Velocity variations in ventilated rooms as a method for creating comfort.

The aim is to develop a new method for comfort in settings with high thermal load in buildings that do not require continuous cooling but cooling only during shorter periods. Example of such buildings is schools. The present ventilation and control systems are designed for supply of air at a constant flowrate or to respond to relatively slow variations in load or step changes in load. The slow variations in load are mainly governed by the diurnal cycle and sudden step changes in load are mainly due to people entering or leaving a room. Systems of today are monotonous in the sense that the indoor climate is kept almost constant over long periods. However, there are indications that intermittent variations in velocities can be beneficial to people's perceived comfort. For example when people feel too warm the introduction of a short "breeze" of "high velocity" air may make them feel more comfortable. One example is window airing. The use of (non-turbulent) variations as a stimulus for creating comfort has not as yet been explored systematically or been technically implemented. The idea is to create velocity variations in the head region on people. Both momentum (mixing ventilation) and pure buoyancy driven (displacement system) ventilation are used for creating velocity variations. In addition to using the ventilation system for introducing velocity variations, stirring generated by propellers (ceiling fans) are used. The paper reports on the velocity field obtained in the occupied zone.