Updated 23 October 2026 · First published 27 December 2024. Rewritten with the EU rules that apply, current sensors and sources for every figure.
A freezer door left ajar on a Friday night is still the classic way to lose a cold room full of stock. Paper logs and a thermometer on the wall only tell you after the fact. A wireless sensor tells you while there is still time to shut the door or move the goods.
This guide covers what EU food and medicine rules actually ask for, how to get a radio signal out of a steel cold room, which sensors fit which job, and how to set the system up so the alarms are worth listening to.
What EU Rules Ask For
There is no single "cold chain law". Three texts cover most of what food and pharma businesses in the EU deal with:
| Who | Rule | What it asks for |
|---|---|---|
| All food businesses | Regulation (EC) 852/2004 | A HACCP-based procedure with critical limits, monitoring at critical control points and corrective action when a limit is breached. Annex II adds that the cold chain is not to be interrupted. |
| Quick-frozen food | Regulation (EC) 37/2005 | Recording instruments that monitor air temperature at frequent, regular intervals in transport, warehousing and storage. Instruments must comply with EN 12830, EN 13485 and EN 13486, and records are kept for at least one year. |
| Medicines (wholesale distribution) | EU GDP guidelines 2013/C 343/01 | Temperature mapping of storage areas, calibrated monitoring equipment, alarms for excursions, and records kept for at least five years. |
Getting a Signal Out of a Cold Room
Walk-in cold rooms and freezers are steel boxes lined with insulation, and steel blocks radio. LoRaWAN's sub-GHz signal copes far better than Wi-Fi or Bluetooth with walls and distance, but a closed steel room is still a hard case. Two habits solve most of it:
- Keep the electronics outside, put the probe inside. A sensor with an external probe sits on the outside wall, and the probe cable runs through the door seal or a cable gland. The radio is not fighting the steel, and the battery is not sitting at -25 °C.
- Put a gateway close by. One indoor gateway in the plant area or corridor usually covers a whole site's fridges and freezers. If you are unsure, ask us: advice on placement is free, and we offer a paid RF survey for larger sites.
Choosing the Sensor
All four sensors below are listed by Milesight as EN 12830 compliant. Specs are from Milesight's own datasheets and product pages.
| Sensor | Best for | Key facts |
|---|---|---|
| Milesight TS201 | Probe in a fridge, freezer or product | Stainless steel 316 food-grade probe, -40 to +125 °C, ±0.5 °C from -10 to 85 °C. IP67. Stores 4,000 readings and resends them after a network outage. Device body rated -30 to +55 °C, so mount it outside deep freezers. |
| Milesight TS301 / TS302 | Cold rooms where staff want to see the reading | LCD display, one or two probes. With the PT100 food probe: Class A, typically ±0.4 °C. Stores up to 10,000 readings, exports CSV. Enclosure IP65, probes IP67. |
| Milesight EM320-TH | Air temperature and humidity inside chilled areas | Built-in sensor, -30 to +60 °C, typically ±0.2 °C from 0 to 60 °C. Food-grade housing, IP67. Stores 3,000 readings. Milesight quotes over 10 years of battery life at a 10-minute interval. |
| Milesight EM300-TH | Dry stores, ambient warehouses, transport cages | Built-in sensor, -30 to +70 °C, IP67. Stores 2,800 readings. A good general-purpose choice where food contact is not an issue. |
For a quick rule: a probe sensor for anything colder than about -25 °C or for product temperature, a display model where staff walk past it every day, and a built-in sensor for air temperature in chillers and stores. See the full range in our cold chain collection.
How the System Fits Together
Sensors report every few minutes to a gateway, the gateway forwards the data to a LoRaWAN network server, and a platform turns the readings into dashboards, alerts and reports. You can use a public network server, a private one, or the server built into many gateways.
Setting It Up So the Alarms Mean Something
Frequently Asked Questions
Do my sensors have to meet EN 12830?
For quick-frozen food, yes: Regulation 37/2005 requires measuring instruments that comply with EN 12830, EN 13485 and EN 13486. For other food and for medicines it is not written into the same rule, but EN 12830 compliant recorders make audits easier.
Will a LoRaWAN sensor work inside a freezer?
The probe will. Keep the sensor body outside where possible: steel walls weaken the radio signal, and each model has an operating temperature range for the electronics. The TS201 body, for example, is rated down to -30 °C.
How long should I keep temperature records?
At least one year for quick-frozen food under Regulation 37/2005, and at least five years under the EU GDP guidelines for medicines. Your national rules or HACCP plan may require longer.
How many gateways do I need?
Usually one for a single building, placed near the cold rooms. Large sites or several buildings may need more. We offer a paid RF survey if you want certainty before you buy.
Can you set the sensors up before shipping?
Yes. Send us your LoRaWAN network server details with the order and we will pre-provision the devices so they are ready to add to your network.
Sources
- IIR: The role of refrigeration in worldwide nutrition, 6th Informatory Note (2020)
- Regulation (EC) No 852/2004 on the hygiene of foodstuffs
- Commission Regulation (EC) No 37/2005 on temperature monitoring of quick-frozen foods
- Guidelines on Good Distribution Practice of medicinal products for human use (2013/C 343/01)
- EN 12830:2018 Temperature recorders for temperature sensitive goods
Setting Up Cold Chain Monitoring?
Tell us how many fridges, freezers and cold rooms you have and we will suggest sensors and a gateway, ready to join your network.