Sensor Lights

Why would you use movement sensors in lighting?

Many people are familiar with manual control of lights using a wall mounted light switch. In residential or in smaller commercial environments this type of control works well. However, in larger environments where there are many occupants, the control of the lights tends to be neglected and the lighting can remain on far in excess of its required time.

Installing sensor lights means they are triggered by people entering the area, this reduces the amount of wastage when people are not present. In some areas, such as a fire stair, this is particularly important as lighting is rarely required, except in an emergency. Installing sensor lights in these locations saves a significant amount of money through electricity reduction as well as reducing maintenance costs.

Saving money is a significant motivation for property owners as is reducing their CO₂ emissions.

Types of movement sensors used in lighting

There are typically 2 main sensor types currently used in lighting. They are passive infrared (PIR) and microwave. (Other sensor types are used however are more expensive and less common such as ultrasonic instead of microwave and dual sensors with a combination of ultrasonic and PIR). 

Whilst both PIR and microwave have been around for many years their use has recently increased significantly with the change in 2010 to solid-state lighting – LEDs. Unlike traditional lighting, LEDs are not negatively impacted. There are also thermal sensors which may ultimately replace all other sensors when the price comes down. 

Both of these sensor types have pros and cons and need to be carefully selected for the right environment.

 

_	PIR	Microwave
Typical locations	Outdoor lighting, office areas	Carparks, fire stairs and no occupancy indoor areas i.e. corridors
Sensitivity	Under sensitive in higher background temperatures.	Consistent detection over all temperatures.
	Over sensitive in lower temperatures.
	Triggered by heat sources only	Triggered by all moving objects i.e. moving tree branches
	Requires large movement	Responds to small movements
	Can be negatively impacted by dirt	Limited environmental impact
Detection	Can be insensitive when walking directly towards the sensor.	Can sense movement through some types of walls.
	Can detect occupancy (limited), primarily movement	Detects movement only
	Positioned exterior to the light	Can be located within the fixture
	Range and coverage limited	Range can be extended, especially in confined spaces as it bounces off walls

Learn more about sensors and lighting - where to from here?

How do sensors work?

Microwave sensor emits microwave signals and measure the time taken for the signal to be reflected back to the sensor, this is known as the echo time. The echo time is used to calculate the distances from all the stationary objects in the detection zone. A person moving into the detection zone causes a disruption in the microwave beam, changing the echo time and triggering the lights.

PIR sensors use an infrared light sensor to detect the movement of people or objects. They pick up on the heat signature of warm bodies, such as humans or animals that are warmer than their surroundings.

 

Installing & commissioning a sensor light

Traditionally sensors were mounted external to the light fixtures and controlled a group or circuit, switching multiple lights. More recently, since the broad adoption of LEDs, sensors are now incorporated within many light fixtures. This significantly reduces the cost and complexity of installation as well as increasing the sensor coverage. 

Connecting a sensor into a lighting system however does require additional planning to ensure the correct settings are applied for the environment which the lights are installed. Adjusting the sensitivity (range) of the sensor, the time that the lights remain on once movement is detected and whether or not the light is staged to off or remains on a low standby level, are all decisions that the installing contractor needs to make.

These considerations change considerably depending on whether the lights are located in an office, a car park, a fire stair or a warehouse.

Spending time ensuring that the settings are correct makes the difference between a successful lighting installation or something that causes frustration for those using the area.

Will sensor lights save money?

One of the major benefits of the installing sensors is the financial return. Significantly reducing electrical consumption by either dimming the lights down or switching them off when they are not needed directly reduces electricity charges and indirectly also reduces maintenance costs.

The best example of this is in a Fire Stairway which is typically used less than 1% of the time. Where there are no sensors these fire stair lights are running 24-hours per day with no one using them. Another example is a car park which outside of the peak periods of morning and evening typically has very little movement. In both these examples the lights should be set to a very low standby, that consumes very low power, significantly reducing electrical consumption charges, whilst retaining the ambience through low light levels.

What are the best commercial sensor lights?

There are many lights and sensors now being offered for sale.  The best lights are those that are designed specifically to operate with sensors. In addition, the sensor technology should be suitable for the environment within which the lights will be situated and that the settings are easily understood and accessible. It should be noted that sensor lights can switch on and off hundreds of times a day therefore reliability of both the sensor and the lighting control gear is critical. Find the best sensor lights for your business.

For lights that are installed at height – greater than 4m, it is preferable that the settings can be adjusted by a remote control. This enables changes to be easily made from the ground rather than having a requirement to obtain lift equipment to get access to adjust the sensors.

Some of our LED sensor lights