Boarding the home automation bus

Energy efficiency in buildings is a focus of many building owners, occupiers and residents in the commercial and residential sectors. Recent discussions on energy costs, efficiency and carbon tax regulations have highlighted a growing need to be aware of better ways to increase the efficiency in buildings.

Prior to 1997, the European electrical community had three main solutions for home and building control - EIB, BatiBUS and EHS. These three solutions were backed by their respective associations (EIBA, BCI an EHSA) and were individually very popular in certain countries and industries. Each tried to develop their markets separately and work towards their own place in European standardisation.

EIB had a great success in the German-speaking countries as well as northern Europe, BatiBUS was strongly supported in France, Italy and Spain, and EHS was preferred by whitegoods manufacturers.

In 1997, these three groups came together to discuss the development of a new, common, home and building control standard that could be recognised as an international standard. The groups met over a period of time and challenged themselves with a number of difficult requirements of the new standard. Their imagination proposed a number of goals:

• Independence of all manufacturers
• A common open standard for the control of commercial and residential buildings
• A standard system with the ability to control all building requirements, lighting, security, shutters, HVAC etc
• Publishing the specification as an international standard
• Verification testing and certification of all compliant products by a manufacturer independent body

The result was the formation of the KNX Association in May 1999 as a non-profit organisation. The KNX specification was published in 2002 and was based on the well-proven EIB Specification, supplemented with new configuration mechanisms and communication media originally developed by BatiBUS and EHS. The KNX specification was defined as IEC15453 and is still the world’s only standard for home and building automation.

An advantage of being defined by this standard is that a wider variety of applications such as lighting control, energy management, heating and ventilation, shutters, blinds, security and audiovisual are available through the same bus technology.

The KNX Association is a membership-driven organisation based in Brussels. Members of the association represent all application areas of home and building control.

The aim of the KNX Association is: the worldwide promotion of KNX technology; marketing and system strategy of the technology; standardisation, development and sales of KNX tools; publishing distribution of the KNX journal; and coordination of KNX partners, KNX training centres, KNX scientific partners, KNX national groups, user groups and KNX associated partners.

Membership of KNX is available in a number of forms depending on whether you are an individual, a manufacturer, a certified training centre, a university or research institution, or a KNX-recognised national group or users group. As confirmation of the open nature of KNX technology, there are currently more than 230 different manufacturers of KNX products producing over 7000 different certified devices.

What is KNX?

KNX is an installation bus that provides a cost-effective and flexible solution for a wide range of different tasks in residential, commercial and industrial buildings. The KNX Association in Belgium controls the KNX specification and upholds the integrity of the system. The association is completely independent of any manufacturer. An electrical manufacturer can become a member of the association and through this membership can manufacture products to be compliant with the KNX standard. However, being a member is not the only requirement to market a product. Every product developed for the market must be submitted to the KNX Association for independent testing and verification that it is 100% compatible with KNX. Only after successful testing by the association can a manufacturer offer their product to the market with the KNX logo. Using this uncompromised process, the KNX Association ensures the utmost integrity of all KNX-compatible products.

KNX evolved from the initial specification to be approved by the European national committees and CENELEC Bureau Technique as the EN50090 European Standard in 2003. As KNX can be used not only for automation of electrical installation equipment but also for HVAC, the KNX Association proposed the specification to CEN for publication as a European standard for building controls. The KNX specification was then published by CEN as EN 13321-1.

As the KNX proven technology and product portfolio developed large interest in countries outside of the European community, the KNX Association initiated the necessary steps to have the KNX standard approved at an international level. As a result, in November 2006, the KNX protocol, including all transmission media (twisted pair, power line, radio frequency and IP) was approved for publication as ISO/IEC 14543-3-x International Standard.

This makes the KNX technology the world’s only open standard for all applications in home and building control, ranging from lighting and shutter control to various security systems, heating, ventilation, air conditioning, monitoring, alarming, water control, energy management, metering as well as household appliances, audio applications and much more.

