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would instantly seal them off and con-tact authorities [see “The Road Ahead”on the Web at http://www.spectrum.ieee.org/WEBONLY/publicfeature/aug03/bbroad.html].

For now, though, efforts to makebuildings smarter are focusing on cut-ting costs by streamlining building oper-ations like air conditioning and lighting.Building automation is critical to theseefforts, mainly because it could reducethe annual operating costs of buildingsby a whopping 3.6 to 7 cents per squaremeter, according to a 1999 study con-ducted by the U.S. National Institute ofStandards and Technology [see “Gettinga Handle on Costs,” http://www.s p e c t r u m . i e e e . o r g / W E B O N LY/publicfeature/aug03/bbcost.html.]

Towers of Babel

If building automation is such a fabu-lous boon, why hasn’t it caught on every-where? Start by considering that the termbuilding automation is a catchall for asprawling category of control and com-munications technologies that link build-ing systems that are typically controlledseparately—like electrical distribution,fire, security, heating and air condition-

Can building automation systems overcomeinteroperability problems to assert controlover our offices, hotels, and airports? By Deborah Snoonian

If only you could work in a building where you could keep your office as youlike it, icicle-cold, while your neighbor turns hers into a sauna. If only youroffice lights and computer could flicker on every morning when you swipedyour security card in your building’s lobby, so that you would be ready to workwhen you sat down with your first cup of coffee. And while we’re on this flight

of fancy, wouldn’t it be reassuring to know that your building would shield you fromharm in the event of an earthquake, or even a chemical or biological attack?

SmartBuildings

Buildings could do all these thingsand more, if only they had brains.

As it happens, a few buildings alreadydo, and they’re getting smarter. Thebrainiac of buildings, the U.S. Pentagon,opened for business on 12 September2001, the day after terrorists crashed aplane into it. Thanks to a network of digi-tal sensors and controllers that let opera-tors close dampers and turn off fans, thefire from the crash was confined to onewedge of the building. [For more details,see “Saving the Pentagon,” p. 23.]

The Pentagon’s costly, proprietaryautomation system isn’t likely to find itsway into ordinary office buildings anytime soon. But that doesn’t mean thatwe’ll be stuck with “dumb” buildings forthe foreseeable future. The good news isthat two open communications standardsfor building automation are finally takinghold in the marketplace. One, known as

BACnet (for Building Automation andControl Networks), has been endorsedby the American Society of Heating,Refrigerating, and Air-Conditioning Engi-neers, Atlanta, Ga. The other, called Lon-Works, was developed by Echelon Corp.,San Jose, Calif. (“Lon” stands for localoperating network.) These two standardshave the best chance yet to turn the tideof the long, disappointing history ofsmart building control and automation.

In the meantime, technologies likethose deployed in the Pentagon, alongwith some even more advanced, arebeing tested in government and univer-sity research labs. Among other things,they’ll let future buildings minimizedamage when an earthquake hits by auto-matically changing the way weight is car-ried by internal structures. Or upondetecting a harmful chemical substancein the building’s air ducts, the system

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Web browser

Internet

Security

Lighting

Web server

Escalator

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Remote Control via the WebFrom a Web browser [far left], facilities maintenance engineers can control any number of

buildings, thanks to building control communications protocols such as BACnet and LonTalk,

which are compatible with the Internet protocol. While such remote control is not yet widely

deployed, demand from building owners is driving the trend to monitor and tweak building

functions such as lighting, fire safety, security, internal conveyors such as escalators, and

heating, ventilation, and air-conditioning (HVAC) systems via the Web.

ing, and elevator and escalator systems.To be effective, any automation systemmust enable all these mechanical andelectrical systems to work from a singlebuilding control point.

That’s a tall order because those sys-tems, and the digital controllers that runthem, are made by scores of manufac-turers, use proprietary hardware andcommunications protocols, and mayeven be administered through specialworkstations that are almost impossibleto integrate into a single control setup.

BACnet and LonWorks take differentapproaches to integrating these diversesystems. BACnet, developed in the mid-1990s, is a communications-only standarddeveloped for a building’s mechanical andelectrical systems, particularly heating,ventilation, and air conditioning (HVAC).Companies that manufacture such sys-tems are now beginning to make devicesthat “speak” BACnet rather than, or inaddition to, proprietary control languages.

LonWorks, on the other hand, com-bines a communications standard, Lon-Talk, with a piece of hardware, the NeuronChip from Echelon Corp. Born in the early1990s, LonWorks has already caught on inthe transportation and utilities industriesand has been adapted for buildings; it isinstalled in more buildings worldwidethan the BACnet standard.

Fortunately, the two arenot mutually exclusive.BACnet can let Echelon’s

Neuron Chips interact with building con-trol devices made by other manufacturers.

