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.
A 7000 watt generator us typically intended for 2 - 15 or 20 amp circuits at 120 volts or 1 - 30 amp circuit at 240 volts. When you say, power a house, if you mean the whole house the answer is, No. You would need a generator capable of supplying a continuous 24000 watts or more to do that.