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Do the dimming sums

Aug 2016 Energy Efficiency, Lighting | Comments Off on Do the dimming sums
Do the dimming sums

Leading the way as the energy saving measure of choice for commercial building managers, dimming controls are one of the quickest energy efficiency upgrades to employ. But contractors must consider the challenges of combining LED and incandescent lighting on one system, as Kevin Norman, senior product marketing manager at Newey & Eyre, explains

Dimming technology has long played an integral role for businesses looking to take control of their lighting and energy consumption.

In fact, a recent Carbon Trust survey of professionals who buy energy-consuming equipment for their businesses, found that nine out of 10 businesses had invested in lighting controls in the past year and that 82% of the 135 respondents expected further investment in the next 12 months.

The argument for lighting upgrades becomes even more compelling when you look at the affordability and payback potential. Interestingly, according to a recent sample assessment of ESOS submissions, the Carbon Trust also found that – while lighting alone isn’t the largest consumer of energy in commercial premises – energy-saving lighting measures are actually the most accessible by businesses.

One of the most effective and popular ways to reduce maintenance costs and energy consumption is by implementing LED technology. This is due to the extended product life of LED lamps that can last up to 50,000 hours as well as an improved efficiency of 96% on traditional options.

What’s more, as the cost to manufacture and purchase LEDs has reduced significantly in recent years, they are far more comparable in cost than traditional options – plus payback within two years is now achievable in most applications. In some instances, LEDs can offer dramatic energy savings of up to 96%.

To enhance the positive impact LEDs have on reducing energy use, lighting controls are key for any commercial application. Through incorporating a dimming system, end-users will enjoy the energy efficiency benefits and also have an opportunity to create a relaxing ambience setting that provides an optimum lighting environment for a workforce.

However, as many contractors will be aware, when it comes to combining LED and incandescent lamps on one system, the installation of dimming controls is no easy feat. This is where load disparity, poor product quality and conflicts in technology can cause issues for installers.

Combining technology

For the most part, installing a dimming system is relatively straightforward. Harnessing the capabilities of DALI (Digital Addressable Lighting Interface) can mean that the installation of lighting control systems is neither complex nor costly. The DALI standard enables dimmable ballasts, transformers, relay modules, emergency fittings and controllers from different manufacturers to be incorporated into a single control system.

A DALI lighting control system can be used to cover anything from a single luminaire to 64 DALI devices connected to a single buswire, and beyond that, multiple DALI networks can be created.

It is also possible to add the benefits of LED to a DALI control system using LED converters that are easily programmable via the DALI interface. A DALI system offers a number of key benefits including accurate digital dimming and lamp and balance failure detection. And, for easy installation, latest innovations such as Newey & Eyre’s own brand Newlec DALI network solution are provided with just four elements; an occupancy detector, remote control, power supply unit and a multi-purpose connection box.

Overcoming LED challenges

However, LEDs do present challenges for installers. When LEDs were first introduced, they proved incompatible with the existing triac-based dimming technology and customers were left with the irritation of flickering lights.

Now there are dimmers and dimming systems specifically designed for use with LED sources. The dilemma is that while there are systems suited to incandescent or LED lamps, mixing both on one circuit can be problematic.

With new-build applications, there is the luxury of designing the system from scratch to ensure that every element of the lighting system is compatible. But where the customer is looking for a transition from all-incandescent lighting to the energy-saving benefits of LED with a combination of both, a different approach is needed.

Applying LED loads to incandescent dimmers can result in poor performance and can also reduce control life. Unfortunately, calculating the load simply by totalling the wattage of the individual LEDs on the circuit will not work. This is because the wattage that an LED is sold at – for example, 12W – represents its wattage in continuous operation. This does not take into account the start-up inrush current that is considerably higher, by around a factor of 10. This will have the effect of ‘deceiving’ the dimmer so that it appears as a much higher ongoing load and could, in turn, shorten its life.

Equally, an LED driver may not perform well with a very minimal load so while it is easy to meet the minimum load requirement with incandescent lamps, it may need a higher number of LEDs to meet that requirement.

Dimmer dilemmas

While LEDs are unsuited to triac dimmers, some digital dimmers are equally unsuitable for incandescent lamps. One issue is load on the circuit and with an LED system it is important not to exceed the maximum rated load of the dimmer.

If the dimmer is LED specific, the tungsten load from incandescent lamps is likely to overload it and, even if this does not happen, the fact that the incandescent lamps will pull more load than the LEDs will lead to problems such as flickering. Even with more powerful dimmers, the variation in loads from different types of lamp can cause an inconsistency in performance.

Although compatibility between incandescent and LEDs raises issues, they are not insurmountable and a lot depends on product selection. While some LED-specific digital dimmers cannot cope with high or mixed loads, some are sufficiently robust. Zano Controls’ ZBAR remote dimming pack, for example, is designed to support a high number of LED lamps on a single circuit. This gives it the capacity to handle a reasonable level of mixed load.

Tested prior to installation

A situation to avoid is on-site ‘testing’ – that is waiting until all of the components in the system are installed in the customer’s premises before you find out whether it will deliver the quality and consistency of dimming performance required. Again, this comes down to choosing branded products from reputable manufacturers who will have already tested various combinations of LED and incandescent lamps against their product ranges, and can offer technical support teams to help guide and troubleshoot.

And so, while the complexities of combining LEDs and incandescents on one circuit may at first appear off-putting, the energy saving potential is substantial.

Once an effective dimming system is in place, end-users will be privy to reduced energy consumption just from lighting alone; improving a building’s energy performance and delivering significant financial savings for years to come.