Friday, 28 April 2017

Health warning

The impact of indoor air quality on the comfort and well-being of students is gaining increased attention. Dr Hywel Davies, CIBSE Technical Director, summarises some recent research on the subject and describes the latest guidance on new schools design

The need to maintain air quality in schools is a hot topic - literally. The Government is scheduled to publish a revised version of Building Bulletin 101: Guidelines on ventilation, thermal comfort and air quality in schools. The document provides guidance on the design and construction of school buildings in order to provide good indoor air quality and thermal conditions to create effective conditions for teaching and learning. 

A draft of the proposed amendments has already been published. They call for the designers of schools in areas of poor air quality or in low emission zones to give careful thought to keep internal pollution within acceptable levels. One way of achieving this is to design a building to be airtight and then use an appropriate air infiltration system to help remove the harmful particulates, such as from diesel vehicles, from the air supply. For filtration to be effective, without consuming excessive amounts of energy, the filters can be incorporated into a mechanical ventilation system with heat recovery, although it is also important that they are readily accessible for cleaning and changing.

The Government is revising the guidance on school air quality to reflect
the increasing evidence of its importance
The 2017 publication will supersede the 2006 edition of BB101: Ventilation of School Buildings. The addition of the term “air quality” to the title reflects the increased importance to government and other organisations are now giving to maintaining good indoor air quality in schools.

One reason for the increased focus on air quality was the publication of the Royal College of Physicians’ report Every Breath we take: the life long impact of exposure to air pollution. This highlights the dangerous impact air pollution and poor indoor air quality is having on our nation’s health and in particular how exposure to air pollution may affect mental and physical development in children. The report explains that children living in highly polluted areas are four times more likely to have reduced lung function in adulthood, but improving air quality has been shown to halt and reverse the effect.

Improving indoor air quality in schools was a topic at the CIBSE Building Performance Conference. Speaking at the conference Prof. Dejan Mumovic, Deputy Director of the Institute for Environmental Design and Engineering at University College London, made reference to two recent research papers – one on the impact of carbon dioxide (and temperature) on student’s cognitive performance and the other on the economic benefit of the impact of reducing indoor exposure to nitrogen dioxide in children attending primary schools.

Children living in highly polluted areas are 4x more likely
to have reduced lung function as adults
Mumovic referenced a study undertaken in Saudi Arabia on classrooms with all female students aged 18-21. The research set out to understand the impact of indoor ambient temperature and carbon dioxide (CO2) concentration as an indicator of the effect of ventilation rates on student’s cognitive performance in educational buildings.

The study found that temperatures in Saudi classrooms are typically 20°C, with a high ventilation rate of 15 litres per second per person. These conditions were taken as the baseline for the study. Cognitive tests were then undertaken at classroom temperatures of 20°C, 23°C and 25° and with CO2 concentrations of 600 parts per million (ppm), 1000ppm and 1800ppm. 



When classroom conditions were at their most extreme, with a CO2 concentration of 1800ppm and temperature of 25°C, students took 72% longer to complete the cognitive tests and made 32% more errors. This demonstrates the importance of designing classrooms that can be kept at optimum temperatures for learning throughout the school year. 

Mumovic also referenced a study by the London School of Hygiene and Tropical Medicine.  This used  environmental and health data collected in primary schools to assess the potential economic benefit of reducing indoor exposure to nitrogen dioxide (NO2) in children in London. Nitrogen dioxide is a gas produced by road traffic and other fossil fuel combustion.  The study estimates that 82 asthma exacerbations per school could be averted annually by reducing outdoor NO2 concentrations. 

The study estimates that the monetary benefits of reducing children’s indoor NO2 exposure while at school could be as much as £60k per school from a parents’ perspective, using a willingness-to-pay approach.

82 asthma exacerbations per school could be averted annually by reducing
 outdoor NO2 concentrations.
According to Transport for London, there are 2270 schools within 400m of roads in London, so the number of primary schools likely to be affected is significant, as are the economic benefits of reducing NO2 levels, for example through road closures during school hours.

CIBSE has published TM57: Integrated school design to provide guidance on the environmental design of schools. The document is suitable for building services engineers and other members of the design team including: architects, contractors, client bodies and users, who have an influence on the design outcomes. It is available from http://www.cibse.org/Knowledge/knowledge-items/

In producing this Technical Memorandum CIBSE’s aim has been to provide simple and clear guidance to help steer both the design team and school staff towards creating places where teachers and children can become inspired. A checklist of criteria on its own will not constitute successful design -  school designers must also make the effort to visit existing school buildings and to study exemplar cases to fully experience the results of the design process, both good and bad. The design of school buildings is an area where engineering input from experienced building services engineers can prove invaluable, and have a long lasting and significant impact on pupil health and performance. Time spent in design can certainly deliver a long term dividend that makes it a good investment.


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