1 Principle of IAQ Control Principle of IAQ Control Goal: - - PowerPoint PPT Presentation

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1 Principle of IAQ Control Principle of IAQ Control Goal: - - PowerPoint PPT Presentation

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Typical Indoor Air Contaminants Department of Mechanical, Aerospace, and Manufacturing Engineeri Department of Mechanical, Aerospace, and Manufacturing Engineering ng College of Engineering and Computer Science College of Engineering and

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Indoor Air Quality (IAQ) Strategies Indoor Air Quality (IAQ) Strategies

  • -- Source Control, Ventilation or

Source Control, Ventilation or Air Purification? Air Purification?

By Jensen Zhang

Department of Mechanical, Aerospace, and Manufacturing Engineeri Department of Mechanical, Aerospace, and Manufacturing Engineering ng College of Engineering and Computer Science College of Engineering and Computer Science Syracuse University Syracuse University

Building Energy and Environmental Systems Laboratory (BEESL) http://EnergySystems.syr.edu http://www.eqstar.org http://www.coees.org

J.S. Zhang, 7/7/04 2

Typical Indoor Air Contaminants

Inorganic gases

CO, CO2, SO2, NOx, O3, etc….

Organic gases

Volatile organic compounds (VOCs)

  • Formaldehyde, benzene, toluene, styrene, 1,4-

dichlorobenzene, 4-phenyl cyclohexene (4-PC), nonane, decane, undecane, dodecane, etc….

Radioactive gases (e.g., Radon) Particulate pollutants

Bioaerosols derived from

  • Virus, bacteria, fungi, protozoa, dust mites, pollen
  • Asbestos, dusts, etc….

J.S. Zhang, 7/7/04 3

Typical contaminant sources: outdoors

J.S. Zhang, 7/7/04 4

Typical contaminant sources: indoors

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SLIDE 2

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J.S. Zhang, 7/7/04 5

Principle of IAQ Control

Flow entrainment & mixing

Q, Cs

C

C = indoor concentration C = indoor concentration V = room/building volume V = room/building volume

R F

Air diffuser jet Air diffuser jet Return/exhaust Return/exhaust

Ventilation Ventilation Indoor Indoor emissions emissions Air filtration/purification Air filtration/purification

J.S. Zhang, 7/7/04 6

Principle of IAQ Control Goal:

C < Ccriteria

Governing equation:

V dC/dt = R(t) – Q(t) [C(t) – Cs(t)] – F(t)

Rate of Rate of contaminant contaminant accumulation accumulation Rate of Rate of source source emission emission Rate of Rate of dilution by dilution by ventilation ventilation Rate of Rate of reduction by reduction by purification purification

= = – – – –

J.S. Zhang, 7/7/04 7

IAQ Control Goal:

C < Ccriteria

Strategies

Source/emission control Ventilation Air purification (cleaning/filtration)

J.S. Zhang, 7/7/04 8

Building Material Emissions

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J.S. Zhang, 7/7/04 9

Why Study Material Emissions? 300+ VOCs identified (accounts for over 50%

indoor contaminants)

Many VOCs can cause discomfort and

adverse health effects

Indoor VOC concentrations are usually much

higher than outdoors

J.S. Zhang, 7/7/04 10

VOCs from Three Oil-based Wood Stains

2 6 .0 2 8 .0 3 .0 3 2 .0 3 4 .0 3 6 .0 3 8 .0 1 2 3 4 5 6 7 8 9 1 e + 7 1 .1 e + 7 1 .2 e + 7 1 .3 e + 7 1 .4 e + 7 1 .5 e + 7 T i m e

  • >

A b u n d a n c e T IC : [ B S B 1 ]W S 1

  • H

S 1 .D 1 7 1 8 1 9 2 1 6 1 5 1 4 1 3 1 2 1 1 1 9 8 7 6 5 4 3 2 1 2 6 . 2 8 . 3 . 3 2 . 3 4 . 3 6 . 3 8 . 1 2 3 4 5 6 7 8 9 1 e + 7 1 . 1 e + 7 1 . 2 e + 7 1 . 3 e + 7 1 . 4 e + 7 1 . 5 e + 7 1 . 6 e + 7 1 . 7 e + 7 1 . 8 e + 7 T i m e

