Changing the way we flick the switch

In today’s climate of growing environmental awareness and rising energy prices, saving energy is more important than ever, and one of the most effective ways to do so in a commercial environment is by controlling your lighting, which not only saves energy, it also saves money.

Traditionally, lighting control systems have involved complicated relays, dimmers, switches and motion sensors wired throughout offices and leading back to a central point; and have required specially trained technicians to program the systems and tailor them to clients’ needs. Unfortunately, a legacy of some systems has been that they utilise time-based functions - where large areas of lighting are activated even though the area may not be occupied. While this market will always exist due to the desire for lighting control solutions at the upper end, there is an emerging market for standalone solutions with wireless capability if required. As we all now know, wireless simply means fewer wires where the communication between units is done through RF signals.

Sensor technology has changed significantly over the past few years. Previously you had older-style 240 V connected detectors, which had little-to-no intelligence and couldn’t do much more than adjust a timer, typically up to 20 minutes (lux hold off); and in some cases adjust sensitivity as well. Whereas now you have sensors with multiple features designed to suit most applications. The level of intelligence that can now be built into printed circuit boards enables manufacturers to include features that were unheard of. Along with this, lighting manufacturers have also been developing more efficient control components that include digital dimming ballasts so that fluorescent light levels can be adjusted to suit the requirements of occupants.

These new-generation detectors are available with a wide range of options, which makes it important to select the correct detector for the chosen application. As with most industries, there will always be a certain amount of confusion due to the variety of choices available, and the presence of products that may or may not fit its purpose. So it is important to know the exact capabilities of the detectors being considered, read the fine print and be assured that the chosen detector will perform as required. Understanding the functionality required and the clients’ budget is key when deciding on the detectors that should be used.

These days, there are detectors that are capable of controlling ventilation loads as well as controlling lighting and can be linked to building management systems via volt-free contacts. Consideration needs to be given to the size of an area; whether it’s an open office or cellular, a classroom or corridor. It is also important to consider whether there is a need for either absence detection (manual ‘on’ auto ‘off’) or presence detection (auto ‘on’ auto ‘off’); whether there are dimmable ballasts; where daylight harvesting can be employed to best take advantage of available natural light; and whether lighting loads should be turned off if there is sufficient daylight available (even when movement is detected), and turned on if those daylight levels decrease.

One of the most important issues to consider with intelligent automated lighting design is the activity within each specific area that is being lighted, and to select the lighting detectors accordingly. For example: bathrooms, kitchens, storerooms, copier rooms etc are all areas in which the levels of movement are high but the duration of stays are short; so in those circumstances, detectors that are sensitive to movement and switch off lighting loads shortly after movement is no longer detected are a suitable solution. However, in offices, activity and movement can be quite low and limited to workspaces, so the wrong detector could switch the lighting load off at inappropriate times, causing considerable annoyance to occupants. Ensuring the correct detector is provided is paramount to reduce possible nuisance tripping.

Using a variety of technologies most scenarios can be catered for; from passive infrared detectors with a range of 8 metres, through to microwave detectors with ranges of up to 30 metres and built-in lux level sensors. Some detectors also have the added benefit of being able to set two separate levels of sensitivity, making it possible to ensure that detectors only operate in the offices or areas they are supposed to control, ie, a detector in the off state can have a lower sensitivity to ensure it only activates when someone enters the zone, versus turning on when someone walks past the zone. The sensitivity in the on state can be set higher to allow for minimal movement in the zone while it’s occupied.

With the more advanced detectors it is now possible to have an initial time-out period (this is the time that starts from the last movement being detected) after which the load can begin to dim down to a programmed level, usually 10%, then stay at this level for a further 60 minutes before switching off entirely. With these more advanced detectors, scenarios like this can be achieved through the use of an infrared programming handset.

Internationally, and recently in Australia, there is increasing demand for detectors in warehousing facilities. In these types of buildings detectors can be incorporated in conjunction with a lighting upgrade where the traditional high-bay fitting is replaced with a more controllable high-bay fluorescent fitting. Again, various options are available and dependent on the clients’ requirements, a suitable cost-effective solution can be provided using standalone detectors. A suitable detector would ideally have a range of up to 40 metres diameter when installed at 15 metres high and have a wireless option for more control.

In some instances, labour and working environments can become a major cost component if reconfiguring of existing wiring is considered.  An example might be that the storage racks run in one direction and the lighting rows are wired to run across the racks rather than down the aisles. This could mean that the existing high bay is exchanged for a fluorescent fitting with motion detector and lux control built into the fitting to save on labour costs; reducing the installation to a simple swapover and commissioning from the ground level using an IR programmer. Although the consumption of the fluorescent high bay is in some cases only slightly less than the original fitting, the ability to control the fitting can improve energy savings by up to 40%.

In many circumstances, the option of a fully networked lighting control system can be overkill. The client needs to understand the difference between what they want as opposed to what they need. Commercial buildings usually operate the same way every working day; once this is determined a functionality specification can be written and the most suited solutions provided. This may be a fully networked monitored option, it may be a standalone detector or it could be a solution that combines both.

It is quite common for clients to look at a building, or a series of buildings, and go for the easy wins with a two-stage approach. The first stage might be the bathrooms, print utility room, car park or other areas where there is an obvious saving to be made by turning the lights off. The second stage could concentrate on more typical office areas: open offices, foyers etc. By implementing a two-stage approach, clients can both hit their energy targets sooner and work within their budgets.