Evaluating the operating Cost o Large Appliances

[Eric Thomas]

Evening all,

Let's talk fridges. Does anyone know how to evaluate the cost of operating large appliances? I could be overthinking this (I'm an Engineer by trade, so that's on brand), but my logic is, if I rent out three units and save $20 per month on electricity. I could save about $720 a year in operating costs. The problem is, I have no idea what metric determines this. If I go down a rabbit hole, I'll eventually learn how fridges work, so I figured I'd ask the BP peeps first. 

Please let me know if this is a massive waste of my time.