We recommend that displacement systems are simulated by dividing the room into two levels:
A proportion of the gains are assigned to each level, as described below.
The system air is supplied at low level and passed on to the upper level.
As a rule of thumb, convective gains occurring in the lower level from people, equipment or lights should be apportioned between the levels in the ratio 1/3 to the lower level and 2/3 to the upper level. This ratio reflects the tendency of the warm air to rise in plumes.
The 2/3 ratio must be added as a watts figure as opposed to W/m2, as holes and windows in a floor reduce the calculated watts. Therefore a floor with a 100% hole (or window) will result in no watts from a W/m2 entry.