Establishing a standard way of working with other people and other companies has always been a goal, no matter the industry. For example, Microsoft established the standard for computers, making it easier to transfer files from one user to the next because everyone uses the same operating system. Some may argue that there are better ways to transfer data, but no one can question that right now, Microsoft is the standard.

In the hvacr controls industry, the battle is still raging over which standard will be more widely accepted: ASHRAE-sponsored BACnet or Echelon-generated LonMark. Both promise interoperability, which endusers are anxiously waiting for, given the ordinarily proprietary nature of the controls industry. Just the thought of being able to plug in different components from different manufacturers and have them work harmoniously brings joy to the hearts of many building owners.

But many manufacturers have aligned themselves with either BACnet or LonMark, so for the near future at least, endusers will still need to struggle with components designed for one standard or the other. So what do the people behind BACnet and LonMark think about this important and everchanging scenario today?

On the BACnet side, Clair Jenkins, chair of the BACnet Manufacturers Association (BMA) Marketing Committee, and president and co-founder of Alerton Technologies, Inc., (Redmond, WA); and Jim Lee, acting president of the BMA, and president and ceo of Cimetrics, Inc. (Boston) answered our questions about the competing standards.

On the LonMark side, Kevin Lynch, executive director of the LonMark Interoperability Association (Palo Alto, CA) gave his viewpoint about the state of the industry.

Q. Why was LonMark introduced when BACnet was already in the works?

LonMark: Actually, the LonWorks platform predates BACnet by several years. Prior to becoming an ANSI standard (ANSI/EIA 709.1-A-1999), and part of other international standards including IEEE 1473 (train control), TC247 (building automation), AAR (electro-pneumatic train braking), and the SEMI standard (semiconductor manufacturing equipment), the market, particularly the buildings market, had already accepted the LonWorks platform as its de facto standard for control.

While this market acceptance was occurring, BACnet was being worked on as an interoperability standard for hvacr systems. Companies in the LonWorks industry recognized the need for interoperability beyond hvac into other systems like lighting, elevator, access, security, and so on.

Q. What was the response of BACnet manufacturers when LonMark seemingly jumped into the game?

BACnet: There was a variable response according to market position. It was looked upon as another protocol, redundant, and not optimized for our industry.

Q. Why should BACnet be the industry standard rather than LonMark?

BACnet: BACnet is a consensus developed standard. It was developed by our industry for our industry. LonMark was developed as a one-size-fits-all control network. BACnet is not controlled by one manufacturer—Lon is. Lon can only be implemented on a limited number of chips, while BACnet can be implemented on almost any chip. BACnet also accommodates a variety of system architectures and is scalable to new networks (both large and small).

Q. Why should LonMark be the industry standard rather than BACnet?

LonMark: For the same reasons as outlined above, because many in the buildings market have already accepted the LonWorks platform as its de facto standard for control.

Q. What are the biggest differences between LonMark and BACnet?

LonMark: The two are really very different and in many ways not directly comparable. BACnet is a specification for supervisory system interoperability. In fact, if you read the beginning of the specification, it’s designed for interoperability among computers, not devices. Further, BACnet is implemented as a gateway solution with computers tying together disparate building subsystems.

LonMark certification, by contrast, pertains to devices, yet systems based on the LonWorks platform, utilizing LonMark products, are used at the both the supervisory and device level in applications worldwide. Further, LonMark devices are certified to interoperate at the device level in a distributed architecture, wherein nodes on the network are ‘peers.’ Therefore, a system using LonMark devices doesn’t need gateways, routing, or arbitrating traffic among various subsystems, nor is it limited to hvacr systems only. In fact, one could make just about every system in an automated building utilizing LonMark-certified products.

BACnet: BACnet was designed to be scalable both in application and in using a variety of networking technologies. LonWorks was developed for device-level networking. LonWorks is wedded to its data link. There are no clear speed/bandwidth or node/admin upgrade paths. It’s also easy to move BACnet into new networking protocols. Lon is fundamentally limited by Neuron Technology, so architectural choices are limited.

Q. What do you think are the most important factors for an engineer or facility owner to consider before beginning to specify or select a system?

