This makes it easier to find appliances and calculate the cost of appliances by groupings. Default wattages for given appliances are listed in the next column. Of course, appliance wattages vary, and the results are only as good as the inputs you select. That would be the GIGO aphorism - garbage in, garbage out. So, if you have a better wattage, input that number in the watts box.
Many appliances do have a wattage listing on the appliance.
Hours of operation per month. In the last column, again, defaults are entered, but the final calculation is only as accurate as your input here. For example, the number of hours per month your furnace operates, is typically not known. You can simply estimate, or you may wish to track the operation more closely on an average day during the heating season to figure a more accurate estimate. Remember, this entry is for the number of hours this appliance is used each month.