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BIM-based wind-driven rain modelling using ISO 15927-3 and geometry-based exposure

Acquah, Richard ; Niklewski, Jonas LU and Sandak, Jakub (2026) In Building and Environment 295.
Abstract

Wind-driven rain (WDR) is a key source of façade moisture risk. ISO 15927-3 estimates WDR using static wall-factor tables, limited in scope and unable to capture façade-specific geometry or sheltering. This study introduces a BIM‑native workflow that dynamically computes wall factor as a geometry‑derived exposure fraction, evaluated per façade cell via ray tracing and power‑law‑based cell‑level height‑scaling factorization. Implemented in Revit, the method automates ISO corrections for terrain, topography, and obstruction, and outputs exposure fraction, wall indices, and catch ratio with façade-resolved visualization. For the cases studies presented, the BIM-Ray Tracing approach (mean absolute errors 0.03–0.06), achieved accuracy close... (More)

Wind-driven rain (WDR) is a key source of façade moisture risk. ISO 15927-3 estimates WDR using static wall-factor tables, limited in scope and unable to capture façade-specific geometry or sheltering. This study introduces a BIM‑native workflow that dynamically computes wall factor as a geometry‑derived exposure fraction, evaluated per façade cell via ray tracing and power‑law‑based cell‑level height‑scaling factorization. Implemented in Revit, the method automates ISO corrections for terrain, topography, and obstruction, and outputs exposure fraction, wall indices, and catch ratio with façade-resolved visualization. For the cases studies presented, the BIM-Ray Tracing approach (mean absolute errors 0.03–0.06), achieved accuracy close to CFD and outperformed ISO 15927-3 with runtimes suitable for early design. While turbulence and edge recirculation remain better addressed by CFD, the workflow enables exposure mapping, rule-based checks, and integration with ISO 15686 service-life performance analysis.

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author
; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
BIM, Building performance modelling and WDR index, Hygrothermal performance, ISO 15927-3, Rain impact simulation, Ray tracing, Revit plugin, Wind-driven rain
in
Building and Environment
volume
295
article number
114447
publisher
Elsevier
external identifiers
  • scopus:105032355701
ISSN
0360-1323
DOI
10.1016/j.buildenv.2026.114447
language
English
LU publication?
yes
id
806be847-0c04-4a08-8bed-9b4eb9615101
date added to LUP
2026-04-20 14:24:38
date last changed
2026-04-20 14:25:36
@article{806be847-0c04-4a08-8bed-9b4eb9615101,
  abstract     = {{<p>Wind-driven rain (WDR) is a key source of façade moisture risk. ISO 15927-3 estimates WDR using static wall-factor tables, limited in scope and unable to capture façade-specific geometry or sheltering. This study introduces a BIM‑native workflow that dynamically computes wall factor as a geometry‑derived exposure fraction, evaluated per façade cell via ray tracing and power‑law‑based cell‑level height‑scaling factorization. Implemented in Revit, the method automates ISO corrections for terrain, topography, and obstruction, and outputs exposure fraction, wall indices, and catch ratio with façade-resolved visualization. For the cases studies presented, the BIM-Ray Tracing approach (mean absolute errors 0.03–0.06), achieved accuracy close to CFD and outperformed ISO 15927-3 with runtimes suitable for early design. While turbulence and edge recirculation remain better addressed by CFD, the workflow enables exposure mapping, rule-based checks, and integration with ISO 15686 service-life performance analysis.</p>}},
  author       = {{Acquah, Richard and Niklewski, Jonas and Sandak, Jakub}},
  issn         = {{0360-1323}},
  keywords     = {{BIM; Building performance modelling and WDR index; Hygrothermal performance; ISO 15927-3; Rain impact simulation; Ray tracing; Revit plugin; Wind-driven rain}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Building and Environment}},
  title        = {{BIM-based wind-driven rain modelling using ISO 15927-3 and geometry-based exposure}},
  url          = {{http://dx.doi.org/10.1016/j.buildenv.2026.114447}},
  doi          = {{10.1016/j.buildenv.2026.114447}},
  volume       = {{295}},
  year         = {{2026}},
}