Shirvanabad Old Town Courtyards

The quarter had been lit for twenty years by 6000K wall packs on the building corners, at levels well above anything the standards asked for, and residents still described the lanes as unsafe. The reason was visible within ten minutes of the first night walk: every fitting was a bare source at eye level, so pupils were permanently constricted and the doorways between them read as black holes. High illuminance had produced low visibility. That is a common and expensive mistake.

We removed the wall packs and rebuilt the scheme around vertical illuminance on faces rather than horizontal illuminance on paving. Low bollards and recessed step lights now hold four lux average on the lane surface, but semi-cylindrical illuminance at 1.5 metres never falls below 1.5 lux anywhere on the route, which is what actually lets one person recognise another at ten paces. Overall connected load across the quarter fell by sixty-eight percent, and the residents association reported the lanes as brighter.

Colour temperature carried the second half of the argument. The sandstone is a warm ochre and 2200K amber renders it far closer to daylight memory than the 4000K the municipality initially specified. Amber also sits well outside the peak sensitivity of the insect populations the ecologists were worried about along the eastern wall, and it made the retained tungsten lanterns on the mosque forecourt sit correctly in the same picture rather than looking orange and abandoned.