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Association of Energy Engineers
George Owens is a past president of "Association of Energy Engineers", an "Energy Manager of the Year" and an "Energy Managers Hall of Fame" inductee.


What Is All the Fuss About Interoperability?
BACnet From an End Users Perspective
by George R. Owens, PE, CEM

This paper gives the end user guidance on the benefits and issues surrounding interoperability and a brief review of the history and the current state of technology for Energy Management Systems. Emphasis is placed on how to go about getting the right system that will generate savings and reduce installation and maintenance costs.

The BACnet standard is relatively new and just now beginning to be specified and installed. This paper is written at a time before BACnet has been fully integrated into the industry and extensively field proven, although major installations (1) have been successfully demonstrated.

Since an Energy Management Decision is a long term commitment, it is important for the end user to understand the impact of BACnet on their current and future purchases. Otherwise, you may be specifying and installing an Energy Management System destined for premature obsolescence.

Cost and flexibility is why. Up until recently, each and every supplier of Energy Management Systems had only proprietary designs. If you wanted modifications or additions, you would generally only have one choice, to go back to the original supplier and pay their prices. Fortunately, efforts have been underway to allow one supplier's equipment to "talk" to another's via the BACnet standard. This will allow end users the flexibility to purchase equipment from different suppliers to get an optimum system at the least cost.

Automatic controls were developed in the late 1800's and a workable night thermostat was developed in the very early 1900's.

Not until the 1970's, with multiple energy crises, and increasing costs, did the idea of conserving energy become really important to building owners. The most important new technology was the advent of the computerized Energy Management System. These early systems provided centralized control, unattended, with electronic accuracy. However, these early systems tended to be bulky, not user friendly, unreliable, and very expensive to install and upgrade. The earliest Energy Management Systems were installed in the early 70's and utilized small "mainframe" style computers that were costly, bulky and hard to program. The term "user friendly" had yet to be invented. The next generation (late 70's) graduated to a minicomputer or a vendor's proprietary CPU design.

During the late 1980's and 1990's, technology changed the face of Energy Management. The personal computer (PC) and increasing computer literacy of the general population was responsible for improving the performance of Energy Management Systems. The PC brought with it an easy to use graphical interface that improved the effectiveness of the operator interface. Now, the operator had a tool to use in understanding and controlling energy systems.

Again, going back to the earliest Energy Management Systems, all external devices were hard wired back to the computer. Then a distributed format evolved utilizing multiplexed signals over a common wire or over the electrical distribution system (power line carrier). The multiplex system did a lot to reduce the cost of wiring input/output devices. Now we have moved to the beginning stages of true interoperability between systems and components. Although they are not yet fully "plug-and-play" compatible, these early systems do allow for the mixing of some components today.

And the world of interoperability is here, today. There are over thirty suppliers of controls and manufacturers of HVAC, lighting, fire alarm, security and electrical systems that have or are developing capabilities for interoperability using the BACnet standards.

The BACnet Standard 135-1995 (2) was developed by the American Society of Heating, Refrigeration and Air-conditioning Engineers, Inc. (ASHRAE) to promote a common methodology to allow devices from different vendors to communicate with each other. BACnet compatible devices are available from a variety of controls' vendors and equipment suppliers today.

LonWork's LonTalk is a subset of the BACnet standard. LonWorks is often implemented in either a standalone fashion for smaller systems or as the preferred communications method for unitary controllers as a subset of a BACnet installation.

You might think of BACnet as a standard language for passing information back and forth amongst various suppliers' devices. For example, this could be a command to turn on a fan or an outside temperature reading being shared with multiple controllers.

Capital Cost Reductions-Initial Installation

The biggest advantage for the end user will be lower prices due to competition from multiple vendors. BACnet also allows equipment suppliers to design dedicated controls into their equipment at the factory. Then, when the equipment arrives in the field, it's a simple matter of connecting a control cable and the Energy Management System will be able to talk to the equipment and vice versa. The labor costs of a field installed Energy Management System are normally more than 50% of the total cost, the efficiency of factory installed controllers provides for a lower total cost.

Capital Cost Reductions-Modifications, Upgrades and Expansions

An even greater reduction in cost will occur whenever an existing system is modified, upgraded or expanded. Until BACnet, I often referred to the relationship between the Energy Management System supplier and the owner as a marriage. Like a marriage, one has to choose their partner with care because a divorce is painful and expensive. With the suppliers each having different protocols, the ability to change or upgrade the system was nearly impossible except from the original supplier. The only other alternative was to (remove and replace) divorce the original supplier with a new one. Under this scenario, the cost for a divorce would be prohibitive and the original supplier has little incentive to be cost competitive.

Operating Cost Reductions

Besides the cost of any major modification, upgrade or expansion, the cost for maintenance and repair (M&R) services on a BACnet Energy Management System, will be less. Maintenance costs typically range from as low as 5% of the original installed cost per year up to as high as 15%. The cost varies widely depending upon the local market and the extent of services contracted. Over the life of the system M&R costs could exceed the installed cost. With BACnet implemented, more suppliers could provide M&R services on the Energy Management System and use their own or other's parts for replacement. This will result in lower costs for M&R services.

The Best Technology

In my experience, all of the Energy Management System suppliers have strengths and weaknesses. One vendor may make a great humidity sensor and another might have the best VAV controller in the world. With BACnet, the system installer has the flexibility to pick and choose the components that are optimum for the job.

