Category Archives: CO2

BETTER AIR MEANS BETTER PERFORMANCE – Customer Application Case Study. Belimo


We all know the situation; a meeting where your performance drops sharply. In most cases, this is a direct result of the poor quality of the air in the room.

Original Article from

Uncomfortable situations like this need not arise. CO2 displays by Rotronic make it easy to measure air quality, and the results can be used to initiate the appropriate measures. In an enclosed room, some 25 to 35 cubic metres of fresh air per person per hour are needed, given normal activities. This ensures that the carbon dioxide (CO2 ) content remains below 1,000ppm (ppm = parts per million [value of the proportion of carbon dioxide in the air]), and that the volatile substances exuded by humans are extracted to a sufficient degree. By comparison, the CO2 concentration in outdoor air is around 400ppm. The CO2 concentration is a good indication of the quality of the air in a room. The consumption of air rises particularly quickly in meetings, with many people in small rooms. By the time we notice this productivity has already declined. A CO2 sensor is the answer here. Alfred Freitag, Sales Manager for Switzerland at Belimo Automation AG, points out that a meeting should be interrupted when the CO2 concentration reaches 1,200 ppm and the room should be ventilated. The CO2 content in the air then drops rapidly, and productivity increases again.

The right to good air

Every person has a right to healthy indoor air (WHO). In the case of workplaces, the labour laws require that air quality and room climate must not represent a health hazard for employees. In the private sector, there are no regulations, and the owner is responsible. However, the Swiss Cantonal building regulations require energy-efficient buildings. This requirement can be met only when the buildings are airtight. Consequently, free exchange of air is no longer possible. Martin Bänninger, director of the SVLW (Swiss association for air and water hygiene), has this to say: “Most Cantonal building laws, or municipal building regulations, state the principle that a building must not endanger life or health of the building‘s users.” Furthermore, buildings must be erected according to the rules of the building trade, as laid down in the standards, directives and bulletins (SIA, SWKI).

Careful planning of ventilation systems

Today, however, an adequate supply of fresh air cannot be taken for granted. In densely built-up housing areas, normal ventilation through the windows is of limited value. A good room climate cannot be achieved by regular airing in all buildings – climate-regulating systems are a necessity. Building owners and ventilation planners should therefore conform to the specifications in the SWKI Directives – “Hygiene requirements for room air systems and devices” – starting with the positioning of the air intake, through the controls of the ventilation and heating systems to the instruction of the occupiers. In the case of more complex systems, the responsibilities for surveillance and maintenance must also be clearly defined. “The maintenance of the system should have high priority,” Alfred Freitag emphasises. To keep the ventilation systems functioning reliably, and to keep them hygienic, they must be carefully planned, constructed, regulated and maintained. Rotronic CO2 displays can then be used to monitor these ventilation systems, the data being read out via USB stick when necessary. Asked why Belimo decided in favour of the Rotronic CO2 displays, Alfred Freitag says, “We were very competently advised by Rotronic CEO Michael Taraba. He took care of our needs personally. In addition, the visualisation of the measured data was very important to us. They are simple and clear to read on the Rotronic display. Hitherto, Rotronic has proved a very reliable partner.” In addition, the Rotronic display permits global assessment of the air. It measures CO2 , humidity and temperature. This allows suitable countermeasures to be taken.

Product Snap Shot – CO2 Displayco2-panel_front133

The wall-mounted or bench-top CO2 display is
an inexpensive display unit that simultaneously measures and records CO2 , humidity and temperature. Equipped with the field-tested and proven ROTRONIC HYGROMER® IN-1 humidity sensor, this instrument offers unbeatable value for money. The instrument can be configured directly with buttons, and stored data can be exported to a USB stick for analysis with the free Rotronic software package SW21.

Mapping Services from Rotronic

Ensuring product quality while in transit or storage is an important part of the GxP guidelines. To comply with the legal regulations all storage and transport facilities must be thermally mapped to ensure products are not being affected by extreme temperatures. Rotronic specialises in these services and offers efficient and tailored solutions.

What are the typical temperature mapping Applications?Wherever temperature-sensitive products are produced, stored or transported, mapping is indispensable to show that product quality requirements and standards are being met. mapping-process

What do we offer?
Rotronic will discuss with you the details of your mapping project, including timescales, budgets, regulatory requirements to ensure we deliver the optimal schedule. We offer a transparent service structure ensuring you get only what you need. This segmented service has been very well received by our customers. We can even present and detail all GxP compliant data directly to your auditors taking all the stress out of your audits.


