In the world of LED lighting that demonstrates black and white energy savings, controlling energy efficient lighting effectively is more important than ever to both ensure maximum energy savings and create environments that encourage maximum productivity.
Often lighting control systems are implemented in such a way that they interfere with the tasks being done or prohibit effective operation by way of system in-operation or incorrect tuning, thereby decreasing productivity.
For example a motion sensor with a very short time-out – the time since the sensor has detected motion before it switches lights off. This causes nuisance ‘offs’ even when employees are still present causing them to be diverted from their tasks to ‘make the system see them’ so they can return to their tasks.
Besides the obvious safety issue of being left in the dark, this continued interruption has real and negative impact on employees satisfaction and therefore performance.
A 1-2 comb of LED lighting and lighting control drives the best energy savings and productivity when implemented and tuned for each facility and each space in these facilities.
How Much Energy is Saved with a Lighting Control System
This is a loaded question. Let me explain.
The issue is the baseline measurement.
For example does one assume that if the lighting is not controlled that it is left on for 24 hours?
No? Then what?
In existing facilities, this can be more easily measured and quantified by undertaking an audit prior to the LED lighting and lighting control upgrade. And then, once the new systems are installed, undertaking a follow up audit.
In new-build facilities the energy savings calculation must be estimated based on assumed or expected usage. Knowing the operational hours of general circulation zones, architectural lighting areas and external zones can assist to provide relatively accurate energy savings numbers.
Once the systems are installed in these new facilities the energy and energy savings can then be measured and managed and fine-tuned further to match how the facility is actually used.
Fortunately, Australian Standards for both lighting levels and controls strategies are legislated. These Standards provide a baseline performance requirement to ensure, in most building types, the right light is provided for the tasks at hand and appropriate systems are in place to reduce energy wastage from the lighting.
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What Are the Strategies and How Much Energy Do they Save?
We will use the new facility as an example and operate under the assumption that if not controlled, the lights would remain on for 24 hours. That is, we cannot depend on humans to remember to do the right thing, rather we will install a system to guarantee a level of light, comfort, and savings.
With that assumption, there are 2 key lighting control strategies that will provide the highest return on investment in the shortest period.
Scheduling and Occupancy Detection.
Scheduling is the function of controlling when lights are extinguished and when they can be turned on.
Whilst in simple terms it may be turning all lights off everywhere in the facility at 7pm and turning all lights on at 7am – saving 50% of the assumed 24 her lighting operation – this is not practical.
Different parts of the facility such as the office, docks, warehousing, manufacture, amenities, carparks (toilets, kitchens) – all have slightly different operational hours. Additionally, different times of the year require different lighting operation including public holidays, seasons and special events.
Therefore having separate lighting control schedules for each of these separate zones, seasons and events provides more than the 50% savings from the brute force approach first described.
Further, controlling when the lights CAN BE turned back on, rather than automatically turning everything back on at a pre-determined time allows for humans.
That is, humans are predictably unpredictable and the lighting control system needs to be responsive to this unpredictability whilst maximising energy savings.
This is when lighting control schedules are layered with Occupancy detection strategies.
Occupancy Detection involves the placement of a range of occupancy sensors in high and low-traffic areas with the intent to provide the right light at the right time. That is, when humans are occupying the zones, and when they are not, extinguishing the lighting.
Credit: FORSCHUNGSZENTRUM JÜLICH/MARC STRUNZ-MICHELS
Widespread use of Occupancy Sensors in offices, warehousing and manufacturing zones will provide the best result with potential energy savings of up to an additional 25% when fine tuned to the facility’s specific operation.
Sophisticated Lighting control systems can use these 2 strategies together to provide a finely tuned energy saving system every day, year on year, automatically.
For example, during normal operating hours the occupancy sensors provide a 30 minute period of lighting. If no occupancy is detected during that period, then that zone’s lighting is dimmed to a dwell level such as 25% of maximum light output for a 5 minute period, for example.
This serves to provide a light buffer. If occupancy is detected during this period then lighting is immediately returned to the prescribed level. If no occupancy is detected then the lighting is dimmed to off over a 30 second period as a final comfort light buffer.
During after hours operation these time-outs (originally 30 minutes) are reduced to 10 minutes and the dwell level (originally 5 minutes) is reduced to 1 minute, automatically via the lighting control system schedule. In this way, after hours operation of the lighting control system serves to save more energy without interrupting the occupants.
This is just 1 example of layering lighting control strategies to maximum energy savings, ROI and occupancy comfort.
More Lighting Control Energy Savings Strategies
There are a large number of other strategies that can provide incremental energy savings to these 2 core strategies.
However, depending on the facility and the ROI requirements, the added costs compared to the added energy savings do not always meet the payback periods required.
If maximum energy savings is the key however, and payback takes a back seat some of the these other strategies can meet that goal.
These are not discussed in this short paper due to brevity but further details can be found in the RAPIX Design Guide which can be found here: