|
The
International Journal of Ventilation
Volume 3 No 2 September 2004:
Paper 5: Controllable Background Ventilation in Dwellings - The
Equivalent Opening Area Needed to Achieve Appropriate Indoor Air Quality
I Ridley, J Fox, and T Oreszczyn
Bartlett School of
Graduate Studies, University College London, Torrington Place Site,
Gower Street, London,
WC1E 6BT
Abstract
In dwellings there is a desire
to reduce ventilation heat loss, by reducing uncontrollable air infiltration, at
the same time as providing adequate indoor air quality by controllable
background ventilation. In England
and Wales, the background ventilation requirements in part F of the Building
Regulations at present are expressed in prescriptive terms. The adopted European
Standard, EN13141-1:2004, provides a means of assessing the performance of
background ventilation devices, such as trickle ventilators, and gives a
standard method of measuring the equivalent area of the ventilator.
This paper compares the levels of background ventilation produced by
background ventilators with the presently required free area of 4000 mm2,
to that produced by larger vents, with an equivalent area of 4000 mm2.
Two computer models of a domestic dwelling are used to predict the ventilation
rates and relative humidities achieved in houses with different levels of
background air tightness, when fitted with trickle ventilators of different
equivalent areas. The simulations suggest that both background ventilators that
have a free area of 4000mm2 and
background ventilators with an equivalent area of 4000 mm2,
provide an adequate ventilation rate, (that is average heating season
ventilation rate of approximately 0.5 ach-1),
and adequate IAQ, (including average heating season RH<70%), when fitted in a
semi detached dwelling that achieves currently recommended levels of air
tightness of 10 m3/hr.m2 at 50 Pa, and in tight
dwellings with levels of air tightness of 5 m3/hr.m2
at 50 Pa.
Key words:
background ventilation, air infiltration, dwellings, indoor air quality,
computer simulation.
|
|
