Mike Collins, Managing Director of Ovia Lighting, looks at some of the essential lighting control technologies that can help provide energy-saving solutions for contractors.
Lighting control systems don’t necessarily have to be complex or expensive. They can be simple and effective, offering benefits like energy savings and convenience. Simple systems are often less expensive to install and maintain than complex, networked systems. Popular control technologies include PIR sensors, microwave sensors and photocells, and an explanation of how they work, their advantages, and applications will help contractors choose the right system for the lighting projects they are working on.
PIR Sensors (Passive Infrared Sensors)
PIR sensors detect motion by sensing changes in infrared radiation caused by temperature shifts, such as a person entering a room. When motion is detected, the sensor activates the connected lights. After a preset time without further movement, the lights turn off automatically.
PIR sensors are passive, meaning they don't emit any energy; instead, they passively detect infrared radiation. All objects, including humans, animals, and even inanimate objects, emit infrared radiation as a result of their temperature. A PIR sensor typically consists of a Fresnel lens to focus infrared radiation, a pyroelectric sensor to detect changes in infrared radiation, and an infrared filter to block out other light wavelengths. When a person or object moves within the sensor's field of view, the infrared radiation pattern changes, and the pyroelectric sensor detects this change. This change in the infrared pattern triggers the PIR sensor, which then sends a signal to an attached device, such as a light or an alarm, to activate. PIR sensors detect a positive differential change as an object enters the detection area and a negative differential change as it leaves.
PIR sensors offer a number of advantages. They are energy-efficient – lights activate only when needed, reducing energy usage and helping to lower energy bills. They are convenient, as they eliminate the need for manual switches. They can offer customisable settings, with sensitivity and timing adjusted to suit specific needs.
Applications:
PIR sensors are commonly used in in lighting for security and energy-saving applications, particularly in areas with intermittent use like hallways, driveways, bathrooms, and around entrances, such as front doors, porches, and gardens.
Microwave Sensors
Microwave sensors work by emitting low-power microwave signals (usually at 5.8 GHz) and detecting reflections from nearby objects. They use the Doppler Effect to emit low-level microwave signals across a detection area. These signals reflect off objects and return to the sensor. Any changes in the echo pattern caused by movement trigger the lights to turn on. Unlike PIR sensors, microwave sensors can detect movement through thin walls or glass.
Microwave sensors offer a number of advantages. They operate effectively across all temperatures, unlike PIR sensors which may be affected by heat or cold. They can detect motion through non-metal materials, allowing hidden installations or integration into luminaires. They also offer energy savings as they can include advanced features like daylight harvesting, dimming options, and RF communication to control multiple luminaires simultaneously. Their dust-proof and smoke-proof design ensures a longer lifespan compared to PIR sensors.
Applications:
Microwave sensors are ideal for large commercial buildings, hybrid workspaces, and areas requiring precise occupancy-based lighting control. They are also suitable for outdoor installations where environmental conditions might affect other sensor types.
Photocells
Photocells measure ambient light levels using photoresistors or photodiodes. Lights automatically turn on when surrounding light falls below a preset threshold (e.g., at dusk) and switch off when sufficient daylight is present (e.g., at dawn).
Energy efficiency is one of the advantages of photocell technology. By preventing the use of unnecessary lighting during daylight hours, energy savings of up to 40–84% can be achieved, depending on usage. Because they prolong lamp lifespans, they can offer cost savings through the reduction of electricity bills and maintenance costs. They provide hands-free operation for outdoor lighting systems like streetlights or garden lights and they can be integrated with smart systems for remote monitoring and control.
Applications:
Photocells are widely used in outdoor lighting systems such as streetlights, car parks, and gardens. They are also integrated into smart city infrastructure to optimise energy consumption based on real-time conditions.
Crucial controls
PIR sensors, microwave sensors and photocells can each play a crucial role in lighting control. Each lighting control technology offers unique benefits tailored to specific environments. PIR sensors excel in residential spaces for convenience and security, microwave sensors provide robust solutions for commercial settings with advanced features, while photocells are ideal for outdoor applications focused on daylight optimisation. By integrating these technologies strategically, significant energy savings can be achieved while enhancing functionality and sustainability.