How will you benefit?
• Modular service structure
– Transport qualifications / validation
– Temperature mapping study
– Stress tests – and findings
– GDP training for dealing with drugs
– Servicing and maintenance of the entire system
• Competent supervision by experienced and qualified engineers
• Best accuracy test equipment and competence as renowned logger manufacturer

What do you get?
• Accurate climate data of measured environments (Warehouses, Room, Lorries, etc …)
• FDA and GxP-compliant mapping reports (Basis for audits)
• Detailed data analysis (Provides information on critical areas)
• Ongoing monitoring and alarming on request

What other GxP-Services does Rotronic offer?
• Validation
• Calibration
• Engineering
• Personnel training

What parameters to be monitored?
• Temperature
• Relative Humidity
• CO2
• Differential pressure and Pressure

Rotronic offers device ranges for all applications

Wish to discuss a mapping project? Please contact us today!
Dr Jeremy Wingate

Energy Efficiency and Indoor Air Quality

Some of the key factors for improving energy efficiency in relation to indoor applications are the control of Relative Humidity (RH) and temperature. The question is, how to control RH to acceptable levels in an energy efficient manner. Energy efficient humidity control has a very strong bearing on thermal comfort, Indoor Air Quality (IAQ) and eventually on the health and performance of occupants in air-conditioned buildings.


Passivhaus buildings are built to a voluntary standard to improve energy efficiency and reduce ecological footprint.

IAQ control seeks to reduce Volatile Organic Compounds (VOCs), and other air impurities such as microbial contaminants. As such it is important to control relative humidity which can be a key factor leading to mould growth and the presence of bacteria and viruses, dust mites and other such organisms.

Buildings rely on a properly designed ventilation system to provide an adequate supply of cleaner air from outdoors or filtered and recirculated air


Buildings may rely on dehumidifiers like the one above to reduce RH levels to a comfortable range

Air-conditioning systems typically employ a high level of air recirculation to save energy during cooling and dehumidification. Typically recirculation rates are around 80-90%, but can sometimes be even higher. The challenge is not so much in dehumidification, but in doing so without having to overcool. As such, ventilation is integrated for general comfort and economical saving.

Rooms are often designed with specific conditions in mind including temperature, humidity, brightness, noise, and air flow. Careful engineering and implementation of building automation and control is the only way to ensure energy efficiency and building operation conditions are met during occupancy, at the lowest possible costs.

IAQ Facts:

Energy Efficiency (EE) refers to either the reduction of energy inputs for a given service or the enhancement of a service for a given amount of energy inputs.

Relative humidity is highly temperature dependent, so if the temperature is stable, it is much easier to achieve a stable RH.

Air in our atmosphere is a mixture of gases with very large distances between molecules. Therefore, air can accommodate a large quantity of water vapor. The warmer the air, the more water vapor can be accommodated.

Why the need to measure, temperature and relative humidity?

Precise temperature control of air which is supplied to a room results in maximum comfort for the occupants. The temperature should be held constantly at a particular set point to achieve this comfort.

Readings from temperature transmitters installed in the air supply duct are compared to readings inside a particular room. It is easiest to achieve a constant room temperature if there is little difference between the two values. Air temperature control in supply ducts can be employed in rooms in which the air handling unit is used mainly for the renewal of air.


Rotronic manufactures temperature and humidity transmitters such as the one above which are suitable for use in spaces where appearance is a factor.

It is with good RH control that we can process the air for air conditioned rooms independent of the state of outside air and the processes taking place in the room. This way the RH remains constant or within the preset limits and thus energy consumption for humidification and dehumidification is minimized.

Air conditioning is supposed to maintain room temperature and RH as precisely as possible through the use of systems which monitor and control temperature and humidity in the room (or in the air supply ducts to the room). Systems must be dynamic to manage the changing room air quality depending on the occupants and usage.

With precise measurement and control of temperature and humidity, energy consumption for humidification & dehumidification as well as heating and cooling can be reduced leading to energy efficient building operation with lower energy costs and healthier occupants.

Phil Robinson
Rotronic UK

CO2 in Garages and Tunnels.

