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Smart sensor technology – definitions of the most common terms

We try to keep jargon and technical language to a minimum on our site, but the nature of what we do means using some terms not everyone will be familiar with. Whether you’re new to the world of smart building management or you’d like a quick refresher, you’ll find definitions of some common terms below.

Smart-building sensor technology

The A-Z of smart-sensor technology


An actuator receives the signal from the sensor, gateway or controller and acts on it – perhaps by switching off a light or adjusting the heating or ventilation. It lets you automate control of local systems with minimal impact on your IT operations.

Ambient energy

Energy present in, and harvested from, the surrounding environment. Our sensors harvest energy from four main sources: motion, light, electromagnetic fields and temperature difference.


Stands for application programming interface. An API is a bit like a messaging service – it allows two applications to talk to each other.

We found a helpful example here (and the video is worth a watch too). Say you’re looking at flights online and want to compare airlines to find the best option. The site’s API sends your request to a number of airlines’ databases, then gathers their responses and presents them back to you.

In our sensor systems, our smart gateway converts selected data to a usable format and sends it to your cloud system or internet-of-things platform using secure APIs.


The use of systems to operate equipment or machinery with minimal or reduced human input – for example, a heating system that switches itself on when it detects a low temperature.

Battery-free, battery-less

Able to run without batteries. Most of our sensors use energy-harvesting technology to get their power from the surrounding environment. Tiny energy converters enable sensors to function without batteries or wires, making them virtually maintenance-free.


Stands for building management system, also known as building automation system. A BMS gives you an efficient way to monitor and control conditions and equipment in the building, such as heating, ventilation, lighting and security.


Cloud computing allows us to access computing services, such as servers, storage, databases, software and more, over the internet. In the past, programs or applications would be downloaded onto a physical computer or server. Cloud computing gives greater flexibility and better security. Because data is stored online (‘in the cloud’), it can be accessed at any time and from anywhere you need, even if your IT equipment fails.

Since smart sensors and other internet-of-things devices produce a lot of data, cloud-based storage is ideal. Cloud-based platforms, such as IBM Watson IoT and Microsoft Azure IoT Hub, allow us to access and use that data through a user-friendly portal.

Energy converter

Self-powered sensors harvest energy from four main sources: motion, light, electromagnetic fields and temperature difference. Energy converters change that kinetic, solar, electromagnetic or thermal energy into electrical energy to power the sensor.

Energy harvesting

Energy-harvesting sensors or switches work by collecting tiny amounts of energy – such as light, temperature differences and kinetic motion – from their environment. It means they use very little power and require virtually no maintenance.

EnOcean protocol

See ‘Wireless standards / protocols’.

EnOcean technology

EnOcean is the company that developed the patented energy-harvesting wireless technology we use in some of our sensors and systems. The technology is used by leading manufacturers and is present in hundreds of thousands of buildings around the world.


A gateway receives signals from the sensors and makes it usable. It converts the data into industry-standard formats, which means it can be securely integrated into any software or platform.


Stands for Internet of Things, a term used to cover internet-connected devices or objects that ‘talk’ to each other by gathering and communicating data. That could be anything from a temperature sensor to a fitness tracker, a security camera that sends alerts your phone, to an egg tray that helps you avoid home-baking disasters. IoT-enabled devices are often described as ‘smart’.


JSON (JavaScript Object Notation) is an open-standard file format that uses human readable text to display data. We use JSON to standardise sensor data across multiple protocols and formats.

Kinetic energy

Energy from motion – for example, the movement of doors, windows or machine components. The kinetic energy harvested by our sensors is converted into electrical energy by an electro-dynamic energy converter, which works a bit like a dynamo.


MQTT (Message Queuing Telemetry Transport) is a simple messaging protocol – based on a publish and subscribe principle, its ideal for transmitting data between devices as It’s been designed for applications where bandwidth and battery power may be at a premium, which makes it ideal for IoT devices.

PIR motion sensor

PIR stands for passive infrared. Each motion sensor has two slots made of a material that’s sensitive to infrared light. When the sensor is idle, both slots detect the same amount of ambient infrared radiation. When a person enters the sensor’s field of view, the movement reaches one half of the sensor before the other. It’s this change between the radiation detected by the two slots that tells the sensor someone is present.


A set of rules or procedures for transmitting data between electronic devices. See also ‘Wireless standards / protocols’.


Repeaters, gateways and actuators are all types of receivers – components that receive the signal transmitted by the sensor.