  • >

A b u n d a n c e T I C : [ B S B 1 ] W S 5

  • H

S . D 1 5 1 4 1 6 1 8 1 9 2 1 7 1 3 1 2 1 1 1 9 8 7 6 5 4 3 2 1 2 6 . 2 8 . 3 . 3 2 . 3 4 . 3 6 . 3 8 . 1 2 3 4 5 6 7 8 9 1 e + 7 1 . 1 e + 7 1 . 2 e + 7 1 . 3 e + 7 1 . 4 e + 7 1 . 5 e + 7 1 . 6 e + 7 1 . 7 e + 7 1 . 8 e + 7 1 . 9 e + 7 2 e + 7 2 . 1 e + 7 T i m e

  • >

A b u n d a n c e T I C : [ B S B 1 ] W S 5

  • H

S 1 . D 1 7 1 8 2 1 9 1 6 1 5 1 4 1 3 1 2 1 1 1 9 8 7 6 5 4 3 2 1

2-butanone nonane decane undecane

WS3 WS6 WS9

J.S. Zhang, 7/7/04 11

VOCs from Two Water-based (Latex) Paints

5 .0 1 .0 1 5 .0 2 .0 2 5 .0 5 1 1 5 2 2 5 3 3 5 4 4 5 T im e

  • >

A b u n d a n ce T IC : 9 8 2 9

  • 6

.D P T 4 ( L a te x )

  • H

e a d s p a ce a ce to n e 2

  • m

e th y l 2

  • p

r

  • p

a n

  • l

1

  • b

u ta n a l

5 .0 1 .0 1 5 .0 2 .0 2 5 .0 2 4 6 8 1 1 2 1 4 1 6 1 8 T im e

  • >

A b u n d a n ce T IC : 9 8 2 9

  • 7

.D P T 6 ( L a te x )

  • H

e a d s p a ce a ce to n e e th y l a ce ta te n

  • b

u ty l e th e r

1-butanol 2-methyl 2-propanol acetone

n-butyl ether

ethyl acetate acetone

PT4 PT6

J.S. Zhang, 7/7/04 12

Particleboard (at t=24 h, by GC/FID)

9 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 8 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 F i l e n a m e : D : \ R E S E A R C H \ M E \ D R Y _ P R O D \ W O O D \ P A R T B O ~ 1 \ P B 4 \ P B 4
  • 4
R U N C h a n n e l : A = F I D

1 2 3 4 5 6 7

1 Hexanal 2 α-Pinene 3 Camphene 4 β-Pinene 5 α-Terpinene 6 Limonene 7 γ-Terpinene

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J.S. Zhang, 7/7/04 13

Full-scale Environmental Chambers

J.S. Zhang, 7/7/04 14

Emission Characteristics “Wet” coating materials:

High initial emission

rates and fast decay rate

Three emission periods

evaporative controlled

initial period

transition period diffusion controlled final

period

Affected by air velocity

High Low

Range of Individual VOC Emission Rates (Zhang et al. 1998)

J.S. Zhang, 7/7/04 15

Emission Characteristics Dry materials:

Low emission rates

and slow decay rate

Diffusion controlled

process

Not significantly

affected by air velocity

High Low

Range of Individual VOC Emission Rates (Zhang et al. 1998)

J.S. Zhang, 7/7/04 16

Minimization of Source Emissions Material selection Pre-conditioning Encapsulation/sealing Reformulation

Oil versus water-based paints

Change of manufacturing processes

Recycled tire materials—temperature control

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J.S. Zhang, 7/7/04 17

Strategies for IAQ Control Source/emission control Ventilation Air purification

J.S. Zhang, 7/7/04 18

Adequate Ventilation for IAQ Outdoor air quality Amount of outdoor air Room air distribution

Delivery of outdoor air to the occupied spaces

“ASHRAE Standard 62-1999: Ventilation for Acceptable Indoor Air Quality”

J.S. Zhang, 7/7/04 19

Outdoor Air Quality: National Primary Ambient-Air Quality Standards* Long Term Short Term ug/m3 (ppm) Averaging ug/m3 (ppm) Averaging SO2 80 (0.03) 1 year 365 (0.14) 24 hours PM10 50 1 year 150 24 hours CO 40,000 (35) 1 hour CO 10,000 (9) 8 hour NO2 100 (0.055) 1 year O3 235 (0.12) 1 hour Hydrocarbons 160 (0.24) 3 hour Lead 1.5 3 months * Set by U.S. Environmental Protection Agency (EPA)

