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Sensor sizing & selection rules — technical reference

Written by Vemco Support | Aug 19, 2026, 2:27:29 AM

This is the technical reference behind the Vemco Sensor & Solution Advisor. It states the exact rules used to pick sensor models and quantities for a space. Use it to answer sizing questions directly. For a guided calculation, the interactive Solution Advisor produces a full bill of quantities from the same rules.

People counting at entrances

Quantity rule: 1 sensor per door, unless a door is wider than 4 m — then use 1 sensor per 4 m of width (round up). A single overhead counter reliably spans about 4 m at typical entrance heights.

Model by ceiling height (door counters are entrance-mounted, picked by height, not by floor area):

Ceiling height

Sensor

Over 14 m

Xovis PC3SE-H (14–20 m)

6–14 m

Xovis PC3SE

Up to 6 m, LoRaWAN preferred (no PoE)

Milesight VS133 (LoRaWAN people counter)

Up to 6 m, standard

Xovis PC2SE

Re-ID (unique visitors / journeys)

Same per-door quantity rule. Re-ID runs on the Vemtrack platform and needs a TDI edge AI unit.

  • Door sensor: TD2000 G3 if ceiling ≤ 4 m, otherwise TD1501 G2.

  • Edge AI unit (one per site), sized by sensor count: TD4001 T2 for ≤ 4 sensors, T6 for ≤ 8, T21 above that.

Full-area tracking (space stitching)

Multiple sensors stitched into one continuous tracking area. The key decision is AI mode vs No-AI mode, because Xovis AI extensions (demographics, age/gender, view direction) only validate up to about 4.0 m.

AI mode

No-AI mode

Max ceiling

4.0 m (warns above)

Any height

Sensors allowed

PC2SE, PF-L

PC3SE, PC3SE-H (taller ceilings)

PF-L AI band

2.4–3.25 m

n/a

Staff exclusion

Not on PF-L

n/a

  • Overlap: stitched sensors must overlap, so reduce each sensor's coverage dimension by ~0.5 m for the hand-off. Effective covered area per sensor is therefore smaller than its raw footprint.

  • PF-L is chosen for open-area tracking when the zone is larger than ~150 m². In AI mode above 4 m the advisor warns and adds 1 AI-extension licence per sensor.

  • Multisensor group limits: PC parent max 9 sensors; PF group max 15; above ~350 sensors use the Xovis SPIDER processor.

PF-L is only for open-area tracking (malls, airports, large halls, area > ~200 m²). It is never used as a door counter — entrances always use the PC-series rule above.

Zone & desk occupancy

Need

Sensor & quantity

Individual desks

VS340 — 1 per desk

Open-plan zone occupancy

VS121 — ceil(area × 0.7 / 100); ~1 per 100 m² usable, 16 sub-regions each

Meeting rooms

VS370 — ~1 per room (ceil(area / 150) as estimate)

Air quality / IAQ

Quantity: ceil(area / 120) — roughly 1 sensor per 100–150 m².

  • AM319 (9-in-1: CO₂, PM2.5, PM10, TVOC, HCHO/O₃) for office, hotel, airport.

  • AM103 (CO₂/temp/RH) for simpler demand-controlled ventilation.

Energy & ESG (CSRD / ESRS E1)

Stream

Sensor & quantity

Scope

Electricity, main incomer

CT3xx set (3 CTs) if 3-phase; 1 CT if single-phase

Scope 2

Sub-circuit submetering

1 CT per sub-circuit (CT101/103/105 by load)

Scope 2

Solar PV

1 CT on each inverter

Renewables

EV charging

1 CT per charger circuit

E1-5

Gas / district heating (M-Bus or Modbus)

UC300 per meter/substation

Scope 1

Gas / heat (pulse output)

EM300-DI per meter

Scope 1

Water

EM300-DI (pulse) or UC300 (M-Bus/Modbus) on the meter

E3

Sensors supply measured activity data (kWh, m³, Wh). Emission factors that convert this to tCO₂e are applied in the Vemcount ESG dashboard, not measured by the sensor. Confirm whether a gas/heat meter outputs pulse, M-Bus, or Modbus before quoting — it decides EM300-DI vs UC300. Full mapping is in the CSRD / ESRS E1 article.

Smart restroom

Requires a cubicle count — the advisor asks for it rather than guessing. Per cubicle count c:

  • VS330 occupancy and WS201 paper monitor: 1 per cubicle

  • Soap level: ceil(c / 3); GS301 gas/odour: ceil(c / 8); WS303 (people/feedback): max(2, ceil(c / 4))

Waste, leak, temperature, HVAC, access

Waste bins

EM400-TLD (indoor), EM400-MUD (outdoor/compactor)

Leak / water

WS303, EM300-SLD (spot), EM300-MLD (membrane)

Temperature / humidity

EM300-TH

HVAC / thermostat

WT series thermostats

Door / access

WS301 open/close

LoRaWAN gateway

Whenever any LoRaWAN sensor is in the solution, add a Milesight UG65 gateway: ceil(area / 2000), i.e. roughly 1 per floor/zone. Gateways are infrastructure, not licensed sensors. LoRaWAN sensors connect to ttn.vemcount.app over UDP 1700.

Platform & licensing

  • Vemcount: people counting, occupancy, IoT/environment, energy.

  • Vemtrack: Re-ID / unique-visitor analytics (TDI).

  • Each sensor is one annual licence (ARR). Sensors are source-agnostic — hardware can be bought anywhere; Vemco licenses the software. Gateways and edge processors are not licensed sensors.

For a full bill of quantities from these rules, use the Sensor & Solution Advisor. For a complex multi-site or ESG project, contact support@vemcogroup.com for a site survey. See also the Xovis coverage tables article and the CSRD / ESRS E1 ESG article.