A well-insulated electric oven is used 24 hours per day to heat treat steel parts in a factory. Parts are loaded into the oven and heated to 2200 F. To load and remove parts, every 20 minutes the oven's 3-ft by 4-ft door is opened for two minutes. With the door open, heat radiates into the factory as a black body. 1. When the door is open, at what rate (BTU/s) does the oven lose heat? Ignoring the energy necessary to heat the steel parts from room temperature, what is the oven's average power (KW) consumption? . If electric power costs $0.15/KW-hr, what is the cost ($/day) associated with opening and closing the furnace door?