Boost Natural Light: Advanced Techniques in VELUX Daylight Visualizer

7 Tips to Get Accurate Daylight Simulations with VELUX Daylight Visualizer

Accurate daylight simulation helps designers, architects, and homeowners make informed decisions about skylights, windows, shading, and interior layouts. VELUX Daylight Visualizer (VDV) is a powerful tool, but results depend on setup and input quality. Use these seven practical tips to improve the reliability and usefulness of your simulations.

1. Start with correct room geometry and scale

• Model the room dimensions precisely: floor-to-ceiling height, wall positions, and any recesses or lofts.
• Include adjacent rooms if they affect light flow (open plans, corridors).
• Ensure openings (doors, staircases) are placed and sized accurately.

2. Use accurate material properties

• Assign realistic reflectance values for floors, walls, ceilings, and furniture. Typical starting values: ceiling 70–90%, walls 30–60%, floor 10–40%.
• For glazing and glazing layers, set correct visible transmittance (VT) and any coatings. Incorrect glazing data is a common source of error.
• When using textured or patterned finishes, approximate their average reflectance rather than default high-contrast textures.

3. Define windows, rooflights and obstructions precisely

• Model the exact type and position of VELUX roof windows or skylights, including mounting height and projection.
• Include external obstructions: neighboring buildings, trees, parapets, and overhangs. Even small overhangs significantly affect direct sunlight and glare.
• For exterior shading devices, model geometry and material (opaque vs. translucent).

4. Choose appropriate sky and weather settings

• Use climate-based sky models (IES or CIE overcast/clear) for the most realistic annual or seasonal analyses.
• For specific times/dates, set geographic location, date, and exact time to capture solar angles and shadows properly.
• When comparing scenarios, keep sky settings consistent across runs.

5. Set sensor grid and view points carefully

• Place illuminance sensors at the correct working plane (usually 0.75–0.85 m for desks) and at multiple heights if needed.
• Use a sufficiently fine grid density in areas with steep gradients (near windows, under skylights) to avoid smoothing important variations.
• For glare assessment, add multiple viewpoint positions where occupants will be positioned.

6. Increase simulation quality where needed

• For quick previews, lower-quality settings are fine; for final decisions, increase sample counts and convergence criteria.
• Use higher accuracy for illuminance maps, daylight factor calculations, and glare metrics (sDA, ASE, UDI).
• Allow more time for rendering when including complex fenestration, light-scattering materials, or detailed landscaping.

7. Validate and iterate with measurements or reference cases

• Compare simulation outputs with on-site measurements (lux levels, measured glare) when possible and adjust material or glazing properties to match.
• Run sensitivity checks: vary reflectances, glazing VT, and obstruction positions to see which parameters most affect results.
• Keep versioned models of key design alternatives to track how changes influence daylight performance.

Final checklist before delivering results:

• Room geometry and openings verified
• Material reflectances and glazing VT set
• External obstructions modeled
• Correct location, date/time, and sky model selected
• Sensor grid placed at appropriate working plane
• Simulation quality increased for final runs
• Results validated or sensitivity-tested

Following these tips will make your VELUX Daylight Visualizer simulations more accurate and decision-ready, helping you optimize natural light, reduce glare, and improve occupant comfort.