As the height of high-rise buildings increases, the effect of thermal pressure cannot be ignored. The infiltration of cold air is affected by wind pressure and heat pressure. The following is the common calculation method of the cold air permeability of high-rise buildings under the comprehensive action.
I. hot pressing
In winter, the temperature inside and outside the building is different. Because of the density difference of air, the air in the room enters into the gap between the doors and windows on some floors of the bottom floor, rises through the vertical through passage such as the stairwell inside the building, and then exits from the gap between the doors and windows on the first floor of the top floor. This pressure that causes air to flow is called hot pressure.
The thermal pressure on both sides of the outer door and window gap of the building is only a part of the theoretical thermal pressure P. its size is related to the layout of the internal through passage of the building, the state of courage and the tightness of the door and window gap, that is to say, it is related to the Yin force from the air to the air.
2. Partial pressure of ground heating
In the calculation of cold air infiltration in high-rise buildings, the change of wind speed with the change of building height should also be considered. The wind speed changes with the increase of height are all with regularity.
When the wind blows through the building, the air penetrates through the door and window gap in the direction of the windward side, and seeps out from the leeward side gap. The infiltration of cold air depends on the air pressure difference between the two sides of the door and window. The wind pressure difference between the two sides of the doors and windows is related to the resistance of the whole flow path and the energy of the wind speed itself.