Day and Night, Glass Helps Illuminate Oakland’s New Cathedral

The use of light in architecture can render stunning results. And while the concept is not new, its use as a design focus in Oakland, Calif.’s Cathedral of Christ the Light (winner of an AIA 2009 National Honor Award) is unique. Designed by Craig Hartman of Skidmore, Owings & Merrill LLP’s (SOM) San Francisco office, advanced technologies were employed in order to create a “luminous structure and evocative architecture with modest materials while minimizing the building’s ecological footprint.” Simply put, without the use of glass as a major design element, the resulting project would not have been the same.Located on a two-block site that overlooks Lake Merritt, construction of the Cathedral of Christ the Light began in 2002 with initial design work and was completed last September. Hartman explains there were two key initial design considerations.

“First was the site and then second was a personal interpretation of what the history of the church has been in terms of space and especially light,” says Hartman. “In regards to the site, we are on the Pacific Rim and in a place that is extremely multi-cultural, so we were not designing for a single culture. And then also, was making a building reflective of the Catholic Church’s history in a way that was not just about replicating forms from the past, but trying to find the essence of what that sacred space might be.”

To develop that essence, Hartman worked extensively with glass. He used it to create the qualities of a lantern that would glow during the day from sunlight and in the evening from the light within.

The veil glass, which was supplied by Viracon, played a significant part in making this possible.

“For the veil wall, the glass assembly is an insulating, laminated fritted unit. And each assembly component has its own performance task,” explains Keith Boswell, technical director for SOM. “The insulating glass (IG) units were used for two reasons: first, to provide the highest-performing make-up of low-E IG for minimizing heat gain and heat loss. Secondly, since we are going to have a temperature gradient from low to high due to the displacement cooling, we needed to minimize the amount of condensation we would get compared to either a laminated unit or a monolithic unit.”

Perhaps one of the most awe-inspiring features of the cathedral is the Omega Wall, which re-images a 12th-century sculptural depiction of Christ from the façade of Chartres Cathedral in France.

“There are two ends of the building, the entry side (the Alpha wall) and the alter side (the Omega wall). The entry end faces due south where there is bright, direct sun,” says Hartman. “In both walls we have a surface of glass on the exterior, which is triangulated in order to allow the surface to conform to a compound, complex surface. There’s a curve at the base and it tips inward and upward and creases at the top. The sanctuary within is protected by a second layer of 1/8-inch thick aluminum panels that mirror the glass in a triangulated pattern. However, the aluminum (which is about 18 to 24 inches in board of the glass) is designed differently in the way it relates to the light. On the Alpha side we have tipped these triangulated panels inward as they move upward, and as they tip back and forth between one another. We can take the very direct, bright sun from the south, bounce it off these inwardly tipped panels onto a neighboring panel–much like the pedals of a flower opening up to bright sunlight–and that creates a dramatic condition of light on the panels.”

Hartman continues, “It’s the same design on the Omega wall except the aluminum panels are folded up tight against one another. What we have done there is perforate those panels with small holes that range from ¼ inch to 1-¼ inches and within that range there are about 140 sizes from big to small. We used these to create a gray scale and using computer techniques we applied this to a scan of a re-created image of Christ. We’ve translated that into this veil where you read pixels of light coming through these openings in the metal from the translucent glass behind.”

He continues, “The idea was to make this image, like that of the overall building, change as the quality of light changes. So it comes and goes; it really is like a veil, which sometimes, depending on the nature of the light, is very strong and vivid. That’s typically when the light is strong on the outside and less so on the inside. As you get more light, either through light coming off the ceiling and down on the surface of the image or as light becomes brighter on the inside moving toward evening … that begins to diminish in its intensity,” Hartman says.

Per direction from the diocese, the cathedral had to be built in such a way that it would still be standing centuries from now. It’s also a significant example of how glass can be used to create something that’s actually more than what it may appear to be.

“In terms of using of glass, the idea was to create an architectural structure about light and the atmosphere so that you [see] the building [differently] throughout certain times of the day. What’s new and different is that you also read it with light from within; the light is carried from the sun striking the inner side of the veil in which the face itself [the image of Christ] becomes luminous,” says Hartman. “What we have done is consider glass not just for its transparency, but about how glass can be used in combination with other materials to create a more profound experience of light.”

To read more about the Cathedral of Christ the Light, don’t miss the March-April edition of the Architects’ Guide to Glass and Metal, available in booth 1855 at the AIA National Convention taking place April 30-May 2 in San Francisco.

*Photo by Timothy Hursley; provided for use by SOM