Ventilation and Air Leakage

Denver heating and air companies define air leakage is the passage of air in and out of various cracks or openings in buildings. It is also sometimes referred to as infiltration. Air leaking into a building may be caused by wind pressure or by differences in temperature inside and outside of the building. In the former case the wind builds up a pressure on one or two sides of a building, causing air to leak into the building. The action of the wind on the opposite side or sides produces a vacuum that draws air out of the building.

When the wind hits the front side of the building, its momentum builds up a pressure higher than inside the building, which causes the air to leak through any cracks present. AS the wind traverses the length of the building the air currents as the continue past the other side converge and produce a vacuum along this side by induction. Because the pressure on the outside of that side is lower than the inside of the building, air leaks out. Air leakage due to temperature difference or thermal effect is usually refereed to as stack or chimney effect. Air leakage due to cold air outside and warm air inside takes place when the building contains cracks or openings at different levels. This results in the cold and heavy air entering at low level and pushing the warm and light air out at high levels, the same as draft taking place in a chimney. This should be considered when designing for optimal HVAC and furnace efficiency.