Modern vehicle engines emit many harmful substances, including carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), hydrocarbons and some 20 other gases. It is known that all engines produce CO, particularly at cold start. To protect ourselves from this toxic gas, vehicles are installed with catalytic converters. This means that a warm running modern engine with converter generates 140 times more CO2 than CO.

catalytic_converterCatalytic converters convert a lot of the CO produced by an engine into CO2.

Facts and Figures

The longest tunnel in Switzerland will be the Gotthard Base Tunnel (under construction) that will be 57km long. The tunnel is a railway tunnel.

The longest car tunnel in the world is located in Norway, the Laerdal tunnel, 24km.

The LEP tunnel in Cern, Switzerland/France is a 26km circular ring.

Why the need to measure CO2?

Old vehicles (pre-catalyst) generate a lot of carbon monoxide pollution, to solve this, modern vehicles were installed with catalytic converters. Catalytic converters are not very efficient during cold start up but once warm they can convert CO to CO2 very effectively. This means modern engines emit much higher quantities of CO2 than CO. It is well-known that CO is extremely toxic but CO2 in high levels can also be hazardous to health. To ensure healthy air quality it is important to provide excellent ventilation in garages and tunnels, however running a ventilation system constantly is inefficient especially when few cars are running at a time.

SAM_3014Levels of CO2 in large indoor car parks can become extremely dangerous if not properly controlled.

In garages and tunnels vehicles can be operating in both warm and cold conditions, therefore it is important to measure both CO and CO2 to ensure a safe environment. Today there are laws around the measuring of CO – the maximum allowed value is 35 ppm. There are however, currently no rules on measuring CO2 but this is equally as important.

How does it work?

A meter can both control and alarm locally, as well as being part of a larger complete system. This application is similar, for example, to the ventilation requirements in a classroom.

The ventilation need depends on the number of cars running in a garage or tunnel instead of the number of students in a classroom. The sensors usually used to measure CO2 and CO in public garages and tunnels are capable of covering an area of around 250 m2.

Reduced Costs

A study was made in a garage containing 77 parking places and covering an area of 1,445 m2. The study showed that using sensors to control the ventilation reduced the fan operating time by 90% compared to constant running. The electricity cost was about €0.09 per kW/h (including energy tax and VAT) and the fan used 1.5 kW/h in operation. This meant that the demand-control solution produced an energy saving, per month, of 970 kW/h, and a resulting reduction in running-costs of ca 85.32 €/month. If all residential garages were equipped this way the sum of energy saved would make for a considerable benefit to society and the environment. A larger garage would have saved even more money thanks to the controlled ventilation system.

c700x420Ventilation plays a vital role in keeping in door parking spaces safe, especially when busy.

Another benefit is fewer people suffering from CO or CO2 poisoning being admitted to hospitals. As well as being good for the health of the general public, This helps reduce the costs of health care to the government.

Phil Robinson                                                                                                           Rotronic UK


Incubators in General

Right from the point when human beings started to cultivate land they were strongly dependent on external influences. The levels of rain, sunshine, CO2 as well as soil quality defined the success rate of plant growth. Like plants, every organism has its specific requirements for optimal reproduction. Incubators are used to artificially generate an organism’s ideal environment. Even the ancient Egyptians learned that the rate of successfully hatched chickens increased drastically when they put the fertilized eggs in a big oven built out of bricks that was permanently heated slightly. Although in that case, only the temperature was “controlled”. The Egyptian egg oven can be considered the earliest incubator. But hatching eggs is only one application where incubators are used. Other important usages are the growth of bacteria, viruses and spores for research, diagnostic analysis or even drug production

“Egyptian Egg-oven.” Published in “The Penny Magazine”, August 10, 1833.

Facts & Figures:

India’s poultry industry has to expand from 2010 until 2013 annually by 12-15% to fulfil local demand only.

The average chicken weight doubled since 1934 and is now around 2.5kg.

The US chicken consumption grew from 22kg per capital in 1980 to 39kg in 2011.

Why the Need to Measure

Various elements need to be measured in order to provide an ideal environment for organisms to reproduce.


For incubators that are used for chicken hatching, temperatures from 37.2°C to 37.7°C are ideal for incubators with fan circulation. If the incubator has no fan 38.8°C is recommended for best results. For bacteria generally 35°C is best.


