Code and data for Geometrical Levels of Detail for Indoor Daylight Simulation: An Aperture-aware Definition

Folder structure

• code:
  • jobs: example cluster job scripts.
  • postprocess: post-processing scripts for analysis and visualization
  • src: main source codes for daylight simulations, and cubic-illuminance implementations.
• Figures: figures and plots for both vizualisation and data analysis in the paper.
• inputs: geometries, simulation grids, and weather files for rooms 1 and 2. Please refer to 4TU repository for full access.

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Solid angle calculation

Area-Weighted Solid Angle (AWSA)

The Area-Weighted Solid Angle (AWSA) is calculated as:

$AWSA = \frac{Ω}{A_w}$

where:

• $Ω$ — cumulative apparent solid angle subtended by the window mesh triangles from the centroid of the non-permanent object, counted only when the line between the object's centroid and a triangle's centroid is unobstructed by other objects in the room (steradians).
• $A_w$ — total window area in the room (m²).

The implementation is in input_station.py, function calculate_solid_angle().Threshods class

This includes a visibility check. For example, if from the centroid of the red flower box (❌). the first conjunction point () on the connecting line to the windows () is on the window pane(🟦), then the solid angle of that triangle is added to the total solid angle of the window as seen from the centroid of the flower box.

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Cubic sensor grids and cubic quantities

The analysis grid in this work represents head-poses as shown in the blue region in the figure below, as opposed to the workplane (in red):

This is implemented in cuttle class in cuttle.py , which has two key functionalities:

1. Creates cubic sensor definitions from a given list of points (as a simple .txt) for 2-phase simulation. space_angle is set to 0 by default, which means the cubic point directions will be aligned with the global coordinate system (see the figure below). If a non-zero space_angle is provided, the cubic sensors will be rotated accordingly.

2. Calculates the cubic quantities from the raw Radiance results, with quantities that correspond to those proposed by Christopher Cuttle.

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About the Daylight simulation engine

This respository uses an advance 2-phase annual daylight simulation (see CBDM.py) method based on Radiance v5.4.

Citation

If you use the code/program (or part) of this work, please cite our paper:

@article{FOROUZANDEH2026115367,
title = {Geometrical levels of detail for indoor daylight simulation: An aperture-aware definition},
journal = {Building and Environment},
pages = {115367},
year = {2026},
issn = {0360-1323},
doi = {https://doi.org/10.1016/j.buildenv.2026.115367},
url = {https://www.sciencedirect.com/science/article/pii/S0360132326011686},
author = {Nima Forouzandeh and Lars O. Grobe and Eleonora Brembilla},
keywords = {Standardisation, Radiance, Digital twin, Scan-to-bim},
abstract = {This study proposes a formalised framework for defining indoor Geometrical Level of Detail (GLoD) for daylight applications, based on a solid angle descriptor called Area-Weighted Solid Angle (AWSA). Unlike previous approaches that rely on object size or semantics, the proposed method prioritises the inclusion of non-permanent indoor objects based on their obstruction to window surfaces. This allows for a more relevant abstraction and classification of indoor geometry for daylight simulations. Two use case rooms with single- and multi-sided window configurations were analysed under different sky conditions using Climate-Based Daylight Modelling (CBDM) and evaluated through Total Annual Illumination (TAI) on sensor grids placed either on a horizontal working plane or at multiple six cubic directions. Results show that annual illumination was over-predicted when using the simplest GLoD level (GLoD0), compared to the most complete (GLoD3), up to a 41 % at the working plane and up to 77 % at head positions. Sky conditions influenced absolute TAI values but did not markedly change the relative influence of GLoD on either directional (cubic) or non-directional (work-plane) evaluations.}
}

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License

This repository uses the MIT License. This allows free use, modification, and redistribution with attribution. (see also ./LICENSE)

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If you have any questions, comments, or suggestions, please feel free to contact me at: Forouzandeh.nima@gmail.com; n.forouzandeh@tudelft.nl

October, 2026

Copyright (C) 2026 | Nima Forouzandeh