© Christian Richters
© Christian Richters


Seattle Central Library

Order Volume

12.889 m² | 10.405 m²


Rem Koolhaas, Office for Metropolitan Architecture
LMN Architects
Light Planner: Kugler Tillotson Associates




Façade | Roof

Seattle Central Library

Seattle, Washington, USA

At first glance, the new Central Library in Seattle looks more like a stranded spaceship than a public building. Architect Rem Koolhaas sets a contrast to the conventional attire of the venerable institution with his twelve-storey glass prism. Its exciting shape and sophisticated utilization concept are expected to attract new groups of visitors to the library if the client has his way.

The façade resembles an enormous rhombic lattice. The inclined girders of the complex steel construction give it a distinctive appearance, as well as providing protection in the event of an earthquake. 10 000 insulating glass panels, the majority of which being diamond shaped, are fitted into the construction. Most of these insulating glass units have an insert of expanded aluminum, a new development by OKALUX of Marktheidenfeld in Germany for Rem Koolhaas. The glass units OKATECH give the outer skin a metallic sheen and make the façade glint radiantly in the sunlight. As far as visitors to the library are concerned, the insulating glass panels create a soft light in the reading areas, acting as a sunshade and preventing glare. The glazing is semi-transparent: the finely meshed perforation pattern of the intermediate layer allows people inside the building to view the outside world while providing the visual finishing touch for the observer standing outside.



The expanded metal insert is not only a distinctive design element, it also performs the function of a directionally selective daylight system. The thermal sun protection provided by the glazing for a high angle of sunlight incidence reaches minimum values on the high façade sections (g-value up to 0.13 for vertical irradiation). This is due to the innumerable, asymmetrically directed metal perforations. These act as miniature shading elements and make the insulating glass panels a technically perfected synthesis of sun protection and transparency.

In accordance with the more stringent Ug-value (btu) requirements in the USA, triple glazing is predominantly used throughout the library. The details of the window structure are as follows: 6 mm tempered safety glass outside, 2 mm cavity with expanded aluminum insert, 6 mm partially tempered safety glass with a sunlight and heat protection coating. Depending on the position of the glass panel in the building, this is followed by a 8 to 12 mm wide gas-filled cavity and 6 mm partially tempered safety glass or, alternatively, 2 x 5 mm laminated safety glass, e.g. for overhead glazing.

A total of 10 000 panes of glass were fitted in the façade and half of these had customized dimensions – a logistic challenge in terms of production, delivery and installation. The complex façade of Seattle Library was realized by seele L.P. of Chicago, a subsidiary of seele GmbH & Co. KG in Gersthofen. Rem Koolhaas and his Office of Metropolitan Architecture in Rotterdam were given local support by LMN Architects of Seattle, who have already realized numerous public authority projects in the USA.