1. Characteristic of carbon dioxide and application fields of its sensors

Our planet is surrounded by a layer of atmosphere, of which oxygen accounts for about 21%, 78% is nitrogen, and 1% is other gases. Among these 1% gases, a small part is carbon dioxide, about 350 - 450 ppm (one millionth, or 0.035% - 0.045%), which is 1.5 times heavier than air; it can absorb infrared wave and produce greenhouse effect.

The higher the content of carbon dioxide in the air, the greater the impact on the human body. When the content of carbon dioxide is higher than 0.7%, the human body will feel uncomfortable; when it exceeds 10%, the human body will appear coma or death; when it reaches 20%, the human body will die in a few seconds. Therefore, in densely populated areas, carbon dioxide content is a very important parameter, directly related to human comfort and safety.

At the same time, it is also an important element of photosynthesis in plants. It can also be said that without carbon dioxide, there would be no vitality of nature. That's why carbon dioxide is a necessary parameter in plant experiments.

In chemical industry, after chemical reaction, a lot of high concentration carbon dioxide gas will be produced, and in beer, cola and other beverages, carbon dioxide must be added; mixing carbon dioxide and nitrogen into "ideal" gas, acting on the inflatable packaging of fresh food, can make the activity of cells in fresh food maintain a certain time, delay its life process and maintain a certain degree. The degree of freshness. Therefore, due to these characteristics of carbon dioxide, such as airports, buildings, offices, factories, mines, greenhouses, laboratories, chemical industry, food preservation and other industries will need to measure carbon dioxide value.

2. Importance and application of carbon dioxide parameters in HVAC

Firstly, HVAC: HVAC stands for heating, ventilation and air conditioning, while IAQ stands for indoor air quality. To maintain low energy consumption, almost closed heating and air conditioning systems are used. This can be checked by measuring the level of CO2, depending on the number of people in the room or due to other activities (e.g. cooking with gas).

The accumulation of pollutants is often associated with the lack of adequate ventilation, which can have a dangerous impact on building residents, vehicles and people in other enclosed areas. Proper ventilation is important not only for people's comfort, but also for the economic operation of heating and air conditioning systems.

OSHA (US Occupational Safety and Health Administration), CO2 lists STEL (short-term maximum exposure limit, 15 minutes) 30000ppm and TWA (Time-weighted average exposure limit, 8 hours) & nbsp; 5,000 ppm standard. OSHA had some suggestions for indoor air quality rules in 1995 if CO2 levels exceeded 800. For ppm, fresh air is needed.

Therefore, CO2 is a very important parameter in HVAC. There is a close relationship between indoor CO2 concentration and ventilation. Whether in space, with more or less people, this system can effectively save valuable energy and maintain good indoor air quality.

Generally speaking, the benefits of installing a ventilation control system based on CO2 control show that the investment in equipment can be rewarded by the energy saved within two years. In building ventilation control, CO2 sensors are widely used in airports, office buildings, shopping centers, training centers, hospitals, factory workshops, subway, cinemas and other high-level places where people gather for entertainment and activities.

3) Background of the UK GSS ultra-low power carbon dioxide sensor

The market demand of ventilation control based on carbon dioxide sensors is occurring. The increasing market demand benefits from the advantages of energy efficiency: through proper ventilation control, up to 25% of building energy saving can be achieved, while promoting the comfort of indoor employees and improving work efficiency.

GSS and Schneider electric innovation have been working in depth to develop an ultra low power NDIR carbon dioxide sensor for building and residential markets. This carbon dioxide sensor has first-class low power consumption and performance, and the path to a high-precision carbon dioxide monitoring solution compatible with long-life batteries or solar cell power supply devices is thus opened. Because of its simplicity, cost-effective installation and flexibility, this innovative wireless battery-powered sensor, which integrates carbon dioxide, temperature and humidity, provides an ideal solution to meet the market for building HVAC control.