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CO2 SENSORS FOR HEALTHY INDOOR AIR AND ENERGY-EFFICIENT BUILDING OPERATION
In times of increasing awareness about air quality and energy efficiency, monitoring the indoor carbon dioxide concentration plays a central part. Here we present CO2 sensors from SAUTER that allow demand-based ventilation, thus optimising energy consumption while ensuring healthy air inside the building.
Current relevance
The key indicator of room air quality is the concentration of carbon dioxide (CO2). In recent years, far greater attention has been paid to the importance of measuring CO2. This is due mainly to its effect on indoor air quality and the health of room users. The coronavirus pandemic further underlined the significance of proper ventilation, making CO2 monitoring a critical factor in indoor health and safety protocols. This is because we now know that the spread of viruses depends on their concentration in the air that we inhale and the period of exposure. It has been shown that CO2 concentration is an optimal reference value for aerosol and virus concentration.
The main strategy for lowering CO2 levels in indoor areas is through ventilation using fresh outside air. Mechanical ventilation systems and filtration technologies help reduce CO2 and other harmful air pollutants. These measures are crucial for the health and productivity of people in buildings.
Can health and energy efficiency actually go hand in hand?
Since the pandemic, the focus has shifted toward energy efficiency. The current revision of EU directives on overall energy performance provides an opportunity to take both health and energy into account. The question arises, however, as to whether there are conflicting objectives between maintaining healthy air quality indoors and reducing the energy consumption of buildings. The reason for this is that new and refurbished buildings are now largely airtight in order to minimise heat loss.
Mechanical ventilation systems are a key factor in lowenergy buildings and passive houses for counteracting the downsides of vastly improved building insulation. This is achieved by sophisticated ventilation control systems through high-quality sensors, supplying plenty of fresh air and reducing levels of harmful substances. Demand-controlled ventilation means constantly adapting the amount of outside air supplied to actual requirements. In other words, only the exact air quantity required is supplied and conditioned (heated, cooled, humidified or dehumidified) at any given moment. The aim is to optimise the ventilation system equally in terms of user comfort and energy efficiency.
Measuring the CO2 concentration through sensors is therefore essential. Better air quality increases safety, comfort and efficiency – especially in rooms with differing occupancy levels such as meeting rooms or training rooms. There are various methods for measuring CO2 and a large number of products are available. Different CO2 sensors are used and include semiconductor, electrochemical and infrared sensors.
CO2 sensor requirements
No matter the measuring process, the following requirements apply to all CO2 sensors for providing demand-controlled ventilation:
Accuracy
Exact, reliable readings over long periods with low susceptibility to interference are essential. Frequent sensor calibration to ensure consistent results could be a challenge for widespread application and even deter from choosing a particular product.
Security of investment
High long-term stability always pays off. The lesser the maintenance expense and need for recalibration, the lower the life cycle costs.
Integration capability
Building management systems (BMS) allow the complex relationships and dependencies during operation to be effectively recorded, displayed and analysed. They can then be optimised so as to achieve the best possible energy efficiency while ensuring maximum user comfort at the same time. Integrating CO2 sensors in BMS can be complex, particularly if different communication protocols are used, for example.
The main problems with faulty devices are measurement errors caused by dust, dirt, rapid ageing and temperature and humidity fluctuations. Frequent readjustments make the devices even costlier.
High-quality integrated solutions from SAUTER
The method predominantly used for sensors in building technology is infrared spectroscopy. The measuring system consists of a light source, measuring section, optical filter and receiver. The filter lets through light on a wavelength specifically absorbed by CO2. The signal received therefore changes, depending on the CO2 concentration in the air.
Accurate and stable control calls for high-quality sensors. SAUTER CO2 sensors can be used everywhere and tick all the boxes for a precision measuring system – including long-term temperature stability, lasting reliability and rapid measurement and response times.
CO2 sensors with NDIR dual-beam measurement
NDIR (non-dispersive infrared) technology utilises the property of CO2 molecules to absorb infrared light at a certain wavelength. Dual-beam CO2 sensors use two measurement channels – one with a filter for CO2 measurement, the other with a filter for a reference spectrum. The reference measurement enables automatic compensation for when measuring conditions change and the light source ages. With the measuring accuracy of dual-beam CO2 sensors constantly high, they are ideally suited for all applications and building types.
Room transducers, EGQ 220 and 222
The comprehensive range of room transducers for measuring temperature, humidity, VOCs and CO2 have recently received a new, timeless design.
CO2 sensors with photoacoustic NDIR measurement
The photoacoustic sensor principle works by sending a light signal that is absorbed by the CO2 molecules. This generates molecular vibrations, in other words energy, which in turn produces a pressure wave inside the measuring chamber. This is measured with a microphone. This acoustic wave vibrates proportionally to the CO2 concentration. These sensors are mechanically robust and enable greater miniaturisation.
Smart Sensor viaSens, FMS 116 and 196
The Smart Sensor viaSens is a true all-rounder. It measures VOCs, temperature, humidity, brightness, occupancy and sound level –and now also CO2. It also features an animated LED ring, Bluetooth technology and MQTT.
Clear and tangible benefits
As awareness grows and technology improves, it is likely that buildings and facilities will increasingly employ CO2 monitoring as standard. This will ensure not only a healthy and pleasant environment, but also energyefficient, demand-based building technology.
As an added bonus, monitoring also yields economic advantages. With air quantity reduced by 20% to meet the actual demand, electric drive power drops by almost 50%. This leveraging means that adding CO2 sensors to the ventilation system quickly pays for itself. According to VDMA 24773, fitting sensors in various building types offers potential savings of up to 70%.
Further information on the Smart Sensor viaSens can be found on our website: https://www.sautersmartsensor.com/en
