When I was a teenager on a school trip to Rome I was mesmerized by the Pantheon’s fusion of lighting and architecture. It caused butterflies in my stomach. The visit to the Pantheon is more than just a memory to me. It was the moment that I became aware of the influence of daylight in a room and, of course, on how people experience the room.   The fusion of lighting and architecture in the Pantheon is not a coincidence; it’s designed that way. Daylight enters the oculus, the round opening in the highest point of the domed roof, and hits the floor with a nearly constant daylight factor of 1% – meaning the light is distributed very evenly.   The combination of the geometry of the building, the angle under which daylight penetrates the building and the reflection on the walls of approximately 30% results in an even spread of daylight in the room. In fact, daylight in the Pantheon is so well designed that it doesn’t only light the room, it also forms a solar clock that indicates the time, the date and the beginning and end of the four seasons.   I think it’s sad, then, that daylight seemed to fall out of fashion after the Second World War as re-construction took place as quickly and cheaply as possible. During the 1990s, daylight design started to return to prominence and today its importance is no longer completely overlooked.   But are we making the most of daylight – as the builders of the Pantheon did? No, not remotely.  

Daylight is only considered when all the other parties – client, architect, structural designer, installer and contractor – have finished the design. If the lighting designer keeps costs really low, they are allowed to puncture a hole in the building envelope to ensure the daylight at least meets the minimum requirements.  

Because lighting design is not integrated into the design process, existing knowledge of designing with daylight is not being used to the fullest. And this is despite the fact that integrated lighting design is much easier using modern software tools.