Sensor Lights for Commercial Buildings

Last updated: 02 July 2026

PIR and microwave built the market — but thermal, mmWave radar and time-of-flight sensors are changing it. A plain-English guide by use case, with a sensor-type recommendation table and the AS/NZS rules that govern each.

For nearly thirty years, two sensor types ran the entire commercial lighting market: passive infrared and microwave. If a light in your office, warehouse or stairwell switched itself off when nobody was around, one of those two was behind it. They are cheap, proven, however, both have their limitations.

Why this matters

Occupancy sensing is one of the cheapest energy levers in a building. Switching or dimming lights when a space is empty typically cuts lighting energy by up to 30% in offices, and far more in intermittently-used spaces like warehouse aisles, car parks and back-of-house areas. It is also no longer optional. The National Construction Code (NCC) Section J requires that 95 per cent of the lighting load in most spaces larger than 250 m² is controlled by a time switch or an occupancy sensor.

So the question is not whether to use sensors — it is which sensor, in which space. Get it wrong and you get the two complaints every facilities manager knows: lights that drop out while people are still working, and lights that never switch off because the sensor triggers on a passing forklift or a gust through a roller door. We covered the basics of this in an earlier knowledge-centre article on sensor lights; this piece updates it for the sensor types now available in the market.

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Includes the sensor reference guide, NCC compliance checklist, warehouse tuning guide and retrofit decision checklist.

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The two incumbents — and their blind spots

Passive infrared (PIR)

PIR detects the heat of a moving body crossing its field of view. It is inexpensive, sits outside the fitting, and works well in enclosed spaces where it has clear line of sight — private offices, meeting rooms, toilets. Its weaknesses are well known: it misses a still person (someone reading or on a long call), it struggles to see someone walking straight towards it rather than across it, and it goes under-sensitive when the background is warm. Dust and grime on the lens degrade it over time.

Microwave (high-frequency)

Microwave sensors emit a high-frequency signal and measure the echo, so they pick up far smaller movements than PIR and can see through thin partitions and around objects, covering roughly an 8 m radius from the fitting. The flip side is over-triggering: untuned, a microwave sensor will hold the lights on for any moving object nearby — a swinging door, a fan, traffic the other side of a plasterboard wall. In a warehouse or car park that sensitivity is a feature; in a quiet office it is a nuisance that has to be dialled back.

The new generation

Thermal (low-resolution infrared imaging)

Newer thermal sensors build a coarse heat image of a space rather than just reacting to movement. Because they read shape and direction, they can tell a person from a forklift, count how many people are present, and — critically — hold the lights on for someone sitting perfectly still. The resolution is deliberately too low to identify anyone, so no recognisable image is ever stored, which sidesteps the privacy objection that kills camera-based counting. The same heat image can flag a motor or switchboard running hot for predictive maintenance. Our own view, and the direction the market is heading, is that thermal may eventually replace both PIR and microwave as the cost comes down.

Millimetre-wave (mmWave) radar

mmWave radar detects micro-movements as small as the rise and fall of breathing, which makes it excellent at confirming a stationary person is still there. It works in any light and through thin barriers. Like microwave, it needs tuning to stop it reacting to movement outside the intended zone, but its presence-detection accuracy is a clear step up from PIR, especially in areas with special requirements or challenging environments.

Time-of-flight (ToF) and infrared arrays

Time-of-flight sensors fire an infrared pulse and measure how long it takes to return, building a depth map of the space. Independent research (Energy and Buildings, 2021) has shown occupancy-counting error rates as low as around 0.4 per cent. They are privacy-preserving, cover roughly 10 m, and are strong for accurate people-counting. Due to cost and commissioning requirements, they are currently recommended for specialist areas only.

Sensor recommendations by use case

Sensor selection depends on the space, the way people move through it, environmental conditions, and the standard that governs it. Here is the short version.

