FMJ.CO.UK CIBSE STANDARDS FOCUS
NOVEMBER 2019 37
People spend up to 90 per cent of their
time indoors. It will come as no surprise,
therefore, that there are increasing concerns
about the quality of air and the health impacts
of air pollution inside o ices, schools and other
building types. Air pollution indoors, which
is o en down to a mixture of pollutants from
both inside and outside the building, can be
significantly worse than outdoors.
Pollutants from indoor sources include
particulate matter and nitrogen oxide from
combustion sources (such as gas cooking or indoor
fires), chemicals released from building materials,
finishes, furnishings, paints and cleaning products.
Outside air pollution is generally the result of
emissions from tra ic as well as more site-specific
sources such as industrial or agricultural activities.
Pollutants can be introduced indoors through air
infiltration, open windows or be drawn inside by
the ‘fresh air’ intake of ventilation systems.
There is growing awareness of the importance of
indoor air quality (IAQ) on occupant productivity
and occupants’ health and wellbeing. Symptoms
such as headaches, skin irritation, drowsiness and
even respiratory problems have all been attributed
to poor IAQ. In o ices, IAQ issues can lead to
complaints from occupants, lost productivity and
even sta absences.
The latest issue of CIBSE’s Technical
Memorandum TM40: Health and wellbeing issues
in building services (due out later this month)
points out that a number of studies
have found benefits in improving
IAQ by avoiding pollutant
sources, providing
adequate ventilation
rates and filtering the
air supply if needed.
The literature review
carried out as part
of the TM40 update
has found some
studies which reported
improvement if fresh
air rates were improved
“beyond current best
practice recommendations”,
for example reducing nonspecific
awareness of the importance
of indoor air quality (IAQ) on
occupant productivity and
occupants’ health and
symptoms such as headaches,
There is growing
wellbeing.”
irritation, self-reported lethargy and sick leave.
The document says that two large, recent reviews
have concluded that “in working (non-industrial)
environments, the optimum fresh air rates would
be between 20 and 30 litres/second/person”.
This figure is a significant increase compared
to current recommendations of a minimum fresh
air requirement of 8-10 l/s per person for a typical
mechanically ventilated space. However, in TM40
CIBSE highlights that this is a developing area and
that most studies “support the current guidelines
on fresh air rates, avoiding mixing and recirculation,
and recommended CO levels”.
In the large majority of cases, studies show that
the main issue with indoor air quality starts with
ventilation rates below good practice and below
the design intent, o en through inadequate design,
installation, commissioning or maintenance. This
points to the need for much better implementation
of current guidelines, rather than a radical revisit of
target ventilation rates.
There is currently no comprehensive and robustly
implemented regulatory framework on indoor air
quality in the UK – as is the case for most countries.
In the current Building Regulations in both England
and Wales, ventilation is currently used as a proxy
for IAQ. Building Regulations Schedule 1, Part
F, states that “there shall be adequate means of
ventilation provided for people in the building”.
Adequate is defined as a ventilation system
“capable of limiting pollutants originating within a
building which would otherwise be a hazard to the
health of the people in the building”.
Appendix A of Approved Document F sets out
current recommended levels of moisture and
common pollutants, such as nitrogen dioxide
and carbon monoxide. It also recommends that
exposure to volatile organic compound (VOC) levels
should not exceed 300g/m averaged over eight
hours. In addition, the dra revision to Document
F also proposes maximum recommended levels of
formaldehyde.
ADDRESSING IAQ ISSUES
There are concerns that under the current
regulatory regime lack of verification
and testing for air pollutants on
completion of a building
means that poor IAQ issues
are going undetected
prior to handover. The
consultation dra
goes some way
towards addressing
those concerns
by emphasising
the importance of
commissioning and
measuring actual
ventilation rates at
completion; it is also hoped
that wider changes as part of
the implementation of the Hackitt
review will provide better and more
consistent enforcement in the future.
The lack of a comprehensive framework for IAQ
may change in the future, however, following
recent amendments to the Energy Performance of
Buildings Directive, which require national energy
regulations to “optimise health, indoor air quality
and comfort levels”. While not specifically setting
levels of indoor air quality, the EPBD amendments
make reference to 2009 World Health Organization
(WHO) pollutant guidelines for the maximum
concentrations of various volatile organic air
pollutants, including benzene, naphthalene,
nitrogen dioxide and formaldehyde.
CIBSE’s forthcoming TM40 uses the WHO’s
maximum concentration guidelines. CIBSE advice
is that these guidelines should be seen as ‘interim