ignition energy Ignition energy is the spark energy (in joules) which ignites the most easily ignited mixture of the test gas with air at atmospheric pressure. All flammables (including dusts) have minimum ignition energy (MIE) input required to initiate combustion. The MIE depends on the specific chemical or mixture, the concentration, pressure, and temperature. The MlE’s of a few typical gases are: Gas Ignition energy (pJ)