What an interesting problem! As a mechanical engineer I know that this could be simplified to a lumped capacitance heat transfer problem. If you wanted to get

What an interesting problem! As a mechanical engineer I know that this could be simplified to a lumped capacitance heat transfer problem. If you wanted to get a little fancier you could setup a thermal circuit, but that wouldn't take more than a few minutes. Looking up a few constants and knowing the number of cars in the garage would enable you to know not just why the garage is hot, but roughly how hot it should be on a given day. This is a great example of why it is important to work with people in other disciplines when trying to solve a problem! I can't tell you the first thing about javascript or web hosting, but I've got heat transfer locked down.