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CASE STUDY:
Circular Congregational Church Addition

Charleston, South Carolina

Green, and of Its Time: A 328-year-old congregation, in an architecturally conservative city, commissions a modern church classroom addition with a multitude of sustainable-design initiatives.

By Charles Linn, FAIA

Some architectural review boards have a reputation for being so dedicated to protecting their city’s historic fabric that even seasoned local architects tremble at the prospect of trying to get their approval for work, unless of course, it apes the architecture of the past. Charleston, South Carolina’s board was formed almost 80 years ago, and has a reputation for being tough.

Circular Congregational Church Addition. Charleston, South Carolina
Photo © Richard Leo Johnson/Atlantic Archives, Inc.
Circular Congregational Church Addition. Charleston, South Carolina

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KEY PARAMETERS
LOCATION: Charleston, SC (on the Atlantic Coast at the confluence of the Ashley and Cooper rivers)

GROSS FLOOR AREA: 3,000 ft2 (279 m2)

COST: $1.2 million

ANNUAL PURCHASED ENERGY USE (BASED ON SIMULATION): 16.5 kBtu/ft2 (187.4 MJ/m2)

ANNUAL CARBON FOOTPRINT (PREDICTED): 5.8 lbs. CO2/ft2 (24 kg CO2/m2)

PROGRAM: Classrooms, porches, exterior courtyard, nursery, meeting rooms

Temp./Dew Points   Sky Conditions   Precipitation
Temp./Dew Points   Sky Conditions   Precipitation


TEAM
OWNER: Circular Congregational Church
ARCHITECT: Frank Harmon Architect
LANDSCAPE ARCHITECT: Gregg Bleam Landscape Architect
ENGINEERS: 4SE, Inc.
ENVIRONMENTAL CONSULTANTS: Orbital Engineering (energy); Living Roofs (green roof consultant)
LIGHTING DESIGN: LightTech Architectural Lighting Design
CONTRACTOR: NMB Construction

SOURCES
GREEN ROOF: Sarnafil (green roof waterproofing system), Carolina Stalite (growth media)
COATINGS: Sikkens Cetol 23 (wood rainscreen); Tnemec Typoxy (steel); OSMO polywax (flooring)
ELEVATOR: KONE EcoSpace
DUAL FLUSH TOILET: Caroma Caravelle
HEAT PUMP: FHP Manufacturing
WALLBOARD: USG Synthetic Gypsum
WINDOWS: Eagle HarborMaster with low-e4 coating
LOW-FLOW FAUCET: Sloan electronic
LIGHTING: Lithonia (interior downlights) Lumier; Canplas (exterior)

But, Charleston’s Circular Congregational Church was founded around 1681, making the city review board seem, by comparison, like a relative newcomer. Yet for being such a mature organization, the church’s tradition is not to allow itself to be moored to the past. For example, the white congregation was very vocal in its opposition to slavery prior to the Civil War, and had received African Americans as members since early in the 19th century.

So, when it came time to build a classroom addition a few years ago, parishioners wanted a structure that would be “of its time,” says Whitney Powers, AIA, a member of the congregation who served on the building committee. The two existing buildings on the campus, an 1851 Greek Revival parish house and the 1890 Romanesque Revival sanctuary, were designed in the popular architectural styles of their day. To build something that was a revival of a revivalist-styled building didn’t seem to make sense.

And, they wanted a green building. “We have been touting the ideas of living simply and slow growth for a long time,” Powers says. “We have always been an open and embracing congregation and we wanted our building to continue to be a vehicle for the community to use.”

Architect Frank Harmon, FAIA, was hired to design the addition. The resulting structure respects Charleston’s architectural traditions in its proportions, materials, and color selections, and by using devices such as porches, and overhangs. But it is decidedly not historicist. “We always attempt to respect tradition,” says Harmon. “And, one of the ways that we do that is to choose native materials, and to remind ourselves of the ways that people living here before us would have designed to take advantage of natural ventilation and daylighting. These sound dumb, but it is amazing how often people forget them.”

The basic organization of the building is simplicity itself—two pairs of classrooms stacked one on top of the other, with the parish house at one end, and the stairs and elevator grouped at the other. Extensive windows and glass doors on both the east and west elevations provide cross-ventilation whenever needed, and enough daylight that the compact fluorescent downlights can be turned off most days. Ordinarily, glass exposures to this extent are to be avoided on these elevations, because of the problems associated with glare and heat gain. However, it is possible here because deep balconies shade the first-floor windows, and the second-floor exposures are protected by the overhanging roof. During the late afternoon an adjacent building also shields the west elevation. “One of the big pluses is that all of the circulation is outside, so we did not have to heat and cool it,” Harmon notes.

When heating or cooling is required, ground-source heat pumps are used. The wells are drilled beneath the stairs, and were splayed so they could be placed far enough apart to be effective. An extensive green roof also helps keep the second-story rooms cool. All of the rainwater from the roof is collected and stored for reuse in a cistern beneath the children’s courtyard, a patio on the south side of the building. A traction elevator was installed, which uses about one-third as much energy as an equivalent hydraulic lift and requires no hydraulic oil. This elevator provides wheelchair access to both the second story of the classroom addition, and the adjacent parish house.

The materials chosen by Harmon reinforce the congregation’s commitment to living simply. The exterior is a rainscreen of locally sourced Spanish cypress, complemented by recycled yellow pine flooring. The children’s courtyard is paved with recycled brick, and the meditation garden is covered with loose gravel which minimizes rainwater runoff. The structural frame is made from 67 percent recycled steel on concrete foundations made from fly-ash cement, and the wallboard is 90 percent recycled gypsum. All the coatings and stains have low-VOC content, including the finish of the steel, a specially formulated color called “Charleston Green.”

Most architects are used to working within small footprints and sites which have restricted access. But this churchyard required some sitework that was somewhat out of the ordinary: The remains of church members who had been buried in the churchyard, as well as above-ground vaults and headstones, had to be relocated. “This was an emotional process,” says Powers. But, she says that graves were probably moved when the parish house was built.  This precedent made the decision to do it somewhat easier, but gaining consensus “was still arduous.” 

The addition’s funding was collected from many donors outside the congregation, and the church raised twice what a consultant said was possible. Powers believes the fact that it was a green building helped. She says, “This is because people saw it as a responsible, sustainable, community-centered building.”

 

This article appeared in the November 2009 print issue of GreenSource Magazine.

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