Indoor Air Quality

Indoor Air Quality (IAQ) refers to the air quality within and around buildings with particular emphasis on how it relates to the health and comfort of occupants.

BESA formed an IAQ Action Group two years ago with a view to providing clearer technical guidance for members and the industry at large on this important topic and also to raise awareness at the government level, with the general public, and across the sector through its marketing and PR departments.


A Beginner's Guide To Indoor Air Quality

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Health campaigners back our ‘Beginner’s guide’

The BESA Health & Wellbeing in Buildings group has produced a ‘Beginners Guide’ to improving Indoor Air Quality’ (IAQ) in partnership with affiliate member Mitsubishi Electric.

The Guide has gained the support of leading campaigners and healthcare experts including World Health Organisation (WHO) advocate Rosamund Adoo Kissi-Debrah, the British Lung Foundation, and Global Action Plan – the organisers of National Clean Air Day.

Designed to be easily digestible and non-technical introduction to the subject, the ‘Beginner’s Guide to Indoor Air Quality’ offers advice and guidance for employees and visitors to commercial buildings and, with so many people now working from home, includes some easy tips for optimising IAQ in residential settings.

The controversy and debate around air quality has never been more heated and this has thrust the broad topic of building ventilation and air cleaning into the limelight – particularly as more people start to consider returning to offices, schools and public buildings in the wake of the pandemic.

This digital publication can be downloaded for free here – and it is also being promoted to the widest possible audience including consumers, commercial building managers, school leadership teams, policy makers etc.

The Beginner’s Guide will also be of interest to engineers and specialist firms involved in designing, commissioning, and managing indoor environments because it provides a useful overview of the main topic areas. It would work as a starting point for anyone looking to set up a strategy for tackling the poor IAQ that is having a detrimental impact on thousands of UK buildings and their occupants.

With an introduction from Kissi-Debrah, the guide, which includes a wealth of information provided the Health & Wellbeing in Buildings group, explains how the ventilation and building services industry is able to turn buildings into ‘safe havens’ to protect occupants – particularly children who face the greatest risks – from the worst impacts of contaminated air.

“This guide is an invaluable non-technical introduction to the issue of IAQ and explains how we can make our own indoor environments safer and healthier for us and our children.” said Kissi-Debrah, who is also honorary president of the group.


Back to school

Decades of under-investment in school buildings has been brought sharply into focus by the pandemic. School managers had very few weapons at their disposal with which to fight the virus and what budget they did have was largely used up on social distancing signage, improving handwashing facilities, boxes of tissues and PPE.

When it became apparent that the virus was airborne, most had no adequate mechanical ventilation and reverted to opening windows to try and increase airflows. Now that schools are preparing to re-open on March 8, they are at least armed with greater knowledge about how the virus moves around indoor spaces, but few have the means to act on that knowledge.

Many schools can only rely on opening windows to try and increase indoor airflows, but BESA says most of those in urban settings should not because of their location next to busy roads making them vulnerable to air pollution and noise. In any case, opening windows does not guarantee the air change rates needed to reduce viral loads. It is completely temperature and wind direction dependent and likely to leave unventilated, stagnant spots around the room. That freezing child next to the window might be virus free, however!

One of the UK’s top experts on building ventilation is also a member of the government’s scientific advisory group SAGE. Professor Cath Noakes has been a vocal proponent of “engineered solutions” to the IAQ challenge and has identified gaps in a strategy that relies on natural ventilation.

She has been telling the government that engineering controls should sit above measures that rely on human behaviour such as distancing and wearing face coverings in any “hierarchy of risk control”.

“We don’t have all the answers, but we do know we need to ventilate better,” she told a recent BESA webinar. “This is not just about flow rates as it depends on the size of the space. 10 litres per second per person is the ideal, but if people are close together and for an extended period, we may need more flow rate. You can also have quite a lot of people in a large space with lower ventilation rates.”