While LonWorks may have a headstart in some industries, BACnet ispoised to challenge LonWorks as a pre-ferred way to handle building control.Backed by a powerful trade association,it was specifically designed for buildingautomation systems and was adopted asStandard 16484-5 by the InternationalOrganization for Standardization (ISO,Geneva, Switzerland) in January 2003.

The BACnet standard comprises rulesfor data communications for hardwareand software used in building control. Atits heart are 23 virtual object types thattogether represent much of the function-ality a building needs to operate. Thesevirtual objects, such as “analog input,”“binary output,” “schedule,” and “calen-dar,” can be grouped together to representthe functions of real building systems.The objects are characterized by a set ofproperties that are used either to repre-sent information about theoperation of the system or toprovide operating parametersand commands to the system.

A room air-conditioning sys-tem, for example, might have an“analog input” virtual object with

a property that tells the HVAC systemwhat the temperature sensor in the roomis reading at the moment. Another of theair conditioner’s virtual objects might be a“schedule” with a property that would setthe system’s set point to 20 ºC at night.

Because the standard is compatiblewith the Internet protocol (IP), BACnetobjects and devices can be viewed via stan-dard Web browsers. Its workstation maybe in a dusty basement, but a maintenanceengineer sitting in front of an Internet-connected PC in London could conceiv-ably set lighting, temperature, and escala-tor speeds in a mall in Montreal [see“Remote Control via the Web,” below].

But as valuable as BACnet is in lettinga building communicate to maintenanceengineers and to the outside world, it alsomakes it possible for devices inside a build-ing to talk to one another. BACnet defines

Remote site

Fire alarm

Netw

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Internetprotocol

Microcontroller

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1. Fire

Fire signal

General signal

5. Energy management

10. Comfort

Command

“OK” signal “Stop fan” signal

BACnet

LonTalk

Fan

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a set of message types that enable data tobe shared among the different devices ina building automation system, resolvingconflicts when two different messages arebeing received by a single device.

For example, when a smoke detectorsenses smoke, BACnet defines the way asignal from the smoke detector is relayedto a switch that would close off thedampers in a ventilation system, pre-venting smoke from spreading through-out a building. Furthermore, BACnetallows users to set up to 16 levels of pri-ority for command messages coming to,say, damper controllers from buildingautomation software, such as energymanagement, fire safety, and comfort-level programs.

Fire, for instance, might have the high-est priority level of 1, comfort 10, andenergy management 5 [see “Setting Pri-orities,” above]. So if it’s cool outside, theenergy management program will senda message to start a fan and draw in out-side air to save money on air condition-ing. If there’s a fire, the fire safety pro-gram will send a message to stop the fan.If it’s a cool day and a fire breaks out, thefire safety message will have priority, evenif the energy management messagearrives afterward.

A developer’s dream

This setup of priorities is an importantdistinction between BACnet and Lon-Works, according to H. Michael New-man, manager of the utilities computersection at Cornell University, Ithaca,N.Y., who chaired the committee that

developed the BACnet standard. “InLonWorks, the last command wins, nomatter when it arrives,” says Newman.“With BACnet, you can assign prioritiesbased on the job and situation, andthey’re enforced by the protocol.”

BACnet is compatible with a variety ofnetworking standards, including Ethernet,ARCnet, and LonTalk. Almost anythingthat runs behind the walls of a building—twisted-pair copper, coaxial cable, fiberoptics—can accommodate BACnet sys-tems, an advantage over proprietary con-trol systems that typically work with onlyone kind of cabling.

Coupled to an ARCnet network,BACnet lets technicians set a limit onhow long a device will have to wait beforeit can send a message on the network—important for time-critical applications,like fire safety. In contrast, LonTalk isn’tcompatible with ARCnet.

Often makers of BACnet-based build-ing systems add optional properties tostandard object types to make them runmore efficiently or effectively. For in-stance, in the temperature sensor exam-ple, an HVAC company might add aproperty to the “schedule” BACnet vir-tual object type that would have the sen-sor send its temperature information to acentral database periodically. The data canthen be analyzed to advise owners onhow to run their buildings to maximizeenergy efficiency and slash expenditures.

That capability is fundamental toBACnet because it means engineers caneasily develop new applications and func-tions within the framework of the existing

standard. Some developers say this fea-ture gives BACnet an edge over Lon-Works and vendor-specific standards.

Certification of BACnet-compliant de-vices has been under way since 2001, butso far only a handful of controllers, forthings like thermostats and fans, havebeen certified. Nevertheless, the standard’sbackers estimate that thousands of build-ings in 80 countries are using BACnet-compliant automation systems. It’s beingdeployed in numerous clusters of build-ings, including some on the PennsylvaniaState University campus in UniversityPark and in a group of new residence hallsat Cornell University, as well as in Cor-nell’s new nanotechnology research center.

