Photometric calculations are carried out first, using Lighting Reality and DIALux — establishing illuminance, glare control, and obtrusive light performance for a facade concept, or lux levels and uniformity against BS EN 12464-1 for a commercial or workplace interior. Only once the calculation is correct do we develop the layout in CAD and BIM, coordinated with the facade design or the ceiling grid and wider fit-out. Calculating before modelling means the layout reflects a design that’s already been verified, not one adjusted after the visualization or drawing is issued.