Incubator and shaker for growing cell cultures in liquid media


For growing bacteria, high levels of humidity are required, the majority need 90%rh or higher. The widely known food poisoning bacteria “Salmonella“ only grows at 95%rh and above. For most moulds 80%rh is already sufficient to promote growth.

Humidity is also extremely important when hatching chicken eggs. Within the egg is a tiny air bubble that gets bigger during the growth of the embryo, but if the humidity level is to low the fluids that are essential to the final growth of the embryos are lost too quickly. A humidity level between 50-60%rh is considered ideal.


Inside an incubator which is able to control humidity levels.

Carbon dioxide

In nature the CO2 level in a chickens nest is around 0.4% or 4000ppm compared to the surrounding air that has only 400ppm. Keeping the CO2 level in an incubator between 4000ppm to 6000ppm is necessary for a normal development. Especially in the late development of the eggs, the embryonic production of CO2 increases as incubation proceeds and therefore should be removed from the environment to keep the CO2 at a safe level.

Also in the research of cross-breeding or genetically modifying plants, a controlled CO2 environment is key to speed up the development process.

Philip Robinson                                                                                                       Rotronic UK

Measuring CO2 in a Greenhouse

CO2 in Greenhouses in General

CO2 is one of the key ingredients of photosynthesis, meaning it is essential for plants to grow. Monitoring CO2 in a greenhouse allows optimisation of plant growth conditions, resulting in more efficient plant growth and higher crop yield. Different plants need different levels of CO2 in the air to maximise development.



Facts & Figures

One of the largest greenhouses in the world is in Almeria, Spain where greenhouses cover almost 50000 acres (200km2)

In the Netherlands, greenhouses occupy 0.25% of the total land area.

The Netherlands has around 9000 greenhouse enterprises that operate over 10000 hectares of greenhouses and employ some 150000 workers: 80% of the manufactured produce is exported.

Why The Need to Measure CO2

It is essential to monitor CO2 levels at all times because different plants have different needs regarding CO2. Before photosynthesis, CO2 is collected by the enzyme RuBisCO. However, RuBisCO is just as happy to collect O2 as it is CO2. In C3 plants, RuBisCO collects CO2 from the air as soon as it comes through the stomata on the leaf. This means that if levels of CO2 in the air are low compared to levels of O2, the RuBisCO will just collect more O2 and the plant growth will be less efficient. In a C4 plant, there is an extra step during which CO2 is ‘filtered’ from the air and passed on to the RuBisCO. During this extra step, CO2 can be stored, meaning the stomata do not need to be open all of the time, helping to prevent water loss. In the C3 plant, the stomata need to be open more as there is not such storage of CO2. A third kind of plant, a CAM plant, can only collect CO2 at night, as its stomata are closed during the day.

Tomato_leaf_stomate_1-colorStomata on a tomato leaf

It is important to have close control of the ventilation of a greenhouse to utilise CO2 to maximum effect without risk
of damaging plants. Generally, the best practice is to provide increased CO2 to young plants and parent plants regularly, and to all other plants for a short period during spring. If the plant is sensitive it is extremely important to have pure CO2, to prevent damage. Up to 1 000 ppm CO2 is estimated as a good level.

If the levels of CO2 are too high in the greenhouse, plants can be damaged. If CO2 levels rise too high, plants will close their stomata to protect themselves, resulting in less transpiration, and therefore less nutrition is drawn through the plant, slowing down growth. CO2 levels vary considerably over a 24 hour period. This is because during the night, plants can stop photosynthesis (in the absence of light) and begin respiring. this means plants will switch from using CO2 to producing CO2.

plantsWhen there is plenty of light, a plant will photosynthesize, but when light levels are too low plants will begin to respire instead

What is the Result?

If all plants of a crop are grown in the same conditions (including CO2 levels), the chance that all plants will be ready for harvest at the same time is increased. The annual consumption of CO2 in a greenhouse is generally about 5-10 kg/m2, only in exceptional cases does would it be higher. The effect, of using CO2, on profit varies considderably. For example, tomatoes and cucumbers can give 8-10% higher return when growin in optimal CO2 levels. Plants grown in a CO2 enriched environment generally produce greater biomass than other plants, particularly in the roots, allowing faster growth and resulting in stronger plants with an increased reproductive rate.

