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While much is known about the impact of glazed facades on indoor thermal temperatures and energy efficiency, University of Adelaide researchers are exploring its effect on outdoor conditions.

PhD candidate Elham Sanagar Darbani, School of Architecture and Civil Engineering, explored the impacts of the emissivity - the ability of material to emit radiation - of the glazed facades of buildings typical of the Adelaide skyline on outdoor environments.

"We studied how the glass' emissivity affected the mean radiant temperature (MRT) and longwave radiation (LW Rad, commonly known as infrared IR)," said Elham.

"MRT helps to show us how a human body can be impacted by the exchanges of radiant energy with its surroundings; when the MRT is higher than the temperature of the exposed skin or outer layer of clothing, the body experiences a net radiative heat gain.

"Thermal comfort depends on the body's heat exchange with its surroundings, which is influenced by differences in temperature between the body and its environment.鈥�

"This is incredibly important as so many people work outside, and it also affects pedestrians."

Elham, together with Dr Ehsan Sharifi and Professor Veronica Soebarto, collected data from the Mawson, Benham and Braggs buildings on the University's City East campus.

The findings were published in the journal .

"Braggs was the main focus of the study, but together they form an urban canyon similar to typical layout in the city of Adelaide. Braggs is a relatively new structure composed of approximately 40 to 50 per cent glass, 30 to 40 per cent metal panels, and 10 to 20 per cent concrete," said Elham.

"We ran 64 simulations for the city's hottest and coldest days in 2024, each representing a different combination of glass emissivity and facade orientation to see how it would affect the MRT and LW Rad."

Emissivity levels ranged from regular, untreated glass with a high emissivity to advanced, energy-efficient coatings, which have a very low emissivity.

"Results show that higher-emissivity facades increase MRT and LW Rad, particularly in summer, making the outdoor environment feel warmer to people,鈥� said Elham.

"MRT emerged as the most sensitive parameter to emissivity changes, with seasonal variation affecting comfort. In winter, higher emissivity slightly improves the cold conditions, while in summer, lower emissivity enhances outdoor environment with a higher rate.

"The highest MRT occurred around 3pm on a summer day and noon on a winter day and when the facade faces West at 15:00, the MRT decreases by 3.6 掳C in summer and 4.0 掳C in winter, if the glass emissivity is reduced from its highest level (regular glass) to its lowest (low- energy efficient glass).

"By contrast, when the facade was oriented to 135掳 from North, which was identified as the coolest orientation during summer, the MRT reduction at 3pm is more modest, dropping 1.16 掳C in summer and 1.05 掳C in winter."

Using low emissivity glass would reduce the MRT by up to 5掳C in summer, with marginal penalty in winter, said senior author Professor Soebarto.

"If we can reduce the emissivity of glass used in buildings, it will improve the outdoor temperature and comfort in those spaces," said Professor Soebarto.