OK, I see what they're doing: it's an underground or bermed "room". Of course the temp is lower in winter and higher in summer, but still cooler than ambient. It needs to be ventilated and drained properly and the reason it's called a root cellar is because it appears to be a storage area for produce. But one chap says he can keep milk in his till the sell by date, so I think it'll be good for many things except potentially meat and keeping beer and wine chilled. Kinda knew that though.
Useful, but we'll still need a small propane refrigerator. We will need around $1,000 for a small one, I think. The solar power models are even more expensive... oh well. The bunky is not supposed to be kitted out though - we put real budget into the building of the main house for appliances, but not the bunky. Dreams don't come cheap. That's what research is for.