I enjoy comparing the Dutch architecture to the Danish. I suspect the kitchen might be what got called a "summer kitchen" where I grew up in the US... a separate kitchen intended for use in the hot seasons where you didn't want the warmth in the house. And the potato house would be similar to a root cellar or a spring house. Does it have cold water running through? In the US (I grew up in PA) a lot of places had spring houses where there was a natural spring or perhaps near a stream. The cool moving water channeled through the building and being built down into the ground a bit worked like a natural fridge in summer and in winter often helped prevent freezing. Things like milk would be set into the water, if they had it, and the room would be used for storing potatoes, carrots, apples, etc. In many areas the ground would permit digging them deep enough under the house to have a real cellar that would stay cool despite the hot kitchen above, but a lot still used a separate root cellar or spring house, especially if the ground was rocky. They didn't have to dig as deep that way.