https://github.com/my-hub30/solar-radiation-figure-issue/blob/main/solar%20radiation%20issue.png
Hello friends:
I am writing to seek your assistance regarding a simulation issue we encountered while using Daysim. We have been using Daysim to simulate solar irradiation on building surfaces for a small case study in Singapore based on a weather file collected from the local climate station. However, we found that the simulation results for facades are confusing.
Specifically, we have generated figures for each month, at a fixed time, to show how the facades’ irradiation changes based on global horizontal irradiation (GHI). For a given month and time of day, there is little difference in the angle between sun and buildings, so we would expect the larger the GHI, the larger solar irradiation. However, we have found that for facades, the curve initially increases and then decreases, particularly at times of day when there is no direct irradiation on facades, such as the East facades in the afternoon and West facades in the morning. (See the attached link above) This occurs for all facades and buildings we have simulated in Singapore.
We are writing to inquire about the cause of this phenomenon and how it works in Daysim. We would greatly appreciate it if you could provide us with any insights or explanations regarding this issue.
Thank you very much for your assistance!
