Measurements and control of air motions within a building.

There are a number of methods available concerning with distribution of air in buildings. Within control research, one can find new control algorithms which have not yet been used in practice. These new algorithms open the possibility of developing andimplementing of new demand controlled ventilation systems.In a building the internal air motions are due both to differences in temperature andpressure differences caused by the ventilation system. Therefore, one fundamental question is to what extent it's possible to control the air motions within a building using fan powered ventilation in combination with temperature control.The aim of this paper is to report on measurements done to examine the influence oftemperature differences between rooms on the air exchange through open doors in a buildingand to explore the use of modern control technique to minimise the temperature difference.The result of the measurements shows that even very small (0.1-0.2C) temperaturedifferences between rooms cause bi-directional air flows in the doorways of a magnitude thatexceed the flow rates caused by the mechanical ventilation system. Therefore it is necessary tocontrol the temperatures in the rooms to make it possible for the ventilation system todistribute the air to those parts of the building where it is needed.