If we are simulating a non-rectangular building with a variety of light fittings at different mounting heights, does this mean that we can't use this program?
"The design calculations are based on the assumption that the room is rectangular, that the luminaires are all of the same type and are all mounted in a symmetrical layout at the same height." If we are simulating a non-rectangular building with a variety of light fittings at different mounting heights, does this mean that we can't use this program?
This description of the design calculation which you quote is correct but the question requires some further clarification:
1)These simplifications are inherent in the CIBSE design method, which we use.
2)The lighting layout is not the input for the design calculation, but the result (a layout that gives the required illuminance below the maximum glare).
3)The design calculation uses a bounding rectangle. This is the minimum size rectangle, aligned with the view x and y axes, that completely encloses a horizontal section through the room at the luminaire mounting height. After the calculation any light fittings that are not within the room volume are automatically removed. So, even for the design calculation, the room shape does not matter.
4)However, the purpose of the design calculation is only to provide a useful starting point for a lighting layout to be simulated. After a design calculation the user can (and often will) modify the resulting symmetrical layout (e.g. add, change, move, or delete luminaires) before doing a simulation (which can cope with any room geometry, mixed luminaires, non-symmetrical layouts and mixed mounting heights). For example, users may want to add wall washes or corner spots, because a symmetrical layout tends to give darker walls and corners.
5)The way the question is phrased indicates that this difference between design calculation and simulation may not be fully understood.
6)If you already know your lighting layout there is no need to run the design calculation at all, but proceed directly to simulation.
