Civil Engineering Reference
In-Depth Information
3.1 Subject
Examples of adverse effects associated with the intake of airborne pollutants were
discussed in ''
A Multiple-Case Study of Passive House Retrofits of School
Buildings in Austria
''. For any of these pollutants, there is a probabilistic dose-
response function that determines wetter a certain dose will be likely to trigger the
effect or not (Calthrop and Maddison
1996
; Mendelsohn and Orcutt
1979
; Page
and Fellner
1978
; Van Bree et al.
1995
). The form of these functions is dependent
on the specific pollutant. It can be either linear or nonlinear, include a 'no effect'
threshold or not (Lewtas et al.
1997
; Roberts and Martin
2007
) and be modified by
specific sensitivity of the subject such as age, allergy, pregnancy.
3.2 Space
A series of processes in the ventilated space create the conditions that allow
getting from a flow rate, delivered by the ventilation system, to the dose inhaled by
an occupant (Meng et al.
2012
; Hsu et al.
2012
). First of all, the layout and size of
the air supplies and exhausts (Hviid and Svendsen
2013
; Aziz et al.
2012
), the
production of buoyancy forces in the space and other momentum sources create a
specific and usually unsteady flow field in the space (Gong et al.
2010
; Peng and
Davidson
1997
). Specific approaches include displacement ventilation, creating
more or less stable zone fresh air in the occupied zone of the space (Zhong et al.
2012
), and personal ventilation, which directs the fresh air directly at the occu-
pant's breathing zone (Makhoul et al.
2013
; Pan et al.
2012
). The geometrical
distribution and type of sources in the space, as was elaborated on above, will
interact with the flow field, and this results in a spatially distributed concentration
and associated ventilation efficiency for each of the pollutants (Jones et al.
2007
;
Sandberg and Sjoberg
1983
; Villafruela et al.
2013
). The presence, behaviour and
whereabouts of occupants in the space (Guerra Santin
2011
; Yun et al.
2011
; Lee
et al.
2012a
) will both influence the flow field, due to their movements and the
thermal plume generated by their metabolic heat output (Thomas et al.
2011
;
Zukowska et al.
2012
), and determine their exposure to the pollutants. Flow
conditions in the microenvironment of the breathing zone, again influenced by
movement and thermal plume, and personal factors such as breathing rate will then
determine the intake and dose (Rim and Novoselac
2009
; Schuda et al.
2009
;
Djupesland and Borresen
2000
). The complete set of modifying factors influencing
the relation between source strength, rather than the ventilation rate, and dose,
including ventilation, is integrated in the 'intake fraction' concept (Bennett et al.
2002
; Laverge et al.
2013a
).