Philip Robinson                                                                                                       Rotronic UK

CO2 and Indoor Air Quality (IAQ)

Indoor Air Quality in General

The quality of the air in a room can greatly affect the health, productivity, and well being of any occupants. Previously the temperature and humidity of indoor air were considered as the most important parameters contributing to air quality, but there are several other factors which must be taken into account.

Indoor Air Quality (IAQ) problems are very often caused by gases or particles released into the air by pollution sources. This can be avoided by carefully selecting the materials which are to be used inside dwellings, offices, classrooms, gymnasiums, hotels, shopping malls, hospitals and in all en-closed spaces which are inhabited. But there is another source of air pollution, which cannot be avoided. this other source is people themselves. Every time a person exhales, CO2 is released. Inadequate ventilation may increase CO2 concentration to an unhealthy or even life-threatening level.


CO2: made up of 2 oxygen atoms, double bonded to a single carbon atom.

The most important control parameters for a good Indoor Air Quality are temperature, relative humidity and CO2 concentration. If these values are used with an intelligent air conditioning system, an energy efficient air supply can be used to produce a high quality atmosphere.

Facts & figures:

CO2 is a naturally occurring molecule consisting of two oxygen atoms and a single carbon atom.

At standard temperature and pressure CO2 is a gas, invisible and without any smell or taste.

CO2 is 50% heavier than air and has no liquid state under atmospheric pressure.

In the earth’s atmosphere CO2 has a concentration of 390 ppm by volume.

The worldwide industry produces approximately 36 billion tons of CO2 per year.

Industrial activities are responsible for an increase of atmospheric CO2 concentration and thus for an increase of global warming (greenhouse effect).

Influence of CO2 on Humans

Only a small amount of the atmosphere is made up of CO2, the prevailing components are nitrogen and oxygen. The natural outdoor atmosphere CO2 level is approx. 390 ppm. Increasing this concentration causes several symptoms of poisoning, ranging from drowsiness at around 1´000ppm to unconsciousness and even death at above 10´000 ppm. Even if a  rise in CO2 concentration has not yet severely influenced the health of people, it may reduce their productivity, efficiency and well-being.



Some of the possible health effects

How to Measure CO2

The most common measuring method for CO2 concentration nowadays is based on a spectroscopic principle. Sending infrared light (IR) with a wave length of 4.23 μm through a gas sample. CO2 molecules in the sample absorb the light at this wavelength. an IR sensor is then used to detect any changes in the energy levels of the light after passing through the sample. The more C)2 in the sample, the more of the light that will be absorbed, and the weaker the IR signal will be when it reaches the sensor.


Example of an IR CO2 sensor

The sensitivity of a CO2 sensor increases with the length of the light path through the sample gas. Thus the sensor used in Rotronic CO2 measuring devices makes use of multiple reflections of the IR beam on the walls of the probe chamber. this means the small CO2 sensor (2.5 cm x 5 cm) has a measuring path length of 12.5 cm and is accordingly sensitive. This type of sensor is called a NDIR (Non Dispersive Infra Red) sensor. This means that a broadband IR light source is used and the measured wavelength is filtered out at the end of the beam in front of the IR detector.

Why the Need to Measure CO2

New energy efficient demands lead to more airtight buildings and ventilation being completely turned off at night. Intelligent HVAC systems must be able to adapt themselves to situations with changing occupants of rooms. One answer is Demand Controlled Ventilation (DCV) with built-in CO2 sensors. By using DCV, huge amounts of energy can be saved without any drawback for the occupants. According to a study of the UN Climate Panel 40-50% of world energy is used in buildings. Only the adoption of the EU Directive on Energy Efficient Buildings would result in saving 30-45 MT of CO2/year. As HVAC (Heating, Ventilation and Air Conditioning) is responsible 40-65% of energy usage in commercial and public buildings, a balance between comfort and energy saving must be found.


A large HVAC system

One example demonstrates the evidence of CO2 controlled room ventilation. The exhaled air of a human contains up to 40´000 ppm CO2. In one hour a person breathes out 15 litres of CO2. Thus in a classroom with a volume of 200 m³ occupied by 25 pupils the CO2 concentration increases in one hour by 1´875 ppm!

Especially in wine cellars, breweries, the beverage industry and other industries in which CO2 may be produced or processed the constant measuring of CO2 concentration is absolutely vital to prevent a deadly threat to the employees. This is not only a rational procedure but is also enforced by official regulations in nearly every developed country.

Philip Robinson                                                                                                       Rotronic UK