Putting the intelligence into intelligent buildings
Whether you are designing a whole new building or refurbishment, or starting with a single floor or department, KNX makes sense, argues Stephen Payne.
KNX is an international open-source building-control standard and puts the intelligence into intelligent buildings. Control and monitoring devices are integrated and work together logically For example, fans can operate automatically when air quality levels fall, lights can switch on or dim when natural light levels level change, HVAC systems can turn off in a room when no-one is there. KNX control is now widely used in projects ranging from private residences to some of the largest commercial projects in the UK, details of which can be found on the KNX UK web site (first address below).
KNX does away with the problems of isolated building-management devices by ensuring that all components communicate via one common language, which is not dependent on any one manufacturer.
The KNX standard products are available from over 250 manufacturers, leaving systems integrators free to mix and match, picking the best product for each job and safe in the knowledge that they will ‘talk to‘ each other. For instance, my company (Theben) is pretty much unbeatable on KNX presence detection and carbon-dioxide monitoring — but would not claim to lead the way in, say, audio-visual systems or door entry.
The level of collaboration between the companies manufacturing KNX devices is refreshing to see and sounds the death-knell for proprietary systems and expensive lock-in maintenance contracts. This collaborative mindset has also led to the development of KNX gateways to popular protocols such as DALI, BACNet and OpenTherm. KNX has truly established itself as a hub of building control.
KNX integration leads to the energy management and cost savings that today’s carbon-reduction agenda calls for. In all jobs, you are going to be asked about energy efficiency and probably required to answer for it at board level. Taking advantage of KNX compatibility can put you ahead of the game. KNX training courses and seminars are offered by various providers. Again, details are available at the knx web site.
In a nutshell, products are installed on a KNX bus cable. For many devices this pair of wires provides the signalling information and power for devices like the Theben compact office-presence detector. Other devices, such as heating actuators will of course need a separate power supply to run the devices they are controlling.
All KNX devices are connected to the KNX cable via twisted pair, radio frequency, power line or IP/Ethernet, and can exchange information. Devices on the bus can be sensors, actuators or displays needed for the control of building-management equipment. Almost all building functions can be controlled, monitored and signalled via a uniform system without the need for extra control centres. In larger building there will be a permanent ‘control station’, but nothing more demanding on the budget than typically a dedicated PC. For smaller buildings or family homes, an integrator can simply plug in a laptop to program or adjust the system.
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| Lighting control has traditionally been a major application for KNX, such as Terminal 5 at Heathrow Airport using Theben KNX products. |
Programming installed KNX-compatible devices is then managed using a single software tool, currently ETS 4, available from the KNX Association (second address below). KNX leaves building owners and managers in complete control.
KNX products are all thoroughly tested for compliance by the KNX Association, ensuring they operate seamlessly together on the KNX network; you simply won’t get compatibility issues or be tied to one company.
KNX-compliant products are available for controlling the following applications.
• Lighting
• HVAC
• Intruder alarms
• Audio visual systems
• Blinds and awnings
• Energy management … and many more.
KNX is not just for prestige projects like MediaCityUK at the Salford Quays redevelopment. I would encourage anyone involved in a partial refurbishment — hospitals ward by ward or firms refurbishing floor by floor, for example — to start to introduce KNX and build gradually on their new infrastructure.
The choice of KNX devices and the manufacturers making them is ever growing and, importantly, subject to real free-market competition so that manufacturers are driven to keep prices down and keep innovating. Building designers really need to look at the long-term cost of ownership before choosing which way to go on building management.
The majority of building control in the UK projects that have employed KNX are focused on lighting. But 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 of carbon-footprint accounting and high fuel costs will make sure that we achieve these savings within the built environment. I am equally sure that KNX is going to enable us to do so now and in the future.
Stephen Payne is KNX systems manager for Theben’s UK subsidiary Timeguard Ltd
