ABSTRACT
Natural ventilation is an economic means of providing air changes in a building. Older homes had varying degrees of air leakage and a natural ventilation that ensured a healthy internal environment. Ventilation and heating for an assembly hall or similar building may be achieved by admitting cool external air through low level convectors. Larger ducting in a ventilation system will require a higher velocity to maintain a pressure drop equivalent to the smaller distribution ducting that it serves. The capital cost of installing mechanical systems is greater than natural systems of air movement, but whether using one or more fans, system design provides for more reliable air change and air movement. Passive stack ventilation passive stack ventilation is a system of vertical ducting from room ceilings to roof outlets providing ventilation by stack effect and wind passing over the roof. Additional rapid or purge ventilation is also required for every unit of office accommodation.
