KNX has arrived
KNX ticks all the boxes as the only truly-open and international bus protocol for modern, future-proof building management. So what’s holding us back, muses Steve Payne, time and climate control manufacturer Theben’s champion for KNX technology in the UK.
The demand for comfort, convenience, safety and energy efficiency from air-conditioning, lighting and access control systems is driving the growth of intelligent building control and management. With the KNX network communications open protocol this does not mean ever-more wiring running from the sensors and actuators to the control and monitoring centers, with all the extra design and installation effort, increased fire risk and soaring costs. A single KNX bus wire will carry control data to and from devices throughout a building and – here’s the key point – because it is a truly open protocol you can choose KNX-compatible devices from different manufacturers on merit, safe in the knowledge that they will work together. There are now about 200 manufacturers producing KNX-compatible devices and I fail to see any reason why anyone involved in a new build or refurbishment project, be it for a family home or a commercial office complex, would not be designing in KNX at the outset.
KNX does away with the problems of isolated building management devices by ensuring that all components communicate via one common language, one that is entirely independent of any manufacturers or software application. All bus devices are connected to the KNX cable via twisted pair, radio frequency, power line or IP/Ethernet, and are able to exchange information. Bus devices can either be sensors or actuators needed for the control of building management equipments. Almost all of building functions can be controlled, monitored and signaled via a uniform system without the need for extra control centers. In larger building there will be a permanent ‘control station’, but nothing more demanding on the budget than typically a dedicated PC or two. For smaller buildings or smart homes, you can simply plug in a laptop to programme or adjust the system.
Some of you may remember EIB (European Installation Bus or Instabus), EHS (European Home systems Protocol) and BatiBUS, predecessors to KNX. The basic concept it’s the same, it has just grown up a bit.
Where are we now?
The UK is lagging behind Europe in the adoption if this truly remarkable standard, with probably less than 10% of new projects adopting the standard.
This may be because of our traditional Chinese Walls between lighting control (seen as electrical) and HVAC control (falling into the M&E camp). It may be because building control still means lighting control to many of us. Perhaps we are wedded to the DALI protocol, which is no bad thing and is in widespread use in the UK – but that should not be a barrier to taking advantage of KNX as there are now several KNX-DALI gateway devices available. Similarly, there are gateways with the EnOcean wireless protocol and the American Society of Heating, Refrigerating and Air-Conditioning Engineers’ BACNet.
Of course, there are lot legacy proprietary lighting management systems already in the marketplace, which restrict end users choice of devices and usually involve them in expensive engineering contracts. Some now offer a degree of HVAC and access control, but I do not believe that they are, or ever can be truly comprehensive building management systems in the KNX sense. With KNX the capital outlay is low – simply the cable. The software is free and runs on a standard PC. The choice of devices you can connect is ever growing and, importantly, is subject to real free market competition so that manufacturers are driven to keep prices down and to keep innovating. You really need to look at the long-term cost of ownership before choosing which way to go on smart homes – and when you do that I am confident that you will agree with me that KNX has to be the way forward.
The main focus of building control in the UK projects that have employed KNX is still on lighting. A quick look at my own sales book tells the story: while Theben offers a complete range of KNX-compatible devices including superb multi-channel room controllers, the bulk of sales are still for the sophisticated presence detectors used to automate lighting. Yet we all know that real energy savings are going to come from the integration of all building systems, and I have no doubt that sooner or later the financial imperatives will make sure that we embrace KNX to achieve these savings.
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