HVAC and dreams of integration: how did we arrive at today's contenders for building connectivity? - Cover Story

Engineered Systems, August, 2003 by Anto Budiardjo

What can HTML or XML do?

How does the integration business differ from the HYAC business?

These questions are important, and the answers moreso. While the HVAC industry is poised to do well in integration, it isn't a given. Take a minute and get the big picture by starting with the building controls dream, then moving into the present and toward the future

THE DREAM

A man arrives in the dead of night to his place of work; he swipes his access card on the front door and is let in. Sensing that someone is in the building, the system turns the HVAC system to standby, calls the elevator to the ground floor, lights all (and only) the corridors to his office, sets his office temperature to his preferred level, and enables the PA to play his preferred type of music ...

This dream has been told in the building control circles for almost two decades.

To almost any user of buildings, the benefit of such a system is obvious when depicted in such a simplistic manner. Why is it that years later, these "dream systems" are only found in a handful of buildings? The dream buildings that do exist are typically demo systems or follies of building owners who spent such a fortune on these systems that many might regard them as having more money than sense.

What is the impact of such a vision to HVAC-centric designers, engineers, operators, and facility managers? The responsibility of these professionals is the maintenance of comfort and energy--not lights, access, elevators, and music!

The term "building automation" suggests the process of automating a building's systems; automation should be able to facilitate the coordinated interplay between all of the systems in the building if it is going to provide the maximum benefit to the owner or occupier. After all, a lighting circuit is logically no different from a fan (each is a digital output), and an occupancy signal is an occupancy signal, whether it comes from the access system or some other occupancy detector.

The dream described above has been shared over the past decades by many of the early adopters in the HVAC industry: manufacturers eager to provide their customers with more value from their systems, and contractors who are rapidly becoming integrators. They see that if they can provide additional benefits to their customers, they would be able to retain those customers. For those who have delivered such solutions, it has been an incredibly effective way to increase business and retain loyal customers.

For years, technology was a clear barrier. In the 1980s, it was simply too hard to connect these systems with each other; the only method available was volt-free relay contacts which are very inflexible and expensive. The early '90s saw serial data communications as the way to make systems talk to each other; with the promise of RS232 as the savior. Though elegant in theory, such system-to-system connectivity proved cumbersome as integrators fought with different proprietary protocols, incompatible versions, and expensive project-specific solutions.

Seeing an opportunity for a standard method to connect systems, numerous technology groups embarked on the development of standards. There was a time in the mid-'90s when dozens of standards were being developed and promoted, but for the most part they were not compatible with each other--that would have made life way too easy!

THE TECHNOLOGY

At the turn of the 'century, there were basically four contenders remaining for the role of connecting devices and systems together in buildings: Modbus[TM], Konnex (EIB), LonWorks[TM], and BACnet[R].

ModBus was originally designed by the industrial controls industry and is typically used for device-to-device connectivity, primarily for devices such as diesel generators, UPSs, and PLCs (programmable logic controllers). While it is likely to remain in use for some time to come, it has no likelihood of system level interconnectivity. ModBus was not designed to do so.

Konnex, an association created by the merger of EIB, BatiBus, and ProfiBus, is primarily a European initiative supported most significantly by the Siemens conglomerate in Germany. Again Konnex has little to offer the system-level solution, and it does not seem to have much energy or support anywhere other than Europe.

That leaves LonWorks and BACnet, both with a great deal of support globally and both approaching the problem at a system level (to a differing degree) as well as at the device level (also to differing degrees). This article is not intended to be a comparison of LonWorks and BACnet, but it makes the presumption that in the North American market at least, both of these initiatives will remain alive for some years to come. There is simply too much momentum for either to be dismissed overnight.

The wild card is the technology the building industry is gaining from the IT and network industries. Propelled by the same need for standards, the Internet was born to be the ideal integration network protocol that today is able to connect millions of devices across the globe. So, why is it not used more in buildings? Why is the Internet (or TCP/IP to be more accurate) not the answer to all of our connectivity problems?