42 Oc tober 2002 BACnet ® Today | A Supp lement to ASHRAE Jour na l

GEMnet Project LinksBuildings in 3 States

n 1996, the Pacific Rim Region of the General Services Administration (GSA), aspart of its ongoing efforts to meet energy efficiency goals, embraced an ambi-

tious plan to renovate building automation systems at the Phillip Burton FederalBuilding located at 450 Golden Gate Avenue in San Francisco — a 1.4 million ft2

(130 000 m2), 22-story structure. The project’s design cycle coincided withASHRAE’s release of the BACnet standard for building automation communica-tions. GSA and its design team decided to deliver this project as not only a majorconservation effort, but also the first large-scale demonstration of a multi-vendor,BACnet automation network.1

just completed installation of an extensive Modbus power moni-toring system at the Phillip Burton Federal Building with theintent of eventual expansion to other sites.

Collectively, these components form the GSA Energy andMaintenance Network (GEMnet), an infrastructure that willpermit GSA to support local building managers, provide aframework for management and analysis of maintenance andbuilding performance data, automate certain CMMS func-tions, provide common interfaces, and monitor and controlfacilities remotely.

This article reviews the objectives in creating the wide-areainfrastructure and data management strategies that representthe core of GEMnet delivered in Phase I, and describes thearchitecture and design of the pilot implementation involvingreal-time integration of eleven facilities ranging from a 6,000 ft2

(557 m2) off ice building in Tucson to the 1.4 million ft2

GSA has applied the lessons learned at the Phillip BurtonFederal Building to additional facilities, and over the past twoyears has completed an integration project connecting 11 ex-isting buildings in three states via a wide-area BACnet/IP net-work and common database framework. This project representsthe first phase of a broad initiative to integrate building auto-mation systems (BAS) regionally, and interface them to otherapplications such as a computerized maintenance manage-ment system (CMMS).

In parallel, GSA has been customizing and fielding itsCMMS, developing Web interfaces for remote access to a cen-tral database, experimenting with the use of third-party clientsoftware to directly poll remote building automation systemsfor point data (bypassing traditional BAS front-end softwarealtogether), initiating a retro-commissioning program to bringexisting BAS to an acceptable level of functionality, and has

I

450 Golden Gate: the first large-scale BACnet project.

By Michael R. DeNamur

The following article was published in ASHRAE Journal, October 2002. © Copyright 2002 American Society of Heating, Refrigerating and Air-

Conditioning Engineers, Inc. It is presented for educational purposes only. This article may not be copied and/or distributed electronically or in

paper form without permission of ASHRAE.

GovernmentConnections

The Walsh Courthouse shows that open protocol and wide area net-working can be applied to an existing proprietary control system.

BACnet ® Today | A Supp lement to ASHRAE Jour na l Oc tober 2002 43

(130 000 m2) Phillip Burton Federal Building in San Francisco.We’ll share the experiences encountered in evaluating and ap-plying open protocols, wide-area networking technologies anddatabase management standards to deliver an integrated andfully Web-enabled network.

Vision and ObjectivesAs one of the nation’s largest property owners, the GSA main-

tains and operates a wide array of facilities spread over anextensive geographical area. The Pacific Rim Region (gener-ally referenced as “GSA” in this article) alone has a portfolioof roughly 20 million gross ft2 (1.8 million m2) of federallyowned space.

In 1999, GSA embarked on a plan to create a region-wideBAS infrastructure. This was motivated by a desire to bettermanage GSA’s diverse holdings — buildings with a variety ofexisting BAS, in varying condition, with underused data ac-quisition potential and designed with little regard for enter-prise IT concerns. In addition, eachfacility could not be expected to have aBAS expert on staff. The California en-ergy crisis had not yet materialized, butthe urgent need for demand reductionprograms, apparent by late 2000 andearly 2001, brought attention to theneed to centrally trigger local tempera-ture setback programs.

