Energy savings reported in the study ranged from 9 percent to 10.3 percent for office applications, and 12.7 percent to 17 percent for retail.

Materials & Resources

“Sustainable design is a double-edged sword,” says Dean Hofelich, a senior designer and associate at LDa Architecture and Interiors, Cambridge, Mass., “in the respect that it helps narrow the field of potential finish materials.” Like other interiors experts, Hofelich laments that the field can sometimes be too narrow, but the point is an important one: Certain materials and systems are simply much more sustainable choices than others.

Suspended systems are, in general, a good choice because the base materials “are of recycled content, and can be recycled,” Hofelich explains. Some designers consider the open plenum choice to be a greener choice, because literally “de-materializing” the ceiling would reduce the simple quantity of resources used to build. But as is borne out in the CISCA life-cycle study, there are other implications of that choice more keenly felt in the long run.

After figuring for such considerations as locally sourcing materials, managing construction waste, recycled content, and recyclability, the designer must then consider the intended use in order to properly specify for durability, maintenance, and restorability. In terms of resilience, one potential downside of a suspended ceiling is the ongoing need to access the plenum to maintain other systems—lighting, electrical, HVAC, and data/telecommunications cabling; each time a tile is removed or handled for access, there is some material deterioration of both the grid and the tile. This leads to replacing access panels, tracks, and tiles, and eventually may require refurbishment or replacement of the entire ceiling.

Some types of ceilings are more robust than others, say architects, although the typical cellulose panels in soft metal grids are similarly resilient, says WDG Interior Architecture's Isogai. “We don't see a lot of difference in the performance of different types of suspended ceilings,” he explains. “What we see is that the required maintenance and repair of interacting systems determines the wear-and-tear on the suspended ceiling.”

Another maintenance aspect unrelated to accessing the plenum, says Isogai, but just as common, also involves HVAC system operation. “At the air diffuser locations and return-air registers the ceiling tends to get dirty,” he says, adding, “It is a real challenge to avoid that.” According to ceiling consultants, soil-resistant finishes are available that ameliorate this effect.

Indoor Environmental Quality

Most manufacturers of ceiling products, whether components of suspended systems or finishes for open plenum spaces, offer low-VOC emitting options for the binders, glues, coloring agents, and other component materials used in the ceiling panels and metal profiles. Increasingly, vendors have made the low-VOC feature a standard offering, recognizing the impact of interior finishes on indoor air quality (IAQ).

Other elements of a sustainably designed ceiling might include a reflective finish that enhances a natural daylighting strategy by bouncing light from windows further into the building. Ceilings can also be specified to soften and diffuse harvested daylight in the same way. In each case, the light reflectance (LR) value can have an effect on other performance attributes, such as acoustics.

A suspended acoustical ceiling typically reflects about 75 percent of the light striking its surface,⁴ for an LR value of 0.75. Yet there are recent advances in material and finish technology meant to increase the LR values in order to improve the energy efficiency and overall efficacy of indirect ambient ceiling lighting. Reflecting up to 90 percent of the light that hits their surfaces for a value of about LR 0.90, these newer products can help improve the brightness of interior spaces and reduce energy use by as much as 18 percent, according to the study “Performance Benefits of High-Reflectance Ceilings” by the Weidt Group, an energy and environmental consultancy headquartered in Denver.

Other benefits of high-LR ceilings according to the Weidt Group analysis include better balance of light diffusion—which helps improve occupant comfort and productivity while reducing the potential for glare. Also there is an associated reduction in light-loss factors (LLFs), the measured variables that determine horizontal illuminance or light level (lumens) available in a building space. Most of the LLF inputs are related to lighting system performance: lamp lumen depreciation, ballast factor, and luminaire dirt depreciation. A fourth measure, called room-surface dirt depreciation (RSDD) adds an LLF for dust and soil accumulation on all room surfaces, but especially the upper walls and ceiling. RSDD can be estimated from handbook tables in IESNA Lighting Handbook.

The light reflectance of a ceiling in the United States is generally given by the standard ASTM E 1477-98, Standard Test Method for Luminous Reflectance Factor of Acoustical Materials by Use of Integrating-Sphere Reflectometers. The test is a component of the ASTM Classification E 1264, which determines the luminous reflectance factor (LRF).