Hespeler library both window and mirror

Library buildings are thoughtfully designed. The buildings of Idea Exchange, the Cambridge public library system – Queen’s Square, Hespeler, Preston, Clemens Mill and the new Old Post Office branch – certainly are. Designed and renovated in different eras, each expresses a distinct personality.

The 2007 Idea Exchange Hespeler is a rarity: a building with another entire building contained inside it. Yet it’s not as well-known as it should be.

Kongats Architects, whose work is often strongly perpendicular with crisp textures, designed this award-winner. A sober, brick Carnegie library of 1922, nests within a clean geometry of patterned glass about three times its size.

The Carnegie interior was stripped, but front and side exterior elevations are intact, with many windows and doorways opened up. Between the doubled front facades, the building-within-a-building is cramped, but it works well at the Carnegie’s sides: one anchors a second-floor reading room, the other a beautiful, if underused, stairway atrium. In the former, gauzy curtains screen the expanses of glass.

Outside, few buildings in the region change their appearance with the changing light as much as this one does. Transparent and reflective, a window and a mirror, more or less of each in combination. In bright sunlight, the Carnegie shines through. In shade, from some angles the exterior is a perfect mirror. At twilight, reflected sunset skies superimpose on the glow from inside, a dynamic work of art.

Design disappears. Interacting with it, we’re nonetheless unconscious of it: this article’s typeface does its job best when we don’t notice its design. Design also asserts itself, steering perception and behaviour: our smartphones promise the world through a five-inch screen. Most design, such as that of Hespeler Idea Exchange, does both at once.