Adopting the overlay principle

May 2003 Integrated Solutions

In today’s highly serviced buildings, intelligent systems play a crucial role in maintaining comfort, security and life safety. Covering services as diverse as CCTV, access and fire, lifts, HVAC and lighting intelligent systems are steadily increasing in power and sophistication.

This is often at the expense of ease of use and sometimes with scant regard to lifetime costs. For nearly 20 years, technology has been promising the building designer and facilities manager a simpler, standard communications network. What is it and where is it?

International standards such as Echelon, LonWorks, BACnet and EIB are already de-facto standards in the building-controls industry. Yet the actual number of 'standard' systems installed is small. The lion's share of installed systems is still proprietary, based on manufacturer's own protocols developed in-house, often over many years.

In America, the BACnet solution for building controls has been endorsed, and this standard has received widespread support, with leading BMS and HVAC suppliers already meeting conformance criteria.

In Canada, systems provided to public buildings have to conform to the CAN (Controller Area Network) protocol. Defined originally in 1984, CAN offer realtime communications at relatively high transmission speeds (up to 1 Mbps), and at relatively low cost.

So, like it or not, the big picture is certainly pluralistic rather than monopolistic. There is still no single, emerging world standard for building controls. Furthermore, there is no possibility of a worldwide, or even a regional standard for all building controls systems. Any of these standards will ultimately take a part of the market, but it will only ever be a part. And in this big picture, there will always be a need to share and exchange information between different systems for controls purposes.

The manufacturers' perspective

The vast majority of building system manufacturers want to sell only complete solutions, including controls, actuation devices, software, PCs, networks, engineering, commissioning and maintenance. The idea of making the very heart of their system compatible and interchangeable with everybody else's, rightly makes manufacturers rather nervous - even though facilities managers might welcome it.

The overlay principle

So, as long as there is a multiplicity of different standard networks, and a vast range of proprietary networks, there will always be a need for 'overlay' systems where integration of control values or management information is required.

Having products which 'overlay' existing, tried-and-tested building control systems make sense. The overlay products are developed 'onto' the manufacturers equipment, rather than the manufacturer re-developing a product in order to make it comply with a third-party standard.

Manufacturers retain the ability to develop their own systems as they wish, with technology which is appropriate and effective for their marketplace. With the overlay approach they have no costs to cover, and no integration issues to consider.

The integrated system can be let as a distinct package of work just like the BMS, lighting, CCTV, access and security systems. Only a few years ago, integrated solutions were strictly for the major property developer, the shopping centre, the pharmaceutical giant, or the corporate head office. The costs of the integration product precluded its use anywhere else. With the advent of overlay networks, integrated solutions can now be provided for the smallest sites: lifts, HVAC, lighting, banks and even telecom mobile base stations and repeater sites can all benefit from a common overlay infrastructure which aids facilities management, maintenance and site efficiency.

Benefit-based solutions

The building controls industry has to reach the point where it delivers benefit-based solutions, rather than trying to solve a problem that should not really need solving. Creating a common applications layer is the future, not making all systems communicate together at a very low level.

The power of integration can be truly realised when a lighting system, a BMS and an access system all share a common alarm handling function, because this allows us to provide the manager with a standardised method of operation. Split up a fire system, a BMS, an access system and a lighting controls package into their component parts and they are fundamentally similar. Rather than trying to make these individual components communicate using the same technique, why not begin the process of sharing the functionality?

Chiller data can be stored and displayed by the same part of the integrated system that handles data logging for the outside light sensor. Security systems would have their alarms handled by the same component that handles alarms on behalf of the air conditioning system. None of these systems would then need to worry about alarm handling or data logging ever again. The 'application' becomes common, not the underlying network and protocol.

By creating these 'macros' of functionality, the user is delivered not just integrated values but a truly integrated system.

By adopting the overlay principle:

1. The manufacturers have the freedom to develop their unique offerings, at the pace they choose, without being boxed into an often not quite applicable open systems protocol.

2. The end-user and owner have the freedom to choose from a wide variety of solutions and installers without being held to ransom by a single sub-set of manufacturers.

3. The integrators can confidently tie systems together, at low cost, using a common platform designed specifically to do the job.

4. The specifiers and system engineers can continue to evaluate solutions that best fit the budget and level of functionality needed, but still deliver an integrated and efficient solution.

For more information contact Chris Grice, Inet Industries, 031 767 0201,

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