Energy use initiatives are pressurising building operators into improving efficiency and lighting controls protocol DALI could offer a lucrative opportunity for contractors. But is it easy to commission or even the only option?
Energy efficiency continues to be a key driver within the lighting industry and the Climate Control Levy (CCL) plus Part L of the Building Regulations have increased the pressure on building operators to find more efficient ways of managing their electrical loads.

Amendments to the Building Regulations for new installations and major refurbishments in the private sector already require specific lamp and luminaire types, or a minimum efficacy of 50 lumens per watt across the whole installation. However, a considerable number of existing sites still use large numbers of standard fluorescent tubes, which are likely to cause efficacy to fall below this limit, especially when you consider lumen depreciation over time.

Among the options to increase the efficiency of lighting systems is DALI – the digital addressable lighting interface. Put simply, this is an interface standard that describes a protocol for digital communications between lighting controls devices.

Because many of the major manufacturers have joined DALI-AG, the pan-company organisation formed to develop the protocol, users are guaranteed compatibility between lighting control equipment and are also secure about future expansion of their lighting systems. For contractors, the ease of installation and cost benefits to the client represent a business opportunity.

Configuration
DALI consists of 19 bits of data that enable up to 64 control devices to be addressed individually on a two-wire control bus, divided into a possible 16 lighting groups and 16 lighting scenes. The DALI control wires to the ballasts, along with those from the control devices, can be run parallel to the mains or within the same conduit. The control signal has no polarity and the functional assignment of luminaires to lighting groups is not defined until after installation.

Although a lot of technology has gone into the concept behind DALI, one of its appeals for installers is that it is easy to apply for a wide range of applications such as offices, conference rooms, hotels, factories and leisure facilities from pubs to museums.

One example is Philips Lighting's MultiDim range, which consists of an integrated range of DALI-compatible devices. Each unit in the network has its own unique address, which allows it to be switched and controlled independently. Every control device can be made to control any luminaire or group of luminaires on the DALI wire and changed later using software. All units are supplied pre-configured so that they are fully operational out of the box, says Philips, while to programme more complex systems it can be reconfigured with Windows-based software.

Within TridonicAtco's range is the K210/K211, designed for dimming LED sources for 12 or 24 Vdc. The K211 enables switching with switchDIM, plus DSI signals or control via DALI. The K210 series provides three independent output channels controlled via DALI. It says that extremely long line lengths (up to 300 m) are possible and the units include a range of circuit control features. The company is also set to launch WinDIM@net, a system that interfaces with the TCIP protocol allowing multiple site control (of which more in a moment).

Big network or small network?
DALI compatible systems are not the only solution for lighting control systems and some experts are questioning whether the technology is really delivering anything unique. "I can't help but wonder whether DALI isn't where dimming controls were about five years ago," reflects Dominic Meyrick of Hoare Lea & Partners. "We need another technology leap without passing costs to the clients if DALI is going to prove to be more than a gimmick."

Meyrick cites a recently-completed job at the Apollo Theatre in Victoria where he used DMX controlled from a simple theatrical control panel. "Theatre lighting designers have been using these for years but I was amazed by the levels of control and the cost-effectiveness," he recalls. "We had a £4000 lighting control desk for two networks of 512 addresses each. Some of these suppliers are now looking at the architectural lighting market and with DMX so well established and Echelon compatible, I wonder whether DALI has been introduced a bit too late."

Stewart Langdown of TridonicAtco counters that DMX is not set up for commercial applications and that its 512 limit may be too small for larger installations. He points out that DALI can in fact be used as a subsystem, with gateways to much larger protocols such as TCIP or BACNet that give it, in effect, unlimited range. "This is really the future," says Langdown. "In the States we have major projects running combining these systems and the point is that what we have is software-controlled, unlike LonWorks we are not hardware-restricted."

From the building owner's point of view, there is little doubt that lighting and dimming controls are becoming pretty much a necessity if they are to show that they are meeting their energy use requirements under the Building Regulations. Once the preserve of boardrooms and conference areas, the ability to set lighting and reconfigure it as layouts change has moved to the mainstream areas of commercial interiors.

Whether DALI is the only way forward, it is certainly the route backed by serious manufacturer muscle. For their part, they are keen to show that all options remain open. Philips Lighting's Barbara Wheeler stresses that her company's recent run of DALI workshops included independent speakers and encouraged debate about the issues rather than being used as a promotional tool.

Stewart Langdown points out that this is an ideal time for installers to be looking at the technology. "Installers should not be scared about the protocols being talked about," he stresses. "There is nothing about DALI that a good electrical contractor should not be able to get to grips with after a bit of help from the likes of TridonicAtco. And for large-scale projects they simply need to bring a systems integrator on board. This is really an opportunity to provide commissioning and diagnostic services to clients and charge for the time and expertise, rather than for traditional installation.

"There is a tremendous amount of work going on at the moment. In the second or third quarter of next year we should be talking about DALI-driven inverters taking us into emergency lighting. The world's three biggest ballast manufacturers – ourselves, Philips and Osram – have taken this decision to step forward with an open system. There is a big opportunity for installers to partner with manufacturers and take the leap forward," advises Langdown.

DALI in a nutshell

The Digital Addressable Lighting Interface (DALI) is basically a standard that ensures lighting control systems from different manufacturers work together. Up to 64 control devices can be addressed individually, divided into 16 lighting groups. The protocol operates on a two-wire system, which means easy installation and the configuration of luminaire addresses is not required until installation is complete. The major manufacturers have formed an umbrella organisation – DALI-AG – to promote the initiative and ensure that they work together to maintain a common standard. The 26 members include Delmatic, Erco, Helvar, Lutron, Luxmate, Osram, Philips, TridonicAtco, Universal Lighting Technologies and Wila. There are a number of test projects around the world, particularly in northern Europe and the USA. UK installations include universities in Stirling, Bristol and Cardiff, KPMG’s offices in Bristol, and in London, the RNIB offices and Coutts Bank. You can read more on DALI at the organisation’s web site at www.dali-ag.org.

Source

Electrical and Mechanical Contractor