Before revision: SI units: {| border="0" cellpadding="2" |- |align=where: | |- !align= ΔP |align== available pressure difference, in mmWC |- !align= Mg |align== molecular weight of gas, in g / mol |- !align= a |align== atmospheric pressure, in kPa |- !align= h |align== height or distance, in m |- !align= To |align== absolute outside temperature, in K |- !align= Ti |align== absolute inside temperature, in K { |} Induced flow The draft (draught in British English) flow rate induced by the stack effect can be calculated with the equation presented below.
After revision: SI units: {| border="0" cellpadding="2" |- |align=where: | |- !align= ΔP |align== available pressure difference, in Pa |- !align= C |align== 0.0342, in K / m |- !align= a |align== atmospheric pressure, in Pa|U.S. customary units:| border="0" cellpadding="2"|-|align=where:| |-!align= ΔP|align== available pressure difference, in psi|-!align=C|align== 0.0188, in °R/ft|-!align= a|align== atmospheric pressure, in psi|-!align= h |align== height or distance, in ft|-!align= To|align== absolute outside temperature, in °R|-!align= Ti |align== absolute inside temperature, in °R |- !align= h |align== height or distance, in m |- !align= To |align== absolute outside temperature, in K |- !align= Ti |align== absolute inside temperature, in K { |} Induced flow The draft (draught in British English) flow rate induced by the stack effect can be calculated with the equation presented below.