How to use TI millimeter wave occupancy sensors to design energy-efficient smart air conditioners

Compared with the past, people in developed countries/regions and developing countries/regions now rely more on air conditioners (AC) to obtain comfortable living spaces. Therefore, energy consumption is also increasing rapidly.

According to the International Energy Association’s “Future of Refrigeration” report, air conditioning accounts for 10% of today’s total energy consumption. It is estimated that by 2050, this usage will triple, which is equivalent to the current total power generation capacity of the United States, the European Union and Japan. By 2050, the number of air conditioners in residential and commercial buildings worldwide will increase from 1.6 billion today to 5.6 billion. This is equivalent to 10 new air conditioners sold every second for the next 30 years.

The role of occupancy sensing in air conditioning

By adapting to indoor activity levels and directing airflow to where it is needed more, human body occupancy sensing can make air conditioners smarter and more energy-efficient. Figure 1 shows some scenarios in which occupancy sensing (such as presence/absence, activity and personnel location detection) provides feedback. By adjusting the room temperature and directing airflow to indoor occupants, it can help save energy and Make the environment more comfortable.


How to use TI millimeter wave occupancy sensors to design energy-efficient smart air conditioners

Figure 1: A scene showing how the feedback obtained from occupancy sensing determines the air conditioner usage

Passive infrared sensors and camera solutions are two technologies used in air conditioning occupancy sensing. Passive infrared sensors have low cost and low power consumption, but have a high false detection rate under bright sunlight and lack sensitivity to fine motion. In contrast, the camera can provide excellent resolution, but may have a higher false detection rate, especially for detecting shadows and portrait images. Passive infrared sensors and camera solutions are optical sensors, and optical design will be required in the design, requiring additional openings, which may affect the appearance design.

The entire industry uses occupancy sensing to achieve energy saving, and is also committed to making air conditioners smarter through edge processing. In addition to controlling the operation of the air conditioner through presence detection to improve user comfort, there is also continuous efforts to adopt a single sensor technology. In the future, air conditioners will integrate additional functions for user safety monitoring, such as fall event detection and vital signs monitoring, including heart rate and respiration rate.

Advantages of millimeter wave sensors in occupancy sensing

TI millimeter wave (mmWave) sensors provide a rich data set that contains precise range, speed, and direction of arrival information for each object in the relevant area. Through the digital signal processor (DSP) that performs object detection, classification and tracking, it is possible to obtain personnel occupancy information, such as the presence, absence, number of personnel, and the precise location of the personnel relative to the air conditioning equipment. Air conditioning equipment can use this information to make informed decisions; for example, when someone enters a room, the sensor will track the person’s presence in the shortest preset time before turning on the airflow. If the person stays in the room, the air conditioner guides the airflow to the person by using tracking/location information to provide comfort. The air conditioner will also adjust the temperature according to the number of people in the room to achieve greater comfort and better energy-saving effects.

In addition to the accuracy and precision of the data, TI’s millimeter wave sensors provide many advantages when creating energy-efficient smart air conditioning solutions, including:

Reduced false detections

Can operate normally in harsh environments

Beautiful product design, small appearance

Using sensing technology instead of cameras can reduce privacy concerns.Under the premise of protecting privacy, realize people counting and target tracking

Realize edge intelligence

TI millimeter wave 60GHz sensor integrates FM continuous wave transceiver, on-chip monitoring and calibration mechanism, Arm? Cortex?-R4F microcontroller and C674x DSP on a single chip. This integration feature can support the realization of intelligence on highly integrated sensors and real-time data processing in the device itself.

An example application uses TI’s IWR6843 60GHz millimeter wave single-chip sensor to achieve occupancy sensing for commercial and residential air conditioners. The sensor that processes the data uses Capon beamforming for human detection and can intelligently classify objects to reduce false detections to a greater extent. This sample application demonstrates the detection accuracy of persons (including moving and stationary) of +/-10 cm, and the indoor detection distance can be as long as 8 meters. The counting density is 3 people per two meters. When the number of people is less than 5, the accuracy is 100%; when there are 9 people in the room, the accuracy is 85%.

In the near future, air-conditioning will become a completely independent system based on data, without the need for remote control or human-computer interaction through the air-conditioning control unit. The sensor technology in the air conditioner continuously collects data in order to provide better comfort. For example, in an office environment, the sensor can determine over time that the most people are in the office from 9 am to 5 pm. Based on these data, the system will learn to direct more airflow during busy hours, and limit or turn off airflow during off-peak hours, in order to reduce energy consumption and thereby save corporate costs.

The demand for residential and commercial air conditioners continues to grow and will triple by 2050. Occupancy sensing using millimeter wave technology can reduce overall air conditioning energy consumption by as much as 35%. Looking to the future, millimeter wave technology will not only continue to have a greater impact on the operation of HVAC systems, but also reduce the overall emissions of pollutants in the environment.

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