LonMark: Clearly the most important thing is, “does it work?” There are millions of LonWorks products deployed in the world today that we interact with on a daily basis. You can find LonWorks products at work in things like BART, New York City subway trains, San Jose International airport, numerous buildings, and a host of other applications from homes to buildings to transportation systems. A second important factor is to look at the bigger picture of your automation solution: Is it just the heating system, or do you want to automate your elevator, security, lighting, fire suppression, blinds, access control, parking control, and other things as well? Do you want to leverage existing systems or information from one system to another? Do you want to use IP (the Internet) as a high-speed communications backbone from one building or floor or location so your facilities managers can better trend and analyze things like energy consumption, uptime, and occupancy? Do you want an end-to-end solution that is future-proof? If any of these are important, then you should take a close look at LonMark certified products.

BACnet: These items should be considered: The ability to interface to IT and other systems; Future expansion; Interoperability within the building (e.g., hvac equipment, fire/life safety, access control/security, lighting, elevators/escalators, equipment monitoring); and Interoperability between buildings.

Q. Under what circumstances would you recommend that someone choose a BACnet system?

LonMark: BACnet has a role where a facility has two or more separate, closed, proprietary systems that need to be linked together at the workstation level. BACnet will link together the closed "islands of automation" and save the facility owner from replacing all of the legacy systems. This is the type of application for where we believe BACnet is a reasonable alternative to LONWORKS networks using LONMARK devices.

Q. Under what circumstances would you recommend that someone choose a LonMark system?

BACnet: Personal choice, although we’d question the need to. But it might be necessary if a customer requires Lon in their specification.

Q. Is there anything else that engineers need to know about LonMark vs. BACnet?

LonMark: I think that the argument for LonMark speaks for itself.

BACnet: LonMark offers islands of interoperability, while BACnet offers real interoperability.

Q. What are LonMark’s greatest strengths?

LonMark: Field-tested functionality, in the millions of units. It’s based on the de facto standard for device networks worldwide. It’s backed by a “who’s who” of controls companies. There’s a codified certified process. It’s international. We offer an end-to-end solution that includes Internet connectivity.

BACnet: Marketing. They also have standard definitions for devices.

Q. Where do you think LonMark could improve?

LonMark: We spend a considerable amount of time discussing, coordinating, and developing additional profiles for devices. We strive to communicate the benefits of open systems to endusers and specifiers and could ideally spend more time in our efforts in further outreach programs.

BACnet: Cost. Compare an eight bit microcontroller and RS-485 ($1 for microcontroller and $1 for RS-485 transceiver) to a Neuron and a free topology transceiver ($3 or $4 for a Neuron and $10 for FTT transceiver). Performance. The FTT is limited to 78K baud (most common Lon data link). Commoditization of high bandwidth technologies — low-cost Ethernet is moving into Lon’s space. Lon is restricted by the limited power of the Neuron chip.

Q. What are BACnet’s greatest strengths?

LonMark: BACnet is great for connecting together closed, proprietary control systems for customers who don't want open, interoperable technology. That's the application in which BACnet can be usefully applied.

BACnet: BACnet was designed by the building automation industry specifically for building automation networking, from small field controller to the network level. It currently supports a large number of network technologies (i.e., Ethernet, ARCNET, PTP (RS-232), MS/TP (RS-485), BACnet/IP, and LonWorks).

Contrary to what some may think, BACnet is designed specifically for building automation and controls system applications. One of the greatest strengths of BACnet is that it can be implemented all the way from the management level (workstations) all the way down to the field device level, such as native BACnet vav box controls. Such total native implementation of BACnet eliminates the need for gateways and “islands” of interoperability and provides the greatest opportunity for a building owner to achieve full interoperability at any system level.

BACnet also offers scalability and the ability to evolve as the technology changes. Perhaps BACnet’s greatest asset is a standard representation of data agreed on by our industry. BACnet’s object and service data definitions are the core value behind BACnet.

Q. Where do you think BACnet could improve?

LonMark: BACnet needs to be more in tune with the drive toward open, interoperable automation systems. Our view is that BACnet would make a logical and welcome addition to the LONMARK Interoperability Association so that the work that has been done on workstation-level issues won't be marginalized.

BACnet: We need to simplify the specification of systems. The industry is in the early stages of learning to specify open systems. We also need standard definitions for devices.

Q. What developments are LonMark working on right now?

LonMark: The biggest thing we’re working on is certifying LonMark products. Year after year we’ve experience over 100% growth in the number of LonMark certified products available on the market and we expect to maintain that momentum.

Q. What developments are BACnet working on right now?

BACnet: We’re working on BACnet Testing Laboratories and wide-area networking, as well as coming up with standard definitions for devices. We’re also determining configurability for devices and networks.

Q. Is there room for both LonMark and BACnet in the industry?

LonMark: Sure, it’s usually a safe bet that there will be alternatives. However, it’s clear to us that the lion’s share of the market for automated buildings will use LonMark devices.

BACnet: Yes.

Q. Where would LonMark like to see itself in five years? Ten years?

LonMark: The proliferation of the Internet has created tremendous business opportunities, is changing the way that companies approach business, and is having an increasingly positively effect on our lives. The resultant business opportunities being explored by both established and energetic, well-funded start-up companies can be neither predicted nor underestimated.

It is in these emerging business models that we see unlimited opportunity for intelligent, open, interoperable device networks like those built on the LonWorks platform and LonMark certified products. Appropriately, these are the same markets served by members of the LonMark Association.

I envision the establishment of task groups and efforts focused specifically on applying these new models to both the “traditional” and emerging market spaces for networked everyday devices. I look forward to additional enduser, service provider, and IT-focused companies participation in the LonMark Association. The viewpoint provided by these organizations enables development of spot-on devices and services that provide increased value to customers. We will continue the development and expansion of LonMark certified products and will increase education programs focused on the benefits of interoperable control networks based on the LonWorks platform.

Q. Where would BACnet like to see itself in five years? Ten years?

BACnet: We would like to see it adopted as an ISO Standard. We’d also like to see it as the dominant standard for networking building systems together, such as the integration of hvac, fire/life safety, security, lighting, elevators, and any other building systems. We will also continue to evolve and gain acceptance for the design and implementation of building systems. ES

BACnet as a True Industry Protocol Standard

(Ed. note: In contacting these organizations to confirm the accuracy of their own quotes, it became clear that each party felt misrepresented by the other. Thus, we have given each group a chance for rebuttal. Here is what BACnet submitted.)

The manner in which BACnet was developed compared to other protocols is distinctly different. BACnet was developed in an open forum, giving the entire industry an opportunity to have input and to participate. This differs from a closed and proprietary manner in which other protocols have come to market. The goal of BACnet was to gather a consensus within the industry. This fulfills a key element in qualifying BACnet as a true industry standard.

As a protocol standard, BACnet is totally nonproprietary. No company owns or controls the protocol. You do not have to purchase specific chip sets from a manufacturer to implement BACnet, unlike some other protocols. This means that the protocol is not dependent upon the survival of a specific company, nor at a whim can the protocol be modified and changed. This differs dramatically when compared to LonWorks.

BACnet is the only such protocol to be adopted as a true ASHRAE/ANSI standard. It has also become a recommended NEMA standard for fire protections systems, a Korean standard (KS X 6909) as well as a proposed European standard, and worldwide ISO standard. This differs again from other protocols that have been heavily marketed in hopes of simply becoming a de facto standard. Being a true ASHRAE/ANSI standard is a key advantage and benefit over other protocols that simply call themselves a “standard.”

BACnet was developed specifically for the controls and building automation industry. As such, it was conceived to be applicable throughout the entire system architecture, from workstations all the way down to simple field device controllers, such as vav boxes, etc. It did not find its way into the controls world after having made the rounds in other industries. It is technically superior, having the scalability for systems of virtually unlimited size, and uses standard network types. Non-control companies are also implementing BACnet. Security, fire protection, lighting, and other manufacturers are also offering products with BACnet capability. BACnet continues to adapt to new technologies, such as the adoption of BACnet IP.

Today, there are thousands of BACnet installations in operation on virtually every continent. Momentum is shifting very heavily in favor of a true standards-based protocol for building control systems.

Leading control manufacturers are now members of the newly formed BACnet Manufacturers Association (BMA). These companies include, Siemens Building Technologies, Inc., Johnson Controls, Inc., Honeywell, Trane/BASD, Automated Logic, Delta Controls, Alerton Technologies, American Auto-Matrix, Inc., Belimo Air Controls, Teletrol Systems Inc., as well as Lithonia Lighting and Simplex.

A key thrust of this organization is the formation of BACnet Testing Laboratories (BTL), which will test for BACnet compliancy and interoperability of products from all BACnet manufacturers that submit product. Products tested and found to be in compliance will carry the BTL logo on their respective labels. This greatly ensures the industry of the ability to integrate various BACnet-based equipment.

The controls industry is undergoing a dramatic change. BACnet is the most important technological change to come to this industry since DDC was introduced many years ago. The ability to marry products of various types from various manufacturers is quickly becoming a true reality. We’ll continue to see this trend mature and strengthen in the years to come. BACnet will be the heart of this change.

LonWorks as the Industry’s de facto Standard

(Ed. note: In contacting these organizations to confirm the accuracy of their own comments, it became clear that each party felt misrepresented by the other. Thus, we have given each group a chance for rebuttal. Here is what LonMark submitted.)The LonMark Interoperability Association took a very different tack than others in addressing the issue of interoperability by tackling the thornier and more important notion of how one creates end-to end systems that interoperate at the device, controller, and workstation levels. Much the way that the computer and telecommunications industries moved to eliminate closed standards, LonMark set out to eliminate all closed proprietary building control systems in favor of an end-to-end solution for open, interoperable systems.

Achieving this goal required the close collaboration of manufacturers, specifying engineers, systems integrators and building owners. Further, the Association chose to base its specification on the LonWorks platform for device networking, an open, standards-based technology (including ANSI 709.1, ANSI, 709.2 and ANSI 709.3, and IEEE XXX). By providing an end-to-end infrastructure for implementing interoperable systems, LonMark, provides end-users with a choice of products from a range of manufacturers. In fact, you’d be hard pressed to find even a single LonMark solution that uses only one vendor.

LonMark interoperability is driven by the needs of the industries it serves, and its success is a result of the extensive participation by the building automation industry. Active involvement by the who’s-who of the buildings industry, including Honeywell, Invensys, Johnson Controls, TAC, and Siemens, among the 260+ companies participating in the LonMark Association, provides testament to widespread acceptance and the value proposition of the LonWorks platform.

The fact is that LonWorks networks consisting of LonMark products enable multiple subsystems, with devices from a variety of suppliers, to be seamlessly connected and Internet enabled. Numerous examples of the integration of multiple systems (hvac, access, security, fire) for building automation can be found at the LonMark website ( and Echelon website (

Because LonMark products are LonWorks -based, and reside on a LonWorks network, systems can grow to an incredible size (up to 64,000 nodes on a single domain with thousands of domains on a single network). There are millions of LonWorks devices installed today, developed by over 3500 companies, in applications ranging from building automation, industrial, transportation to the home market. Recently, Enel SpA, the world’s largest publicly traded electric utility, announced a three-year plan to add an intelligent LonWorks networking infrastructure to virtually every home in Italy — 27 million of them. Entire countries are moving to LonWorks networks.

LonMark products extend even further in the Internet Age. Consider that the platform supports true IP integration. Virtually any device on a LonWorks network can become an Internet host without rewiring or rebuilding the product. In essence delivering the best of all worlds: an extremely reliable, optimized device network based on open standards, and an extremely fast nearly ubiquitous standards based backbone for high-speed communication needs. Additionally, LonMark objects can be published as services on a Jini™ ad hoc network or integrated via services deployed across the industry standard OSGi compliant gateways.

In conclusion, the robust capabilities provided by LonWorks networks and LonMark devices are enabling owners, specifiers, and integrators to realize significant advantages over traditional proprietary systems. We’d love to see BACnet get more in tune with the drive toward open, interoperable automation systems. The best way for them to do that is to join the LonMark Interoperability Association, so that the work that has been done on workstation-level issues won’t be marginalized as the market moves inexorably toward open, interoperable LonWorks systems using LonMark products.