VENTILATION

Sun (Auckland), Volume III, Issue 919, 12 March 1930, Page 6

VENTILATION

Human Senses the Best Guide TECHNICAL SUBJECT Queer notions regarding ventilation appear to be 'commonly held. Many People imagine that lofty rooms necessarily provide an abundance of breathable air, but this is very far from being the case. It has been found by experiment that the expulsion of used air from the lungs does not affect air at a height of more than 12£ feet from the floor. If mechanical ventilation be resorted to, the whole of the air in a room may become breathable, provided always that the mechanical apparatus bringing in fresh air or taking out foul air. is provided with sufficeut inlets and outlets. Fans which simply stir up air already used are worse than useless. The best level at which to extract the heated air from ordinary living rooms appears to be at from eight to ten feet from the floor. This heated air is not always the worst for breathing, since many of the poisonous gases are heavier than the ordinary atmospheric air, and so remain at low levels. The subject of ventilation is a highly technical one, and heating and ventilating experts constitute a very highly specialised calling in many large communities. Draughts are excluded from a welldevised ventilation system, which depends for its success on the frequency with which the air content of an apartment is changed. The number of times an hour the entire contents of a room should be renewed depends on the particular uses to which it is devoted. * Wherever it is obtainable, natural ventilation is to be preferred to mechanical, since the best mechanical apparatus is subject to breakdowns. The human senses are perhaps the best guides in determining whether apartments are well or ill-ventilated, but these are not infallible, since continued occupation of an ill-ventilated room may cause the occupants to accommodate themselves gradually to an increasing degree of vitiation, the results of which .are only seen later. If such a room 'be left and returned to, however, normal senses will discover the danger and common sense will usually seek and supply the remedy.