Energy Savings Guide

PIR vs mmWave Motion Sensors: Which One Actually Saves More Energy?

Not all motion sensors work the same way, and picking the wrong type for a given room is one of the most common reasons households give up on motion-triggered lighting entirely.

How Each Technology Actually Works

PIR (Passive Infrared) sensors detect changes in infrared heat signature caused by movement. They're cheap, reliable, and battery-friendly — but they only detect motion, not presence. A person sitting still reading a book can fall out of detection range within a minute or two, triggering an unwanted "lights off" event.

mmWave (millimeter-wave radar) sensors detect actual presence, including tiny movements like breathing, whether or not the person is moving around. This makes them dramatically more reliable in rooms where people sit still for extended periods.

Where Each One Belongs

Room Type	Best Sensor	Why
Hallway, garage, closet	PIR	People are naturally moving through; cheaper is fine
Home office, living room	mmWave	Extended stationary occupancy; PIR causes false "off" events
Staircase	PIR	Transit space, motion is guaranteed
Reading nook / bedroom seating	mmWave	Same stillness problem as home office

The frustration pattern to avoid: installing PIR everywhere, getting annoyed by lights shutting off while occupied, then disabling motion sensing entirely and losing all the energy-saving benefit. Match the sensor type to the room, and this never becomes a problem.

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Frequently Asked Questions

Is mmWave always better than PIR?

Not for every room — PIR is cheaper and perfectly reliable in transit spaces where motion is constant. mmWave's advantage is specifically in rooms with extended stationary occupancy.

Do mmWave sensors cost much more than PIR?

Typically somewhat more per unit, but the price gap has narrowed significantly as the technology has become more common.

Can I mix both types in the same home?

Yes, and this is actually the recommended approach — PIR for transit spaces, mmWave for rooms where people sit still.