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There is a considerable body of evidence to show that levels of CO2, TVOC’s (total volatile organic compounds) and extremes of temperature have a damaging effect on cognitive performance and that improving ventilation lowers this significantly.

Optimal Learning Environments

There is a considerable body of evidence to show that levels of CO2, TVOC’s (total volatile organic compounds) and extremes of temperature have a damaging effect on cognitive performance and that improving ventilation lowers this significantly.

A study at Harvard University 1 conducted a blind trial to measure the difference in cognitive performance between buildings with poor ventilation, and hence high levels of VOC’s and CO2, and those which had good ventilation, thus lower levels of these contaminants. On average cognitive scores were between 61% and 101% higher in the well-ventilated buildings.

The graph below shows the effect of poor CO2 levels in buildings 2.

When parents send their children to school they would expect the classroom environment to be controlled to ensure good cognitive performance. Frequently though, that is not the case.

In a study by the Royal Aberdeen Children’s Hospital 3, concentrations of CO2 were measured over 3-5 days in 60 naturally ventilated classrooms of primary school children in Scotland. Concentrations of CO2 were related to the class average annual attendance and proportions attaining a national standard for reading, writing, and numeracy, adjusted for socioeconomic status and class size.

They concluded that inadequate classroom ventilation, as evidenced by CO2 concentration exceeding 1000 ppm, is not uncommon and may be associated with reduced school attendance. A relationship between inadequate classroom ventilation and adverse health outcomes in children may be present.

A teacher at Reigate Grammar School decided to measure CO2 levels in his classroom during a double lesson 4. After one-and-a-half hours it had reached 2,300ppm, compared to an outdoor normal of 400ppm.

Temperature also affects comfort and learning. The Illinois Department of Public Health 5 has determined that the optimum classroom temperature range for learning is 18ºC – 24ºC in winter and 23ºC – 26ºC in summer.

Therefore, measuring classrooms for temperature and CO2 can inform us if students are learning in optimal environments.

At SSE we have taken sensor data (temperature and air quality CO2) and created analytic models to identify how environments are being controlled and if promoting a healthy cognitive performance for students.

We collected sensor data from the individual classrooms, and we only used the data from when the classroom was occupied (i.e. during school term time) and excluded everything else (weekends holidays, etc.) All of the sensor measurements were evaluated to see if they were in the good or bad cognitive zone. In the example below a full years’ worth of sample data was used and each graph represents a single classroom. This was used to identify how frequent students were learning in sub-optimal zones that would impact on concentration levels. An optimal environment is shown in blue and a sub-optimal in red.

As can be seen from the image above this example is stark, a number of the classrooms have consistently been outside of the optimal environments and as a consequence are inhibiting student attainment and educational achievement.

At SSE we can use these analytic models to provide actionable insights that will help identify poor performing classroom environments and provide an opportunity for our analysts and engineers to improve the classroom environment, by using the building controls to ensure adequate ventilation.


  • Ensure learning areas are promoting good cognitive performance.
  • Identify where control drift or deviations are impacting on the learning environment.
  • Reduction in communicable infection, absenteeism, and asthmatic symptoms.
  • Higher levels of oxygen.
  • Reduction in the quantity of contaminants.
  • Ability to change heating, ventilation and air conditioning through Remote Services.

This work was carried out by Alex Park and his team at our Energy Management Centre in Glasgow

If you would like to improve the air quality of your school, or any other building, call us on 0345 072 9529, or email us at info@sseenergyoptimisation.co.uk


1 “Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments”, Allen J.G., MacNaughton P., Usha Satish U., Santanam S., Vallarino J., Spengler J.D., Environmental Health Perspectives, v 124, No 6, June 2016.  doi.org/10.1289/ehp.1510037.

2 “Carbon dioxide detection and indoor air quality control”, Bonino S., Occupational Health & Safety Magazine, April 2016

3 “Classroom carbon dioxide concentration, school attendance, and educational attainment”, Gaihre S., Semple S., Miller J., Fielding S., Turner S., School Health, 2014, 84(9), 569-74, doi: 10.1111/josh.12183

4 “School hopes fresh air will help clear exam minds”, Staufenberg S., Schoolsweek website, 2019

5 “Healthy Schools- Healthy Learning” Department website.

SSE Enterprise

Energy Solutions

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