Refers to the difference in height between the air intake and discharge. Where intake is situated lower down than the spill in the house.
The temperature inside the building.
The temperature outside at the time that the calculation relates.
With the power that the Earth's gravity counteracts the thermal momentum upwards.
Refers to the density of the flowing medium, usually air
Pressure differential is the difference in pressure created by the thermal forces which causes the warm air rises and is replaced with cooler.