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KNX Here, Now and Everywhere

Whether you are designing or a whole new building or refurbishment, or starting with a single floor or department, KNX makes sense, argues Stephen Payne, KNX Systems Manager for Theben’s UK subsidiary, Timeguard Ltd.

The demand for comfort, convenience, safety and energy efficiency from HVAC, 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 over 250 manufacturers, with more joining KNX all the time, producing 1000’s of KNX-compatible devices. It’s only logical for anyone involved in a new build or refurbishment project, be it for a family home or a commercial office complex, to 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 manufacturer. All 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 large visualization touch screen. For smaller buildings or family homes, you can use a visualization touch screen to make adjust the system or a laptop can be plugged into the systems by the System Integrator for more in-depth changes.

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 evolved to give us KNX. And KNX is no more expensive to install than any other Cat5 cabled system. So why settle for less?

Where are we now?
The UK is lagging behind Europe in the adoption of this truly remarkable standard, but there are clear signs that we are starting to catch up. Nevertheless, I would still estimate that no more than 10% of new projects are adopting the KNX standard.  

Consultants need to change their specifications to include KNX, but this will mean that both lighting control specifiers and HVAC control specifiers will need to get together and not work separately. It may also be because building control still means lighting control to many of us. Yet even our preference for the DALI protocol - which is no bad thing – this is not 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 and with OpenTherm boiler controls.

Of course, there are a lot of legacy proprietary lighting management systems already in the marketplace, which restrict end users choice of devices and can involve them in expensive engineering and maintenance contracts. Some do 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. Yet once installed, there is a degree of inertia because ripping them out and replacing them with a more-open system represent a large initial outlay. Nevertheless, I would encourage anyone involved in a partial refurbishment  for example a hospital working ward by ward or firms refurbishing office space floor by floor to start to introduce KNX and build gradually on their new infrastructure. The KNX software currently ETS4 software is available from the KNX Association in Brussels and runs on a standard laptop.  The choice of devices you can connect is ever growing, more will have been launched at the Light & Build Show in Frankfurt in April and, importantly, 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 building management – and when you do that I am confident that you will agree with me that KNX has to be the way forward.

The majority of commercial building control projects in the UK that have employed KNX are focused on lighting control. A quick look at my own sales book tells the story, while Theben offers a wide range of KNX-compatible devices including superb multi-channel room controllers and its award winning air quality sensor, the bulk of sales are still for our sophisticated Presence Detectors. This however is changing, building owners know that it’s not enough just to turn the lights off when no one is present; you have to turn the heating down as well as a myriad of other things. We all may 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 of carbon footprint accounting and high fuel costs will make sure that we achieve these savings. With a KNX system designed in from day one, you will be ready with all the flexibility you need, whatever the future may hold.  

Stephen Payne, KNX Systems Manager, Timeguard Ltd

Stephen Payne, KNX, Timeguard Ltd,building control,electrical digest,