It became clear that GSA needed anIT framework for facility managementthat offered greater access to buildingdata and a platform to share it betweena variety of building management ap-plications such as a CMMS that GSAwas fielding at the same time. By ne-cessity, this platform would need to in-tegrate a variety of existing (legacy)control systems — some with open andothers with proprietary communicationnetworks — and serve as a common,vendor-neutral, enterprise level plat-form for future additions.

Goals of GEMnet include creating awide-area IT framework for facility man-agement offering:

• Data management platform for maintenance program infor-mation, performance benchmarking, equipment diagnostics

• Interface to complementary applications and automationof otherwise manual applications

• Integration and central technical support of multiple fa-cilities (and existing systems) over a broad geographic area

• Selective region-wide energy management strategies

Another goal was to have common user interfaces overlyingcommon data.

While the day-to-day maintenance and operation of its facili-ties was the main objective, GSA’s facility management teamalso was interested in using the GEMnet network to feed a com-mon database of facility information. GSA envisioned this data-base engine being queried for custom reports and used bythird-party applications for maintenance management, systemdiagnostic analysis or energy reporting. For example, GSA hopedthat through the common database, tenants might be able togenerate their own service requests, and that out-of-range tem-perature alarms could automatically trigger service calls throughthe CMMS. GSA also was investigating an innovative approachto equipment diagnostics that would depend on third-party soft-ware analysis of operating data collected in a central database.

Method and PlanMany factors were considered in the definition of the Phase I

GEMnet architecture and technical approach. The BACnet pro-tocol was selected as the network communications standard.This was a logical evolution of the BACnet infrastructure al-ready in place at 450 Golden Gate and several other sites com-pleted more recently. BACnet also was recognized as robustand well supported for scheduling and alarm management ap-plications, which would be key to central management of mul-tiple, remote facilities. It was expected that other non-BACnet

Operating conditions and critical alarms at the Sandra Day O’Connor U.S. Courthousein Phoenix can be viewed by GSA staff in real-time via a standard web browser.

44 Oc tober 2002 BACnet ® Today | A Supp lement to ASHRAE Jour na l

systems — including exist-ing proprietary control sys-tems, and potential futureadditions employing stan-dard protocols such asLonWorks® and Modbus—would need to be accommo-dated and would beintegrated to the BACnet-based network via appropri-ate routers and gateways.

It was determined that awide-area intranet wouldprovide the networking me-dia connecting all facilities.The performance of a net-worked connection far ex-ceeded dial-up phone lineconnections, and the op-portunity to integrate addi-tional services — such asweather and utility informa-tion — offered much flex-ibility and promise forfuture expansion. Further, tomeet the objectives for a simple, common user interface, thePhase I infrastructure of GEMnet was designed as a Web browseraccessible control network. The BACnet/IP network would in-clude a Web server hosting HTML pages reflecting real-timefacility data. The operator interface would be via a traditionalWeb browser, allowing GSA’s staff to easily view data and ex-ecute control requests.

Through GEMnet, GSAintended to create muchmore than an integratedBAS network. Rather, theobjective has been to createan IT infrastructure that en-abled a more proactive ap-proach to facilitymanagement. Therefore, atthe core of the GEMnet architecture is a database server, collect-ing and archiving critical facility data. Using well-defined andsupported data structures, building operational and performancedata would be available to those beyond the traditional facilitymanagement team. And, the same building data could be ac-cessed by software applications with more powerful and spe-cialized analysis tools than the typical operator workstationused for monitoring and control.

GSA identified several candidate facilities for the pilot de-ployment of GEMnet. Like most property owners, GSA has a

variety of existing buildings, and it was clear that GEMnet wouldneed to integrate a number of legacy control systems. Therefore,the design of GEMnet was not dependent upon wholesale con-trol system renovations. Among the criteria for selecting candi-date facilities was the presence of an existing DDC system, andthe opportunity to realize energy and operational improvementslocally as well as part of coordinated regional initiatives.

Thus, the key compo-nents of the GEMnet archi-tecture were determined:multiple facilities with ex-isting DDC systems, gate-ways and routersconnecting them to aBACnet/IP wide-area net-work, a central information

database, third-party software applications, BAS Web server,and remote Web-browser user interface (Figure 1).

