IoT sensors serving the smart city

A city is not merely a collection of buildings and roads, but a living organism. To function well it needs "senses" — and this is precisely the role played by IoT (Internet of Things) sensors. Contrary to a widespread misconception, this is not about surveillance: the goal is to serve residents' comfort and safety more effectively.

1. Why does a city need "senses"?

If we imagine the city as a living organism, then the network of IoT sensors is its nervous system. These tiny devices continuously sense their surroundings — from a free parking space through air quality to the fill level of a waste container — and feed the resulting information back into city operations. The emphasis is not on the individual, but on the better functioning of the system as a whole: on making services match real needs more precisely.

2. From reactive operation to predictive care

Traditional city operation is reactive: it acts only once the fault has already occurred — the lamp has burned out, the container has overflowed, the water loss has run away. Sensed data, however, enable predictive maintenance, which addresses problems even before they arise. This shift in approach is not only cheaper and faster, but also more caring: the city thinks ahead on behalf of the resident.

3. Practical applications

The approach is not theoretical: it is backed by concrete, commercially available devices, each for a well-defined urban task.

• Parking — the Bosch Parking Lot Sensor is a radar-based sensor glued to the asphalt that signals free parking spaces in real time, reducing the unnecessary traffic caused by searching for a space.
• Air quality — the Libelium Waspmote is a solar-powered sensor mounted on street-lighting poles that continuously measures air quality, including the levels of pollutants and CO₂.
• Waste management — the ultrasonic fill-level meters from Nordsense and Sensoneo monitor how full containers are, so collection is dispatched only when it is genuinely needed — preventing unnecessary trips.
• Street lighting — the motion-sensing modules from Signify and Schréder enable adaptive, on-demand lighting, striking a balance between energy savings and a sense of safety.
• Water management — the Diehl Metering HYDRUS smart meter, besides measuring consumption, also detects leaks and signals immediately, before the loss becomes significant.
• Noise measurement — the Cesva TA120 Class 1 noise monitor measures only the decibel level; it does not record conversations, so the measurement does not infringe privacy.
• Traffic — the thermal cameras from FLIR help optimise transport without facial recognition, preserving anonymity, in a GDPR-compliant way.

4. The architecture of the system

From the sensors to the intervention, data travels through four interdependent layers:

1. Sensing — the sensors gather environmental data.
2. Connectivity — the data is transmitted over low-power networks (for example LoRaWAN, NB-IoT).
3. Data processing — processing takes place on cloud and edge computing resources.
4. Action — the processed information is turned into a concrete intervention, decision or service.

5. Data protection: built in, not bolted on

The key to the empathetic smart city is that the system is built on data protection from the outset. Instead of personal data, the sensors produce statistical indicators while preserving anonymity — all in line with the principle of "Privacy by Design", that is, built-in data protection. The information generated takes on an Open Data character, so it serves not surveillance but the information of citizens and the transparency of city operations.

6. Where is development heading?

The technology is advancing in two directions. Through Energy Harvesting, sensors can operate without battery replacement, from energy drawn from their surroundings, which radically reduces the maintenance burden. The Digital Twin, in turn, creates a complete virtual replica of the city, on which the consequences of decisions can be simulated in advance — before they are realised in reality.