input is delivered to the air as loss through steam or convection and radiation. Without an increase in food temperature, the DOE test procedure would find the efficiency to be zero. Cooking procedures such as reduction of a sauce, braising meat, simmering, and so on are significant uses of a cooker, but efficiency of these practices is not modelled by the procedure. In 2013 and 2014 DOE developed and proposed new test procedures to allow direct comparison of energy transfer efficiency among induction, electric resistance, and gas cooking tops and ranges. The procedures use a new hybrid test block made of aluminum and stainless steel. The proposed rule lists results of real lab tests conducted with the hybrid block. For comparable (large) cooking elements the following efficiencies were measured with ±0.5% repeatability: 70.7% - 73.6% for induction, 71.9% for electric coil, 43.9% for gas. DOE affirmed that "induction units have an average efficiency of 72.2%, not significantly higher than the 69.9% efficiency of smooth—electric resistance units, or the 71.2% of electric coil units". DOE noted that the 84% induction efficiency, cited in previous Technical Support Documents, was not measured by DOE laboratories, but just "referenced from an external test study" performed in 1992. Independent manufacturers tests and other subjects seem to demonstrate that actual induction cooking efficiencies usually stay between 74% and 77% and occasionally reach 81% (although these tests may follow different procedures). These clues indicate that the 84% induction average efficiency reference value should be taken with caution. For comparison and in agreement with DOE findings, cooking with gas has an average energy efficiency of about 40%. It can be raised only by using special pots with fins. When comparing with gas, the relative cost of electrical and gas energy, and the efficiency of electricity generation affect overall environmental efficiency and user cost. Ventilation Energy lost from gas cooking heats the kitchen, whereas with induction cooking, energy losses are much lower. This results in less heating of the kitchen and reduces the required amount of ventilation. Gas stoves are a significant source of indoor air pollution. Gas cooking efficiencies are lower once waste heat generation is taken into account. Especially in restaurants, gas cooking can significantly increase air temperature in localized areas. Extra cooling and zoned venting may be needed to adequately condition hot areas without overcooling other areas. In a commercial setting, induction cookers do not require