ProcessTwelve candidate facilities were targeted for the pilot imple-

mentation of GEMnet. These federal buildings and courthouseswere spread over seven cities in the states of California, Ne-vada and Arizona, and included existing control systems fromthree different manufacturers. Six facilities had existing BACnetcontrol systems that had been installed or upgraded in the past

Figure 1: GEMnet architecture uses BACnet and Internet standards to create a wide area dataand communications infrastructure.

Tucson Border PatrolTucson, Ariz.

Santa AnaCourthouse

Santa Ana, Calif.

Phillip Burton FederalBuilding

San Francisco

Walsh CourthouseTucson, Ariz.

DeConcini FederalBuilding, Tucson, Ariz.

Auxiliary Applications• Fault Detection and

Diagnostics• Energy Monitoring• Maintenance

Management

SQLServer

Database

GEMnet Server

BACnetRouter(Typ.)

Web Browser-Based Access

O’Connor CourthousePhoenix Tucson Federal Building

Tucson

Proprietary/BACnetGateway (Typ.)

National ArchivesRecords Administration

San Bruno, Calif.

John F. Shea Federal BuildingSanta Rose, Calif.

Phoenix Post OfficePhoenix

Las Vegas Federal BuildingLas Vegas

BACnet/IPBACnet EthernetProprietaryTCP/IP

ExternalData

Sources (future)

INTERNETTCP/IP

• Weather Forecast• Utilities• Service Providers

‘GSA needed an IT framework for facility man-

agement that offered greater access to building

data and a platform to share it between a variety

of building management applications.’

BACnet ® Today | A Supp lement to ASHRAE Jour na l Oc tober 2002 45

few years. For these facilities, the integration to GEMnet wasstraightforward. A BACnet/IP router served as the bridge be-tween the local BACnet network in the building, and theGEMnet network connecting all facilities.

For the other buildings a variety of vendor-supported or third-party gateways were used to make existing proprietary (or other-wise non-BACnet) communication networks compatible withGEMnet’s BACnet standard. These gateways served well for thepurposes of the pilot installation, however they required addi-tional setup and configuration and have inherent limitationsthat are not present for facilities whose existing control systemsalready supported BACnet. Nonetheless,they proved legacy systems can be rea-sonably and practically integrated withBACnet for basic operations such as re-mote monitoring and control. One of theoriginal candidate buildings was deferredfor future integration since no supplier-supported or third-party integration prod-uct yet existed to make it compatible withthe BACnet/IP network.

Throughout the process, some limited amount of BAS ex-pansion was completed by the addition of various energy-re-lated input points to allow all buildings to communicate acommon set of operational data. For example, kW meters wereadded in some facilities to provide energy data necessary toevaluate performance and enable regional demand managementapplications in the future. However, all of the pilot phase facili-ties were connected to GEMnet with no significant changes totheir existing control systems.

It was determined that a virtual private network (VPN) would becreated to support this first phase deployment. Firewalls wereincluded at each site to secure the GEMnet VPN from the rest ofthe Internet. While the GEMnet network infrastructure uses theInternet as a communication highway, it is effectively isolatedfrom all other non-GEMnet nodes. As further protection, the Web-server software supports secure socket layers (SSL) — the same128-bit encryption used to secure online credit card transactions.

With one exception, the facilities connected to Phase I GEMnetnetwork use digital subscriber line (DSL) connections operat-ing between 150 kbps and 6 Mbps. In the remaining case, DSL

service was unavailable and an ISDN (in-tegrated services digital network) connec-tion operating at 128 kbps was provided.

Users connect with GEMnet facilitiesby pointing their standard Web browserto the GEMnet BAS server address andlogging in with an assigned user ID. Se-curity is maintained by password con-trol. Once validated, operators are able

to view, and if authorized, control data points from any loca-tion with an Internet-connected PC. A progression of nestedimages allows operators to easily navigate through the systemto select the specific building and level of detail view theydesire (Figure 2). Each image is presented as a Web page. Javaapplets provide animation to show fan and pump operation inthe same way that more traditional Web pages show corporatelogos and banner advertisements. Similar applications are pro-vided for time of day scheduling, trending and alarm manage-ment (Figure 2, lower right screen). Users interact with all

Figure 2: GEMnet graphics are

presented as Web pages and

viewed with a standard Web

browser.

