Fresher week

Pupils’ performance improves as the amount of fresh air supplied to the classroom increases. This is what researchers at the University of Reading have proved after investigating the relationship between children’s health, well- being and performance and indoor air quality.

What makes the findings significant is that they are based on data taken from the pupils’ actual performance. The study was based on surveys at eight primary schools around Reading built in the past 20-40 years. All except one did not have mechanical ventilation and in most there was no temperature control available to staff.

Investigations were carried out in two classrooms at each school for at least three consecutive weeks. The first week was used to monitor classroom conditions without modifying any of the indoor climatic parameters and to familiarise the children with the performance tests. In the second and third weeks a mobile ventilation system was installed in each classroom to control the ventilation rate and maintain the temperature within limits.

The ventilation system consisted of a fan outdoors connected to 200mm-diameter ductwork to supply air into the classrooms through window openings, which were sealed using Perspex plates. The capacity of the supply fan was selected to provide 200l/s, matching the prescribed level of 8l/s per person in a classroom under Building Bulletin 101. Silencers reduced noise transmission through the ductwork. In the classrooms the air was distributed using Softflo air terminal units, which consist of a perforated duct with small nozzles. The supply air temperature was controlled by a duct heater and a mobile air-conditioning unit built into the system.

The system was set to provide outdoor air or to recirculate the classroom air. Staff and pupils were not told which they were receiving. Conditions during the first week’s testing were generally cooler indoors and outdoors compared with the second week.

Physical measurements: CO2 concentration, air temperature, wet bulb temperature, relative humidity (RH), air velocity and light level were continuously monitored and recorded at three-minute intervals. Separate units were placed outdoors and in corridors to measure CO2 concentration, temperature and RH. The concentration of airborne particles and noise levels were also measured.

Subjective evaluations: Pupils completed a simple questionnaire about the classroom environment, thermal sensation, mood, symptoms of sick building syndrome and lifestyle, such as hunger and sleep the night before. The 9- to 10-year-old age group was selected because they spend most of the day in classrooms.

Pupil performance tests: Traditional paper-based tests were carried out for 40 minutes, including simple addition and subtraction and reading comprehension. Also, new software was developed that uses algorithms to study changes in pupils’ cognitive performance under different air-quality conditions. These 20-minute tests were conducted on laptops.

The tests were all given to pupils on the same days and at the same time, before the lunch break when CO2 concentrations had reached the morning maximum.

Results

The project is still in the data collection phase so the results of the physical environment and paper-based performance tests from only one school are presented. Detailed analysis of the performance results, including the computer tests, will be published on completion.

Figure 1 shows a typical CO2 pattern in one of the classrooms during a day when performance tests were completed. The 156m3 room was occupied by 23 children and one teacher. The schedule, including lessons and break times, can be clearly seen from changes in the CO2 concentrations. The uncontrolled condition on figure 1 shows the CO2 level before any intervention. The CO2 concentrations obtained during the week of recirculation ventilation match closely the uncontrolled levels. When the ventilation system was switched on to provide outdoor air, the CO2 concentrations fell dramatically and remained at less than 1000 parts per million throughout the day.

Results for the subjective responses to the classroom environment immediately after the pupil tests are shown in figure 2. Children in classroom A perceived the air to be fresher and the classroom less noisy, and their general feeling about the environment was significantly better with the outdoor air supply than with recirculation. There was a trend approaching significance towards higher alertness, better work mood and tendency for less tiredness and increased attention after paper tests conducted at the higher ventilation rates.

On the reading comprehension task, children in classroom A obtained an average mark of 9.4 with improved (outdoor) ventilation and 8.1 on recirculated air. No significant change was found in the marks of children from classroom B between the two experimental conditions.

Pupils in classroom A tended to work more accurately in addition and subtraction tasks and showed a slight improvement in the overall performance of addition at the higher ventilation rate. Similarly, the pupils in classroom B made significantly fewer errors and achieved better performance during subtraction at the higher ventilation rate. For classroom B the changes in the performance measures of addition were not significant.

Starting to add up

When data for classrooms A and B were pooled under the common hypothesis that the children work better under improved ventilation, significant or close-to-significant improvement was obtained in the overall performance of both addition and subtraction. Separate analysis was carried out for children with higher mathematics skills (25 pupils for both classrooms), ie excluding those who had an error rate higher than 50%. This showed more significant effects, with these pupils increasing the number of error-free units under improved ventilation conditions.

The average temperatures were somewhat higher under the recirculation condition in classroom A and under improved ventilation in classroom B. It would appear that the thermal conditions in classroom B have, to some extent, affected perceptions of air freshness, mostly because of the increased enthalpy of inhaled air at high ventilation. The children in classroom A who perceived a change in air freshness under improved ventilation also reported more positive neurobehavioural symptoms (alertness, attention, tiredness) and work mood.

A significant impact of the ventilation rate on the work performance of pupils was observed in both classrooms. Summarising the effects, the overall performance of all children increased under improved ventilation by 5.1% and 5.8% for addition and subtraction while pupils with higher skills increased by ~7% .

The magnitude of the effect is in the expected range seen in earlier studies and the Reading results strengthen the evidence that improved ventilation has a beneficial effect on learning performance.