Paper 6
Multizone Age-of-Air Analysis
Max
H. Sherman
Lawrence
Berkeley National Laboratory, USA
Abstract
Age-of-air is a technique
for evaluating ventilation that has been actively used for over 20 years.
Age-of-air quantifies the time it takes for an elemental volume of
outdoor air to reach a particular location or zone within the indoor
environment. Age-of-air is
often also used to quantify the ventilation effectiveness with respect to
indoor air quality. In a
purely single zone situation this use of age-of-air is straightforward,
but application of age-of-air techniques in the general multizone
environment has not been fully developed.
This article looks at expanding those single-zone techniques to the
more complicated environment of multizone buildings and in doing so
develops further the general concept of age-of-air.
The results of this analysis show that the nominal age-of-air, as
often used, cannot be directly used for determining ventilation
effectiveness unless specific assumptions are made regarding source
distributions.
The results herein will
allow improved accuracy of age-of-air calculations in complex
environments. The link between
local age-of-air and ventilation effectiveness is hereby improved and the
ability to use age-of-air measurement to estimate distribution
effectiveness is increased. Use
of these results will improve the design of future measurement efforts
using tracer gases in multizone environments.
Key words: multizone,
ventilation, air exchange rate, indoor air quality, age-of-air.
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