Comparing two solar-clad roofs in Sydney, Australia, one is exposed under its panels and the other is decorated with native grass and plants. It is found that the average efficiency of the panels on the green roof is increased by 3.63%, and the average daily output is 13% larger than that of the traditional roof. . It is believed that these improvements stem from the lower temperature of the green roof, thanks to its plants-which also provides many additional benefits.
The roof of Daramu House in the Barangaroo area of Sydney’s inner city is covered with local grasses and plants. Its roof garden was completed by Junglefy in September 2019.
The roofs of two adjacent office buildings in the Barangaroo district of Sydney provide researchers with a rare opportunity to see the true impact of green roofs on solar arrays. The results of the study are substantial—compared to traditional roofs, the average daily power output of solar arrays installed above plant beds is 39 kW, or 13.1%, which is higher.
The research was led by Peter Irga of the University of Technology Sydney and funded by the Sydney City Council to study the traditional array of International House and the green roof array of Daramu House (called dual solar roof).
In the eight months of their study, both roofs produced a lot of solar energy. The traditional roof produced 59.5 MWh, while the green roof produced 69 MWh.
“Despite the similarities in architecture and location, the effect of urban geometry on the solar irradiance on each roof is obvious outside the time when the sun is close to/at the peak of the sun… During these times, green roofs produce The average energy output is about 6% higher than that of a traditional roof. Before and after these hours, the influence of urban geometry confounds the reportable efficiency (-3.6 to 16%),” the study wrote.
After correcting for these differences, it was found that the efficiency of the panels on the green roof increased by 3.63% on average on any day. Thereafter, during the eight-month study period, the green roof generated an additional 9.5 MWh of green electricity, corresponding to a retail market value of US$2,595.
It is believed that this increase in efficiency stems from the fact that green roofs are much cooler than traditional concrete roofs during the day, which means that the panels will not overheat and therefore perform poorly. In some cases, the temperature of the green roof is as high as 20°C, and the temperature fluctuations at night are much smaller.
Although it is becoming more and more popular, there is currently a lack of research confirming the benefits of green roofs. In addition, the study pointed out that “few studies compare similar buildings exposed to similar environmental conditions due to close proximity.”
In addition, the significant increase in the output of solar panels also found that the insect species diversity of the green roof increased nine times, and the bird species diversity increased four times. It also reduces some air pollutants, improves rainwater management, and improves building insulation.
“In terms of the magnitude of the positive impact relative to costs, green infrastructure may be the simplest and most effective measure we can take to help our cities achieve sustainable development,” the study wrote.
The authors of the study described their findings as “substantial,” although they noted that only two roofs were monitored.
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Post time: Aug-25-2021
