To calculate the change in temperature, subtract the initial temperature from the final temperature. Example: 84.2 degree Fahrenheit - 41 degrees Fahrenheit = 43.2 degrees Fahrenheit. The temperature from morning to afternoon changed by 43.2 degrees Fahrenheit.
It needs 12 volts so it will be the standard modern power supply provides 12 volts of power.
Volts are units to measure voltage and watts to measure power, hence the question is not answerable in the current form. When you use electricity from a 220VAC socket outlet, the power in watts that you consume depends on the amount of current that flows from the socket in addition to the voltage level of 220VAC.