Building systems used to be fully compatible and interoperable. Prior to digital controls, the best systems were built with pneumatic controllers. Electric signals are complicated. There’s voltage. There’s there is binary packing of data. There’s non-standardized xml vocabularies. Pneumatics were simple. Pressure was everything.
Many institutional owners of buildings resisted the new-fangled digital controls for a long time. When own a large number of buildings, interoperability is more important. Before real standards for networking and remote communications, the most important interoperability was with the maintenance technician. As Roger, the long time head of HVAC for UNC explained to me “No matter what the problem, we can clear it from here with a tank of pressurized air”. This means that at UNC, and on many campuses, most of buildings still have pneumatic systems.
Pneumatic systems work best for continuous operation. They usually cannot perform automatic setbacks. Setbacks refer to adjusting the building temperatures up or down (depending on season) outside of business hours. Just as in the home without a digital thermostat, it is a rare building operator who will consistently and reliably perform manual setbacks.
At UNC, we have been looking at some innovative approaches to retrofitting pneumatic systems for automated central operation.
Cypress Semiconductor is one of the old-line silicon valley firms. Cypress has come up with a digital retrofit for pneumatic thermostats. The digital thermostats are then linked by a wireless network back to a central controller, enabling the thermostats to be re-set remotely. Cypress further claims that the thermostats collect data on system health through analyzing fluctuations in air pressure. The central controller is a standard PC, so an operator can use the web to re-set the thermostats.
The external interface to that PC is a traditional building system protocol. Cypress would have better served itself if they had reached further. Buildings that have pneumatic systems do not usually have effective or extensive building operations systems in place. At the next level, owners are trying to crack the façade of proprietary building systems and to achieve enterprise interaction. Interposing traditional building control protocols just gets in the way.
Enterprise interactivity will let these systems respond to the business of the occupants. Conference rooms could be heated and cooled based upon schedules in the corporate calendar. Larger building operations could respond changes in business schedules and to changes in staffing. In this year’s tight economy, building operations could respond to Friday furloughs in response to signals from human resources. Enterprises expect abstract web services such as oBIX, not low level protocols, even if repackaged in TCP/IP or even XML.