J.S. Zhang, 7/7/04 20

Outdoor Air Quality (ASHRAE 62-99)

Satisfy EPA National Primary Ambient-Air Quality

Standards

Conduct air sample analysis for specific

contaminants of importance

Reduce outdoor air supply temporarily (e.g., during

rush-hours)

Use air purification devices

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J.S. Zhang, 7/7/04 21

Amount of Outdoor Air (ASHRAE 62-99)

Prescriptive procedure

  • Max. Occupancy CFM (L/s)

Application (P/1000 ft2 or 100 m2) per person Office space 7 20 (10) Classroom 50 15 (7.5) Residential living area: 15 (7.5) (& not less than 0.35 air changes per hour)

IAQ procedure (performance based, allows for

integration and optimization)

J.S. Zhang, 7/7/04 22

Adequate Ventilation for IAQ Outdoor air quality Amount of outdoor air Room air distribution

Deliver fresh air to occupants Remove/dilute contaminants

J.S. Zhang, 7/7/04 23

Mixing Ventilation

Diffuser air jet Flow entrainment & mixing Return outlet

C Cin

in

C Cout

  • ut

Ventilation Efficiency=( Ventilation Efficiency=(C Cout

  • ut-
  • C

Cin

in)/(C

)/(C-

  • C

Cin

in)

)≈ ≈ C Cout

  • ut/C

/C≈ ≈ 1.0 1.0 C C

J.S. Zhang, 7/7/04 24

Displacement Ventilation

Low velocity diffuser Return outlet Lower zone with minimal mixing Thermal plume Stratification level Upper zone

C Cin

in

C Cout

  • ut

C C Ventilation Efficiency=( Ventilation Efficiency=(C Cout

  • ut-
  • C

Cin

in)/(C

)/(C-

  • C

Cin

in)

)≈ ≈ C Cout

  • ut/C > 1.0

/C > 1.0

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J.S. Zhang, 7/7/04 25

Personal/local Ventilation

Personal air jets Return outlet Under-floor supply air plenum Partition Primary air

C Cin

in

C Cout

  • ut

C C C C Ventilation Efficiency=( Ventilation Efficiency=(C Cout

  • ut-
  • C

Cin

in)/(C

)/(C-

  • C

Cin

in)

)≈ ≈ C Cout

  • ut/C > 1.0

/C > 1.0

J.S. Zhang, 7/7/04 26

Strategies for IAQ Control Source/emission control Ventilation Air purification

J.S. Zhang, 7/7/04 27

Air Purification Methods Sorption by filter media Photo-catalytic oxidization Others

Bio-filtration Botanical air cleaning Thermal decomposition Non-thermal plasma decomposition

J.S. Zhang, 7/7/04 28

Equivalent Clean Air Delivery Rate (CADR12-hr), Chen & Zhang 2004

Note: Initial efficiencies of the seven sorption-based air cleaners could be ranked as P1>P3>P2>P4>P7>P6≈P5, according to the average CADR12-hr (for all the VOCs except dichloromethane, formaldehyde, and acetaldehyde) 50 100 150 200 250 300 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 (A) P14 (B) P15

Device No.

CADR (CFM) CADR - 12hr (average of all test compounds)

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J.S. Zhang, 7/7/04 29

0.1 0.2 0.3 0.4 0.5 0.6 50 100 150 200

Ventilation Rate, Q: CFM Steady State Concentration, C: mg/m^3

Effectiveness of Current Air Cleaning Devices for IAQ Control

50% more emission Base emission 50% less emission Best off-the- shelf cleaner

Example case: 240 m2 single family detached house (Zhang, 2000)

96 CFM (Base Case: Cs=0.152 mg/m3, Es=22.7 mg/h Toluene, Nc=0.24 ACH, No air cleaner)

J.S. Zhang, 7/7/04 30

Strategies for IAQ Control Source/emission control? Ventilation? Air purification?

“These strategies should be integrated & optimized in building design and operation.”