TL;DR
- ✅ Presence sensors enable smarter automation by accurately understanding human occupancy.
- ✅ mmWave sensors detect static presence beyond traditional motion detection limits.
- ✅ Compare PIR and mmWave technologies to select the right sensing solution.
- ✅ Presence detection improves lighting, HVAC, security, and energy management.
- ✅ Smart buildings need better perception, not simply more connected devices.
Why Do Smart Homes Need Presence Sensors?
A KNX presence sensor detects whether a space is occupied and sends occupancy information to the KNX building automation system.
For KNX lighting and HVAC projects, the key choice is whether you need motion detection or continued occupancy detection. PIR responds to movement, while a 24GHz mmWave presence sensor can detect relatively still occupants when correctly installed and commissioned. This guide compares both technologies and explains where the EDQ255-K fits.
This is one of the most common automation problems identified through WinSmartHome’s customer feedback and project experience. A system may execute commands correctly, but inaccurate occupancy information can still cause lights to switch off while someone is sitting quietly, HVAC equipment to continue operating after a room becomes vacant, or automation to be triggered by movement outside the intended area.
Based on WinSmartHome’s past customer feedback, internal testing and project experience, the following figures reflect our own observations rather than an industry-wide survey:
- 78% of users consider the inability of smart devices to understand human status in real time as one of the biggest limitations of current smart home experiences.
- 65% of households experience false triggers or missed detections from existing automation devices.
- Static presence detection has become an important consideration for premium smart security and automation solutions.
Planning a KNX Presence Sensor Project?
Send us your room dimensions, ceiling height and control requirements. Our team can provide the EDQ255-K datasheet, preliminary product recommendation and pricing information for your project.
These challenges reveal the “last mile” problem of smart automation.
The problem is not whether a device can be controlled automatically. The problem is whether the system can accurately understand whether people are actually present.
Have you ever experienced these situations?
- You walk into a room, but the light does not turn on immediately.
- You are sitting on a sofa watching TV, but the light turns off because no movement is detected.
- You are working quietly at your desk, but the system incorrectly determines that the room is empty.
- You leave a hotel room, but the air conditioning and other devices continue running, wasting energy.
Many homes already use motion-based automation, such as infrared sensors in corridors or microwave sensors in bathrooms. However, the actual experience is often far from perfect:
- Sitting in the bathroom for several minutes, the light suddenly turns off, and you have to wave your hand to activate it again.
- A person is still inside the room, but the system believes nobody is present.
- Someone passes near a corridor entrance, triggering the light even though the area is not actually occupied.
These are not simply inconveniences.
They represent a fundamental limitation of current smart home systems — the lack of accurate human presence awareness.
People leave but the lights stay on? People arrive but the lights stay off? This is not bad luck. The wrong sensor was selected.
The next generation of smart automation is moving beyond simple movement detection toward a deeper understanding of human presence.
Smart homes do not need more devices.
They need better perception.
Presence Sensors provide this missing perception layer, allowing lighting, HVAC, security, and building automation systems to respond based on real occupancy rather than simple movement.
2 Sensor Technologies: Which One Can Truly Detect Human Presence?
Although PIR sensors, and mmWave presence sensors are often used for smart lighting and automation, they solve different problems.
The key difference is simple:
Some sensors detect movement. Advanced sensors detect presence.
Understanding the difference between these technologies is essential when selecting the right solution for smart homes, hotels, offices, and building automation projects.
1. PIR Infrared Sensor — It Only Sees Movement
PIR (Passive Infrared) sensors are one of the most common motion detection technologies used in smart lighting systems. They work by detecting changes in infrared radiation caused by human body movement. When a person walks into the detection area, the temperature change created by the moving body triggers the sensor.
Advantages:
- Low cost
- Low power consumption
- Reliable for short-term movement detection
Limitations:
If a person remains still, the sensor may assume that nobody is present. The sensor may not detect these situations correctly. For example the situations mentioned below:
- Someone sitting on a sofa watching TV
- Someone reading quietly at a desk
- Someone sitting in a bathroom for several minutes
PIR is generally suitable for corridors, staircases, entrances and other short-stay areas. For rooms where occupants remain relatively still, evaluate the selected sensor against the required presence-detection behaviour.
- Corridors
- Staircases
- Entrances
- Storage areas
A PIR sensor knows someone moved, but it does not know someone is still there.
2. mmWave Presence Sensor — Understanding Human Presence
mmWave presence sensors use radar signals to detect body movement and smaller presence-related motion. Compared with movement-only sensing, this technology can support applications where occupants remain relatively still, such as working at a desk, resting in bed or sitting in a hotel room.
Advantages:
- Static presence detection
- Supports presence-related micro-movement detection
- Adjustable detection range and sensitivity
- Suitable for occupancy-based room automation
- Supports applications where occupants remain relatively still
Limitations:
- Requires auxiliary power
- Installation conditions can affect detection results
- Moving curtains, fans, plants and vibration sources may cause unwanted detection
- Range, sensitivity and delay require project commissioning
For applications where comfort, reliability, and intelligent automation are priorities, mmWave presence sensing provides a more advanced solution. And the system can continue to understand that the space is occupied in the following situation:
- A person sitting and watching TV
- Someone working quietly at a desk
- Someone resting in bed
One sensor sees movement. Another understands presence.
PIR vs mmWave Presence Sensor
| Selection Factor | PIR Infrared Sensor | 24GHz mmWave Presence Sensor |
|---|---|---|
| Detection Principle | Detects changes in infrared energy | Uses radar signals to detect movement and presence-related motion |
| Noticeable Movement | Generally suitable | Generally suitable |
| Relatively Still Occupants | May be more difficult to detect | Can support presence detection when occupants remain relatively still |
| Main Installation Considerations | Line of sight, detection direction and temperature conditions | Moving objects, vibration, metal materials, power quality and parameter settings |
| Commissioning Focus | Position, coverage and delay | Range, sensitivity, delay, detection zones and interference control |
| Typical Applications | Corridors, entrances, staircases and short-stay areas | Hotel rooms, offices, meeting rooms and occupancy-based automation |
| Auxiliary Power | Depends on the selected sensor model | The EDQ255-K requires a 12–30V DC auxiliary power supply |
This comparison is intended as a selection guide rather than a universal performance claim. Actual results depend on the sensor model, room layout, mounting height, settings and site conditions.
The difference between these technologies can be summarized in one sentence:
PIR knows “someone moved.”
mmWave knows “someone is still there.”
For modern smart homes and smart buildings, the goal is no longer simply detecting movement. The goal is creating systems that can understand human presence and respond naturally.
Our mmWave Presence Sensor: Designed for More Accurate Human Presence Detection
This is exactly the type of problem the WinSmartHome 24GHz mmWave Presence Sensor is designed to address.
Instead of relying only on obvious body movement, the sensor uses 24GHz radar technology to detect both human movement and subtle micro-movements associated with breathing. This allows the system to continue recognizing a person even when they are sitting, working, reading, or remaining relatively still.
For KNX smart home and building automation projects, the sensor provides several configurable functions:
| Function | Capability |
|---|---|
| Radar Technology | 24GHz mmWave radar |
| Motion Detection | Up to 6 m radius |
| Presence Detection | Up to 5.5 m radius |
| Static Presence Detection | Detects subtle chest and abdominal movements associated with breathing |
| Detection Zones | Left/right zone detection |
| Detection Range Adjustment | 11 adjustable levels |
| Sensitivity Adjustment | 3 adjustable levels |
| Illuminance Detection | Built-in illuminance function for lighting automation |
| Recommended Installation Height | 2.5–4 m |
| Building Automation Integration | KNX |
| Input Voltage | 12–30V DC auxiliary power |
| Operating Current | ≤50mA at 24V DC |
| Standby Power Consumption | ≤1.2W |
| Delay Setting | Adjustable up to 18 hours |
| Ceiling Opening | 45mm |
| Installation Type | Flush-mounted ceiling installation |
The published detection ranges were tested with the sensor mounted at a height of 3m in an indoor environment. Actual detection distance may change according to mounting height, room conditions, occupant position and parameter settings. Detection coverage should be verified during on-site commissioning.
More Than Sensitivity: Configure the Sensor for the Space
The important point is not simply that the sensor is “more sensitive.”
Its adjustable detection range, sensitivity levels, and detection zones allow integrators to configure the sensor according to the actual room and application.
For example, if a plant or curtain is moving near the edge of the target area, the detection range and zone settings can be adjusted to reduce unnecessary detection. In a study room or office, the sensor can instead be configured to maintain presence detection for people who remain relatively still.
This makes the sensor suitable for applications such as:
- Smart lighting control
- Offices and meeting rooms
- Bedrooms and study rooms
- Bathrooms
- Hotel guest rooms
- KNX occupancy-based automation
The goal is not to make the sensor react to everything. It is to configure it to detect the presence that actually matters.
For system integrators, this flexibility is especially important because every project has a different room layout, installation height, detection area, and automation logic. A presence sensor should therefore provide not only better detection capability, but also enough configuration options to adapt that capability to the real environment.
How to Select a Presence Sensor for a KNX Project
- Define the control objective. Decide whether the sensor will control lighting only or also participate in HVAC, room scenes and energy-saving logic.
- Review occupant behaviour. Corridors, hotel rooms, offices and bedrooms have different movement and presence patterns.
- Check the room dimensions. Compare the required detection area with the published motion and presence ranges.
- Confirm the mounting position. Review the ceiling height, opening size, wiring space and distance from nearby equipment.
- Identify interference sources. Check for curtains, fans, plants, vibrating equipment, metal surfaces and high-power wireless devices.
- Plan the KNX logic. Define occupancy objects, delay behaviour, illuminance conditions and group-address requirements.
- Allow commissioning time. Range, sensitivity, zones and delay should be tested and adjusted in the actual room.
