aia/architectural record continuing … · perforated metal and wood ceilings: sustainability,...

Architectural Record Version: 01Issue Date: Dec 05Page No: 1

Filename: AR_Ceilings_PlusWriter/Designer: Angela Haliski/Alison DeFilippisLast Revision: 11-28-05

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Ceilings account for about a third of interior surface areas in most buildings and are often abuilding’s largest and most visible interior surface. As a result, ceiling design andspecification decisions are among the most important prerogatives of design professionals.

A plethora of ceiling systems is available to contemporary designers. While each type mayhave its place in the contemporary palette, it is arguable that perforated ceilings most fullyexpress the adventurous spirit of contemporary architecture.

Consider:• Advances in computer-aided design and manufacturing (CAD/CAM) techniques make it

affordable to create ceilings of almost any size and shape, ending the aesthetic tyranny of the 2 x 4 feet grid.

• High-speed and versatile perforating equipment allows designers to create an almost unlimited range of visual textures and patterns.

• A new type of wood panel makes it practical to perforate wood, creating exciting new design and performance options for wood ceilings.

• Perforated ceilings can meet the objectives of sustainable construction and are being used in LEED certified buildings.

• New acoustical technology makes it possible to use perforated panels to satisfy the need for improved acoustics in architectural projects.

Form-Giving PotentialRapid advances in computer-aided manufacturing (CAM) and product engineering havemade it possible to fabricate customized perforated panels. Ceiling panels can now befabricated to almost any size and shape, with design information from architecturaldrawings used to produce the automated fabrication instructions. This new design processallows architects to break away from the regimentation of traditional grids by using largerpanels that better fit the scale of a room and by creating panels with radii and compoundcurvatures that can flow throughout a freeform space.

Automated punches can make as many as 7,000 perforations per minute. To satisfy thedesigner’s vision, each hole can be in a unique size, shape, and location. This allows panelsto be perforated with an unlimited variety of patterns and unique designs. For example,perforations can be slots, polygons, and oblongs, as well as more traditional circles andsquares. Custom perforation patterns can create corporate logos or graphic motifs on theceiling, and the density of holes can vary from one end of a panel to another to create theillusion of motion.

Perforated Metaland Wood Ceilings:

Sustainability, Acoustics, and

Aesthetics

Provided by Ceilings Plus

By Michael Chusid, RA, FCSI

Raising the standards for acoustical performanceand design flexibility

CONTINUING EDUCATION

Use the learning objectives below to focus your study as you read Perforated Metal and Wood

Ceilings: Sustainability, Acoustics, and Aesthetics. To earn oneAIA/CES Learning Unit, including one hour of health safetywelfare credit, answer the questions on page 12, then follow thereporting instructions on page 11 or go to the ContinuingEducation section on www.ceilingsplus.com and follow thereporting instructions.

LEARNING OBJECTIVESAfter reading this article, you should be able to:• Recognize how advances in computer-assisted fabrication

create new options for the design of customized ceilings.• Understand how perforated ceilings contribute toward Leadership in

Energy and Environmental Design (LEED) credits and environmental considerations beyond the scope of LEED.

• Know about new hybrid wood panels using wood or bamboo veneer on recycled aluminum cores.

• Understand how the acoustical characteristics of perforated panels can be used to meet a variety of architectural challenges.

The planetarium in the Rose Center at the American Museum of NaturalHistory, New York, established a benchmark for perforated acousticalpanels. Designed by Polshek Partnership, the 87 ft. diameter sphere isclad with pearlescent metal panels and perforated to absorb noise in theresonant glass-box enclosure. Fabricating the precise compoundcurvature of the panels was only possible with recent advances incomputer-assisted manufacturing.

Photo Courtesy: Ceilings Plus

1Perforated Metal and Wood Ceilings: Sustainability, Acoustics, and Aesthetics

Reprinted from Architectural Record, December 2005

AIA/ARCHITECTURAL RECORDCONTINUING EDUCATION Series



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Perforated Metal and Wood Ceilings: Sustainability, Acoustics, and Aesthetics


The same machinery that punches the perforations can also be used to create openings forthe installation of lighting and other ceiling-mounted fixtures.

Perforation size, layout, and spacing can vary to create an open area as large as 50 percentor more of a panel. In addition toaffecting appearance, this open areahas practical implications such aswhether fire sprinklers can beinstalled above a ceiling or whetherpanels can be backlit to create aluminous ceiling.

Perforations are also the key toboosting the acoustical performanceof panels. In a post-occupancyevaluation of over 180 workplaces, theCenter for the Built Environment

found that building occupants reported more dissatisfaction with acoustics in theirworkplaces than any of the other parameters measured. Architectural acoustical demandsare higher today due, in part, to the challenges of improving employee satisfaction in openoffice environments, maintaining patient privacy in healthcare settings, and addressingnew noise sources such as cell phones and desktop multimedia.

Perforated ceiling systems deliveroutstanding acoustics. Perforatedpanels typically achieve noisereduction coefficients (NRC) of NRC.75, and even as high as NRC .95 withadditional insulation. More

importantly, perforated panels can be tuned to satisfy the acoustical requirements ofdifferent rooms, such a providing speech privacy in an open office, clarity in a meeting room,

and richness in a concert hall. Tuning an installation is accomplished by changing theperforation pattern, the type and placement of any acoustical insulation, and the distancefrom the panels to the structure above the ceiling. Noise reduction characteristics can varysignificantly among similar ceiling products. When specifying ceiling products, architectsshould review test reports and available information to assess performance qualities. Oncomplex projects, an acoustical consultant can be an invaluable member of the design team.

