Case study: Mt. Airy Public Library
Fig. 1. Exterior view showing south- and west-facing clerestories with exterior light shelves that extend natural light onto the ceilings while shading the large windows below from high summer sun.
While home for Thanksgiving in North Carolina, I visited, with my father, a small city near the Blue Ridge Mountains that served as the model for the town of Mayberry on The Andy Griffith Show. The public library makes a strong case for passive solar and daylighting design… while being a good neighbor, too.
Funded in part by a U.S. Department of Energy Program, the 1984 Mt. Airy Public Library by Mazria/Schiff Associates (now Mazria Odems Dzurec) provides a straightforward, contemporary facility and great case study of passive solar and daylighting techniques.
Using good siting strategies, sawtooth rooftop clerestories, a butterfly roof, light shade louvers, and interior and exterior light shelves, the building uses about one sixth as much energy per square foot as a nearby municipal building.
From Mazria Odems Dzurec’s website entry:
“The library plan (Fig. 2 above) is organized around a circulation spine and main lending desk, from which the librarian can have visual control of the building. A saw-tooth clerestory above the structural bays provides daylight (Fig. 3 below) over the circulation desk, reading areas and reference stacks. A butterfly roof configuration with glazed ends (Figs. 6,7 below) and a central elongated light well provides illumination for the open stacks area.”
“Passive cooling in the building is achieved in a number ways. Shade trees and a light-colored roof membrane reduce the impact of solar radiation in summer. Operable windows allow for natural ventilation when the weather permits, and thick white colored masonry exterior walls provide the thermal lag necessary to delay the effect of the summer sun on the interior until the evening hours when the library is closed. Passive heating in winter is accomplished by storing the heat gained through south facing windows and clerestories in CMU walls, the concrete structural elements and the tiled concrete floor slab.”
The day of my visit was a perfect storm of bad conditions - low temperatures, rain, fog, and overcast skies on a winter day.
Fig. 3. Reading room, lower level, showing sawtooth roof monitors above the structural bays and fixed aluminum shade louvers aligned with the tops of the reinforced concrete frame.
Illumination at interior
Fluorescent ceiling and task lights were on throughout the building. Without a light meter, illumination levels at reading surfaces appeared to be more than adequate, especially in the children’s area (Fig. 4 below). While difficult to perceive the overall character of the building in exclusively natural light on such an overcast day, the general ambience seemed inviting and the perception of a higher ceiling created an interior skyscape striking in its own right, yet not distracting to patrons or staff.
I saw no one looking up to see what sorts of crazy stuff overhead was bringing natural light in. Of course, there were no clouds passing by on a very bright day… everything was admittedly rather muted on a day of this sort.
I was the only person looking up at the ceiling, and people did a good job of going on about their business and ignoring the fool with the camera!
Fig. 4. The well-scaled, well-lit children’s area.
Fig. 5. Reading room looking south, showing fluorescent task lights above computer terminals.
Fig. 6. Looking east toward stacks, showing one half of the underside of the butterfly roof and glazed end (far right).
Fig. 7. Closeup of lightshelf (center right) and butterfly ceiling (top) used to disperse and diffuse natural light over the stacks which enters south-facing clerestory (top right).
Fig. 8. The ramped and stair portion of the building joins reading areas, reference, and open stacks (sorry the photo is a little blurry).
Fig. 9. Exterior view of reading area showing south- and west-facing clerestories with exterior light shelves.
At the exterior, south- and west-facing clerestories with exterior light shelves extended natural light onto the ceilings and deep into reading spaces, while shading the large windows below from high summer sun (Figs. 1, 9 above). These are further augmented by a light court onto which the staff wings overlooks; the aforementioned sawtooth rooftop monitors over the circulation desk, reading areas and reference stacks; and the butterfly roof over the open stacks.
As mentioned before, this building’s concentration on passive solar and daylighting strategies is exemplary for a building of any size or type, and is especially well-suited for a library.
Let’s hope the roof is well-maintained!
Two other strengths of this building seem to be often overlooked in critiques:
The ramped (and stair) portion of the building (Fig. 8 above) not only brings users in wheelchair or on foot together, allowing them to seamlessly navigate a building on a steeply sloping site (an integral solution that anticipates the Americans with Disabilities Act by six years), the change in levels successfully delineates spaces, helps define their character, and introduces a dynamism of views and perspective often missing from relatively small public buildings.
Siting and massing
While the building has the commanding presence befitting a municipal building, its beautiful sloped site with a few well-located mature trees is left uncharacteristically and generously open (Fig. 1), partly due to skillful massing. Surface parking has been kept to a minimum, and the approach to the entrance is both inviting and vintage Modernist. Expanses of hard-wearing North Carolina granite used on the broad, low facades belie an interior in which not a foot of square space is wasted.
- Vital Signs - an analysis by Berkeley architecture students
- Official website for the City of Mount Airy, N.C
- Andy Griffith Playhouse
- Blue Ridge Parkway
Note: Though I had visited once before, I visited this building in 1992 with my Environment and Building Systems class from Virginia Tech, taught by Prof. Mark DeKay, later to become co-author of Sun, Wind, and Light.