Mitigating Urban Thermal Environment through Building Façade Morphology Design: Evidence from Scaled Experiments

Building façades are not merely uniform surfaces but spatial elements shaped by shading devices, balconies, and other architectural features. While the impact of façade materials on outdoor thermal environments is well studied, the influence of morphology remains underexplored. Most research focuses on indoor climate regulation, overlooking effects on exterior microclimates.

This study addresses this gap by employing a 1:10 scaled model of an ideal street canyon in Guangzhou, a hot and humid city, to evaluate how façade morphology, specifically external shading devices, affects the urban thermal environment. Three experimental groups were tested:

• (1) façades with or without shading devices,
• (2) façades with shadings at different angles (45° and 90°).
• (3) façades with varying numbers of shadings (10 and 30 cm).

Measurements were conducted over two days per group in winter (Nov. to Dec. 2024), recording surface temperature (Ts), air temperature (Ta) and black globe temperature (Tg) within the canyon at different heights, and both long-wave and short-wave solar radiation for calculating albedo (see following Fig.).

The results indicate that: (1) External shading devices increased the street canyon’s albedo by 2%, reducing Tg at pedestrian-level by 2.5°C (10%) and Ta by 0.5°C (2%). (2) Horizontal shading at a 45° angle increased albedo by 55%, leading to a 7°C (20%) rise in Tg at the top and a 2°C (7.4%) increase in Ta in the middle section. At pedestrian-level, the differences in Tg and Ta were minimal. (3) Increasing the density of shading devices had a negligible impact on the urban thermal environment.

This study confirms the potential of building façade morphology to regulate urban thermal conditions. Future research will focus on establishing guidelines for climate-responsive design strategies.