A relay is a type of switch that’s controlled by electricity. They can be switched on or off by the presence of a relatively small electric current, and in turn, can switch on another appliance using a much larger current. This is useful for us because sensors only produce a very small current, but often we need them to drive bigger pieces of apparatus that use bigger currents. That means relays can work either as switches, turning things on and off, or as amplifiers, which convert small currents into larger ones.


Repeaters are used to increase sensors’ range, allowing them to transmit data over a larger distance or work around obstructions.

Radio frequency (RF)

Radio frequency is the number of radio waves that pass a point in one second. The shorter the wavelength, the higher the frequency. Frequency is measured in Hertz. Radio waves can have a frequency of anything from 30 Hertz (Hz) to 300 GigaHertz (GHz).

Radio waves

Radio waves are a type of electromagnetic wave – that’s is, a wave composed of alternating electric and magnetic fields. They’re created by accelerating charges or changing magnetic fields. Naturally occurring radio waves are emitted by lightning, and they can also be generated artificially by transmitters. Radio waves are widely used in broadcasting, communications and wireless computer networks, as well as building automation systems.

If you look at the diagram you can see that wavelength is the distance between two equivalent parts of the wave. The frequency is the number of waves that pass a point in one second. When the wavelength is short, the frequency is high.


Another term for energy harvesting. Self-powered sensors work by collecting tiny amounts of energy – such as light, electromagnetic fields, temperature differences and kinetic motion – from their environment. It means they use very little power and require virtually no maintenance.


Our sensors are small wireless boxes that simply stick, click or screw to your chosen surface. They work by detecting changes in conditions and sending the information they gather to a receiver – which could be a repeater, gateway or actuator – via radio signals.


A smart object or device is one that can interact with people, the environment or other objects. It’s a word that’s often used to describe devices connected to the Internet of Things.

Smart building / home

A fairly ambiguous term, but is basically used to describe a building or home that uses a technology such as automated systems, intelligent building management systems, wireless technology, data gathering or smart sensors. Homes or buildings may also be described as ‘connected’, automated’ or ‘intelligent’.

Smart sensor

A smart sensor combines sensing with intelligent capabilities, such as wireless communication or processing ability. For example, it will use advanced calculations to sort through data in the blink of an eye – deleting the parts that aren’t relevant and storing or transmitting the rest.


The data or instructions that tell a computer or device how to work. Physical hardware cannot function without the software to inform it.

Sub 1 GHz band

Refers to wireless protocols that transmit data using radio waves with a frequency (RF) of less that 1 GigaHertz (GHz). This band is particularly useful for IoT devices as it offers a good compromise between range, power consumption and interference.


A switch is a control that’s operated by the user and can be as simple as switching a light on or off.


A transceiver is a device that can both transmit and receive communications – for example, the Pressac smart gateway.

Ultra-low power

Some of our sensors are ultra-low power, using technology to harvest their power from the surrounding environment. As only small amounts of energy are harvested, EnOcean sensors have an extremely low idle current, which means only a tiny amount of energy is consumed while the system is sleeping.


Communication devices that carry a signal over electromagnetic waves rather than some form of wire. Two of the most common wireless technologies are Wi-Fi and Bluetooth.

Wireless standards / protocols

Wireless standards or protocols are different technologies used to carry a signal wirelessly. Different protocols have different ranges, data requirements, security and power demands. Some, including Bluetooth, EnOcean and ZigBee, are especially suited to IoT networks because they can support a lot of low-power devices spread around a home or building.

Bluetooth 5.0 is the latest version of the Bluetooth wireless communication standard. While older versions of Bluetooth were power hungry and worked best for devices that were recharged often, like headsets, mice and keyboards, Bluetooth 5.0 is low energy, meaning it’s far better suited to IoT devices like smart sensors. It’s also faster, with data transfer speeds of up to 2 Mbps, and can communicate over distances of up to 240 meters – four times the distance allowed by Bluetooth 4.2.

Like Bluetooth, ZigBee operates at 2.4 GHz. It works by creating a ‘mesh’, where each device is able to communicate with the next, at a range of 10 to 20 metres.

The EnOcean protocol was designed specifically for low-power, energy-harvesting devices and approved as an international standard (ISO/IEC 14543-3-10) in 2012. Three frequencies are used: 868 MHz for Europe, 902 MHz for North America and 928 MHz for Japan.


Did you find what you wanted to know? We’ll add to this list in future, so if there’s a definition you think we should add, just let us know.


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