To celebrate the centenary of Osram Italy's foundation, the firm decided to break away from normal ideas, committing itself to a project of concrete importance for the city of Milan. The first phase, lighting seven of the city's basilicas, involves a symbol of the cultural and religious history of the city in which Osram is based: the Basilica of St. Ambrose (pictured), the town's patron saint. Incorporating the layout of the original church founded in the 4th century by the saint, parts of the present-day basilica date back to the middle of the 10th century.
Work on the system, designed by Osram and installed by Azienda Elettrica Municipale (Milan's Municipal Electricity Board), began with in-depth analysis of the complex structure and different construction materials used. Brickwork typical of Lombard Romanesque architecture making up the majority of the church imposed warm white light (about 3000K). To intervene as little as possible on the monument itself, installation points on poles and surrounding buildings were chosen, but their distance from the zones being illuminated obliged the designers to use a combination of two different types of light.
The ideal balance was obtained using Halodium outdoor fixtures: some are fitted with Powerstar HQI-T 400 Neutral White quartz arc-tube metal-halide lamps, others illuminate with the white-orange light of Vialox NAV-T/400W Super tubular high-pressure sodium discharge lamps. Most of the rest of the system uses Powerstar HQI-TS 70W and 150W Warm White Deluxe lamps in compact symmetric/asymmetric Twin Beam fixtures.
Three more instruments with a slightly colder light (Powerstar HQI-TS 150W Neutral DeLuxe, 4200K) were installed to further accentuate the lantern and apse covering.
To maintain the secluded feel the basilica retains to this day, areas in the vicinity were deliberately left in semi-darkness and the garden was lit with instruments mounted on 12' (4m) poles along the access pathway and 80cm (2.6') poles on the flowerbeds.
Designers Gianpiero Bellomo and Gianni Forcolini found a suggestive way of accentuating the spiritual bond linking the Milanese to this basilica in particular and a feeling of deep faith. They create the impression of the building's internal warmth by using particularly warm lamps in the upper portico of the narthex, bell tower cells, and lantern loggias. The 2700K light spilling out from these represents the votive candles in the basilica, using instruments fitted with 80W Citylight DSX high-pressure sodium xenon lamps. Thanks to their electronic ballast, these can be switched automatically to reduced power to save energy during off-peak hours--the light is not the characteristic orange color, but more akin to conventional filament lamps. The loggias are illuminated by Lumilux Brick EL slimline weatherproof fluorescent fixtures with 8W and 13W Lumilux Mignon (Interna color) linear lamps.
A total of 268 fixtures (approximately 17kW) were used. The other churches to be lit by Osram are Santa Maria delle Grazie, San Lorenzo, Sant'Eustorgio, San Simpliciano, San Satiro, and San Nazaro in Brolo.