There is a common misconception that lighting control requires a great deal of complexity, and that the more complicated and expensive the controls, the higher the level of functionality and return on investment.In reality, there are many applications that will enjoy significant benefits from simple control strategies, while others lend themselves to a more sophisticated approach.

For example,there is very little to be gained from installing a ‘bells and whistles’ system in a classroom because there is generally very little change once the room has been built and furnished. Here, a simpler approach will be more than adequate.

In contrast, a speculatively built open plan office will experience considerable change in its first year and virtually all open plan offices are subject to ongoing changes in layout throughout their life. In these circumstances,where walls and partitions can be expected to move on a regular basis, there are clear benefits to installing an easily reconfigurable system.

So it’s all about achieving the right balance. End clients pay a great deal of money for their lighting and, understandably, want to get the most from it. At the same time, they generally want to achieve the right level of control for the least capital outlay and low ongoing cost of ownership. Cost of ownership includes the energy savings achieved by the controls, of course, but it also covers the cost of commissioning, maintenance and re-configuration.

Another factor that has a bearing on cost of ownership is ease of use. Systems ought to be designed with the needs of the end user in mind, rather than those of the controls specialist. All too often, the interface between the user and the control system is far too complex and intimidating, which leads the end user to one of two decisions. Either they call in an expensive specialist every time the system needs a tweak; or they ignore the need for adjusting the controls and allow the system to keep performing at less than maximum efficiency.Experience shows that the latter solution is often the path of least resistance.

In addressing all of these concerns,it makes sense to adopt a flexible approach that offers the end user the maximum choice with the optimum performance. Sometimes it will be possible to meet all of the client’s needs within budget but at other times it may be a case of striking the right balance between cost and functionality.

One obvious example of this is at the level of interaction between the user and the controls.In an ideal world,all of that interaction would be via a central computer sited in a convenient location – but this comes at a cost.The alternative is to use controls that can be commissioned and re-configured locally using a hand-held device.

Opting for a system that offers both options builds in the greatest level of flexibility, especially if budgets are adjusted once the project has begun.

Similarly, where a client wants all the bells and whistles but hasn’t got the budget for them, it is often possible to meet 90 percent of those needs with a slightly simpler system that saves as much as 40 percent on the capital outlay.

Installation time, and expense,is another cost area to include in the design deliberations.Systems that offer plug and play connectivity with the minimum of hard wiring will ease the installation burden, as will the use of ELV (Extra Low Voltage)cabling that doesn’t require containment.

Commissioning costs also need to be borne in mind because,by their very nature, complex controls are also more complicated to configure and commission. Here,  a modular control system will enable much of the pre-commissioning work to be done off-site once the design has been finalised,so that on-site commissioning time is kept to a minimum. Obviously this is also an important consideration for fast track projects.

These considerations all lead to a need to establish very clearly

just what the end user wants from the lighting control system before the design process begins. That may seem like an obvious statement but it is quite alarming how often building operators end up with a system that does not suit their needs.

In order to achieve maximum energy savings,many buildings will benefit from a mixture of control mechanisms. Photocell controlled dimming of lighting close to windows will help the user to take maximum advantage of the natural daylight available. Similarly, presence detection in areas that are only used infrequently, or for switching lighting outside normal office hours, is often worthy of consideration.In either case,an element of manual override to provide users with a degree of personal control is generally desirable.

All of these functions can be provided with a relatively simple marshalling box with, say, 10 input or outputs, so that it can be used with a variety of control options.

At a slightly higher level of functionality,there may be a need for some communication between control units.Again,this can be achieved by using more sophisticated marshalling boxes that can exchange control signals without the need for a dedicated control network. A common example of where this need might arise would be in the provision of corridor linking between presence-controlled luminaires in the workspace and luminaires in real and notional corridors.

At the higher end of the spectrum are fully addressable, networked lighting management systems. These enable users to reconfigure the lighting in response to changes in layout without the need to change the hard wiring.

It is easy to see how all of these different levels of functionality could be combined in a tailored solution for a building. Open plan offices might be fitted with an addressable system, while other areas could perform perfectly adequately with less sophistication. Stairwells using presence detection might include control links to adjacent corridors while discrete areas such as toilets and cleaning cupboards only require simple on/off switching when an occupant is detected.

Very often, these different levels of control are defined by those areas falling under the responsibility of the tenant and the landlord. Generally, tenant areas are those that will experience the highest levels of change and have the greatest need for addressable networks, while the landlord’s areas have more modest requirements.

Even with simpler controls it’s important to plan for the future and build in ease of upgrading. In a situation where a simple 10 channel marshalling box with on/off switching will meet the needs of today, there is still a possibility that dimming will provide a better solution 10 years down the line. Controls that can be upgraded simply, just by changing a removable card perhaps, help to build in an element of future proofing.

In situations where a combination of different controllers are used, there are also benefits to be gained from a universal design where the different controllers share many of the same basic components. In this way, maintenance engineers have fewer items of stock to hold and the familiarity with shared components makes their job easier.

One of the great opportunities resulting from the major advances that have been made in control technology in recent years is the ability to provide powerful processing capabilities in a relatively simple and inexpensive package. Modern controls also offer a much higher level of flexibility than their predecessors, so there is no longer an excuse for saddling a building operator with an inflexible system that needs to be changed a few years later.

The choice and the flexibility to meet the needs of today’s working environment are readily available in products that are on the market today. It’s simply a matter of tailoring them to the needs of each project.

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