Should I consider adding ON-OFF or dimming controls to my lights to save even more money?
This is good question. The answer can depend on economics, functions/aesthetics and application.
Is it economic?
On economics, the first point is that an LED retrofit should already have reduced the energy draw by over 50%. So adding controls is working with a much smaller amount of energy to reduce. If adding controls can save another 50%, this means just 25% of the energy draw before the LED retrofit. When analyzing the payback of this, it is important to consider the extra cost of the controls versus the actual energy they will save.
Functions/aesthetics versus economics
The key issue to consider before adding new controls to your LED retrofit project is “what is the objective”? If it is to increase the energy savings, this needs to be very carefully analysed as the economics of doing this may not be cost effective. In short, the payback time for this incremental improvement in energy saving might be very long, so not warranted.
If the objective is to modernize the functionality of a lighting system by adding dimming control or light colour control this is a different matter. Here the cost of doing it is measured against the improved ‘utility’ for the user.
Common applications of motion sensors and daylight sensor systems are in parkades and for outdoor high power lights. These are mostly for ON-OFF control. The control normally includes a timer function where lights are turned off again when no motion is detected or there is adequate daylight.
Dimming controls and light colour controls can be desirable in classrooms, meeting rooms, office spaces and care facilities. Dimming controls can also be used in high-bay applications in warehouses and retail shops where lights can be dimmed, but not OFF, outside of regular use hours.
Types and functions of controls
There is a wide variety of possible controls. These include:
Motion sensors, that send signals to lighting controllers to switch lights ON and OFF
Daylight sensors that provide signals to lighting controllers when there is sufficient light levels for the lights to be turned OFF or to be dimmed.
Dimming controls, that can reduce the levels of the lights – as long as the lights are designed to be dimmed.
Controls that can change the colour of lights – as long as the lights have LED chips of all the core colours used to change the colour temperature, e.g. from warm 2700ºK to very white 6000ºK.
Lighting control systems can combine these sensors and control features. There are various ways that the controls can provide the necessary signals. These include:
Direct wired, by running wires between the control sensors or controllers and the light fixtures – or by the sensors being directly attached to the fixtures
Wireless by radio transmission (RF)
Wireless by WiFi and Bluetooth connections, using smart phone apps.
Retrofits versus new installs
Retrofitting existing lighting systems can be more difficult than a new install as you have to work with the existing lights and their wiring systems. This means it can be costly.
Adding motion sensors and daylight sensors can be relatively straight forward as there are systems that can use sensors that communicate wirelessly with load controllers that are able to switch OFF and ON the AC power supply to banks of lights.
Adding dimming control is more complicated, and costly, as older style lights are most often not designed to be dimmed. This can mean having to change the types of bulbs and ballasts in existing fixtures to ones that are able to be dimmed. A major issue with doing this is that the fixtures lose their original safety certifications (e.g. CSA, cULus, cETLus) and are not considered to be legal under safety regulations. The project requires the electrical contractor to take out the necessary permits to undertake this work, and all fixtures need to be re-certified through inspections by designated safety authorities. Against all this cost, it can be cheaper to just replace all the fixtures with new LED fixtures that have the controllability functions desired.
The bottom line
It is possible to add light controls to existing systems when they are retrofit to LEDs. But it can be very costly. Whether it is wise and economic to do so depends on the objective of doing so – and how it is done. Let Greenlight help. We can provide the analysis of possible technologies and costs to help you make a well-informed judgement.