Talking neurons

LonWorks, developed by Echelon as ageneric platform for networking embed-ded devices used in the transportationand utilities industries, is coming to bewidely implemented in buildings as well.

Echelon’s partners, Cypress Semicon-ductor, STMicroelectronics, and Toshiba,make the Neuron Chip, the system-on-chip microcontroller used with LonTalk,LonWorks’ communications protocol. Dif-ferent chip versions share the same basicfeatures in various combinations: proces-sor cores, memory, communications, andI/O, as well as sensors, actuators, andtransceivers, all in the same package.Depending on the features and quantity,chips usually costs US $3 to $5 each.

In the LonWorks network, the Neu-ron Chip is the basic interface betweeneach device being controlled and the cen-B

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SettingPrioritiesOften, a signal to a device, such as a

fan, must take precedence over

another message. BACnet [top]

allows for 16 levels of priority, and

gives control of the device to the sig-

nal with the highest priority—here,

the fire signal. LonTalk [bottom]

doesn’t use gradations of priority. It

would rely on a separate “fire” chan-

nel to carry emergency signals to

the fan. The same channel could also

carry periodic “OK” messages that

trigger a response if not received.

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tral control system software. The chipsends and receives data over a wired con-nection (or any other medium, includingRF, infrared, fiber optics, and coaxial),as well as to and from a Web server, thei.LON 100, which straddles the build-ing’s LonTalk network and the Internet.For example, a lighting fixture mighthave a twisted-pair wire connected to alighting controller, which would containa Neuron Chip and a twisted-pair trans-ceiver and may control several fixtures.

With LonWorks software applica-tions, building systems are controlledvia networks of standard objects madeup of so-called network variables (NVs).The NVs are lines of computer code thatdefine inputs and outputs of devices,such as temperature, a switch value, oran actuator position setting—all analo-gous to BACnet standard object types.

To control a light, say, the switch wouldbe assigned NVs that correspond to “on”and “off.” Programming the network witha graphical tool, an engineer binds thelight and the switch together by drawing avirtual wire between the two objects. Lon-

Works networks support one-to-many andmany-to-one binding of NVs, regardlessof the function of the actual devices (thisbinding of NVs is similar to the groupingof standard object types to make a BACnetdevice). In this way, the light switch’s “on”NV could kick off actions in one or evenhundreds of other devices—of any sort,in any part of the system—directly, withoutintervention from a centralized controller.

As to whether LonWorks networksallow users to assign priorities to certaincommands—to turn that fan off in theevent of a fire, say, as previously mentioned,or to close a damper—Steve Q. Nguyen,Echelon’s director of corporate marketing,replies that the system does have some pri-ority-scheduling capabilities.

“Instead of binding equal-priority out-puts to a single input, a damper wouldinclude a fire emergency input that wouldbe acted on by the device as a higher-pri-ority action, overriding even the schedul-ing defined by an i.LON server,” Nguyensays. Another option would be “requiringthat an ‘OK’ value be sent periodically bythe smoke control system, without whichthe damper would assume a defaultsafety position,” he adds.

Like BACnet data, data from aLonWorks system can be displayed onstandard Web browsers.

Currently, LonWorks leads BACnet inthe number of devices and products thathave been certified, more than 350 at lastcount, according to Nguyen, who adds thatother not-yet-certified LonWorks productsnumber in the thousands. Worldwide,some 30 million Neuron Chips are de-ployed: in monitoring and controlling sys-tems in 1100 7-Eleven convenience storesin Japan; the huge Le Coeur Défense officebuilding complex in Paris, Europe’s largestinstallation, with some 17 000 devices [seephoto, above]; the Sears Tower in Chicago;and the Bellagio Hotel and Casino in LasVegas, Nev., among others.

Web control

BACnet and LonWorks have come far inthe last 10 years, but neither is yet in aposition to end the long, stubborn historyof proprietary turf battles in buildingautomation. Vendors of mechanical andelectrical systems still make devices thatcommunicate using their own idiosyn-cratic protocols. Even when systems arebased on BACnet or LonWorks or both,manufacturers can still program devices topreclude free-flowing data exchange withother vendors’ equipment. For instance,with BACnet-compliant systems, adding(or failing to fill in) optional fields whendefining a BACnet object type can make

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Le Coeur Défense office building complex

in Paris, the largest such complex in

Europe, is controlled by

17 000 LonWorks Neuron Chips.

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data sharing among devices trickier.For the LonWorks platform, some mak-

ers of controls choose not to design to thestandard’s guidelines, as defined by a groupof companies that has been dubbed theLonMark Interoperability Association.Some even create intentionally closed typesof LonWorks-based products, making inte-gration of the products more difficult.

Hope for an ultimate resolution tointeroperability problems might lie withthat paragon of interoperability, the WorldWide Web, which is transforming the

interface of building control. As morebuilding owners demand remote accessto building systems, manufacturers willhave to make their systems accessiblethrough Web browsers instead of propri-etary workstations—something thatBACnet and LonWorks already allow.

For example, Johnson Controls Inc.(Milwaukee, Wis.) has teamed withMicrosoft Corp. (Redmond, Wash.) to usethe latter’s .NET technology so that John-son’s HVAC, lighting, and other buildingsystems can be monitored and operated

online from any computer. Yet Johnson’scontrollers speak a proprietary languagecalled Metasys, which would make it tech-nologically tricky and expensive for abuilding owner to implement BACnet orLonWorks, or to replace Johnson’s equip-ment with another manufacturer’s.

It’s precisely plug-and-play opera-tion of systems made by different ven-dors that frustrated owners are begin-ning to demand—and that’s the nutthat both BACnet and LonWorks arehelping to crack. •

On the morning of 11 September 2001,

Steve Carter was in his office at the

Pentagon. Carter, an electrical engi-

neer who is the real estate and facilities liai-

son to the Pentagon’s US $1.85 billion reno-

vation program, has worked in the building

for 17 years.

Carter’s office is in the newly renovated

area called Wedge 1, in the Building Opera-

tions Command Center (BOCC), which

opened 8 June 2001. If the Pentagon’s build-

ing systems—heating, ventilation, and air

conditioning (HVAC), fire safety, lighting, and

security—are its nerves, then the BOCC is its

brain. It’s the place where all these systems

come together through a network of thou-

sands of sensors, actuators, and controllers.

Rather than dispatching technicians to fix

a problem, operators in the BOCC can fine-

tune many building systems remotely—for

instance, raising the set point on a thermostat

or turning off a fan in an air-conditioning duct

to prevent smoke from a fire from spreading.

Carter and his colleagues were watching

the World Trade Center’s twin towers in New

York City burning on television when a plane

struck Wedge 1. “All the control boards in the

BOCC went to the fire alarm system, and the

alarms came up bright red,” Carter says.

“We immediately started shutting down

some of the air handlers; our first thought

was, nothing could be this massive.” Shortly

afterward, the BOCC lost power—and the

operators their ability to make adjustments

to the building systems from there.

Carter grabbed a two-way radio and a lap-

top and headed to neighboring Wedge 5 to a

mechanical room housing HVAC equipment.

From his laptop, he tapped into the Penta-

gon’s automation network and sent out com-

mands that closed dampers and turned off

fans around the building to contain the smoke

and starve the raging fire of oxygen.

When he learned that a break in a water

main had dropped water pressure to a point

too low for firefighting, Carter dispatched

engineers to the bowels of the building to

remedy the problem. All in all, eight people

stayed in the Pentagon that day, controlling

the fire damage remotely via workstations

from various mechanical rooms in the build-

ing, with Carter directing the effort by radio.

The next day, the Pentagon reopened. In

all, 189 people had been killed, 125 on the

ground, and the building suffered $501 mil-

lion in damages. But the Secretary of

Defense’s office, the National Military Com-

mand Center, and other mission-critical

areas like data storage centers and wiring

and switch rooms were spared.

None of this was possible back in 1997,

when Carter convinced his superiors to build

the BOCC to streamline day-to-day opera-

tions. He also convinced them that, while

they were installing brand-new HVAC equip-

ment in Wedge 1—the first area to be renovat-

ed—they should also retrofit the 55-year-old

HVAC equipment throughout the rest of the

Pentagon with new digital controls.

Not only would the new equipment, and

the old equipment with new controls, be auto-

mated and operated through the BOCC, but it

could be programmed to work more effi-

ciently, which would help slash energy use by

35 percent by 2010, saving up to $5 million

per year.

Johnson Controls Inc. (Milwaukee, Wis.)

designed and installed the new HVAC system,

linking it to the fire safety system. Engineers

also added leak detectors to the natural gas

system and to the air chillers, and linked them

to the BOCC. Johnson’s equipment uses Meta-

sys, the company’s own control language.

“In 1997, we couldn’t find a vendor with a

fully interoperable system for either BACnet

or LonWorks,” says Carter, adding that these

protocols could be used in the Pentagon as

the renovation progresses. The BOCC itself is

linked via fiber-optic cable to network con-

trol modules in each mechanical room, which

allows for remote (laptop) control.

New capabilities will be added to the Pen-

tagon’s building automation system over

time. Next up is an improved lighting control

system, which may incorporate Internet pro-

tocol–addressable fixtures and occupancy

and day-lighting sensors.

Energy savings aside, the system

Carter fought for went well beyond the

call of duty on September 11. “What was the

value of this system the day it did not shut

down?” he asks. —D.S.

Saving the PentagonD

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