Perforated Metal and WoodMost perforated ceilings are made of sheet metal. While perforated steel panels areavailable, the trend is towards the use of aluminum panels that are lighter in weight andcan have higher recycled-material content. Metal ceilings are available prepainted in a widespectrum of colors, with mirrored or anodized surfaces, and with other unique finishes tofit almost every style or taste.

Recent advances in perforating wood ceilings expand design options still further. Untilrecently, wood panels were made with wood veneers laminated to wood or particleboardcores. The resulting panels were heavy, especially where large panels were required, anddifficult to fabricate into curved surfaces. The acoustical performance of wood panelswas limited by the cost to drill holes in the panels. Even with “gang-drilling,” makingholes in wood panels was slow. The heat from high speed drilling could char a wood core.This meant that perforated wood panels were practical with only limited design optionsand a relatively small percentage of the open area necessary for a full range of noisecontrol options. Drilledpanels, for example, aretypically limited to NRC .45,far below the NRC .75 to .95required in rooms with criticalnoise control requirements.

This has changed, however, withthe development of wood panelswith wood architectural veneerslaminated to lightweight coresof sheet aluminum. Untilrecently, it has been difficultto get enough adhesionbetween wood and aluminumto meet the challenges ofarchitectural service. Thisproblem has been overcomethrough the use of new

Customized perforations are a newmedium for design expression, asdemonstrated in this showroom atNeocon West.

In addition to acoustical perforations, panels can be prefabricated withprecision-located holes for lighting, fire sprinklers, public addressspeakers, and other ceiling penetrations, as demonstrated by Skidmore,Owings and Merrill’s new AOL Time Warner Building in New York City.

Photo:Ceilings Plus

Photo:Ceilings Plus

High levels of noise reduction and glare-free illumination were required inthe First Alliance call center in Irvine, CA. To satisfy both requirements, awhite non-woven acoustical fabric was attached to the top of perforatedceiling panels and back-lit to create a soft, luminous ceiling.

Photo:Ceilings Plus

A new type of architectural wood panel ismade by laminating 1) real wood veneer to 2) light gauge sheet aluminum. For acoustical performance, panels can beperforated and used in combination with 3) an non-woven acoustic fabric insulation.

Photo: Ceilings Plus

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3

Automated equipmentcan perforate panels at7,000 holes per minute.

Researchers found buildingoccupants report more

dissatisfaction with acoustics thanany other parameter measured.






adhesives and a substrate pretreatment that changes the molecular texture of the aluminumsheet for improved tenacity. Aluminum cores, unlike typical wood and particle board cores,are non-combustible, will not support mold, and do not warp when exposed to changes inhumidity. This last point means that construction schedules can be accelerated by installingpanels before HVAC conditions in a building are stabilized.

The new wood-metal hybridpanels can be fabricated onthe same machinery used toperforate and shape metalpanels. The result is realwood panels that weigh aslittle as one pound persquare foot, a fraction of theweight of panels withconventional wood cores.Their light weight makesthem easy to handle andinstall, reduces the cost ofthe substructure from which

a ceiling is suspended, and makes it possible to use wood ceilings in remodeling projects wherethe existing structure could not carry the weight of conventional wood panels. While the weightof conventional wood panels typically requires them to be mounted permanently in place, hybridpanels can be mounted with torsion springs or other simple connections that allow panels tosnap into place and to be removed as required for convenient access above a ceiling. The newtype of perforated wood panels also display the same high acoustical performance and designflexibility as metal panels.

Despite these innovations, new wood panels stillmeet the quality standards of traditionalarchitectural woodwork. For example, veneershave different grain characteristics dependingupon whether they are plain sliced or rotary,

quarter, or rift cut. Different visual effects can also be achieved by specifying the panels tohave book, slip or random matched leaves of veneer. In addition to use on ceilings, these newwood panels are increasingly used on walls for wood paneling.

Going beyond tradition, however, the wood-metal hybrid panels offer superior sustainablequalities, such as finishes with zero volatile organic compounds (VOCs) and, when specified,veneers from sustainable forests or rapidly-renewable sources, in addition to the recycledcontent of their aluminum cores. And while urea formaldehyde, considered a “probable humancarcinogen” by the Environmental Protection Agency, is still used in many conventional woodproducts, the new wood panels have no added formaldehyde.

SUSTAINABLE CEILINGS AND LEEDEnvironmental characteristics can be critical to the design of a building seeking to complywith the U.S. Green Building Council’s (www.usgbc.org) Leadership in Energy andEnvironmental Design (LEED) program. LEED provides a framework for achieving sustainability.The program is based upon a checklist of criteria that, if met, earn credits toward LEEDcertification of the project as a sustainable building.

Over a dozen LEED prerequisites and credits can beimpacted by a building’s ceilings. Ceiling systems cancontribute directly towards LEED credits. This analysisis based upon LEED for New Construction, Version 2.1; .Version 2.2 is scheduled for release in 2006.

Recycled Material Content (LEED Credit MR-4):Ceilings are now manufactured with a wide range of recycled materials, including metal,paper, glass, and slag. Of these, metal ceilings can have the greatest recycled content;some ceilings are now produced with up to 85 to 98 percent recycled aluminum, including

as much as 75 percent post-consumer recycled content primarily from beverage containers.Steel used in ceiling suspension systems can have between 25 percent and 30 percentrecycled material content.

