The Impact of CO2 on Children’s Learning

This webinar took place on Monday 17 march, 09:30 – 10:15


Carbon dioxide, CO2, is a molecule formed from one carbon atom and two oxygen atoms. It is a greenhouse gas and so a contributor to global warming. As CO2 concentrations rise in the atmosphere, heat energy that would normally escape is being trapped. Current levels of CO2 in the UK are approximately 420 parts per million (ppm). Managing CO2 can directly influence the levels excreted. The Covid-19 pandemic lockdowns reduced 17% of global emissions in April 2020 directly linked to reduced vehicles operating; this represents 10 to 20% of CO2 emissions in the UK. Although vehicles contribute to global emissions, addressing indoor air quality (IAQ) is another factor of paramount importance for lowering CO2 emissions. Research indicates that indoor CO2 can have temporary adverse effects on brain function.

sources of CO2: Fossil fuels, Industry, Vehicles. Uses: Photosynthesis, Refrigerants, fuels, future technologies

CO2 sources and uses



In 1904, Doctor Christian Bohr coined the term, the ‘Bohr effect’ which refers to how red blood cells adapt to biochemical changes in the environment. It found that haemoglobin’s ability to combine with oxygen was inversely impacted by blood acidity and blood CO2 concentrations, impacting brain function. Harvard University conducted research which measured cognitive performance in adults across three CO2 conditions (Green+ – 500ppm; Green – 945ppm; Conventional – 1400ppm). Cognitive scores were 61% higher in the Green condition and 101% higher in the Green+ condition compared with the Conventional. Another study looked at children over a 4-week period measuring variables including processing speed and concentration. It suggested that on top of controlling acoustics and lighting that IAQ could additionally increase attainment by 12%.

Ventilation Systems

The BB101 guidelines on ventilation, thermal comfort and IAQ were updated in 2018. This document offers a range of ventilation systems and states that daily CO2 levels in classrooms must remain below 1000ppm, with the option to exceed by 500ppm for no longer than 20 consecutive minutes per day.

Forms of ventilation include natural, hybrid and mechanical. Natural ventilation is commonly used as it supplies air to indoor spaces from outdoor spaces. However, this offers limited control as it relies on natural forces such as wind speed and temperature, at times resulting in poor thermal comfort. Hybrid models merge natural and mechanical systems. Hybrid uses fans to extract warm air from a room and mixes it with cold air from outdoors generating optimal indoor temperatures. Mechanical ventilation uses excessive pre-heating in colder seasons, mixing room air with fresh air. However, this often recirculates pollutants in the room which should have been removed. Smart mechanical ventilation units, on the other hand, are a form of decentralised mechanical ventilation with heat recovery. These provide controlled air flow producing better IAQ, regardless of external conditions. Filters within these units reduce pollutants enhancing IAQ as well as limiting heat loss and energy used.

Lighting, acoustics and other factors can influence cognitive abilities and well-being. However, sometimes we neglect an invisible variable: the air. Covid-19 has created an impetus for improving ventilation and IAQ, and sustainable ventilation systems with heat recovery can benefit both the user and the environment.


Holly Passmore - Thought Leadership Consultant Step Connect2

Written by Holly Passmore, Thought Leadership Consultant, Step Connect2

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