Every luminaire has a photometric light distribution which determines if it is "volumetric." A direct/ indirect unit and a recessed basket unit with a convex prismatic refractor that directs light to the high corners of the room is "volumetric," while a deep-cell parabolic troffer
or a recessed downlight is not.
Newer installations replaced the prismatic lens with the parabolic troffer
. While the parabolics tended to reduce the glare experienced on computer screens, most recently, architects and engineers are using either indirect or indirect/direct luminaires to mitigate the effects of cave lighting and glare, and they are integrating the lighting solution with the overall design of the space.
They found that users preferred a design with direct/indirect lighting and most disliked a design with the standard deep-cell parabolic troffer
found in most offices today.
The parabolic troffer
may still be the majority selection by designers in these spaces if all factors are used.
As to luminaires, in a recent experiment comparing a low brightness, deep-cell parabolic troffer
to one with a convex lens basket with a wide-spread light distribution, where both are installed in identical 10-ft by 10-ft offices, 60 unsophisticated observers came up with the following conclusion: They overwhelmingly voted that the low brightness parabolic was less glary than the convex lens unit, but nevertheless, overwhelmingly agreed that they preferred to work in an office with volumetric brightness.