» Twenty-one years after its completion, the High Museum in Atlanta has a new lease on life. Its collections and signature building, designed by Richard Meier, now happily cohabitate thanks to a renovation by Atlanta-based Lord, Aeck & Sargent (LAS), in conjunction with London-based Arup Lighting.

The museum's original home in the adjacent Memorial Arts Building had little daylight. 'It was not a pleasant place for people to be,' explains Marjorie Harvey, director of architectural planning and design for the High Museum. 'When we started working with Richard Meier, we knew we wanted daylight in the galleries.'

Ultimately, however, Meier's design brought too much light into the museum. Locations such as the fourth-floor galleries, were illuminated with an average of 1,000 footcandles, drastically exceeding the accepted practice of allowable light for a museum setting and artwork conservation, as outlined in the IESNA Lighting Handbook. According to the IES handbook, light-sensitive media such as watercolors should only receive 5 footcandles, and less sensitive media such as oil paintings should receive 20 footcandles

Over time, the museum, in order to exhibit its collection within the difficult lighting conditions, made several of its own alterations-closing over the fourth-floor gallery skylights, building walls in front of windows and installing brown mechoshade inserts in each atrium curtain-wall window module. 'We were able to control the light, but we compromised the architecture,' states Harvey.

The museum's current expansion provided an opportunity to renovate the Meier building in order to bring the daylight under control while maintaining Meier's original design intent. In order to evaluate the scope of work that such a renovation would entail, the museum hired Arup Lighting to prepare a feasibility study.

Arup conducted an extensive field survey of existing conditions and light strike areas. Using a program called Radiance, developed by Lawrence Berkley Labs in California, Arup was able to model to the exact year, day and minute the sun's travel path at any spot in the building. The museum, out of necessity, had actually created its own document-a sort of flip chart of transparencies that noted the day and time of light strikes, with a different color for every month. The worst scenario was in June and July, when the diagonal wall on the third floor received an extreme light strike lasting for 20 minutes. This flip chart dictated where certain artwork could and could not be displayed, and made, from a curatorial point of view, very user-unfriendly galleries

The challenge was to reduce natural light and prevent UV transmission, glare and light strikes within the balcony and adjacent galleries, while adhering to the stringent footcandle requirements. LAS and Arup looked at passive and active technologies, including static blinds and moving parts internal and external to the building, and prismatic glazing on louvers.

To control ultraviolet light, the renovation called for window films on the different glass surfaces throughout the building-the glass block, gallery skylights, and atrium skylight and curtain wall. The glass block surfaces use a film that allows 20 percent light transmission; the pyramid-shaped skylight employ a film that permits only 4 percent light transmission; and the atrium curtain wall uses the most transparent film, allowing 70 percent light transmission. In conjunction with the films, white static shades, fixed at top and bottom, shield each window module. The combination of the film and shades reduces the quantity and penetration of light and instead creates a diffused daylight.

LAS and Arup were aware of the aesthetic implication of applying a series of films to these highly visible glass surfaces, and architect and lighting consultant devised a series of mock-ups to test different films. Darker films were found to be too reflective and visually apparent. The final selection was a series of products from UK-based SUN-X.

The technical and design solutions for the High Museum have exceeded expectations. Arup's visit report in October 2003 noted that 'in all the galleries a UV proportion of less than 10 microwatts per lumen is achieved, and complies with the most stringent UV transmission criteria.' From the beginning of the renovation process, the focus for LAS, Arup and the museum was to preserve the intent of the building while not sacrificing the collection. LAS and Arup worked closely with the museum controlling architectural elements, creating places for the display of certain kinds of artwork, as well as visitor comfort issues. 'People are attracted to light, art and architecture,' says Harvey. Now the High Museum accomplishes that in a daylighting tour de force.

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SIDEBAR: Predicting Daylight at High Museum: The Technology
»Several different computer software tools were used to evaluate and predict daylight conditions at the High Museum. These programs aided the architects and lighting designers in their decision-making process regarding the remedial steps to be taken towards corrective daylighting measures, and also served as new ground in improving the presentation of technical data to clients.

In order to produce the two main software presentations-the sun penetration animations and the Daylight Analysis VR application-the building geometry was first modeled in 3D Studio Max using detailed plans and sections provided by the architect. The detailed geometry was then imported into Radiance, a powerful UNIX-based daylight and electric lighting analysis and visualization tool, developed by Lawrence Berkley Labs in California. Radiance was used to visualize the penetration of the sun into the building for a number of key dates of the year via a series of individually rendered Radiance images combined in Quick Time Professional. Radiance was also used to calculate the luminance due to daylight at thousand of point within the 3D model for every daylight hour of the year, based on real measured weather data.

The combination of 3D model and analysis data from Radiance was used as the basis for Arup Lighting's Daylight Analysis VR application. Key navigation position points are established on the plan to direct users to areas of interest. The user can navigate through the model using the keyboard and select a display wall for further study. When a wall is selected, the user can select a day and time of the year, which then generates a false color image on the wall highlighting the daylight distribution at that time. The false color image is automatically regenerated when the user selects another time or day of interest. Detailed statistical data such as average and maximum footcandle levels are also generated. The annual exposure distribution can also be viewed for each wall. The High Museum renovation project was used as a case study in the development of this VR application. It is the result of internally funded work by Arup Lighting, as the firm seeks improved methods of conveying large amount of highly technical data to clients in a clear and direct means during the design process.

The other form of presentation/study tool used was a series of QuickTime animations. Two hundred individual Radiance renderings were merged together using Quick Time Professional to study the sun penetration within the building. Four views were studied on each gallery floor at the three main solar dates: the summer solstice on June 21, the winter solstice on December 22, and the vernal equinox on March 21. Different colors are associated with the building's five different glazing systems. When viewing the animations, the sun patches each have a unique color depending on the glazing system through which the sun penetration occurs; thereby informing the design team where shading systems were required to prevent unwanted sun penetration in the galleries.

These tools make it possible to work with an ever-increasing volume of complex data, enabling architects and designers to advance the design process and daylighting technology. elizabeth donoff

Lord Aeck & Sargent Architecture John Starr, Principle in Charge; Joshua R. Gassman, Project Architect; Linda Warming, Interior Designer
Arup Lighting Andrew Sedgwick, Director, Arup Lighting; Arfon Davies, Associate; Trevor Loveland, Senior Modeller

This text was prepared with the assistance of Arfon Davies, Associate, Arup Lighting.