Keeping it simple

Relatively simple lighting controls can deliver significant benefits to building operators. Stewart Langdown of TridonicAtco explains how wholesalers can guide their customers to the most appropriate choices.

There has been a lot of discussion in the last few years on how best to achieve relatively quick reductions in energy consumption and, from an end user point of view, this has been fuelled by the need to comply with legislation and energy targets.

As buildings become better insulated so that less heat is wasted, lighting becomes one of the predominant energy users in many buildings so controlling the lighting better definitely represents a quick win. How that is achieved, though, depends on circumstances such as the existing lighting, the budgets available and the knowledge of the people advising on the best solutions.

This is where the wholesaler has an important role to play, in helping to make contractor customers aware of all of the options and the pros and cons of each. And, as control technologies move forward at a considerable pace, it’s important to keep up to speed with the latest developments.

Simple solutions
One particularly interesting development is the way that relatively simple lighting control devices are able to facilitate significant energy savings, rather than requiring the end user to invest in an ‘all singing and dancing’, highly sophisticated lighting management system. Not that there is anything wrong with these but not all projects require the full complement of bells and whistles or, indeed, have the budgets available for that level of outlay.

In fact, the more complex lighting control projects are less likely to involve wholesalers in selling off the shelf products because the systems are often customised to the project.

In contrast, there are many simpler controllers that are sold through the wholesale channel and these will certainly be of interest to contractors as well as end users.

Here, it’s important to emphasise that simple isn’t the same as lacking in functionality. The simplicity relates to the ease of installation and commissioning – and ongoing use by the end user. Indeed, the latter point is very important if ongoing energy savings are to be achieved through the life of the installation.

For example, in a project where the lighting is likely to be controlled by an inhouse maintenance or facilities management department that doesn’t have specialist controls skills, the lighting controls have to be easy and intuitive to use. There are many instances where a change of layout in a building, in terms of moving people and their workstations
around and, perhaps, changing partitioning, creates a need for the lighting control strategy to be modified. However, if the necessary skills aren’t available inhouse, there is a good chance the building operator will override the controls and just have the lighting on all the time – rather than paying for a high-priced controls specialist to come in and carry out the work.

Very often, therefore, ongoing energy savings are more likely to be achieved by using simpler controls with a user friendly interface that is easily understood by someone who is not a controls specialist. The important thing is that the operator feels comfortable in interfacing with the control system – even if it’s just to warn of a problem that requires specialist attention. The worst thing to do is present them with a system that is so intimidating they are discouraged from accessing it at all.

Clearly, the key areas of lighting control relate to not lighting unoccupied areas and turning down the electric lighting when there is plenty of daylight entering the space. For many years, therefore, lighting control has been achieved through a combination of occupancy detection and photocells.

At the heart of many more recent installations is the Digital Serial Interface (DSI). DSI is a digital language that allows the user to switch and dim a wide range of ballasts on a pair of control wires and makes power switching a function of the ballast and not the circuit. It also allows a mixture of different lamp types to be controlled on the same circuit and the data can flow in both directions.

Criteria such as simple maintenance and user friendly operation – along with energy savings and a good price/performance ratio – were particularly important in selecting lighting controls for BP’s offices in Cape Town. Here, the T5 fluorescent lighting is combined with PCA 2/54 T5 ECO digital dimmable control gear and DSI SMART controllers from TridonicAtco.

Unlike most other systems, DSI SMART measures the ambient brightness produced by the combination of natural daylight and the artificial light in the adjacent areas. In addition to a light sensor, the controller contains a motion detector for which the switch-off delay can be adjusted between one minute and 60 minutes. Each sensor controls four luminaires in a ceiling grid of 3m x 2.4m. These are automatically switched or dimmed by the sensors according to the programmed trigger criteria (i.e. illuminance 380 lux and 15 minute switch-off delay on the motion detectors). There is therefore no need for switches. The predefined lighting mood can be individually adjusted with the aid of a remote control, and the preset levels can then be restored simply by reverting to automatic mode.

Moving forward with DSI
DSI is a technology that continues to evolve with increased functionality, opening the doors for more sophisticated lighting control while retaining the simplicity of ease of installation, commissioning and ongoing use. Consequently, there is now considerable choice in the ways that DSI technology can be applied to a lighting installation.

For example, there are luminaire installation modules that incorporate ambient light measurement, constant lighting control and motion detection. Crucially, these can be programmed via an infra-red controller, so that reconfiguring them is straightforward for the building operator.

Similarly, there are also DSI based controls that enable up to 25 luminaires to be controlled from a single unit, so that the lighting is controlled in zones rather than controlling individual luminaires. This helps to reduce overall costs and is ideal for use in large open plan spaces where the lighting requirements are the same across several workstations.

In terms of day-to-day control, newer technologies can also help to take some of the guesswork out of achieving the right delay for when to switch lighting off after a period where no motion is detected. For instance, this time delay is generally based on a gut feeling at first that may then be fine-tuned in the light of experience.

However, newer adaptive time delays monitor the frequency with which presence in the room is detected and then automatically calculate the optimum delay that will achieve highest energy savings without subjecting the occupants to a ‘disco’ effect.

Similarly, because of the potential visual discomfort of lighting going on and off, especially in an open plan area, the lighting can be programmed through a DSI controller to gradually dim to three per cent of full light output before switching off, so this is hardly noticeable to people in adjacent areas.

The important thing here is to be aware of the latest developments, so that you can add value to the basic sale process by offering up to date information that enables contractors to give their customers a better solution.