by ArchitectureWeek

The Amgen Headquarters in Thousand Oaks, California, designed by Los Angeles architects Johnson Fain Partners, was already under construction when the firm Pei Partnership Architects was invited to redesign the fourth and fifth floors for the client's executives.

Although a prominent, prosperous biotechnology company, Amgen wanted the top two floors to project a quiet, unpretentious work atmosphere. They wanted to transform a typically cloistered corporate headquarters environment into a space inviting to staff of all levels, so that the executive committee would not become isolated. Large offices and generous open spaces were to reflect Amgen's success without being intimidating.

The 40,000-square-foot (3700-square-meter) executive realm includes offices, conference facilities, and a two-story skylit atrium. Upon arrival at the top floor, visitors are greeted by a light-filled space and views to the distant mountains to the north and south. Scattered throughout the open spaces of the two floors are informal gathering spaces of various sizes.

Pei Partnership had to work fast to complete the design of the building's top two floors. They began when construction of the structural frame was already complete. Their accelerated design process was tightly coordinated with construction management, including repeated cost estimates and subsequent adjustments.

Design architect Ralph Heisel recalls some of the challenges of working within these constraints. He says the best views and daylight for the executive floors were to the north, east, and south. To the west, the view to the mountains was blocked by a new laboratory building which did not, however, block the harsh afternoon sun. The north-south structural bay along the west side was too narrow for offices, so they made it a circulation spine to serve the large conference rooms.

The conservatory was conceived as a device for giving equal status to the two floors of offices for senior executives. Sun shades reduce glare from the west and soften the less desirable view in that direction. The shades also filter incoming light and give the space is distinctive character.

The Pei Partnership Architects, founded by the sons of I.M. Pei in 1992 , does design work around the world and has offices in New York, Los Angeles, and Beijing.

Discuss this article in the Architecture Forum...

The conservatory/ atrium of the Amgen Headquarters. Photo: Fotoworks/ Benny Chan Fourth floor of atrium looking north. Photo: Fotoworks/ Benny Chan Fifth-floor level of the conservatory/ atrium looking toward the loggia. Photo: Fotoworks/ Benny Chan Fifth floor outdoor terrace, off the loggia, with views to the distant mountains. Photo: Fotoworks/ Benny Chan   Click on thumbnail images to view full-size pictures.