Sensitivity Analysis of Albedo Assumptions in Urban-Scale Solar Irradiance Simulations

초록

Purpose: Urban-scale solar irradiance simulation is complex owing to the influence of surrounding urban morphology. Existing studies have often oversimplified surface albedo by assuming a uniform, generic value, failing to reflect real-world variations. This study quantifies the impact of albedo assumptions on simulation results, focusing on building-integrated photovoltaics (BIPV) on vertical façades—an advancement beyond previous studies centered on rooftop photovoltaics. Method: Urban-scale solar irradiance simulations were conducted using 10 geometrically identical models with varying surface albedo settings. A synthetic model representing building stocks with realistic albedo parameters was developed as a baseline for comparative analysis. Nine alternative models with different albedo assumptions were generated to assess the sensitivity of annual solar irradiance predictions on exterior façades. Simulations were performed using ClimateStudio. To further evaluate the impact of the surrounding urban context, a novel indicator—Weighted Mean Albedo Difference (WMAD)—was introduced. Result: Albedo variations from the baseline model had a minimal impact on rooftop solar irradiance, aligning with previous research. However, a significant influence on solar irradiance was observed for vertical façades, directly affecting BIPV energy yield. Sensitivity to albedo assumptions strongly correlated with surface orientation and surrounding albedo distribution. Greater discrepancies between simplified assumptions and realistic values resulted in higher simulation errors. These findings underscore the critical importance of precise albedo representation in urban-scale models to ensure reliable BIPV potential estimations.

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