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Technology Article: Intelligent Building Control with KNX (1/7/2008)

By Colin Price, Ivory Egg

You might not believe it, but for most people, their car is a lot more intelligent than their existing home or workplace. It has energy management systems, and easily-controllable security, lighting, climate control, audio and entertainment systems. This level of control at home or at work is only a dream for many, but it need not be. With the installation of an intelligent building control system, all off this is possible in the home.

What is KNX?

KNX is the world's only open standard for building control. It is a building management system designed to control lighting, blinds/curtains, heating, ventilation, air-conditioning, security, entertainment systems and energy management throughout a building. It can be installed into a new or existing development, and because KNX-based network is hierarchical, it is equally suited to the smallest home or the largest commercial development.

Energy saving is one of the key features of a KNX-enabled building control system. KNX lighting control systems can be configured to turn lights on when someone enters the room, to monitor daylight levels, and dim or turn off lights when enough ambient light is present. Temperature levels can be regulated in individual rooms, set to different temperatures and heating switched on or off, up or down depending on the occupancy, and so greatly increasing the energy efficiency of the heating system.

KNX controller in dining area offering lighting and temperature control.

KNX products

Integrators and contractors can choose from a pool of interoperable products to build and programme complete control solutions using an ever-increasing range of off-the-shelf components from different manufacturers. Products from companies such as Gira are becoming 'must have' items in the latest property developments and re-developments. Since light switches, door entry systems, thermostats and audio controls can all be sourced from the same manufacturer, in the same style, they allow architects and interior designers to create a consistent look, from the front door to the master bedroom.

Modular KNX controllers offering door entry monitoring and control, and control of audio, lighting and temperature.

All KNX products are thoroughly tested and certified to be KNX compliant. They can be programmed using one common software tool, and because they all 'speak the same language', can operate together seamlessly across the same network. As a result, the amount of cabling that has to be run is greatly reduced, thus saving on material and labour costs and achieving a higher degree of functionality.

KNX products offer a conistent look from the front door to the master bedroom.

Installation

Installing KNX is a relatively simple affair, although some form of training is advisable. Typically, a two-wire installation bus is laid parallel to the 230V power supply network and a 29V DC bus line connects all of the bus users (actuators and sensors) together. In this way, the network structure is simple. An approved 2 x 2 x 0.8mm two-wire cable, usually green in colour, is used as a bus line. The line serves as both an open information exchange between actuators and sensors through two of the cores, and as a protected low-voltage supply for ancillary devices that may require power.

Every KNX device, be it an actuator in a panel or a thermostat on a wall, contains a bus coupler that is connected to the green wire which is daisy chained from one device to another. The only rule the installer must follow is not to close the loop. The actuators are usually mounted on rails in a distribution box and radially wired out to each point of load. Some non-KNX systems use a central controller, but with KNX there is no central controller to fail or re-boot after a power failure, every device works independently and with its own intelligence.

Conclusion

The KNX system is reliable, easily programmable, and offers the designer or system integrator a large choice of stylish control devices. It also offers the flexibility required by modern buildings which are always being adapted and changed to suit the occupants' current needs. Gone are the problems of rewiring, fitting new hardware and the disruption that goes with this type of work. With KNX, an integrator via a laptop can simply reprogramme the system.

KNX is the future for building control. It is a tried and tested formula that works simply and reliably, offering the designer and client a future-proof building. If you aren't already installing or using KNX, don't get left behind - the future most defiantly is KNX!

Colin Price is the Director of Ivory Egg (UK) Ltd. Ivory Egg operates a virtual department store of online shops for the supply of intelligent control components to the trade, and offers expert advice, support and training for KNX products.

www.ivoryegg.co.uk