There are ready markets for scrap aluminum, and the material can be recycled repeatedlywithout degradation of its metallurgical properties. Recycled aluminum requires only fivepercent of the energy needed to make aluminum from bauxite ore. Recycling is a relativelyclean process that produces little pollution other that that associated with the energy usedto melt and process the metal.

Local/Regional Materials (LEED Credit MR-5): Using materials produced near the locationof a project supports the region’s economy,stimulates regionally-responsive architecture,and reduces the energy consumed in transport.Ceilings can help a building qualify for this

Torsion springs hold panels snugly against a concealed grid. With a gentle force, however,panels can be pulled away from the grid sothat the springs can be squeezed and releasedfrom the grid. Panels can then be removed orswung out of the way for maintenance.

Photo:Ceilings Plus

Book-matched, quarter-cut eastern hard maple was selected by YostGrube Hall Architecture for the Kelly Engineering Center at Oregon StateUniversity in Corvalis, OR. The project is expected to receive LEED Silver certification.

Photo:Ceilings Plus

About 18 beverage cans are recycled per square foot of aluminum ceiling.Used cans and other scrap are taken to local reclamation plants wherethey are shredded, melted, formed into ingots, and rolled into sheets.Since a relatively small amount of energy is necessary to melt and reusealuminum, aluminum ceilings have only low entrained energy content.

Photo:Ceilings Plus

Over a dozen LEEDprerequisites and

credits can beimpacted by a

building’s ceilings

Wood panels can providehigh acoustical performance

and design flexibility.

Perforated ceilings can bemade with 85 to 98 percent

recycled aluminum.



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credit if raw materials areextracted or the place offinal manufacturing iswithin 500 miles of theproject. Aluminum ceilingscan be especiallyattractive with regards tolocal extraction ofmaterials. This is becausealuminum made fromlocally collected beveragecontainers can beconverted back to sheetmaterial at small, oftenlocal, reclaimers.

Rapidly RenewableMaterials (LEED CreditMR-6): Bamboo can growto harvestable size in aslittle as three years,regenerates withoutreplanting, and requiresminimal fertilization orpesticides. As aneco log i ca l l y - f r i end l ymaterial, bamboo enjoysgrowing acceptance as an

architectural finish and an alternative to wood in products such as flooring. Recently,bamboo has been introduced as a finish for ceiling panels. Veneers of bamboo arelaminated to recycled aluminum cores in the same way described above for wood panels.

Certified Wood (LEED Credit MR-7): To encourage environmentally responsible forestmanagement, wood ceilings can be made with veneers from sources certified to maintainsustainable forests. For assurance that wood products delivered to a project are actually fromsustainable forests, the ceiling fabricator must be listed with the Forest Stewardship Council(FSC) and must prepare a chain-of-custody certificate for wood building components.

Low-Emitting Materials, Composite Wood (LEED Credit EQ-4.4): Whether made fromtrees or bamboo, the new wood panels contain no added urea-formaldehyde resins in eitherthe aluminum core or the glues used to laminate the veneers.

OTHER LEED CREDITSThe performance of a ceiling system has a significant impact on a number of other criteriawithin the LEED program, even if the ceiling itself is not the direct basis for evaluatingclaims for LEED credits. For example:

Building Systems Commissioning, Measurement and Verification (LEED PrerequisiteEA-1 and Credit EA-5): For optimum energy efficiency, HVAC and other building systems mustbe readily accessible for adjustment and maintenance. This means that ceilings must allowaccess to mechanical or electrical equipment located above the ceiling and that ceilingpanels must be easily removable and resilient enough to be handled without damage.

While lay-in grid ceilingsallow panels to beremoved and replaced,conventional mineralfiber panels are frangibleand can be easilydamaged. And traditionalwood ceilings allow onlylimited access becausesuch panels are heavy.

These limitations havebeen overcome by thenew generation of metaland wood ceilings. Theseceiling systems haveexceptionally lightweightpanels that reduce theeffort required forinstallation and handling.Their light weight alsomakes it practical to usel a rg e r- t h a n - n o r m a lpanels to permitimproved access to aboveceiling equipment. Theyare mounted onto a concealed grid with torsion springs that allow panels to swing out of theway or to be removed and replaced without special tools.

Improved Energy Performance (LEED Prerequisite EA-2 and Credit EA-1): Lightingaccounts for an estimated 20 to 25 percent of annual energy consumption in the UnitedStates. Improving the light reflectance of ceilings can help conserve this energy. Dependingon the finish selected, metal ceilings can provide outstanding light reflectance values. Thehighest levels of reflectance are provided by polished metals with mirror-like finishes. Whilethese are visually exciting, they create too much glare for use in most spaces. Instead, alight-colored matte finish should be used to diffuse light and create conditions for bettervisual acuity.

Indirect lighting can often provide better-quality, glare-free illumination than old-styletroffer luminaires. Their performance, however, depends upon having a reflective ceiling thatwill diffuse light uniformly. In addition, a ceiling must be easy to clean to preventdegradation of the lighting.

Perforated ceilings made with rapidly renewablebamboo and recycled aluminum helped earn aLEED Silver Rating for the recently completedClinton Presidential Library in Little Rock,Arkansas. Designed by Polshek Partnership,bamboo in the 9,000 sq. ft. ceiling wascarbonized by heat-treating until it obtained therich amber color desired by the architect. Thebamboo was laminated to recycled aluminumand custom perforated to provide the desiredappearance and a high noise reductioncoefficient. And because the panels are solightweight, they could be provided in sizes up totwelve feet long by four feet wide to fit the largescale of the Library's exhibit halls.