The KNX Association defines the training requirements for installers and integrators to ensure the qualification standards are also upheld. When an installer has passed the required exam, they are eligible to be a KNX partner. The KNX Association is also the owner and developer of the programming software known as ETS, which also ensures the independence of the system.

The KNX Association promotes manufacturing companies all over the world to become KNX members so that they can benefit from the transfer of know-how and licences within the association, have the opportunity to include their products in the manufacturer and product dependent design and commissioning tool ETS (Engineering Tool Software) and participate in the partnership and research programs of the KNX Association.

The KNX bus system can consist of a single twisted pair cable connected as a line, star or tree format with a maximum length of the bus line of 1000 m. No end-of-line resistors are required in the installation of the bus. The KNX bus is supplied from a 30 V power source and the bus provides both the power supply for most devices on the system as well as the transmission data on the same twisted pair connection. As a result, devices such as switch actuators are at safety extra low voltage levels (SELV) ensuring greater public safety.

In the KNX specification there is no master controller as bus coupling devices on the network have their own EEPROM for the application program and addresses. This means there is no device that is constantly polling on the network and creating unnecessary traffic.

The growth of KNX in the global building automation market can be seen in its representation of KNX partners in over 101 countries.

The same KNX system can be used from a residential home to a seven-star hotel, it just depends how far you wish to go. International references include many private residences, the new Beijing airport, London Heathrow Terminal 5 and the Palace Hotel in Dubai.

Energy efficiency

The awareness of climate change and concerns over depleting natural resources mean that the efficient use of energy is a key social issue. Some European studies suggest that buildings account for about 40% of total energy consumption so considerable energy savings can be achieved through home and building automation practices.

KNX meets the requirements of the top energy performance class for building automation as per the European Norm EN15232. KNX has been proven in scientific studies to provide up to 50% energy savings.

Using a bus system to achieve higher comfort levels in a home has been known for some years. In a fully automated home or building it is possible to control all energy-consuming building systems like lights, heat and ventilation according to the user’s demands. At the KNX Scientific Conference (2006) in Vienna, some studies were presented to analyse the potential of a building control system.

The University of Trento in Italy and the University of Bremen in Germany fitted a building and rooms with KNX controls for lighting, heating and ventilation as part of a research project. Data was logged and analysed between two identical classrooms, one with KNX control and the other with ‘normal’ control systems. For the project the University of Bremen utilised a modern building infrastructure in the Centre for Information and Media Technology. Usually in Europe about 33% of the entire energy demand of residential and commercial buildings is used for heating. After base load heating requirements, the high energy demand can only be reduced through the introduction of an intelligent control system such as KNX. In the project the KNX room was fitted with window switches, valves on heaters, a room temperature control system and a heat energy meter communicating data to the KNX control system. The final result concluded a reduction in heat energy costs of 50% compared to the normally controlled room. Interestingly, the data showed the KNX controlled room was maintained at a temperature within 0.3°C of the normal room even though the heating energy demand was halved.

The yearly energy demand of the lighting system of the building was 500 MWh, which is higher than the heating demand of 435-485 MWh, indicating reduction of lighting energy demand will have a significant impact on the total energy demand of the building.

As the rooms had identical use, the analysis uncovered further interesting data. The KNX-controlled room was fitted with sensors for the presence of occupants, the daylight level, glare and the requirements of necessary illumination at the students’ desks. Using the information from these sensors, the KNX system controlled the lighting levels at their optimum setpoint. Between 1 October 2006 and 5 November 2006, the KNX-controlled room had a total lighting electrical demand of about 33 kWh where the standard room lighting demand was about 67 kWh representing up to 50% savings on the energy demand for lighting was possible.

In November 2010, the KNX National Group Australia was established. The ground was founded, with the support of ABB, Cisco, Hager, mysmartCTI and Somfy.

KNX Group Australia

http://www.knx.org.au/