Preliminary results of studies investigating the the effects of IEQ on the performance of schoolwork by children
Recent experiments have shown that poor indoor environmental quality (IEQ) in office buildings can reduce the performance of office work by adults. It is thus reasonable to suspect that poor IEQ can also negatively affect the performance of schoolwork by children. While it is well documented that IEQ in schools is both inadequate and frequently much worse than in office buildings, there is little direct evidence that classroom performance is being negatively affected. New studies carried out at the International Centre for Indoor Environment and Energy, Technical University of Denmark investigated whether IEQ can affect the performance of schoolwork by children. They were supported partially by American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) through contract 1257-RP “Indoor Environmental Effects on the Performance of Schoolwork by Children” and partially by the Danish Technical Research Council (STVF) as part of the research programme of the International Centre for Indoor Environment and Energy established at the Technical University of Denmark. The preliminary results of the these studies are reported in the following.
Three independent field intervention experiments investigated the effects of increased outdoor air supply rates and reduced air temperatures in classrooms on the performance of schoolwork. They were carried out in an elementary school in Denmark in classrooms with about 100 10- to 12-year-old pupils. The experiment investigating the effect of reduced temperatures was carried out in late summer using two parallel classes of 10-year-old children. The air temperatures were reduced from 23.6oC to 20oC in a 2x2 crossover design balanced for order of presentation, each condition being maintained for a full week. The temperature was reduced using wall-mounted split air conditioning unit. The experiments investigating the effects of increased outdoor air supply rates were carried out in late summer and in winter in four identical classrooms of 10- and 12-year-old children. The outdoor air supply rate was increased from about 5 to 9.5 L/s per person in summer, and from about 4 to 8.5 L/s per person in winter, in each case in a cross-over design balanced for order of presentation. Each experiment was carried out in two parallel classrooms at a time and each condition lasted for a week. The outdoor air supply rate was increased using the existing mechanical ventilation system. In all three experiments the performance of schoolwork was measured using parallel versions of performance tasks representing up to eight different aspects of schoolwork, from reading to mathematics. The tasks were selected so that they could have been a natural part of an ordinary school day. The tasks were administered by the children’s usual teachers. They included: addition of numbers; multiplication of numbers; subtraction of numbers; checking columns of numbers against each other; sentence comprehension; proof-reading of text in which deliberate errors had been inserted; acoustic proof-reading, i.e. listening to a recorded voice and checking a transcript in which deliberate errors had been inserted; and reading a text in which choice points had been inserted to determine whether the children understood the text (reading and comprehension). In addition the teachers carried out check-list observation of the children’s behaviour. Parents and teachers recorded their observations of children’s health and mood in logbooks, and the children themselves marked visual-analogue scales each week to indicate the intensity of various symptoms of ill health. During experiments, the teachers and pupils were allowed to open the windows as usual, and no changes to the lesson plan or normal school activities at school were made, so as to ensure that the teaching environment and daily routines remained as normal as possible. Both teachers and pupils were blind to interventions.
Reduced temperature significantly (P<0.05) increased the rate at which pupils subtracted numbers and performed a reading and comprehension task and the rate at which pupils categorized logical statements as true or false. It tended (P<0.10) to reduce errors when they proof-read what purported to be a transcript, in which discrepancies had been inserted, while listening to a recorded voice reading the original text aloud and to increase the rate at which numbers were compared. In no test (except for acoustic proof reading) was the proportion of errors affected. Increased outdoor air supply rate significantly (P<0.05) improved the performance of the following individual tasks by from 3% to 35%: addition, multiplication, number checking and subtraction in summer, and reading and comprehension, sentence comprehension, subtraction and multiplication in winter. In all the tasks mentioned, there was a statistically significant improvement in the work rate, while the error rate remained constant. For none of the tasks was a statistically significant reduction in performance associated with the increased outdoor air supply rate or the reduced temperature.
Using the performance of individual tasks that were affected by an increased outdoor air supply rate, the average performance of schoolwork was computed and a regression equation against the outdoor air supply rates measured in the classrooms was derived (Fig. 1). The regression indicates that doubling the outdoor air supply rate would improve the average performance of schoolwork by about 15%. It may be seen that there is extremely good quantitative agreement between the results of the two independent experiments, which were performed at different times of year, in different classrooms and with children at two different ages.
Figure 1. Performance of school work as a function of outdoor air supply rate
In conclusion, the present results indicate that improving classroom conditions can considerably improve the performance of school work by children. Since the performance of schoolwork affects learning, they also imply that improving classroom conditions can have lifelong consequences both for pupils and for society.