Sorry uksparky! I overlooked your reply. Yup, they have essentially copied the temporary housing of building sites.

I'm almost 100% certain that these flats are electrically heated. (Very common in Sweden)
You could be right about the hot water: In fact, I think it could be hot and cold water plus the "return" [Linked Image]

A few hundred metres south of this there is a conventional building site. It has the same type of module. Pic here