A design for life

With any 21st century building design, energy conservation is paramount if the demands of regulations, industry targets and client requirements are to be achieved. Building controls play the critical role in the electrical and mechanical design process by providing the operating parameters, strategy, measurement and monitoring functions of the building services.

The plant, equipment and components normally specified to achieve the optimum energy performance of a building against the client’s requirements include luminaires, central battery units, fans, chiller plant, boiler plant, pumps, HVAC systems and other services. It is the building’s control systems that set these items to work.

This is only the start, as the control system has to take into account the ever changing climate/times of day and should be designed to cater for the changing needs of the building and its occupants. Suitable upgrade paths and expansion capability for the future are needed and KNX fulfils all these requirements more successfully than any other form of building control system.

The concept of KNX Open Protocol Integrated Building Control, as opposed to the older traditional approach of many standalone separate systems, has many advantages. Open protocol refers to a bus system based around a known international standard, not manufacturer specific, with one software tool used for programming and available to everyone. One of the key benefits of a truly open protocol bus system is that it is supported by more than one manufacturer and will allow products from many manufacturers to be seamlessly connected together on the same network without the need for special application programmes or drivers.

This gives benefits including multi-vendor products and support; a wide range of applications available on one network, no tie in to one single company, no lock-in to expensive maintenance contracts, a common software platform which is not manufacturer owned, a selection of a wide range of products and standardised training open to all. Furthermore, the full system, including software, can be handed over to the end user for on-going maintenance.

With the open protocol approach, the system will never date as there is an upgrade path to follow and with KNX there is a guaranteed forwards and backwards compatibility of products that could be used on the existing bus network. The open protocol KNX system is also very easy to extend at any later date as new bus lines can simply be added to the existing network. The approach is a bit like Lego for building controls and there is no limit to the size and scale of the KNX system as the technology is equally well suited to large-scale commercial/industrial projects and small residential projects alike.


Sustainability is also a key motivational factor in building design. KNX provides a smarter, more sustainable approach to the design and management of intelligent integrated building control systems. Sustainability is all about considering the balance of energy and associated carbon emissions. It generally would not be considered sustainable to specify a low energy item that has been manufactured in conditions that fall below acceptable standards and, by the nature of the manufacturing process, any energy savings made after manufacture would be outweighed.

The installation phase should also be examined to see if environmental savings can equally be made. It is not uncommon for traditional electrical systems to be installed by a number of different companies with many different sets of cables, materials, components, plant/tools and associated transportation. This traditional model can lead to higher site wastage such as cable off-cuts, leftover packaging etc. and will all add to the overall carbon cost of the construction process.

The lifecycle approach takes into account the operation and maintenance phases of a building control system. Will the systems be easy to maintain, reliable/robust with an upgrade path and spares available in the future? If not, consideration may have to be given to replacing the whole system, defeating the concept of sustainability.

The answer lies in KNX. Integration is all about bringing control applications together and allowing them to operate together sharing information about the space being controlled. The savings to be made, even in a small office, are considerable if, for example, lighting control, fan coil unit heating / cooling, automatic blind control and perimeter low level heating are all controlled by a single KNX bus network with one wall mounted KNX device and a single ceiling mounted KNX presence detector.

Intelligent building control systems have never been in more demand than now but key points of good design practice need to be considered. For example, consider the mechanical design with the electrical design and do not separate the two as there are many cross over points and many aspects that could be designed together. It also pays to have an open mind to integration or one system for all. With the KNX open protocol system approach, this can lead to more efficient building control as many elements under control will interact with each other to give better human comfort.

The introduction of lifecycle costing to the tender process and the review of energy payback calculations will demonstrate the short payback periods that can be provided with KNX integrated building control systems.

Making savings

Designs should look to save on installation/cabling and the promotion of the use of a site-wide IP network for all systems to use. A CAT5e data network, now a standard feature throughout a building, can be used as a network for communication around the building and save on installation, labour and materials. The structured cabling network will prove to be very reliable and is a single asset to maintain. With most control systems very little bandwidth is required so there is no need to worry about overloading the network.

Also consider using the electrical contractor for all of the cabling installation – why have different companies installing different cabling systems? Consider at the design stage the upgrade path and supply of spare parts for the future. Many users are faced with the problem of non-maintainable systems after a very short service life and this can be avoided by adopting the KNX approach. Early engagement of the KNX Systems Integrator is always a good idea for design input and many problems can be solved early on with the specialists on board.

The specification of energy metering and monitoring systems will allow system performance checks and targeting. If the building’s performance can be measured then improvements to the overall energy performance can be considered.

Modular design

A typical KNX installation will normally consist of a control panel designed to house the KNX power supply and other DIN rail mounted devices. The control panel will be sized to suite the project as KNX is a modular system whereby components are selected depending upon the requirements of the project – that is to say that a system can be tailored to meet a specific design specification, not stuck with standard fixed equipment.

This modular design approach gives maximum flexibility without compromising functionality as the system can be designed to overcome many of the well-known site issues such as limited riser space and or ceiling void space.

KNX is now at the forefront of integrated building controls and its principal philosophy is to bring different manufacturers’ products together on one bus network and to be completely interoperable with each other. This offers many advantages so consultants and building services engineers can now move away with confidence from the traditional approach of considering every single control application as a standalone

The new KNX UK Consultants’ Guide discusses all these issues in depth and provides KNX installation and design scenarios together with examples of real installations.

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