Gas sensors: Detecting the invisible enemy
Gas sensors: Detecting the invisible enemy
Buildings exist to protect people from the elements and to otherwise support human activity. Buildings should not make people sick or cause them discomfort, or otherwise inhibit their ability to perform. How effectively a building function to support its occupants and how efficiently the building operates to keep costs manageable is a measure of the building’s Performance.
The growing proliferation of chemical pollutants in consumer and commercial products, the tendency toward tighter building envelopes and reduced ventilation to save energy, and pressures to defer maintenance and other building services to reduce costs have fostered indoor air quality problems in many buildings. Occupant complaints of odors, stale and stuffy air and symptoms of illness or discomfort breed undesirable conflicts between occupants or tenants and building managers. Lawsuits sometimes follow.
If indoor air quality is not well managed on a daily basis, remediation of ensuing problems and/or resolution in court can be extremely costly. So it helps to understand the causes and consequences of indoor air quality and to manage your building to avoid these problems.
Air quality in general, is determined by assessing a variety of pollution indicators. Good air quality is a requirement for preserving the balance of life on earth for humans, plants, animals and natural resources. As such, human health, plants, animals and natural resources are threatened when pollution in the air reach high concentrations.
The Indicators
There many indicators that can impact your indoor air quality such as humidity and temperature, Nitrogen dioxide (NO2), particulate matter (PM2.5), Carbon monoxide and dioxide (CO, CO2), Volatile Organic compounds (VOC) and ozone (O3). Rutronik catalog covers the most common issues that contribute to poor indoor air quality together with Sensirion and Bosch Sensortec. This section will focus on Gas Sensing solutions For CO2 and VOC.
Volatile Organic Compounds VOC
In the field of IAQ research, the term “volatile organic compound” or “VOC” refers to any of thousands of organic (carbon-containing) chemicals that are present mostly as gases at room temperature. Inorganic carbon-containing gases such as carbon dioxide and carbon monoxide are excluded from this definition. VOCs arise from a broad range of different sources. Their presence in atmospheric air can be accounted for by biological processes, for example, metabolic processes in plants, putrefaction or decomposition. Further sources of VOCs in atmospheric air include technical processes in which substances are generated through incomplete combustion (especially in vehicular emissions), or as volatile by-products of industrial or commercial processes.
Organic chemicals are widely used as ingredients in household products. Paints, varnishes and wax all contain organic solvents, as do many cleaning, disinfecting, cosmetic, and degreasing and hobby products. Fuels are made up of organic chemicals. All of these products can release organic compounds while you are using them, and, to some degree, when they are stored.
Elevated VOC levels can have a negative impact on wellbeing, comfort, and cognitive abilities by causing adverse health effects like kidney and liver damage, headaches, skin issues, nose and throat issues, fatigue, and dizziness. An effective reduction of VOC exposure requires the monitoring of VOC levels using suitable sensors.
A large number of applications such as ventilation controls, air purifiers, or Internet-of-Things devices benefit from the integration of VOC sensors.
The amount of volatile organic compounds in indoor air is known as TVOC (total volatile organic compounds), has been established as a practical time and cost-effective method of surveying indoor environments for contamination. Sensirion’s multi-pixel gas sensor SGP enables measurement of TVOC levels and thus helps to increase the efficiency of ventilation and air purification, and increases awareness of VOC sources and indoor air pollution. The SGP features a TVOC and CO2 equivalent signal via an I2C interface, a small DFN package (2.45 x 2.45 x 0.9mm3), and a dust and water protection membrane. These characteristics make the SGP easy to integrate into a large variety of applications such as air purifiers or smart home devices.
On the other hand, Bosch Sensortec family of environmental sensors includes barometric pressure sensors, as well as integrated environmental sensor. Integrated environmental sensors combine barometric pressure, relative humidity, and ambient temperature sensing functions. In order to expand their existing family of environmental sensors, Bosch BME680 integrates for the first time individual high linearity and high accuracy sensors not only for pressure, humidity and temperature but also for VOC gas measurement.
The is a digital 4-in-1 ( gas, humidity, pressure and temperature) sensor module is housed in an extremely compact metal-lid LGA package with a footprint of only 3.0 × 3.0 mm² with a maximum height of 1.00 mm (0.93 ± 0.07 mm). Its small dimensions and its low power consumption enable the integration in battery-powered or frequency-coupled devices, such as handsets or wearables.
Carbon Dioxide (CO2)
Carbon dioxide is a natural component of air. The amount of CO2 in a given air sample is Commonly expressed as parts per million (ppm).
The outdoor air in most locations contains down to about 380 ppm (parts per million) carbon dioxide. Higher outdoor CO2 concentrations can be found near vehicle traffic areas, industry and sources of combustion. Where indoor concentrations are elevated, in comparison to the outside air, the source is usually due to overcrowding. People exhale carbon dioxide—the average adult’s breath contains about 35,000 to 50,000 ppm of CO2 (100 times higher than outdoor air). Without adequate ventilation to dilute and remove the CO2 being continuously generated by the occupants, CO2 can accumulate, which can lead to headaches, lead to loss of cognitive function, and cause asphyxiation.
Most heating, ventilation and air conditioning systems (HVAC) re-circulate a significant portion of the indoor air to maintain comfort and reduce energy costs associated with heating or cooling outside air. When occupants and building operators sense air coming out of an air supply duct, it’s virtually impossible to judge how much of this air is simply re-circulated air and how much is outside air. Current technology allows easy and relatively inexpensive measurement of carbon dioxide ( CO2 ) as an indicator to help ensure ventilation systems (for high density occupancy zones) are delivering the recommended minimum quantities of outside air to the building’s occupants.
Active ventilation is needed to maintain a comfortable and healthy indoor environment, and to improve the well-being and productivity of the inhabitants. Rutronik offers a solution with Sensirion’s and its accurate and stable CO2, temperature and humidity monitoring. This enables customers to develop new solutions that increase energy efficiency and simultaneously support well-being.
Thanks to the dual-channel principle for the measurement of carbon dioxide concentration, the SCD30 sensor compensates for long-term drifts automatically by design. The very small module height allows easy integration into different applications such as demand-controlled ventilation, HVAC equipment, Air conditioners, Air purifiers, Smart home as well as IoT devices.
As part of our broad Sensor portfolio, Sensirion and Bosch provide a complete data on key environmental parameters such as humidity, temperature and VOC gas measurement. Sensirion´s particulate matter (PM2.5), and CO2 completes further our portfolio by opening up new possibilities to create devices that improve our quality of life and increase energy efficiency in air quality applications.
