New IAQ standards for schools
The BB101 guide for ventilation in schools is being updated. Roy Jones of Gilberts (Blackpool) looks at its implications.
For far too long we have accepted lower levels of indoor air quality (IAQ) within our schools, but no more! It is recognised that we need to provide the best possible comfort conditions for our children to allow them to reach their potential and succeed. Many studies, and our own experiences, tell us that when we work in stale and stuffy conditions our concentration and output levels fall.
Now school projects are soon to have a new level of IAQ to deal with. The Department for Education’s (DfE) guidance document, ‘Building Bulletin 101 Ventilation of school buildings’, is being up-dated to fully detail this revised requirement for all schools.
The Education Funding Agency (EFA) has already released the up-date in draft, which will soon be issued and form the guidance for all aspects of design within schools.
As is currently the case, specific targets are still detailed for levels of CO2 (carbon dioxide) within teaching spaces, maximum daily averages of 1000 ppm for mechanical-ventilation systems and 1500 ppm for natural-ventilation systems. These are not to be 500 ppm higher for any longer than 20 minutes in any single day. The exception is that if the outside concentration is high, then the maximum allowable levels will be no more than 800 ppm above the outside carbon-dioxide level, for the majority of the occupied time in the year. (Ref. 1)
From previous experience and testing, the BB101 guidance confirms the minimum amount of ‘fresh; air is typically around 5 l/s/person to keep CO2 within the guidelines set.
Whilst CO2 and temperature sensing remain the only IAQ checks for the daily operation of the classrooms, other specific measures have been referenced for compliance.
The World Health Organisation (WHO) 2010 guidelines for indoor air quality have been used as the basis of the DfE standards, as these are currently more up to date and comprehensive than the levels quoted in Building Regulations Approved Document F (Ref. 2).
As expected within the guide from the WHO, there are specific details to be adhered to relating to health-and-safety legislation, but it also has added detailed guidance to ensure we meet the WHO requirements.
The WHO guidelines are detailed for the protection of public health from risks due to a number of chemicals commonly present in indoor air. The substances considered, in addition to CO2, are benzene, carbon monoxide, formaldehyde, naphthalene, nitrogen dioxide, polycyclic aromatic hydrocarbons (especially benzo[a]pyrene), radon, trichloroethylene and tetrachloroethylene).
All these substances are known in respect of their hazardousness to health and are often found indoors in concentrations of health concern (Ref. 2).
Let’s also not forget that schools are now being changed to academies, where specific skill sets are being nurtured through an altering curriculum on a school-by-school basis. This then offers opportunities for using the space (outside school hours) for a different purpose such as a venue for exacting and specific skills, with their detailed specialist ability to train and develop.
So, many schools now have a multi-functional purpose. They therefore require not just an acceptable building during term time (and normal school hours) but they also need to be able to work outside these traditional times to generate funding and provide the community with a resource, to improve all-round education. To this end the type of system chosen for the school day must now also be able to provide IAQ and comfort conditions to suit activities out of school hours.
The new BB101 standard now recognises ‘hybrid’ units as acceptable options. These have been welcomed, due to their low energy consumption and the effective way in which they can meet all of the BB101 requirements, including the IAQ issues.
Hybrid units are single-sided, fan-assisted (when required) natural- and mechanical-ventilation products. These are the latest product group to be compliant to the current regulations and the soon-to-be-published stricter guidance. The hybrid solution effectively gives the best of both worlds, having a zero-cost natural-ventilation element and a low-cost fan-assisted mechanical-ventilation part.
Manufacturers of hybrid units are now looking at IAQ over and above the temperature and CO2 requirements. Most areas do not require any specific form of outdoor air filtration, but some specific areas subject to high pollution will need it. Hybrid manufacturers are preparing for filtering the air, to ensure compliance in these highly polluted internal and external conditions. Providing a product where extensive filtration is required will be the next step in hybrid evolution.
Hybrid manufacturers have already evolved, providing the enhanced benefit of the units by introducing a heating feature. This removes the need for radiators, thus saving cost, time and space. It also frees up wall space and reduces the risk of damage or harm to occupants. As this market evolves, it is proving to be a popular choice, for end-users, designers and contracting teams alike.
When built to the latest guidance, our new schools will be created to deliver an outstanding educational space with a excellent IAQ and an environment perfectly suited for learning.
Roy Jones is technical director with Gilberts (Blackpool) Ltd.
(Ref, 1) Department for Education’s Building Bulletin 101 — final consultation draft version (March 2016).
(Ref, 2) WHO 2010 – World Health Organisation guidelines for indoor air quality. (http://www.euro.who.int/__ data/assets/pdf_file/0009/128169/e94535.pdf)