the flow in urban waste, and the generation of natural ventilation on the external surface of buildings are the main functions of a rooftop vegetable coating in winter.
These considerations result from the analysis conducted by the experts in energy efficiency of the ENEA Casaccia research centre, where an experimental vegetable coating was implemented on the rooftop of “Scuola delle Energie”: a 20-cm thick soil that houses plants resistant to the dryness of the soil as well as the cold.
“Green rooftops are particularly effective in the summer. Thanks to their function of ‘green coating’, they can reduce the temperature of the solar pavement down to 25 °C, with a strong reduction in the heat flow reaching the interior part of the house”, said Carlo Alberto Campiotti from ENEA Energy Efficiency Unit. “Moreover, vegetable coatings are also useful in winter, though for different reasons. They improve the thermal insulation of the building upper floors and they help reduce problems that may be caused by extreme weather events, such as heavy downpours and torrential rains that are increasingly falling on the cities because of the climate change currently affecting the Mediterranean area”.
Green rooftops would have a significant impact on urban microclimate, even if the weight of the vegetable coating – soaked with water – can reach up to 600 Kg/m2: therefore, it is crucial that when designing a green rooftop, technicians perform statistical calculations of the building.