There must be ample provision for continuous inflow of fresh air and outflow of foul. The best way of providing this is to build to each room separate air flues, carried up in the smoke stack. An outlet should be formed by a warm flue or exhaust, otherwise it acts as a cold inlet. Inlets are best in corners farthest from doors and fireplaces, and should be made to discharge upwards. Gratings in floors should never be used. Outlets in ceilings must not open in a false roof, but must be properly connected with an extract ventilator. The size of inlets and outlets must be adapted to method of ventilation proposed. A much larger area is required when no motive force is provided. Windows should have top and bottom panes arranged to open inward as hoppers. Besides being continuously ventilated by above means, rooms should, as often as possible, be flushed with fresh air through all windows and doors, fully opened. Sunshine is of particular importance in its effects on ventilation and health.

Ventilation also demands provision of a small swing window, as far from the lighting as possible, and near the ceiling.