Photo:Timothy Hursley

Indirect lighting takes on a soft, ambient qualitywhen reflected off the curved wood ceiling in theAmerican Airlines Admirals Club at Los AngelesInternational Airport. According to Rivers &Christian, project architects, conventionalacoustical materials would have absorbed sootfrom the jet exhaust that pervades aviationfacilities; perforated wood panels, however, canbe easily cleaned. They selected hybridwood/metal panels because conventional curvedwood panels were too expensive, heavy, andcould not provide sufficient noise reduction.

Photo:Ceilings Plus

Even large perforated panels can be installed with torsion springs thatallow panels to swing out of the way for above-ceiling maintenance. Thisphoto from the Clinton Library also shows one way that lighting can beintegrated into an attractive design.





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Minimum IAQ Performance and Ventilation Effectiveness (LEED Prerequisite EQ-1 andCredit EQ-2): Indoor air quality (IAQ) depends, in part, on having air diffusers and ventilationdevices that distribute air efficiently and effectively. CAD/CAM fabrication allows metal andwood panels to be fabricated to incorporate diffusers and ventilation devices into an integratedceiling that offers both high performance and a tailored appearance.

Another IAQ approach is to minimize the potential growth of mold, mildew, and othermicroorganisms within a building. The new breed of perforated panels has smooth, densesurfaces that minimize opportunities for growth of microorganisms and can be easily cleaned.Conventional mineral fiber ceiling panels often contain cellulose that can provide nourishmentfor microorganisms. And both mineral fiber panels and glass fiber insulation can retainmoisture necessary for microorganism growth. Perforated panels, however, do not have eitherof these drawbacks since they use a new type of non-woven acoustical fabric that does notsupport microorganisms.

Construction IAQ Management Plan (LEED Credit EQ-3): Perforated panels contribute onlyminimally to indoor air contamination during construction because they are fabricated off-site,reduce on-site cutting and finishing, typically do not contain frangible materials that releasefibers or dust, and have smooth, dense surfaces that are easy to clean.

Daylight & Views (LEED Credit EQ-8): One of the most useful strategies for bringing daylightinto a space is to locate windows as high as possible along exterior walls. This can be at odds withthe desire to drop ceilings so that ducts and other utilities can be run above the ceilings. The newgeneration of ceilings accommodates both needs through the innovative use of curved ceilingpanels to create light scoops or accommodate clearstory glazing and high window walls. Equallyimportant are reflective panel finishes that can help make the most of natural lighting.

Concave panels form light scoops to bring daylight and views into the office carrels in a new National Institute of Health laboratory. Project architectsHLM Design choose metal panels and a non-woven acoustical fabric insulation to meet the lab’s hygienic requirements, and a reflective panel finish for optimum lighting.


At the Guam airport, Gensler used convex ceilings over concourses toprovide maximum depth for ductwork while rising to capture daylightfrom clearstories.






6 Perforated Metal and Wood Ceilings: Sustainability, Acoustics, and Aesthetics

Penn State Building Uses Unique Panel System

Penn State University’s new Information Sciences and Technology Building demonstratesthat metal ceiling panels can deliver unprecedented precision and customization yet stillremain affordable. An S-curve in the building’s plan requires panels that appear to curve, aneffect heightened by cantilevered, sloping soffits. The shimmering metal soffit and ceilingpanels are contiguous, creating a visuallycontinuous sweep across the 102 foot widthof the building. Designed by Rafael VinolyArchitects, the 680 foot long sinusoidalribbon of ceiling is the building’s dominantvisual element.

As the building houses an incubator for the advancement of computerization, it is onlyappropriate that the ceilings in the project were produced with newly hatched computerizeddesign and manufacturing techniques. Each of the project’s 7,500 panels had to befabricated in a different size. Calculating the dimensions of the system was “intenselymathematical” says Al Kiechle, senior project engineer at Ceilings Plus, the Los Angeles-based ceiling fabricator. Panels are tapered on both ends and the dimensions of the inclinedsoffit panels had to be calculated in three dimensions. They vary from 72.6037” in length atthe outside curves of the building to 63.2844” on the inside edge of the building’s curves.Kiechle says, “With conventional metal forming techniques, we couldn’t even measurepanels with this degree of precision.” Instead, Ceilings Plus used automated high-speed,precision CAD/CAM punch presses and brake forms. “This enabled us to fabricatecomponents with a tolerance measured in ten-thousandths of an inch. The differences wereminute, but an error in even one panel would have appeared as a flaw in the geometry of thebuilding.” Kiechle says.

For acoustical control, interior panels have perforations and a non-woven acoustical fabricto create a noise reduction coefficient (NRC) of .75. The factory installed acoustical fabricis gray to match the panel color and reinforce the monolithic appearance of the “inside-outside” plane. Stainless steel torsion springs allow 100% access to the cavity above theceiling to permit easy access to cables and ductwork serving the computer labs located onthe top level.

“Conventional metal formingtechniques can’t even measure

panels with this degree of precision.”

Custom fabricated ceiling and soffit panels appear to flowaround curves of building and to form a “hull” from oneside of the building to the other.

Exterior from End: Photo Credit Rafael Vinoly Architects

Metal exterior soffits required were individually fabricatedto meet the building’s geometry and resist strong windsand thermal movement.

Exterior from Side: Photo Credit Rafael Vinoly Architects

Special software was used to convert the architects’ digital drawing files into a format that could be read by numerically-controlledperforating and metal-forming equipment, significantly reducing the time and costs required for CAD/CAM fabrication of panels forthe project.

