Why indoor air quality is crucial for learning

By VELUX Commercial
Aarup Municipality is rebuild for a day care center/kindergarten featuring VELUX Modular Skylights
Aarup Municipality day care center/kindergarten featuring VELUX Modular Skylights

Poor indoor air quality can not only seriously inhibit students’ concentration and overall performance, but can also lead to increased absenteeism due to illness. Adequate ventilation is therefore imperative for healthy classroom design to help students flourish.

According to the US Environmental Protection Agency (EPA), almost one in 13 children of school age in the US suffers from asthma, the leading cause of school absenteeism due to chronic illness¹.

It's also thought that the developing bodies of children are more susceptible to harmful environmental exposures than those of adults. Children breathe more air, eat more food and drink more liquid in proportion to their body weight than adults do. This alone makes the air quality in schools a matter of concern.

Alarmingly, studies of human exposure to air pollutants, also carried out by the EPA, indicate that indoor levels of pollutants may be two to five times – and on occasion even up to 100 times – higher than outdoor levels.

eBook: Building better schools: six ways to help our children learn

Inadequate ventilation leads to increased pollution levels, a particular problem in classrooms where children have a lower volume of air per child due to high occupancy density. A significant body of research provides compelling evidence of an association between improved student performance and increased classroom ventilation rates. Typical reported improvements in performance with increased ventilation rates range from a few percent up to as high as 15%.²

In a recent study³, an intervention was made to improve ventilation rates in 16 classrooms. The results of computerised tasks performed by more than 200 pupils showed significantly faster and more accurate responses for choice reaction, colour word vigilance, picture memory and word recognition in the classrooms with higher ventilation rates.

According to the findings of the Clever Classrooms study⁴, requirements for good ventilation in classrooms are:

1. Controlled ventilation

Windows and skylights with large opening sizes, ideally with multiple openings, allow users to ventilate classrooms effectively in different circumstances. Top-opening windows and skylights, located high in the room but with mechanisms which are easy to access and operate, allow the hottest and stalest air to escape more efficiently. Roller blinds should not be fitted to these top-opening windows and skylights if they block the air-flow.

2. Room volume

The larger the classroom, the greater the dilution of levels of carbon dioxide and pollutants and the longer good air quality can be maintained. In an average size classroom with a volume of 181 cubic metres, 30 pupils and no ventilation, the air quality becomes poor in just 30 minutes.

3. Mechanical ventilation

Where natural ventilation is inadequate or problematic, it can be improved with the introduction of mechanical ventilation.

4. CO₂ sensors

Installing CO₂ sensors in classrooms allows teachers to monitor the indoor air quality and adjust the level of ventilation accordingly. CO₂ concentration is often used as an indicator of indoor air quality. Outdoor air contains a CO₂ concentration of approximately 400 ppm. An indoor CO₂ level of 1150 ppm provides adequate air quality, 1400 ppm will ensure good indoor air quality in most situations, and 1600 ppm indicates poor air quality (CEN, 2007)⁵.

There's no doubt that creating a good indoor climate should be a key focus of all school modernisation projects and new school builds. This will provide better overall facilities for students to learn and thrive in and for educators to work effectively. Good ventilation is crucial, as it is the only way to maintain good indoor air quality and pollutants at acceptable levels.


  1. Why Indoor Air Quality is Important to Schools (EPA)
  2. Fraunhofer-Institut für Bauphysik IBP (2015) Impact of the indoor environment on learning in schools in Europe (Study Report)
  3. Bako-Biro et al: Evaluation of indoor environmental quality conditions in elementary schools׳ classrooms in the United Arab Emirates, 2012
  4. Clever Classrooms, Summary report of the HEAD project, University of Salford, Manchester (2015)
  5. CEN (2007) EN 15251: Indoor environmental input parameters for design and assessment of energy performance of buildings.