Hi I'm new to the forum and relatively new to the trade, I'm doing an assignment at college this is the question,

Calculate the duty of a condensing unit required to maintain the above ground beer cellar at 10 degrees c in an ambient of 27 degrees c. Take U value of the walls and ceiling 0.75 wm2 degrees c. The internal dimensions are 4m long x 3.5m x 2.5m high (ignore the concrete floor)

which formula do i need to work this out, i obviously don't want the answer as that would be cheating,

thanks Jake