Reflected Ceiling Plan: Photo Credit Ceilings Plus






BEYOND LEEDWhile the LEED program incorporates many strategies for greening a building, it is hardlycomprehensive. Fortunately, it allows credits for innovation in design. Here are a fewsustainability strategies that apply to ceilings yet are not included in the LEED program:

Prefinishing to Eliminate Total VOCs: LEED credit EQ-4.2 can be earned for the use ofpaints and coatings with low levels of volatile organic compounds (VOC) emissions. Ascurrently written, however, the LEED credit applies only to job-site applied materials. Forexample, a coating that is field-applied to a wood ceiling must not exceed the VOC limitsestablished by the Green Seal program (www.greenseal.com). If the wood is factoryprefinished, however, it does not qualify for the credit even though it does not release VOCsin the field.

Consider the case, too, of a factory-applied coating with a chemistry that releases zero VOCs.For example, UV coatings are cured with high-intensity ultraviolet light that causes polymersin the coatings to crosslink without the release of VOCs. While UV coatings have been used formany years in the furniture industry, it is only recently that a low-sheen UV coating suitablefor architectural panels has been developed. The coating produces a durable, non-yellowing,and washable finish that is smoother and more consistent than field-applied coatings.

A similar observation can be made about factory-applied paints. Applicators that roller-coatmetal coil, for example, use solvent recovery systems and then burn the vapors to fuel theirpaint curing ovens, reducing total energy used to paint panels and preventing the release ofVOCs into the atmosphere.

Zero VOCs in the factory would seem to be better for the environment than a low-level ofVOCs on the jobsite, irrespective of any LEED credits. This means that a designer mustsometimes look beyond LEED to see the big picture necessary for sustainable construction.

Prefabrication to Reduce Construction Waste: LEED Credit MR-2 recognizes projectsthat divert waste materials from the construction job site. Construction waste anddemolition debris generates as much as 25% of the solid waste stream in this country.While managing construction waste is important, wouldn't it be better to eliminate jobsitewaste altogether?

Prefabricated metal and wood ceiling systems can be cut to size and for penetrations in thefactory where it is usually easier to collect and recycle trimmings. Prefabrication alsosimplifies installation and coordination at the job site. Where field cutting can not beavoided, aluminum panels are still advantageous for construction waste management.Whereas mineral fiber ceilings can now be recycled at a growing number of collection points,there is no redemption value to the material. Recycled aluminum, on the other hand, hassignificant salvage value and a ready market, powerful incentives to encourage installerparticipation in a recycling program.

Designing for Resource Recovery and Reuse: LEED Credit MR-3 addresses the reuse ofsalvaged or reused materials within the current project. But LEED does not currentlyrecognize the environmental importance of planning for future reuse of buildingcomponents. In other industries, such as automotive and contract furniture, attention isbeing given to designing products that can be readily disassembled so that resources can berecovered and reused at the highest possible level.

While it is easy enough to demolish most ceilings systems, reuse of ordinary ceilingmaterials is unlikely. Mineral fiber panels, for example, are typically discolored after yearsof use, repainting them reduces their acoustical performance, and panels are too frangibleto be collected for reuse. On the other hand, perforated panels resist damage, can becleaned or repainted without loss of acoustical properties, and can be salvaged intact for anynumber of reuses.

Life-Cycle Assessment: Another step beyond LEED’s checklist approach is to conduct arigorous analysis of all environmental consequences of using a product. The Building forEnvironmental and Economic Sustainability (BEES) program developed by the National Instituteof Standards and Technology, for example, attempts to measure “the environmentalperformance of building products by using the life-cycle assessment (LCA) approach specified in ISO14000 standards. All stages in the life of a productare analyzed: raw material acquisition,manufacture, transportation, installation, use, andrecycling and waste management.”

While industry standards for evaluating ceilings are still being developed, perforated ceilingsare expected to have a favorable LCA due to the material, energy, and service life factorsdiscussed above.

Optimized Acoustical Performance: It has been said that the most important factor ingreening a building is to provide an environment in which people can perform at theiroptimum level. The California Department of General Services, for example, has found thatpersonnel salary and benefits account for 89 percent of the operational cost of an office

building, and any gain in occupant productivity translates into enhanced buildingsustainability. The widespread dissatisfaction with the acoustics in workplaces referred toearlier leads to costly errors in communication and reduced productivity due to distractions.

ACOUSTICS AND SUSTAINABILITYPerforated panels provide a spectrum of solutions for these acoustical problems. Whileother types of ceiling panels can reduce, transmit or reflect sound, perforated panels can bedesigned to function in all three of these acoustical modes.

0 10 20 30 40 50 60 70 80 90 100SERVICE LIVE - YEARS

RE

LA

TIV

E C

OS

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Perforated Aluminum Mineral Fiber

Life-cycle assessment showsperforated ceilings are an

outstanding value.

UV-cured finishes emerge fully cured after exposure to an intenseultraviolet lamp. Wood panels with this type of coating have a soft sheen with a more durable, more uniform, and smoother finish than is available with hand applied coatings.


Metal ceilings do not need periodicreplacement. Their life-cycle value is alsoreduced by the salvage value of aluminum.



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ARCHITECTURAL ACOUSTIC FUNDAMENTALS

Sound is the auditory perception of vibration or pressure oscillations that occur in the airaround us. The pitch of a tone can be analyzed in terms of frequency and is expressed inhertz (Hz), the number of vibrations or pressure oscillations that occur per second.Humans can generally hear from 20 Hz (low pitch) to 20,000 Hz (high). While we enjoy thisfull spectrum when listening to a symphony, the critical frequencies for understandingspeech typically occur at mid-range frequencies between 125 Hz and 4,000 Hz. Mostnoises contain a combination or range of frequencies occurring simultaneously.

The intensity or loudness of a sound is related to sound pressure and is expressed indecibels (dB). Because decibels are logarithmic units, a change of 3 dB will be barely

noticeable but a 10 dBchange will appeartwice (or half) as loud.Zero dB represents thethreshold of audibilityand sound pressuresabove 100 dB are loudenough to causedeafness and pain. Oursis an increasingly noisysociety, and occupationalhealth and safetyregulations limit the

duration for which a person may be exposed to very loud noise. Even in less noisyenvironments, however, attention must be given to noise control if we are to provideoptimum living, working and listening conditions.

Noise is propagated and travels in waves in much the same way as ripples spreadingout from a pebble tossed in water. Visualizing this can help to understand how soundis reflected when it encounters a hard dense surface, absorbed when it enters aresilient or porous material, or transmitted through a lightweight construction. Soundwaves can also be focused or dispersed depending on whether they reflect from aconcave or convex surface.

When designing the acoustical environment of a room, one begins by identifying thesources and characteristics of sounds inthe space and by defining the acousticalcriteria (such as loudness, reverberation,speech intelligibility, etc.) that arerequired by its occupants. The acousticsof an open office or restaurant, for

example, must enable occupants to have intelligible yet private conversations. And inauditoria and conference rooms, sound must be carefully distributed so thatperformers or speakers can be clearly heard throughout the room. Once these projectparameters are determined, ceiling and wall systems can be designed to reinforcedesirable sounds and attenuate undesirable noises.

The noise reducing potential of panels is determined with ASTM C 423 - Standard TestMethod for Sound Absorption and Sound Absorption Coefficients by the ReverberationRoom Method. Note that test results can vary depending upon how panels weremounted in the test chamber; a test report that replicates the installation conditionsexpected on the job site should be used. The percent of noise absorbed is typicallycalculated at six frequencies from 125 Hz to 4000 Hz. To simplify comparisons betweenacoustical products, the noise reduction coefficient (NRC) is the average of soundabsorption tests at 250, 500, 1000, and 2000 Hz, rounded to the nearest multiple of

0.05. These mid-range frequencies are used because they cover the spectrum mostimportant for spoken communication.

While an NRC is useful for preliminary product screening, it should not be relied upon forfinal product approval. When test data are plotted on a graph, they usually form a gradualcurve; a peak in the curve indicates that the tested material is especially efficient atabsorbing certain frequencies. This could be desirable if, for example, one needs todampen the whine from a machine operating at that particular frequency. But if the sameinsulation were used in a music hall, it would have the disconcerting effect of hushingcertain notes. For this reason, it is good practice to ask panel manufacturers to furnishcomplete product test reports prepared by qualified, independent acoustical laboratories,especially when designing spaces where high quality acoustics are essential.

It is important to match the reverberation time of a space to the type of listeningenvironment required. Reverberation is the persistence of a sound after the source ofthe sound has stopped; the time it takes for the sound to "decay" to a point ofinaudibility. In a room surrounded by hard, reflective materials, sound bounces fromsurface to surface and may continue to echo or reverberate for several seconds. Thesereverberations could make conversation or music difficult, since each syllable or notewould echo back and forth and interfere with the ability to distinctly hear subsequentsyllables and notes. Offices and recording studios, consequently, are generally designedto have short reverberation times; a reverberation time less than 1 second is generallysuitable for a conference room or class room. In other spaces, however, a longerreverberation time may be desirable. Reverberation times of 2 or 3 seconds may bedesirable in a symphonic hall or church to allow the music to have a "live" feel. Forexample, the long, sustained notes of a pipe organ or choir can help to create the properliturgical atmosphere in a cathedral.

The following formula is used to predict a room’s reverberation time:T = 0.05 V/a

where:T = reverberation time, the time required for a sound to decay 60 dB, in secondsV = room volume in cubic feeta = the total amount of sound absorbing material in a room, measured in Sabins. (A Sabinis equal to one square foot of surface that absorbs 100% of the sound falling on it. Forexample, a window with one square foot of open area would have one Sabin since all ofthe sound energy impinging on the window would leave the room.)

Based on this, thereverberation time canbe decreased by usingperforated panels withacoustical insulation toincrease the soundabsorption (a) in aspace. Alternatively,reverberation time canbe increased by usingacoustically transparentperforated panels toincrease the volume (V)of the space.

Hearing range for young

Hearing range for old

Vowels Consonants

Piano

Middle "C"

High fidelity stereo

Acoustical laboratory tests

NRC

8 1620

31.5 63 125 250 500 1000 2000 4000 8000 16,00020,000

32,000

Frequency (Hz)

Frequency (Hz)

Sou

nd A

bsor

ptio

n C

oeffi

cien

t

0.00.0 250 500 1000 2000 4000

0.2

0.4

0.6

0.8

1.0

A

B

Require complete test reports, notjust noise reduction coefficients,

for final product approval.

Noise reduction is tested at six frequencies, butonly four mid-range values are averaged toobtain a Noise Reduction Coefficient (NRC). Thegraph shows two panels with the same NRC;however “A” has better overall performance,especially in the lower frequencies that arecritical for speech.




9



Noise Reduction: The traditional approach to reducing noise with perforated panels is touse them as a covering over sound-absorbing materials such as glass fiber batts.Perforations allow noise to pass through the panels and into the acoustical insulation whileproviding a durable and attractive finish system. When sound contacts the fibers in theacoustical insulation, the fibers vibrate and convert mechanical energy into friction andminute quantities of heat. Glass fiber insulation batts with a density of three pounds percubic foot can deliver NRC .95 in a one-inch thick installation, and an outstanding NRC >1.00 (equal to absorbing all sound impinging on the ceiling) is even possible when twoinches are used.

It is not always practical to use glass fiber batts, however. Installing batts on the backsideof a panel, for example, raises concerns about the appearance of a perforated panel. Theweight of the batt factors into installation labor. The potential for condensation within theinsulation rules them out in moist environments. And the possibility that fibers will sloughoff the batts makes them unacceptable in certain occupancies.

Fortunately, a new type of non-woven acoustical fabric provides a welcome alternative foruse in most perforated ceilings. These paper-thin fabrics, only 0.2 mm thick, can producean impressive NRC .75 when used with selected perforated panels—performance equal tomany conventional acoustical ceiling tiles. The engineered fabrics reduce noise by creatingresistance to the air flow caused by the oscillating air pressure of a sound wave. To beeffective, perforated panels with acoustical fabric should be installed with at least 16inches of airspace behind them. This is because air is an elastic medium; if the air cavitybehind the panels was shallower, the air would be too "stiff" and would interfere with theair pressure oscillations.

The fabric is available in colors to create visual options: light-colored fabrics can also bebacklit to create luminous ceilings. They are self-extinguishing when exposed to flame andare compatible with the Class A flame spread ratings of metal and wood/metal hybridpanel systems.

Acoustical Transparency: A perforated panel must be acoustically transparent for noiseto pass through it. Transparency is determined primarily by the percentage of open area ina panel. However, a panel with a single large hole will pass less sound than would a panelof equivalent open area but with many small perforations distributed across its face.

Ceilings are often considered to be boundaries that form a barrier across the top of a room.

With perforated panels, however, another paradigm is available: Ceilings are alsomembranes that connect spaces and filter or modulate sound, light, and air. This makesperforated panels an important component in the acoustical designer’s palette.

The following examples suggest how perforated ceilings can be used as pervious membranes:

1. Perforated metal allows varying degrees of physical separation without creating barriersto sound, light, and air. For example, a perforated ceiling in an atrium can provide visualscreening and partial shade for the lower levels while permitting the free flow of sound,light, and air throughout the full height of the atrium.

2. Reverberation time is directly linked to the volume of a space. Where a longer reverberation time is required, a perforated metal ceiling allows the space above the ceiling to be included in the room’s volume. In the Schuster Performing Arts Center,

for example, perforated panels allowed thespace above the ceiling to contribute to the longer reverberation time required fororchestral performances.

Alternatively, perforated panels can be used to decrease reverberation time by making aspace more sound absorbing.

Perforated panels aremembranes that connect spaces

and filter sound, light and air.

Bamboo veneers can be carbonized to bring out a rich amber tone. This mock-up demonstrates how a ceiling’s appearance is altered by the color of a non-woven acoustic fabric; black on left and beige on right.


Perforated panels create separation without isolation and provide criticalprivacy and security in atrium of Goss Graphic Studio, Westmont, IL.


Perforated panels at the Shuster Performing Arts Center, Dayton, OH,allowed space above the ceiling to increase the effective volume of theconcert hall. This allowed Cesar Pelli & Associates and associatearchitects GBBN Architects to create the long reverberation timerequired for orchestral performances.






3. Perforated metal panels can be used as a visual screen for speakers and other audio equipment. This approach allows public address speakers and noise masking devices to be inconspicuously located above perforated metal ceilings to maintain a clean anduncluttered overhead appearance.

Acoustical Reflectors: In many rooms, it is useful to have ceilings that absorb noise incertain areas while reflecting or reinforcing sound in other areas. In a conference room, forexample, the ceiling over a conference table should be reflective to help a speaker’s voiceproject across the table, while the perimeter of a room should be absorptive to reducepotentially distracting noise. In addition, reflective ceilings are often required in auditoriawhere it is necessary to project sound from a stage to the back of an audience.

Sound reflects off smooth flat surfaces in the same way that light strikes a mirror; theangle of reflection is equal to the angle of incidence. In concert halls, convex shapes areoften desired to help scatter sound and prevent acoustical hot spots; curved and facetedmetal ceiling panels can be employed for this purpose.

When a concave ceiling is required, the designer must consider whether it will focus thesound in undesirable ways; if so, perforated ceiling panels can be used to reduceacoustical reflections.

THE NEXT NEW THINGThe past decade has been a time of rapid evolution in ceiling designs. This trend appearsto be continuing unabated into the foreseeable future. Evidence of this is a recentlyintroduced extensible ceiling system that ships in a nested configuration but slides openin the field to match the width of a room or corridor.

Architects continue to explore more complex geometries for ceilings. Scientists areexperimenting with ways to eke greater performance from acoustical materials. Productdesigners continue their search for more aesthetic opportunities. And the criteria forsustainable construction will undoubtedly become more stringent. Clearly, there is noceiling on the innovations yet to come.

Author Bio:Michael Chusid, RA, FCSI is an architectural consultant to Ceilings Plus. His firm, ChusidAssociates, specializes in developing and marketing innovative building products.

PUBLICADDRESSSPEAKER

CEILING ISACOUSTICALLYTRANSPARENT

UNCLUTTEREDCEILING

APPEARANCE

PERFORATEDCEILING PANEL

Public address speakers, fire alarm enunciators, and other acousticalsystems can be located above the acoustically transparent perforatedceiling for increased security and reduced clutter.

In the Linder Theater at the American Museum of Natural History in New York City, unperforated metal ceiling panels were used help reflectsound to the back of the hall. The panels' curves helped to scatter thesound for a more uniform quality throughout the room. KupiecKoustsomitis Architects was the designer.

The "collaboration zone" in the Biodesign Institute at Arizona State University was designed to foster dialog among scientists and research associates. Hard, acoustically reflective finishes such as glass and terrazzo made it necessary to use a NRC .95 ceiling to facilitate speechcommunications. Gould Evans, the project's primary architect, used a perforated wood ceiling to control noise and provide visual warmth. The fully accessible ceiling simplifies maintenance and reconfiguration of cables, pipes, and other utilities serving laboratories. The sameceiling is being used in Phase II, under construction, in an effort toqualify for LEED certification.


Photo: Timothy Hursley



Filename: AR_Ceilings_PlusWriter / Designer: Angela Haliski/Alison DeFilippisLast Revision: 11-28-05

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A I A / A RC H I T E C T U R A L R E C O R DCONTINUING EDUCATION Series

Program title:“Perforated Metal and Wood Ceilings: Sustainability, Acoustics, and Aesthetics ,” (05/12)

AIA/CES Credit: This article will earn you one AIA/CES LU hour of health, safety, and welfare credit. (Valid for credit through December 2006.)

Directions: Select one answer for each question in the exam and completely circle appropriate letter. Aminimum score of 70% is required

to earn credit.

1. a b c d e 6. a b c d e




5. a b c d e 10. a b c d e

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Ceilings Plus (www.ceilingsplus.com) is the leading specialty ceilings producer. Using computer-assisted design and manufacturing, the company fabricates ceilings and walls that are architectural,functional, and affordable. Products include curved Radians™ and extensible Runways™ panels, plus Arboreal® panels with wood veneers on aluminum cores. Panels can be almost any size or shape andperforated to enhance appearance and acoustics.

For sustainability, Ceilings Plus panels can have recycled content as high as 85 to 98%. Arboreal veneers can be FSC-Certified or rapidly-renewable bamboo. Panels have no-added formaldehyde and zeroVOCs. Ceilings Plus products are durable, easy to maintain, accessible and offer outstanding life-cycle value.

LEARNING OBJECTIVESAfter reading this article, you should be able to:

• Recognize how advances in computer-assisted fabrication techniques create new options for the design of customized ceilings.

• Understand how perforated ceilings contribute toward Leadership in Energy and Environmental Design (LEED) credits and environmental considerations beyond the scope of LEED.

• Know about new hybrid wood panels using wood or bamboo veneer on recycled aluminum cores.

• Understand how the acoustical characteristics of perforated panels can be used to meet a variety of architectural challenges.

INSTRUCTIONS Refer to the learning objectives above. Complete the questions below.Go to the self report form on page 11. Follow the reporting instructions,answer the test questions, and submit the form.

QUESTIONS

1. Which of the following is not true about the new generation ofperforated ceilings?a. They allow designers to break away from the regimentation of the

2 x 4 foot grid ceilingb. Panels can be curved to create a third dimension as part of the

ceiling designc. They allow for easy access for maintenance of above-ceiling equipmentd. Panels are easily damaged by changes in humidity

2. Perforated ceilings may help a project qualify for which of the following LEED credits?a. Recycled Material Content (LEED Credit MR-4)b. Certified Wood (LEED Credit MR-7)c. Daylight & Views (LEED Credit EQ-8)d. All of the above

3. Which of the following is an environmental benefit of perforated ceilings that go beyond current LEED criteria?a. Restoration of strip mined landscapesb. Designed for salvage and reusec. Radio-frequency shieldingd. All of the above

4. Automated, high-speed manufacturing techniques create which ofthe following benefits?a. Customized fabrication of ceilings at more affordable pricesb. Factory preparation of openings for light fixtures and other ceiling

penetrations to reduce installation time and costsc. Less waste due to field cutting to simplify job-site recyclingd. All of the above

5. Which of these statements is true about the new hybrid wood panels on an aluminum core?a. They are heavier than conventional panelsb. They are difficult to curvec. They can be perforated in a wide range of whole sizes, shapes,

and patternsd. The adhesives used to produce them contain urea-formaldehyde

6. Which is not an acoustical use for metal panel systems?a. Amplify soundb. Reflect soundc. Attenuate soundd. Allow transmission of sound

7. Which type of acoustical panel can be repainted without losing acoustical performance?a. Acoustical tileb. Glass fiber insulationc. Perforated metal panelsd. All of the above

8. What type of acoustical insulation is increasingly being used instead of traditional glass and mineral fiber insulation to increase the noise reduction of perforated panels?a. Wheat straw agriboardb. Non-woven fabricc. Lead sheetd. Autoclaved aerated concrete

9. In which building type might a long reverberation time be desirable?a. Lecture hallb. Open plan officec. Churchd. Broadcast and recording studio

10. Why is it good practice to select acoustical products based upon test reports and not just an NRC?a. NRC results are difficult to interpretb. Testing is required by building codesc. Idiosyncrasies at certain frequencies could be obscured by an

NRC's averagingd. Test laboratories guarantee the acoustical performance of a building


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