The future is bright for DALI
Up to 16 different light levels can be programmed and stored in the ballast memory using the DALI protocol for controlling lighting, enabling different scenes to be called up quickly in rooms such as this.
Steve Buckley explains how the drive to cut carbon footprints has led to DALI lighting control becoming more relevant across the board. With energy efficiency and consumption firmly at the top of the corporate agenda, many companies are declaring their intention to reduce their carbon footprint. It’s the new buzz phrase that has been picked up by the media and manufacturers alike. Flick through most magazines and you will find a product range that declares its ‘low-carbon’ qualities, despite the fact that it might be the latest in coal-fired, gas-guzzling, patio-heating technology. ‘Going carbon neutral’ is could be said to be losing its meaning. However, that said, lighting control is one area that can actually make a serious impact on energy consumption. We know that in most commercial buildings, lighting accounts for more than half of the electricity used — whatever the size of the business. Manually switched lighting control is largely to blame. Although there are many ways that a company can reduce its carbon footprint, one of the most effective is to use a lighting-control or management system. With a control system, light levels can be automatically regulated or adapted to suit a room’s natural light levels. In addition, occupancy control offers the benefit of switching lights off and on (or even dimming) when a room is vacated or entered. Efficiency by design
The DALI protocol was developed by a group of European lighting manufacturers (including Helvar) with the purpose of establishing a new standard to support the idea of ‘open architecture’ for lighting-control systems. In short, the desire was that devices from any manufacturer could be interconnected to provide true interchangeability across ballasts and controls. In this way, multiple manufacturers can be involved in a system, instead of just a single supplier. This results in lower system and life-cycle costs, as the system designer can select product features from one manufacturer and combine them with products from another. DALI offers a number of design and installation benefits for the lighting designer and building-services engineer. It is cost-effective and versatile, whilst offering enhanced functionality over comparative systems in the marketplace. Individual control of each ballast is one of the most significant benefits provided by a DALI lighting system and gives building designers tremendous design flexibility. Multiple uses of rooms can be easily accommodated, as can the needs or preferences of individual occupants. Up to 16 different light levels can be programmed and stored in the ballast memory. In addition, each ballast can belong to as many as 16 discrete groups, allowing different lighting scenes for workspaces or room applications. Dimming or switching in response to ambient light levels and occupancy are also readily accomplished with the addition of devices such as PIR (passive infra-red) sensors. Wiring is simple and can be carried out with a standard 5-core cable (no separate bus cable is required), and the system is polarity free for ease of installation. In addition, there is no need to wire luminaires in groups as the system is programmed with a PC and software. This approach ensures complete flexibility throughout the life of the system as costly rewiring is not required if there is a change in room use, just simple reprogramming. Central monitoring of luminaire status makes fault finding easier and less time-consuming. DALI systems are suitable for small, medium and large projects. The simplest of systems consists of a power supply, dimmer, switchplate and a DALI-compatible ballast. From there, additional components can be added to this simple energy-management platform, such as PIR and occupancy sensors. Although DALI is specifically targeted at the needs of commercial and architectural lighting it can also be used in the residential environment, and has been to great effect. However, one of the perceived shortcomings associated with DALI is linking together the individual networks, especially in large architectural applications.
The ability to dim fluorescent lights in response to ambient lighting is one of the benefits of the DALI lighting-control system.
The new DIGIDIM router system uses standard Ethernet communication to combine DALI networks seamlessly together. This modularity allows users to create a fully scaleable system suitable for a range of applications — from a single office room to a large office building. Basic system functionality is available ‘out-of-box’, with no programming required, and advanced functionality is achieved with Windows-based programming software. Each router can operate two DALI subnets containing up to 64 control devices and load interfaces on each. The system delivers energy saving features via presence detection and constant light levels. Further automation can be achieved through the programming of scheduled events. OPC server software enables interfacing to the building management systems. The system is programmed using software running on a Windows-based computer, either locally or remotely. After programming, the computer can be disconnected as it is not required for normal day to day functionality of the system. The computer can also be used to monitor and report system status. All data is stored in the flash memory of the DIGIDIM routers, avoiding the need for cumbersome databases. The system can be saved to PC as a backup.
The latest development in DALI lighting control is the Digidim router, which can control up to 64 control devices and load interfaces on two subnets.
DALI is not for all applications, but it offers clear advantages where fluorescent dimming is well-suited and desired. As demand for fluorescent dimming increases, so will the demand for DALI as a control method that offers many distinct benefits. DALI software enables configuration of lighting groups, presets matching the lighting to the use of space whilst offering integrated energy management functions. In addition, as an open system, DALI enables true interchangeability among many vendor products and standardised performance across manufacturers. Steve Buckley is UK sales manager with Helvar.