I don't know. You wait all year for a single-room house-shaped tube with wall-to-wall glass at each end to arrive, then two come along at once. First we had Bunkie, a sort of spare-room-in-your-yard with bunk beds craftily squirrelled away in the walls and roof. Now we have Bunkie's spiritual bigger brother, 2by4-architects' Summer House, with its unfolding, and even-more secretive walls.

Summer House (or, apparently, Island House if you prefer) is a physical embodiment of that least obtainable of architectural golden chalices: the building that fools its occupants into thinking they're outdoors. Summer House takes a mighty-fine swing at it. One of the fully-glazed walls slides away to open up much of its surface, and the adjoining PlatoWOOD wall turns out to to be a gigantic door, so that entire corner of the house opens up to the lake that the house sits by.

The opposite wall is replete with nooks, crannies and hidey-holes with all of the absolute essentials Summer House needs to function. Shower, check. Toilet, check. Kitchen sink, check. Storage, check, check, and thrice check. Unhidden but nevertheless useful is the fireplace that is suspend from the ceiling, the only intrusion the designers have permitted into the spartan white-epoxy space.

The steel-framed construction covers 32 sq m on a man-made island in the Netherlands' Loosdrechtse Plas lakes.

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