‘Users interact with all buildings

in the same way, regardless of

the brand of controls actually

installed in the facility.’

46 Oc tober 2002 BACnet ® Today | A Supp lement to ASHRAE Jour na l

buildings in the same way, regardless ofthe brand of controls actually installedin the facility.

A central structured query language(SQL) database was created to host in-formation on the GEMnet network.Trended data from facilities connectedto GEMnet is collected and archived forreview and analysis. This information canbe used to derive performance metrics tocompare building energy consumption,or to describe historical performance ofa system or piece of equipment.

GSA contracted an engineering firmwith previous standard protocol and sys-tem integration experience to deliverGEMnet as a design-build solution. In co-operation with GSA, they developed thesystem design and technical approach andwere responsible for construction man-agement, working on GSA’s behalf to coordinate suppliers andsubcontractors, and oversee installation and commissioning.

In most cases, the local contractors responsible for originalcontrols installation at the subject sites were employed to addand configure gateways and routers required to integrate astandalone building with GEMnet. Due to the groundbreakingnature of the project scope, the direct involvement of the BASWeb-server manufacturer was also secured as the overall archi-tecture and data storage scheme were defined.

Results and Planned EnhancementsThe Phase I implementation constitutes a relatively large,

core component of a more comprehensive GEMnet initiative.The first sites were sufficiently functional in Summer 2001 toparticipate in the California Independent System Operator (ISO)Demand Response Program.

The implementation of the GEMnet core infrastructure andpilot facilities presented a number of challenges not surpris-ing for a project of its scope: the poor condition of many exist-ing BAS installations, the inconsistent performance of localBAS contractors, and the difficulty in maintaining stable com-munications for a dispersed real-time, Internet-based data net-work. Nonetheless, all were overcome and the GEMnet Phase Iimplementation was substantially complete in Spring 2002.

Moving forward, GSA will focus on making full use of thedatabase, which includes evaluating and expanding the pointdata currently collected. GSA also has been collaborating withLawrence Berkeley National Laboratory and the National In-stitute of Standards and Technology to research appropriateapproaches to performance benchmarking and diagnostics.

The GEMnet architecture also creates alternate paths forintegrating various additional systems and components; i.e.,

real-time communication via a direct BACnet network con-nection, or archived data exchanged through an interface tothe central database server. The relative usefulness of theseapproaches will be evaluated.

GSA plans to add more facilities to GEMnet. The originalcontrols contractor is being engaged at three facilities to add anOEM BACnet server linking the sites to GEMnet network. Also,GSA has created guide specifications so that future construc-tion and replacement BAS projects will be designed to easilyintegrate. The guidelines address local communication proto-col (permitting both BACnet and LonWorks, with standards foreach), networking, instrumentation and general quality control.

SummaryGEMnet builds upon the success of the 450 Golden Gate

project and the proliferation of BACnet by creating a networklinking multiple controls systems over a wide geographicalarea using standard protocol. The groundbreaking aspect ofGEMnet is how it merges IT and BAS to create an infrastructureallowing access to facility data by more people and third-partysoftware applications. The GEMnet infrastructure provides aplatform and flexibility that will allow GSA to imagine andthen realize new ways to manage their facilities in response tomarket and operational dynamics well into the future.

References1. Applebaum, M.A. and S.T. Bushby. 1998. “450 golden gate

project: BACnet’s first large-scale test.” ASHRAE Journal40(7):23–30.

Michael R. DeNamur is director of business developmentfor facility automation services at Comfort Systems USA.

The existing BACnet compatible system at the Lloyd D. George U.S. Courthouse in LasVegas streamlined its connection to the GEMnet wide area communication network.