1. Problem StatementProblem Statement
Ventilation and Indoor/outdoor Ozone Concentration
Research Assistant: Dayi Lai
Principal Investigator: Qingyan (Yan) Chen
Ventilation and Indoor/outdoor Ozone Concentration
Research Assistant: Dayi Lai
Principal Investigator: Qingyan (Yan) Chen
ResultsResults
Research ObjectivesResearch Objectives
Next StepsNext Steps
Cin is a fraction of Cout, and will increase with the increase of ACH.
Ozone is well known for its association with adverse health effects,
such as decreased lung function and respiratory symptoms. Because of
the large amount of time people spent indoors, the indoor ozone
exposures are frequently greater than outdoors.
Outdoor ozone enter the building through three different ventilation
mechanisms: infiltration, natural ventilation and mechanical ventilation.
Then it will react with building surfaces.
Potential Impact of ResearchPotential Impact of Research
AcknowledgementsAcknowledgements
Professor Panagiota Karava from Civil Engineering, Purdue,
Haojie Wang from Mechanical Engineering, Purdue.
Outdoor
ozone Outdoor
ozone
Outdoor
ozone
Indoor ozone
Outdoor ozone entry by
Natural Ventilation
Outdoor ozone entry
by Infiltration
Outdoor ozone entry by
Mechanical Ventilation O3
Wall and floor Window
Human skin
Furniture
Reaction
Investigate relationship between ventilation and indoor/outdoor ozone
concentration, and,
Verify the simplified model:
/ / ( )in outC C a a K 
[ ( )]in
out i i ini
dC
aC a K k chem C S
dt
    
Steady State
Neglect gaseous
phase reaction
No source
(Chen and Zhao 2011)
Where:
Cin---indoor ozone concentration, ppb;
Cout---outdoor ozone concentration, ppb;
a---air exchange rate, h-1;
K---surface deposition rate, h-1;
chemi---concentration of the ith chemical;
ki---reaction rate with the ith chemical;
S---ozone generation rate, ppb/h.
Living lab test Test setup
-20%
+20%
0
0.2
0.4
0.6
0.8
0 0.2 0.4 0.6 0.8
PredictedCin/Cout
Measured Cin/Cout
a<2
2<a<4
4<a<10
Indoor/outdoor ozone concentration and air exchange rate
Measurement vs.
Prediction The prediction generally
have an error of less than
20%. The use of simplified
equation is an easy and
reasonably accurate
method to predict the ozone
I/O ratio.
Use simplified model to investigate the indoor ozone level and
exposure for U.S. major cities of different climate under current
scenario and future scenarios under climate change.
Gain insights about indoor ozone concentration and exposure under
different ventilation pattern.
Propose a method of using different building ventilation strategies to
mitigate the exposure and ozone related morbidity and mortality.
Weather
Data
Heating
Na. Vent.
Cooling
Infiltration
Na. Vent.
Me. Vent.
Out
Ozone
Data
Indoor
Ozone
Level
/ / ( )in outC C a a K 
Ozone reaction with surface