Estimation of irregular obstructed vertical sky components under various CIE skies

Solar radiation and daylight illuminance data on vertical surfaces are crucial for renewable energy utilization and daylighting designs. The prediction of solar irradiance or illuminance on vertical surfaces is more complex than horizontal surfaces under densely-built urban environments. Previously, we proposed a mathematical model to estimate the obstructed vertical sky component (OVSC) under various obstructed skies and the obstructed conditions of infinite-long urban canyons. However, the obstructions may be always irregular in both horizontal and vertical surfaces in real cases. This paper proposes an approach to determine the vertical sky-diffuse component under irregular skyline patterns. Totally, 63 different configurations of the irregular obstructions were identified and the OVSCs were calculated using RADIANCE. The simulated results were used to correlate with those of infinite-long urban canyons. Strong correlations with high determination coefficients were obtained. The findings indicate that the proposed methods are useful for building energy efficient and daylighting designs.