Question about TRANS_VEG in wall temperature calculation

[nilswallenberg]

Discussed in #824

^{Originally posted by kg85112 March 16, 2026}
Hello developers,

My name is G. Kang, and I would like to ask whether vegetation shadow transmissivity (TRANS_VEG) is being properly reflected in the wall temperature calculation.
I am using the version that includes the wall surface temperature (simple step heating) scheme from Wallenberg et al. (2026).

After using the code, it appears that:

1. For ground / roof,
   TRANS_VEG is converted into psi, and then directly applied in the shadow-surface temperature-MRT calculations through an expression such as:
   => shadow = sh - (1 - vegsh) * (1 - psi)

2. For wall surface temperature,
   it seems that the geometric information of how much of the wall is shaded by vegetation is included, but the vegetation transmissivity term psi does not appear to be directly included in the wall temperature calculation itself.

At the same time, in some wall-related radiation calculations, such as in Kside_veg_v2022a.py, psi seems to be used for vegetation-related weighting.

So my question is:
Is TRANS_VEG intended to be properly reflected in the wall temperature calculation in the current version, or is the current structure such that it is not directly included in the wall temperature scheme itself?

I am asking because when I set TRANS_VEG = 100, the ground + roof results respond differently, while wall temperatures still appear relatively high.

Thank you very much.

G. Kang