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Professional
development
The CIBSE Journal CPD Programme
Members of the Chartered Institution of Building Services Engineers (CIBSE) and
other professional bodies are required to maintain their professional competence
throughout their careers. Continuing professional development (CPD) means the
systematic maintenance, improvement and broadening of your knowledge and
skills, and is therefore a long-term commitment to enhancing your competence.
CPD is a requirement of both CIBSE and the Register of the Engineering Council (UK).
CIBSE Journal is pleased to offer this module in its CPD programme. The programme
is free and can be used by any reader.
This module will help you to meet CIBSE’s requirement for CPD. It will equally assist
members of other institutions, who should record CPD activities in accordance with
their institution’s guidance.
Simply study the module and complete the questionnaire on the final page,
following the instructions for its submission. Modules will be available online at
www.cibsejournal.com/cpd while the information they contain remains current.
You can also complete the questionnaire online, and receive your results by return email.
Indoor air quality
Air quality is set to become even more significant in the work of the building professional,
and this CPD article aims to provide an update on those parameters that are currently
thought to contribute to indoor air quality
The built environment is rightly
focusing increasingly on energy
efficiency. But it is important to
remember that a primary purpose
of the occupied building envelope is to
provide a safe and comfortable environment
for people – and this where internal air
quality (IAQ) becomes a key consideration.
Aside from the easily observable
considerations of ‘basic’ occupant thermal
comfort, the effects of the IAQ may have
transitory or lifelong consequences for
building users. Such effects can be highly
visible (as with condensation or mould), or
less so but easily measurable (as with radon
gas accumulation, for example). Some
effects can go undetected and, as such, lead
to environments that become linked to ‘sick
building syndrome’. By maintaining good
levels of IAQ, there are likely to be tangible
financial benefits through increased
productivity and less workplace sickness [1] .
As with any real-world design challenge,
it is impossible to satisfy all occupants of a
building in terms of IAQ. In his seminal
work the late Ole Fanger [2] considered the
integrating effects for thermal comfort.
However, this did not include the effect
of IAQ. His later work included the
development of the ‘olf’, and he attempts
to provide a numerical correlation
between emissions and olfactory response
(human sense of smell). This is a complex
relationship: the ways that people perceive
contaminants will itself be affected by
the other room conditions including
temperature, humidity and lighting, as well
as personal preferences and susceptibilities.
In addition, it is unlikely that
contaminants in the air will be dispersed
evenly in a space, thereby providing IAQ
problem ‘hot spots’. In terms of comfort,
there are published criteria [3] relating to
subjective perception and the acceptable
periods for discomfort.
The principal contaminants that are
associated with causing problems in IAQ
(principally in terms of health) are:
Particulates
The focus here has traditionally been
on PM10, which refers to particles of less
than 10 µm (micrometres). But attention
has increasingly been turning to PM2.5
CPD Programme
(< 2.5 µm) particles that are measured in
µg/m 3 (micrograms per cubic metre).
The recently published SNIFFER report 4
on PM2.5 in the UK provides an extensive
summary of the current state of scientific
knowledge on PM2.5. It concludes that
there are serious health consequences for
long-term exposure to PM2.5 (small particles
are associated with reduced lung function
and increased risk of heart and respiratory
disease) and that currently no safe exposure
limit is really known. The control of PM2.5
in external air is complex because much is
outside local control, although activities such
as smoking [5] , vehicle emissions and a rise
in the use of wood stoves have been shown
to increase localised values. (EU directive
50/2008 has set a limiting value for PM2.5 of
25 µg/m3 in outdoor air by 2015.)
Tobacco smoke
This is generally known as environmental
tobacco smoke (ETS). Although not such a
widespread risk in public areas in the UK,
there are many places around the world (as
well as in domestic and other exceptions
in the UK) where ETS is still a major
www.cibsejournal.com April 2011 CIBSE Journal 53