Technological winds of change

For bems, the eighties and early nineties were about gradually extending the control scope of systems – from central main plant rooms containing boilers and chillers, to air handlers, and then on to terminal unit control. We thought that the bems would become much more than a way of controlling hvac. And we also thought that the graphical user interface supplied with the bems, the 'supervisor', would be the logical place to manage other building services, such as lighting, lifts, access and public address systems. We were happy to refer to these more powerful, more configurable bems as 'advanced building controls' or 'intelligent controls'.

Over the last five years, emerging technologies have blown away many of these assumptions, transforming the way we design, configure, test, document, maintain and manage intelligent building systems. Much of the credit for this can be attributed to the internet, but more properly it is the result of the convergence of a raft of technical innovations in networking, communications, electronics and IT.

Harnessing the web
We are in the midst of a networking and communications revolution where the emphasis is on using standard open network technologies to link buildings, systems, plant rooms, and even devices. Conversely there is a shift away from manufacturers' own proprietary networks. Internet protocol (IP) is now the obvious way to move data from the control layer to the computer screen. Whereas we used to load a whole suite of supervisor software onto a desktop pc, we can now command and control this and other systems from a standard graphical user interface found on virtually every pc, namely a web browser.

Not only that, but a single web page can contain dynamic, real time information from multiple building systems, for example access, security, lighting and hvac, and may be gathered either from one building or from a number of remote sites. Full interactivity is possible, for example permitting values such as temperature and humidity to be displayed and adjusted on screen, and cctv cameras to be manipulated where appropriate.

Further good news is that web pages are constructed using standard off-the-shelf web authoring software, Macromedia Dreamweaver for example, and the cost of constructing graphics for web browsers hardly differs from schematics for bespoke system supervisors.

Rewriting network architectures
In the early 1990s, an EC working group code named TC247/WG sought to standardise system neutral data transmission methods between products and systems in hvac applications. The group defined a model for the structure of bems that had three layers:

• Field level – low level networks connecting intelligent devices and/or intelligent controls.
  
• Automation level – a layer that connects control and monitoring networks to user interfaces.
  
• Management level – a level for the coordination and presentation of systems data for command and control.

One result of TC247 was a complete lack of consensus over standards. No less than nine protocols were agreed for evaluation, three of which, WorldFip, FND and Profibus, were subsequently rejected. The remaining standards are BACnet for the management and automation layers, LONtalk and Konnex. The latter comprises the amalgamation of European Installation Bus (EIB), Batibus and EHS.

Despite the sterling efforts of TC247, the building systems industry has not put its collective weight behind any of the standards selected. In consequence, there is no unifying all-encompassing standard, and another Brussels banana has been born.

It is nevertheless interesting that the three-layer model defined by TC247 has itself become a de facto standard for the way building systems are viewed. It has had a major impact on the way manufacturers and consulting engineer practices have considered the elements of building systems. The three-layer model, then, may prove to be the most enduring contribution from the group.

Tellingly we are now seeing IP installed at the field layer, for example linking door entry controls. The three-layer model is effectively being superseded by a multi-layer model, in which networks, devices and user interfaces are plugged together in a far less rigid way.

Use of language
Couple growth in the use of IP, with the development of the universal language of the world wide web – hypertext mark-up language (html) – and building systems become very exciting. The emphasis shifts from a closed to an open proprietary network technology, concerned with linking devices as objects both flexibly and economically. We are beginning to see packaged plant and power management products with in-built web servers that connect directly to Ethernet. Give them an IP address, and they will serve html pages straight to your web browser.

In order to survive and prosper, suppliers of intelligent systems will need to become ‘systems integrators’ in the truest sense of the phrase.

Internet Protocol isn't the only valid networking solution, though. It is one of a raft of standard networks, including ModBus, JBus, BACNET and Echelon, all of which may be mixed and matched.

Building controls manufacturers are by no means oblivious to the change. Many are now in the throes of developing controllers that serve data across Ethernet using a version of html called Extensible Mark-up Language (XML). This allows formatting and data to be assembled by the distributed controls and served as complete chunks of information. Manufacturers are also exploring the idea of using Simple Mail Transfer Protocol (SMTP) to send out alarm messages from controllers directly by e-mail.

Watchpoints
So, we now have the possibility of complete convergence between IT and building system technologies, with building systems passing data directly and seamlessly across an occupier's Ethernet. In practice, users can access information from any convenient location using web browsers, personal organisers or even mobile phones. There are, however, some potential difficulties to bear mind.

For convergence to occur, building system manufacturers and suppliers must be able to conform fully to IT networking standards. At present, few do. In addition, when connecting onto business-critical networks, installation commissioning and documentation building systems procedures become much more stringent and therefore more costly. Such increased costs need to be anticipated.

It may also be necessary to have closer co-ordination with clients' IT services, preferably away from the construction management table, since any work on client networks can affect building system communications.

The wider picture
The use of emerging IT technology for building management doesn't stop inside a building, of course. Several UK-wide and pan-European projects are currently in progress where estates of buildings are linked via existing high capacity wide area networks (wans). Using the analogy of the wan as a data highway, the estates management system is usually given its own bus lane, providing the bandwidth required via dedicated switches. Critically, the estates system must fit the characteristics of the backbone network or it won't work properly. For example, most building management systems communicate alarm or fault messages from one point to another and therefore require fixed IP addresses. In contrast, many IT systems broadcast alarms, and the IP addresses may be set dynamically using dynamic host configuration protocol.

There are other important issues to be resolved, and these include the management of risk in mission-critical installations, security and the definition of what constitutes good practice in terms of data storage. Data has to be stored somewhere, if it is to be moved from building systems across wans. Internet technologies such as routers, networks and servers, allow building data to be stored more or less anywhere in the world. For mission-critical use, the servers can be easily mirrored and backed-up. Current thinking is that it makes sense to store memory intensive graphics close to the point of use, reading into them only the system values that the operator needs to see. In general, the duplication of system data is regarded as a bad thing, while storing data within its control system is seen as good.

Building users may be easily convinced that building data can be managed, when making the move to web-enabled buildings. However, the matter of security seems to be a common area of concern. But in an open IT based architecture, the threat of a security breach is no different from any other mission-critical applications, such as sales and accounts systems. While industry-standard firewalls and server security features are generally adequate, the principal of a virtual private network (vpn), a method of routing private data across a shared network, provides added protection.

Contracting conundrums
There is much writing on the wall for systems installers. The skill set of most suppliers is centred on engineering closed, proprietary systems. A further layer of skills based around IT networking and html coding will be required in order to properly serve its customers in the future. Given the current disparity in day rates between controls and IT engineers, (with the charge-out for the latter roughly 80% higher), there are tricky commercial implications that need to be addressed.