KNX – why wouldn’t you?

KNX ticks all the boxes as the only truly-open and international bus protocol for modern, future-proof building management. So it makes sense that it ought to be ubiquitous, and to be part of everyone’s thinking from day one of a project. So what’s holding us back?

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 open protocol this does not mean ever-more wiring running from the sensors and actuators to the control and monitoring centres, 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 seamlessly. There are around 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 platform, one that is entirely independent of any manufacturers. The software is managed by the KNX Association on behalf of all the members. All the KNX devices are connected to the KNX twisted pair cable, 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 equipment. Almost all of building functions can be controlled, monitored and signalled via a uniform system without the need for extra control centres. In larger buildings 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 family homes, you can simply plug in a laptop to programme or adjust the system

Maturing technology

Some of you may remember EIB (European Installation Bus or Instabus), EHS (European Home systems Protocol) and BatiBUS which were predecessors to KNX. The basic concept is the same; it has just grown up a bit. The KNX standard is based on the communication (or protocol) stack of EIB enlarged with the physical layers, configuration modes and application experience of BatiBUS and EHS. The physical layer is the first and lowest layer in the seven-layer open systems standard for computer networking and consists of the basic hardware transmission technologies of a network. Due to the plethora of available hardware technologies with widely varying characteristics, this is perhaps the most complex layer in the OSI architecture but the bottom line is that it translates logical communications requests into hardware-specific operations to affect transmission or reception of electronic signals.

All of this need not bother you, of course, you will have chosen KNX because you know that all KNX approved devices will communicate and work together. With the backing of the KNX Association, you have complete transparency on device compatibility and access to a network of support and training services.

Where are we now?

The UK is lagging behind Europe in the adoption of this truly remarkable standard, with probably less than 10% of new projects adopting the standard.

This may be because of our traditional wall 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 lots of legacy proprietary lighting management systems already in the marketplace, which restrict the choice of end user 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.

Yet once installed, there is a degree of inertia because ripping them out and replacing them with a more-open system represents 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 floor by floor to start to introduce KNX. The software is available from the KNX Association and runs on a standard PC. The choice of devices you can connect is ever growing 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 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 wide range of KNX-compatible devices including multi-channel room controllers, the majority of sales last year were for our sophisticated ThebenHTS Presence Detectors. Nevertheless, 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 ensure that we achieve these savings. With a KNX system designed in from day one, you will be ready with all the flexibility you will ever need to achieve them.

Meeting demand

With its network of tightly knit streets, squares and boulevards cascading down into a huge waterfront piazza, MediaCityUK is spread over 36 acres (with a potential to develop up to 200 acres) on Salford Quays, Manchester’s waterfront. The £500million Peel Media development includes a new home for the BBC North, a campus for Salford University, office accommodation for business, retail, 378 apartments and a 218 bed hotel. The first buildings to be completed are the three to be occupied by the BBC, and Peel Media’s studio complex which is the largest high definition studio facility in Europe, featuring seven HD television studios and two audio studios.

Naturally, the project design is at the leading edge of energy efficiency, and KNX open-protocol control over an IP network was an obvious and early choice for the developers, Peel Media. As well as energy savings, the KNX option is allowing for central system monitoring and control of all lights along with automated emergency light testing, system administration reporting and interfaces to other building services such as the fire alarm.

North West-based KNX specialists EnTech (Energy Technologies) Ltd, a Theben Partner, have been successful in securing all contracts for design, installation and commissioning of lighting controls within all BBC Buildings, the Studio Building and Towers, the Salford University Building and the Public Realm.

With a heavy emphasis on digital and creative industries, MediaCityUK workspaces will be catering for unconventional and flexible working patterns, so sensitive presence detection and constant daylight control were high on Entech’s specification list for PIR detectors to ensure that lighting is used effectively and only when needed. This led them to place orders for over 3000 ThebenHTS PIR sensors for the first
phase of this prestigious project.

The sheer size of the project meant that the number of PIR detectors would be counted in their thousands, however this number was significantly reduced by Entech’s choice of the Theben HTS square detection pattern Compact Office KNX Presence Detectors. The square pattern of the detection field, which is determined by the design of the lenses and the sensor inside, makes it easier for project designers to plan the installation without overlapping detection fields and redundancy.

The unit’s built in Constant Lighting Control mean that the required lighting level can be maintained using natural light where possible and the minimum of artificial light; thus maintaining comfortable lighting levels and, where possible, saving energy. Desired lighting levels can be determined detector by detector if required. Commissioning and operation is simplified using ThebenHTS QuickSet intelligent remote controls which are used to transmit settings or call up pre-defined value packets for typical spaces. The option of the clic remote control means that lighting levels in rooms can be changed by the occupant, for example during a presentation the lights can be dimmed and the blinds closed at the touch of a button. Remote controls enable changes to be made to the Presence Detectors without touching them physically.

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