How Ultra-Low-Power Sensor Solutions Enable Smart Buildings

“Today, the infrastructure of the Internet of Things (IoT) is very complete, and its scope of application is not limited to servers and data centers, but is widely used in our homes, offices and factories.

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Today, the infrastructure of the Internet of Things (IoT) is very complete, and its scope of application is not limited to servers and data centers, but is widely used in our homes, offices and factories.

At the outermost edge of the IoT are sensors, which collect data and relay it back to cloud services or process it locally. Sensors are an indispensable part of building intelligence. They can monitor the control environment without anyone controlling, bringing extraordinary convenience and economy, so that when the last person leaves the room, the intelligent building will not forget to turn off. lamp.

The sensor prototype is a relatively simple control system, such as heating and lighting controlled by occupancy detection and temperature measurement, and the technology has matured today. For users, buildings have become more intelligent, which is actually the improvement of the level of system intelligence.

The use of artificial intelligence (AI) will eventually eliminate the need for humans to plan the operational schedule of smart buildings. Simple sensors to detect the overall occupancy of a large area will be replaced by more sophisticated image sensors that can identify individuals and provide more personalized controls. Motion detectors will pave the way for imaging systems capable of recognizing individual faces, gestures and even emotions. Audio control enabled by smart speakers or virtual assistants has also contributed significantly to its rapid adoption.

As buildings become smarter, their capabilities will expand to provide users with a more personalized experience, such as access control and other security features. It’s not just about turning off the lights to save energy when the room is empty, but also allowing only authorized people to enter the room, automatically clearing out insecurity for personal network access, securing the indoor network, and even helping with finding things.

Smart buildings will bring smart energy saving

Lighting and heating account for 40% of overall energy consumption today. Using occupancy detection and adjusting lighting levels based on weak ambient light is obsolete in today’s internet age. The adoption of connected lighting is more advantageous and fully enabled by the technologies that now support and advance IoT development.

Communication is a key element of this. Wireless mesh networking simplifies the connection and reliability of smart lighting accessories. With the continuous maturity of Power over Ethernet (PoE) technology, and LED technology can greatly save energy, there is no need to hire an electrician to install it, and a single low-voltage Ethernet cable can be used to power and connect lighting equipment.

These days, these are used more and more as connecting terminals for lamps. They form an integral part of the smart building network. For example, each luminaire can effectively act as a beacon for indoor navigation. It also becomes easier to add other functions to luminaires such as occupancy detection, asset tracking, environmental monitoring. All of these functions can be implemented by multiple sensors integrated in a single connected device.

It is the development of technologies such as these that will allow buildings to provide more convenience for their occupants, but ultimately the greatest benefit will be energy savings in a smarter way.

Build smarter buildings

The topology of an intelligent building system will depend on sensors and actuators, as shown in Figure 1.

Figure 1: Example of a smart building system topology

A microcontroller or digital signal processor (DSP) at the heart of the system will be responsible for coordinating the many existing sensors and actuators. This will include sensors for occupancy detection, environmental monitoring and access control, in addition to electromechanical or solid state relays for switching lights, while existing actuators may include brushed or brushless direct current (DC) motors to switch doors and windows. Variable lighting levels can be achieved using some form of power modulation such as pulse width modulation (PWM), which the MCU/DSP performs well. The connection will be a combination of wired and wireless, so more and more protocols may be used. Some of these protocols support the same protocols used by the Internet and thus can be accessed directly, while others require a gateway.

Ultra-low-power systems are now on the horizon. Conceivably, MCUs, sensors, and actuators can all be powered by energy harvested from the environment, such as light or heat, thus creating the potential for virtual self-sustaining control systems.

When developing a communication network for a smart building infrastructure, three factors, range, power, and latency, need to be considered, and the weight of each factor depends on the actual application. For example, any difference in wait time between entering a dark room and turning on the lights is very noticeable to the occupant. In this scenario, low latency is important.

In general, local processing will provide lower latency than relying solely on cloud processing resources to make local decisions. If a sensor can determine by itself when someone enters a room and increase the level of lighting, it can improve the user experience overall.

Figure 2: Key factors to consider when developing a smart building communications infrastructure

Figure 2 illustrates how these factors influence the choice of wired/wireless technology. Implementing a simple yet robust mesh network (Figure 3) enables the construction of small networks of networked devices including lamps, fans, and more. Not only does a mesh network provide a way to extend the network far beyond a single node, it also builds redundancy into the network, allowing messages to be passed through the network through any combination of connected nodes. This means that the network will automatically re-route the luminaires if they are unable to deliver messages as signposts due to local disturbances. As a result, most wireless protocols now employ mesh networking.

Figure 3: A mesh network extends the network and provides routing redundancy

Multi-sensor platform delivers more

As technology advances, it becomes increasingly feasible to integrate multiple sensors into a single platform, creating greater value for connected assets, especially if the primary value is defined by their primary functionality. Take, for example, a luminaire whose primary function is lighting, but at the same time it is also an ideal sensor node that can be used to capture large amounts of data.

The value of integrating multiple sensors into a single device increases dramatically. Seemingly ordinary luminaires can become a critical part of smart building infrastructure. The sensor’s small size and ultra-low power consumption allow a small form factor PCB to easily accommodate multiple sensors to monitor occupancy, temperature, humidity, air quality, and more. Using an ultra-low power communication device such as the RSL10 Bluetooth low energy radio, this multi-sensor platform can run for years on a single coin cell battery (Figure 4).

Figure 4: Example of a multi-sensor platform enabled by the RSL10 system-in-package (RSL10 SIP)

In addition, it is now even possible to eliminate batteries entirely and use energy harvested from the environment to power a multi-sensor interconnected platform (Figure 5).

Figure 5: Energy harvesting technology now provides primary energy for smart sensors and actuators

As a result, smart sensors can be placed almost anywhere in a building. For example, relatively small and unobtrusive solar cells could be used to harvest enough energy from artificial lighting to power a multi-sensor platform and periodically send data back to a gateway.

Summarize

High energy efficiency will be the basis for the sustainable development of smart buildings. Achieving the goal of high energy efficiency requires making buildings more energy efficient to achieve lower energy consumption and providing low-power solutions using advanced technologies.

Across the technology stack, from using sensors to accessing cloud services, energy savings will be key. As the number of sensors deployed increases, so does the granularity of control over building utility applications, facilitating energy efficient cycles. But much depends on the energy efficiency of sensors, processors and connectivity technologies. The use of energy harvesting technologies independent of energy sources to achieve self-powering may become a necessary technology in the future as the number increases.

ON semiconductor is pioneering ultra-low power sensing and connectivity technologies, such as the highly integrated Bluetooth 5 solution RSL10. Supplemented by intelligent audio processing and imaging systems, ON Semiconductor has always been committed to providing more energy-efficient and smarter solutions.