EDQ255-K Installation and Commissioning Checklist
Install the sensor at the recommended height of 2.5–4m.
Use a 45mm ceiling opening and confirm that sufficient wiring space is available.
Avoid installation near vibration sources such as outdoor air-conditioning units, pumps, refrigerators and generators.
Keep moving curtains, rotating fans, swaying plants and similar objects outside the required detection area where possible.
Do not block the radar antenna with metal materials or high-current cables.
If a metal plate is installed behind the sensor, maintain a distance greater than 5mm.
Keep the sensor more than 1m away from high-power wireless devices such as routers or wireless hotspots where possible.
Use a stable auxiliary power supply. The product specification recommends power-supply ripple below 100mV.
Test both occupied and unoccupied states after KNX commissioning.
Adjust the detection range, sensitivity, left/right zones and delay according to actual room behaviour.
Frequently Asked Questions
Q1: How Far Can the mmWave Presence Sensor Detect?
The EDQ255-K uses 24GHz radar technology and provides two different detection ranges:
- Motion detection radius: up to 6 meters
- Presence detection radius: up to 5.5 meters
The sensor is designed to detect not only larger body movements but also subtle human presence signals. Its presence detection function can recognize small chest and abdominal movements associated with breathing, allowing the system to continue identifying occupancy even when a person remains relatively still.
The specified detection ranges are based on testing at a 3-meter installation height in an indoor environment. Actual detection distance may vary depending on installation conditions.
Q2: What Is the Recommended Installation Height?
The recommended installation height for the EDQ255-K is 2.5 to 4 meters.
It supports compact flush-mounted ceiling installation, making it suitable for smart homes, offices, meeting rooms, hotel rooms, and other indoor automation applications.
For more precise commissioning, the sensor also provides:
- 11-level sensing range adjustment
- Independent range adjustment for the left and right detection zones
- 3-level sensitivity adjustment
- Adjustable delay time of up to 18 hours
These parameters allow system integrators to configure detection according to the room size and actual application rather than relying on one fixed detection setting.
Q3: Can the Presence Sensor Be Integrated Directly into a KNX System?
Yes. The EDQ255-K is specifically designed for KNX building automation systems.
It uses the KNX communication protocol and supports left/right partition detection for both human movement and presence status.
This allows presence information to become part of KNX automation logic for applications such as:
Presence → KNX → Lighting / HVAC / Scene Control
The sensor also includes an illuminance function. When this function is enabled, lighting can respond to both occupancy and ambient light conditions—for example, detecting movement without automatically switching the lights on when sufficient daylight is already available.
Q4: Why Can a mmWave Presence Sensor Still Have False or Missed Detections?
mmWave provides much more detailed presence detection than basic motion sensing, but correct installation and configuration are still important.
According to the EDQ255-K installation requirements, detection can be affected by moving curtains, swaying plants, rotating fans, vibration sources, metal surfaces, power-supply interference, and installation near high-power wireless devices.
Because presence detection relies partly on detecting subtle chest and abdominal movement associated with breathing, body orientation and very short delay settings can also affect detection. The specification therefore recommends allowing at least 1–2 complete breathing cycles and using an appropriate delay time rather than setting it too short.
For commissioning, installers can use the sensor’s 11-level detection range, 3-level sensitivity, left/right zone control, and adjustable delay to optimize performance for the actual room.
A good presence sensor is not simply the most sensitive sensor—it is one that can be properly configured for the space.
Q5: Can the Left and Right Detection Areas Be Adjusted Separately?
Yes. The EDQ255-K provides 11 sensing-range levels, and the left and right detection zones can be adjusted independently. This can help reduce unwanted detection near a doorway, room boundary or adjacent functional area.
Q6: How Should the Detection Delay Be Selected?
The delay should match the room use and occupant behaviour. A very short delay may cause the system to change to an unoccupied state before sufficient presence-related movement has been detected. The EDQ255-K supports delay settings of up to 18 hours.
Q7: What Project Information Is Needed Before Sensor Selection?
Provide the room dimensions, ceiling height, application type, proposed sensor position, required control functions and information about nearby fans, curtains, plants, metal surfaces or vibration sources.
Q8: Does the EDQ255-K Require an Auxiliary Power Supply?
Yes. The EDQ255-K requires a 12–30V DC auxiliary power supply in addition to its KNX connection. Power availability and wiring should be confirmed during panel and ceiling planning.
Final Conclusion
Smart automation is evolving from simple device control to intelligent environmental understanding.
Smart homes should not only provide remote control. They should actively understand people.
The future of smart buildings is not about adding more devices. It is about creating systems that can sense, understand, and respond to human needs naturally. Presence sensing is becoming a fundamental technology behind this transformation, enabling smarter lighting, better energy management, improved security, and more human-centered automation experiences.
Planning a KNX project?
Send us the room dimensions, ceiling height, application type and required control functions. WinSmartHome can review the sensing requirements and recommend a suitable presence sensor configuration.
Request a Presence Sensor Recommendation