What we measure: carbon dioxide in buildings

Anthea Bellavista

November 18, 2021

Ever felt drowsy after some hours in a meeting room? When CO₂ builds up in poorly ventilated spaces, it can cause lower productivity, drowsiness, loss of concentration and even poor decision-making. As people spend approximately 90% of their time indoors1, monitoring CO₂ is fundamental for commercial buildings like schools and offices.


What do indoor CO₂ levels depend on?

Carbon dioxide or CO2 is one of the many air pollutants that can raise costs for businesses.. Most commonly produced by the air we exhale, CO2 levels can build up indoors in poorly ventilated spaces. In small quantities CO2 is harmless, but when its levels rise it can lead to undesirable outcomes.

The levels of CO₂ in the workplace depends on many factors combined2:

  • The number of people in a space. 
  • How long the space has been occupied.
  • The amount of outdoor fresh air entering the area.
  • The size of the space.
  • Whether combustion by-products are contaminating the indoor air (e.g., idling vehicles near air intakes, leaky furnaces, tobacco smoke).
  • The outdoor concentration.

Learn more about how you can use the  Airthings for Business solution to monitor your buildings Facility managers, get in touch   

Why is monitoring CO₂ more relevant than ever before?

Over years, CO2 in the atmosphere  has received lots of media attention due to climate change hazards. Currently, CO2 concentrations outdoors have reached their peak in over 800,000 years3. This is not surprising considering that humans have increased atmospheric CO2 concentration by 47% since the Industrial Revolution4. But if the threats caused by CO2 in the atmosphere are a cause of concern, its effects indoors should also be considered.  Here is why indoor CO₂ monitoring is more relevant than ever.

  • Occupancy rates are increasing:

    In 2016, an estimated 54.5% of the world’s population lived in urban settlements5. By 2030, urban areas are projected to house 60% of people globally and one in every three people will live in cities with at least half a million inhabitants6. Buildings such as offices and schools are becoming more and more crowded as urban areas become increasingly populated, while space for creatingnew buildings is scarce. As a consequence of this, meeting room participants and students can often feeling drowsy after spending many hours indoors.
  • New, more energy-efficient buildings:

    As buildings and homes become more energy-efficient and airtight, indoor air may not be as fresh. Indoor CO2 concentrations are driven by a combination of outdoor CO2, indoor breathing and the ventilation rate of the building. Indeed, many of the ventilation systems we use today recycle air to conserve energy, essentially moving the old air around rather than bringing in new air. This can result in high CO2 concentrations and poor indoor air quality.


How does high levels of CO2 impact commercial buildings and their occupants?

Monitoring air quality is not only important for health reasons, but also for the savings it can provide to businesses. In fact, in the United States alone, the cost savings and productivity gains from improved indoor environments have been estimated at $25 billion to $150 billion per year7. Here are some consequences of high levels of CO₂ indoors.

  • Poor cognitive performance:

    One study from Harvard University showed that cognitive function scores were better in green buildings conditions by +101% than in conventional buildings8. On top of this, many studies have shown that CO2 levels can reduce brain activity9 and impair higher cognitive functions10. Increasing the ventilation rate in schools can raise children’s scores on tests and speed at tasks, as research has shown11. Monitoring CO2 is therefore essential to improve cognitive performance for building occupants in schools and offices.
  • Low productivity and dissatisfaction:

    Poor indoor air quality in buildings can decrease productivity pencil_with_line (1)and cause visitors to express dissatisfaction. 12 However, research has shown that it is possible to increase speed of work up to 60% by reducing CO2 concentration in the workplace13. Monitoring COappears to be essential in order to guarantee the best productivity in commercial buildings like schools, offices and more.
  • Higher absenteeism:

    Sick leave represents around 2.15% of a country’s GDP for European countries14, which is around £77.5 billion a year for the UK (approximately $99.39 billion) for example15. Many studies have investigated how increasing the ventilation rate in schools can reduce absences.16 On top of this, one study found that a higher ventilation rate decreased the number of sick days by 12% per 1 hour increase in air exchange rate.17 Monitoring CO2 can then help commercial buildings reduce the costs associated with sick leave.
  • Trigger for asthma attacks:

    Asthma symptoms have been linked to CO2 . In fact, results of one study show that asthma attacks increase up to 18% as CO2 levels in the classroom increase.18 Reducing asthma triggers can help reduce costs linked to sick leave while at the same time improving the wellbeing of building occupants. Monitoring CO2 is then fundamental for commercial buildings like schools and offices.








Why is monitoring CO2 useful to understand the efficiency of your building's HVAC system?

Making sure your ventilation system is working correctly is fundamental for the indoor air quality in your building. In fact, investigations found that 52% of the air quality problems indoors were related to inadequate ventilation19.

If you are wondering whether your HVAC system is working efficiently, you can check for it by using your levels of CO2. Indeed, the amount of CO2 in a building is usually related to the amount of fresh air that is brought indoors. In general, the higher the concentration of CO2 in the building, the lower the amount of fresh air exchange.

Improving ventilation and managing the use of space more carefully can help to reduce indoor CO2 and its effects. To do so, you need the data to know when to make a change. Monitoring the CO2 levels with Airthings for Business in commercial buildings gives facility managers, tenants and more the ability to implement measures to keep the air healthy and safe. 

How improving office air quality unlocks greater productivity, wellbeing and operational benefits



1  Harvard Annual review of public https://www.annualreviews.org/doi/10.1146/annurev-publhealth-031816-044420

2  https://www.health.state.mn.us/communities/environment/air/toxins/co2.html 

3  https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide 

4  https://climate.nasa.gov/causes/ 

5 https://www.un.org/en/development/desa/population/publications/pdf/urbanization/the_worlds_cities_in_2016_data_booklet.pdf

6 https://www.un.org/en/development/desa/population/publications/pdf/urbanization/the_worlds_cities_in_2016_data_booklet.pdf  United nations

7  Harvard Annual review of public healthhttps://www.annualreviews.org/doi/full/10.1146/annurev-publhealth-031816-044420#_i1

8  https://green.harvard.edu/tools-resources/research-highlight/impact-green-buildings-cognitive-function

 9 https://www.ncbi.nlm.nih.gov/pubmed/20842164

10 https://www.washingtonpost.com/news/energy-environment/wp/2015/10/27/why-your-office-air-could-be-crimping-your-productivity/?noredirect=on&utm_term=.ee38ebbe40ae

11  https://onlinelibrary.wiley.com/doi/abs/10.1111/ina.12403

12 https://www.ncbi.nlm.nih.gov/pubmed/15330777

National Center for Biotechnology Information,U.S. National Library of Medicine

13 https://emcoruk.com/workplace_productivity.pdf

14  https://www.eurofound.europa.eu/de/publications/report/2010/absence-from-work 

15 https://www.ablrecruitment.com/sick-staff-cost-uk-economy-77-5-billion-year/

16 https://onlinelibrary.wiley.com/doi/abs/10.1111/ina.12403

17 https://pubmed.ncbi.nlm.nih.gov/25789698/

18 https://pubmed.ncbi.nlm.nih.gov/17100666/  

19 https://www.osha.gov/dts/osta/otm/otm_iii/otm_iii_2.html  

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