Use case / space	Recommended sensor type	Why it works here	What to watch out for	Governing standard
Office / meeting rooms	Thermal or PIR + mmWave	Holds lights on for still, seated occupants; no false drop-outs mid-meeting; counts people for space data.	Plain PIR alone will switch off on a quiet, seated room. Tune hold times to the way the room is used.	NCC Section J; AS/NZS 1680 (interior)
Warehouse aisles	Microwave or mmWave, integrated per fitting	Picks up movement deep along racking; per-aisle 'follow-me' lighting so only occupied aisles are lit.	Standalone area sensors leave dead spots between racks; mount the sensor just above the highest stored goods.	NCC Section J
Fire-isolated stairs & corridors	Integrated microwave (triggers before entry)	Senses approach through the door so the stair is lit before you step in; dims rather than fully switching off.	Full switch-off is not permitted — must dim to at least 30% after 15 min. Emergency function is separate.	NCC Spec 40; AS/NZS 2293 (emergency)
Car parks (Interior)	Microwave or ToF, integrated per light	Per-light detection covers blind spots a single area sensor misses; dim-to-standby between vehicles and people.	Avoid one timer-based area sensor for a whole deck; tune out passing traffic and weather movement.	NCC Section J; AS/NZS 1680 (interior)

What this means in Australia

Most development in thermal and radar presence sensing has come from Europe and North America. In Australia, the implication is clear: NCC Section J already requires occupancy control in larger spaces, so sensors are now a compliance requirement rather than an optional upgrade.

Selecting the right sensor is usually a trade-off between cost and performance. In most environments, careful tuning is needed to avoid nuisance switching, and external lighting remains particularly challenging because range limits and fast-moving objects can reduce detection reliability.

In most projects, cost will still drive the decision. Even so, the next generation of sensors is expected to become more accessible over the next few years, giving users clearer performance benefits as these technologies enter the mainstream.

What to do about it

On your next fit out or retrofit, stop specifying 'occupancy sensor' as a generic line item. Match the sensor to how the space is actually used — still, seated work wants presence detection (thermal or radar), not movement detection (plain PIR); long racking and open decks want per-fitting integrated sensors, not one area unit; fire stairs want a sensor that triggers on approach and dims rather than switches off the light. Specifying the sensor type, not just 'a sensor', is what separates a system people leave switched on from one they rip out.

Download the full Sensor Selection Pack

The full sensor-type selection pack adds the working detail:

✓ Sensor technology reference sheet
✓ NCC Section J compliance checklist
✓ Warehouse & car park tuning guide
✓ Fire stair dimming compliance note
✓ Future-proofing checklist

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FAQs about sensor lights in commercial buildings

What's the difference between PIR and microwave sensors?

PIR detects the heat of a moving body and needs clear line of sight; microwave bounces a signal and detects much smaller movement, even through thin walls. PIR suits enclosed offices; microwave suits open or obstructed spaces like warehouses and car parks.

Why do my sensor lights switch off while I'm still at my desk?

Almost certainly a PIR sensor that can't see small movement. Someone sitting still, typing or on a call doesn't generate enough motion to keep it triggered. A presence sensor — thermal or mmWave radar — solves it because it detects a stationary person.

Are thermal sensors a privacy risk?

No. Commercial thermal occupancy sensors use a deliberately low-resolution heat image — enough to see shape and direction, not enough to identify a person. No recognisable image is captured or stored.

Can I leave lights fully switched off in a fire stair to save energy?

No. Under NCC Specification 40, fire-isolated stairs may dim to a reduced level (at least 30% of peak) after a period of vacancy but must not switch fully off. The emergency lighting function is a separate, mandated requirement.

What sensor is best for a warehouse?

An integrated microwave or mmWave sensor in each fitting, set up for 'follow-me' aisle lighting, so only occupied aisles are lit. A single area sensor leaves dark gaps between racking.

Do occupancy sensors actually save much energy?

Yes — typically 5 to 15 per cent of lighting energy in offices, and considerably more in intermittently-used spaces such as warehouse aisles, car parks and back-of-house corridors where lights would otherwise run on full.

Ready to put this into practice?

Download the free Sensor Selection Pack or talk to the team.