Few things make people feel healthier than clean air. Sensor technology is now poised to make the benefi ts of fresher air more available for those working in offi ce and factory environments or commuting in their cars. Homeowners and hotel operators are already familiar with air quality sensors, though they may not think of them in that way. Carbon monoxide (CO) monitors are now required in regions such as the European Union (EU) to warn building occupants of a rise in the level of the poisonous gas, often the result of problems in boilers. Now attention is turning to the use of air quality sensing to improve not just safety but also the quality of life.
People spend much of their time in buildings, such as offi ces and factories, with limited fresh air. For the average person, the EU SENSIndoor project estimates this to be more than 80 per cent of the time. To reduce energy consumption, offi ce and other building owners limit the fresh-air exchange of air conditioning systems. The limit is often benign but it can lead to issues that affect overall health and may be one of the factors in so-called ‘sick building syndrome’.
The source of problems can be substances such as volatile organic compounds (VOCs) that build up over time and are distributed widely through the air conditioning ducts during the working day. Building occupants may complain of problems such as irritation of the eyes, nose and throat, headaches, dizziness and fatigue. The effects can infl ame chronic conditions such as asthma. The nature of VOCs and similar pollutants can lead to individuals becoming sensitised to them after repeated exposure, which exacerbates their conditions. As a result, staff need to take time off to recover. This inevitably leads to losses in productivity.
Continuous ventilation and fresh-air exchange prevents the build up of VOCs and other gases that cause discomfort but increase overall energy consumption. Projects such as SENSIndoor aim to apply sensor technology to solve the problem of energy consumption. Using the measurements taken by sensors integrated into building-management systems, the operation of air conditioning units can be tuned on a real-time basis. If there is no change in temperature that needs to be addressed, pumps and other systems are only activated when the sensors detect a build up of VOCs. Such demand- driven management can balance the needs of occupants with the need to minimise energy consumption and operating cost.
Technology review
Tommy Bodker
Technical Specialist Avnet Abacus
Buildings are not the only targets for VOC sensors. Automotive vehicles represent another area where such sensors can greatly improve the experience of occupants. They also improve safety by ensuring that drivers are not made drowsy by the presence of air contaminants. VOCs are often used in the manufacture of automotive interiors and can escape into the cabin atmosphere over time. Another source of potentially troublesome or even dangerous gases within the cabin lies in the carbon dioxide now used as a refrigerant in vehicle air conditioning systems.
As vehicles move through towns and cities, their occupants become increasingly vulnerable to the fumes produced by neighbouring vehicles and the concentration of pollution around roads. Sensors that pick up increases in CO and other exhaust gases such as nitric oxide can be used to throttle the intake of external air by the air conditioning system temporarily until cleaner sources of air are encountered.
There are many industrial environments and applications where maintaining air quality is critical and workers need to be warned of problems. Divers working on undersea infrastructure are vulnerable to carbon dioxide build-up if scrubbers are not working effectively.
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