Abstract: False-ceiling construction (10), which is intended in particular for institutional kitchens and which false-ceiling construction is composed of modular units, which comprise at leat an intake air unit (11) and an exhaust air unit (18) and, in the area between them, a false-ceiling plate (25), and which false-ceiling construction is formed underneath the ceiling construction (C) proper in a room. The false-ceiling construction (10) includes at least one flow opening (15), passing from the intake air chamber (13) in the intake air unit (11), for a trap-air jet (L.sub.1a) for making the trap-air jet (L.sub.1a) to flow as parallel to the plane (T) of the false-ceiling plate (25) or as slightly inclined in relation to said plane towards the exhaust air opening (20), placed on the exhaust air chamber (19), for the exhaust air flow (L.sub.2). The invention further concerns a method for the flow of air in connection with the false-ceiling construction.

Abstract: The invention concerns a ventilation device, through which impure air is removed out of a room, in particular out of the proximity of a source of impurities at a working point in the room space. According to the invention, through the device, besides the removal of impure air and/or excess heat from the source of impurities as a limited-area removal, air of general removal is also removed through the device, the suction opening for general removal being preferably opened into the same exhaust chamber into which the suction opening for the space for collecting of impurities in the interior of, for example, a kitchen hood is opened. The device may also include a flow opening for the general intake. Thus, the device can operate as a device for limited-area ventilation and for general ventilation serving for the whole room.

Abstract: A focussed ventilation method and apparatus for a work spot wherein at least a first focussed suction (11) and at least one additional focussed suction (13) are arranged to draw the air and/or gas and/or excess heat of the work spot, and arranged to interact so that the first focussed suction (11) draws the more detrimental air in quality than that drawn by the additional focussed suction (13).

Abstract: A focussed ventilation method and apparatus for a work space, in the method and apparatus suction is focussed on the source of impurities of the work spot and/or on the source of excess heat, and the operation of the focussed suction is assisted with the air blown from a wide surface area at a low speed from an incoming air means.

Abstract: A focussed ventilation system where impure gas, or excess heat is drawn off from a source of impurities at the work space (18). The impure gas, or excess heat is moved to a collection zone located in the room space, wherefrom said impure gas, or excess heat is drawn to be treated further or conducted away from the room space.

Abstract: The invention concerns a displacement ventilation control procedure in which the impurity and/or moisture concentration of the air containing impurities which accumulates in the part of the room or hall space above the staying zone and/or their changes and/or their differences are observed and the ventilation of the room or hall space is accordingly controlled. The invention also concerns a ventilation control unit.

Abstract: An air distribution system for distributing air downward from above with very low velocity. The air distribution system has an air distribution terminal (10) from which the air has been arranged to descend substantially merely by gravity effect, with very low velocity. Desired velocity of descent of the air descending from the air distribution terminal (10) has been accomplished by producing a temperature differential between the room air and the air that is conducted from the air distribution terminal (10).