In my experience, Energy Management Systems continue to be one of the best investments in energy management (after lighting) for controlling operating costs and improving comfort and reliability. However, unless the system is designed, installed, programmed and operated correctly, the results will be less than desired. This is true for all Energy Management Systems and even more so for future systems if they are to take advantage of the move to more open architectures.

Educate yourself. Knowledge is the key to success for effective Energy Management Systems. Sources include ASHRAE, The Association of Energy Engineers, publications like Energy Users News, technical conferences, the Internet, Energy Management System suppliers and consulting engineers.

Talk to other end users about their experiences. They've been there, done that. Find out what their experiences have been with Energy Management System suppliers and the energy management strategies that work for your type of operation and buildings. The best bet is to actually go visit the sites and talk to the operators directly.

Interview prospective suppliers. Here you are not only trying to learn about their technology, but their ability to support your system in the long run.

Prepare a performance-based specification. This specification should include all the features desired including BACnet compatibility. The energy management strategies being implemented need to be completely identified if the savings are to accrue. The specification should be specific enough to cover the performance of the system and general enough to allow multiple vendors to present competitive proposals.

Hire a consultant. If you feel you do not have the time or expertise to design, install, program and operate an Energy Management System, a consultant might be the right choice for you. However, insist that the consultant has not only experience in designing Energy Management Systems, but also has hands on field experience in supervising installation, programming and operations. I have seen too many Energy Management Systems that were designed by consultants without field experience that did not meet expectations.

Operations is the key to a successful Energy Management System. The designer, installer and programmer of the Energy Management System get to go home after it is turned over to the owner. The local operator is often left with a complicated system without adequate input and training. From that day on, the operator makes the biggest difference between a "time clock" and an effective Energy Management System. To achieve the desired savings and in my experience generate even greater savings in the future: 1) Have the operator be involved in the design and selection process, 2) provide training during and after installation and 3) have a program of ongoing support, optimization and training in place.

I have been following and writing about the future of Energy Management Systems since 1991 with the papers "Energy Management 2001" and "Energy Management 2005". In 1991, interoperability was just a desire that end users had. With BACnet, that dream has started to come true. In just a few more years, the end user will be able to plug in components just like they can today when matching stereo, computer and telephone components.

With the passage of the Energy Policy Act of 1992, the process of deregulating the electric industry was begun. Deregulation will bring unprecedented changes to the way that utilities are purchased, used and controlled. The number and complexity of utility bills will multiply. Real Time Pricing tarriffs and other time sensitive rates will challenge the abilities of an Energy Management System to control loads in an effective manner to reduce costs. In addition, the rate of change in utility metering, billing methods and control is increasing. It is important that any Energy Management System being specified today have the ability to handle sophisticated energy management strategies and be able to be easily reconfigured to meet changing needs. That is why it is important that any new Energy Management System be specified with BACnet compatibility.

The evolution of the Energy Management System from the inflexible, proprietary system of the 70's to the easy to understand open architecture has occurred over the past 25 years. BACnet's development and further acceptance are allowing end users to obtain better and more cost effective systems. An end user can obtain systems that work and produce the savings desired by following the Tips for Buying Cost Effective Energy Management Systems presented in this paper and spending some time getting educated on Energy Management Systems in general and BACnet specifically.

1. "450 Golden Gate Project, BACnet's First Large-Scale Test", Martin A. Applebaum PE and Steven T. Bushby. July, 1998 ASHRAE Journal

2. ASHRAE Standard 135-1995, "BACnet A Data Communication Protocol for Building Automation and Control Networks"

3. "Energy Management 2001", "Energy Management 2005" and "The Proper Selection, Care and Feeding of an Energy Management System", George R Owens PE CEM, Energy and Engineering Solutions, Inc. These papers can be viewed here.

BACnet is a trademark of ASHRAE
LonWorks and LonTalk are trademarks of Echelon Corporation


George R Owens PE CEM - Experience includes over 21 years in Energy Management in the commercial sector with an additional 9 years of Electrical Engineering in Industry. He is a registered Professional Engineer in five states, Certified Energy Manager, recipient of Energy Awards, publisher and presenter of energy articles, author of book chapters, past seminar instructor with universities' Energy Programs, quoted in newspapers, radio, television and magazines and has served as an advisor to the utility industry on DSM Programs. The subjects of his presentations have covered Utility Deregulation, Energy Conservation, O&M, Commissioning, and the Future of Energy Technology.

George Owens has membership in several professional organizations (AEE, ASHRAE, IEEE, IES, NETA), where he has held committee and officer positions. He is a recipient of the Association of Energy Engineers's International Energy Manager of the Year and was inducted into the Energy Managers Hall of Fame.

1997 - Present: President - Energy and Engineering Solutions, Inc., a firm that provides cost-effective solutions to the Commercial, Real Estate and Institutional sectors with a focus on Energy Management.

1981 -1997: Director of Engineering - Responsible for an annual $85 million utility budget for The Rouse Company which owns, develops and/or manages over 75 shopping centers and 120 office buildings throughout the United States and Canada with 57 million square feet portfolio.

1977 - 1981: Energy Engineer - Federated Department Stores, Shillito's Division. Developed and implemented the Energy Management Program.

1968 - 1977: Electrical Engineer - Proctor and Gamble Company, Charmin Paper Division.

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