LIGHTING PREFERENCES: ROLE OF SEASON, AIR TEMPERATURE, DAYLIGHT QUANTITY, COLOUR OF DAYLIGHT, ACTIVITY, AND ARCHITECTURAL CONSTRAINTS

摘要

The progress of lighting technology offers capability to reduce electric power density for lighting in offices and duration of artificial lighting use through adapted controls. How much energy can we save in lighting? We know that savings of the order of 1 to 2 Euros per m2 and per year are achievable, but not more. The equivalent of 1 or 2 hours of salary of an office worker per year for a 10m2 work place. This demonstrates that the question is in fact raised in the wrong way. It should be: a double question: (1) what would be the best luminous environment at the work place? (2) how could we meet these requirements with the lowest amount of electricity? International standards appear at first glance to be a barrier to energy conservation, since they specify minimum illuminances values. In fact, bringing high illuminances on tasks and lower quantities in the rest of the space can be a way to reduce significantly electric power density (from 15W/m2) to below 10 W/m2. But does this scenario correspond to occupant preferences? Should specified illuminances be achieved at all time or are they only design objectives?