The key factor with an engineered mechanical ventilation approach is that it can give you control over the air movement. The paths taken by air is critical and will be different depending on the layout of the space and the occupancy levels. Displacement ventilation, for example, was shown to be effective in removing viral loads by a Cambridge University study during the pandemic, but it might not be effective in every situation.

The BESA Health & Wellbeing in Buildings group is working with ventilation manufacturers and other specialists to develop low cost engineered solutions that are long overdue but have not yet been produced on any great scale for schools due to shortage of funding

“Before the pandemic, local authorities were facing growing community pressure to address the air quality issues around school buildings caused by traffic pollution. Now, in the wake of Covid-19, the focus has moved inside and, if we want people to feel more confident about returning to any communal building, then this issue needs to be properly addressed,” says group chair Nathan Wood.

A good starting point for any IAQ strategy is the new BESA ‘Beginner’s Guide to IAQ’ produced in partnership with Mitsubishi Electric.


Work so far

The IAQ Group was set up in response to growing alarm across the UK about rising levels of OUTDOOR air pollution.

It was clear that as air pollution worsened there would be a growing problem in buildings unless measures were taken to ensure ventilation and air conditioning systems were adequately designed, installed and (most importantly) maintained to protect occupants.

The growth in the volume and nature of outdoor contaminants is adding to the problem already created by indoor sources of air pollution.

The Group was set up specifically to be collaborative across the building services sector and, therefore, includes members and representatives of other like-minded organisations including CIBSE; BSRIA; the Construction Products Association; the City of London Corporation etc. and with charities such as Close the Door and Clean Air in London.

It has succeeded in bringing key players across the sector together and pooled their expertise in a series of press articles and technical bulletins. The next aim is to produce further technical updates, which will be freely available to members and, eventually, a comprehensive Guide to Good Practice jointly published with BSRIA and CIBSE.

It has published a series of trade press articles and responded to government consultations. It has also hosted and sponsored several technical seminars and provided expert IAQ speakers at industry events including those aimed at specialist audiences like NHS Estates managers and school ventilation engineers.

Click here to view our 'Smart Answer to Indoor Air Quality' webinar. 


Aims and ambitions

Most service and maintenance programmes already include an annual inspection of air handling units and a visual check of ductwork cleanliness, but has no specific measuring process of the actual air in the occupied space.

The Group is now advising contractors, FMs and building clients to take the relatively easy step of extending visual inspections to taking air and microbiological samples to measure the air quality and the cleanliness of ventilation; and inspecting ventilation and air conditioning filters.

Building managers are encouraged to measure and monitor: relative humidity (RH); ventilation rates; possible mould build up; temperature; CO; CO2; VOCs; supply side particulates; NO2 and NOx.  Local factors like heavy traffic levels and Radon gas should also be taken into account.


Technical sub-committee

The Group has set up a small technical group looking into what relevant technical guidance is already available; what legislation (national and international) has a bearing on IAQ; and what steps building engineering services firms could take to support clients.

The main purpose of this work will be to produce practical steps that can be used to supplement the Association’s widely used building service and maintenance tool SFG20.

The committee is proposing a range of relatively low cost, simple remedial measures –such as cleaning intake grilles and upgrading/changing filters – linked to a building ‘classification’ system i.e high, medium and low risk based on a building’s function and characteristics.

Healthcare facilities and many schools are considered high risk; a standard commercial office medium risk; and a storage facility low risk. Where the building is located – near a busy road etc. – and local conditions would be the other main factors.

It is recommending existing sources of guidance including BESA’s own ‘Guide to Good Practice – Internal Cleanliness of Ventilation Systems’ (TR/19).  The group is also looking at the behaviour of building users including opening windows in highly polluted urban areas and the impact that has on IAQ.

Measurements have shown that a well-sealed building envelope and effective filtration of incoming supply air can reduce particle penetration by 78%. There has been a growing interest in airtightness testing to help improve energy efficiency, but that process can also be used to measure IAQ.

For more information and to get involved in this work visit the BESA IAQ LinkedIn page or email: