DIAL GmbH DIALux 4 for download on their primary website. They officially discontinued support around 2022 to promote DIALux evo, which handles entire buildings and modern BIM workflows. Verified Download Sources for DIALux 4.13
While DIALux evo is the modern standard, version 4.13 is still sought after for several reasons: Older versions of DIALux (Windows) | Uptodown dialux 43 download link
DIALux 4.13: The Complete Legacy Download and Transition Guide DIAL GmbH DIALux 4 for download on their primary website
New in DIALux evo 13: Obtrusive Light Calculation - Facebook dialux 43 download link
: Provides a version history archive where you can find DIALux 4.13 (Windows) .
Since the official link is inactive, you can find the installer through these reputable software archives: