Indoor Air Indoor Air Quality ModelingQuality Modeling

Purpose of Indoor Air Quality Purpose of Indoor Air Quality ModelingModeling

To estimate the indoor air pollutant To estimate the indoor air pollutant concentration in a buildingconcentration in a building

To determine the indoor air quality To determine the indoor air quality inside a buildinginside a building

For development and evaluation of For development and evaluation of source-to-dose models of persistent source-to-dose models of persistent pollutants pollutants

Types of Air Quality ModelsTypes of Air Quality Models

One – Compartment modelsOne – Compartment models

Multi Compartment modelsMulti Compartment models

Empirical modelsEmpirical models

Mass Balance ModelMass Balance Model Given by QGiven by Q00+Q+Q22=Q=Q33+Q+Q44

Mass Balance Indoor Outdoor ModelMass Balance Indoor Outdoor Model

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fr

om

outd

oors

Q2

F0 F1

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ir Q

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Room Volume (V)Mixing factor k

Source SDecay R

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n Q

3

Exh

aust

Q4

F0 & F1 are filter efficiency

Pollutant Mass BalancePollutant Mass Balance

V(dCV(dC11 / dt) = k x Q / dt) = k x Q00 x C x C00(1 – F(1 – F00) + k x Q) + k x Q11 x C x C11 (1 – F(1 – F11 ) + k x Q ) + k x Q22 x C x C00 + S – R- k (Q + S – R- k (Q00 + Q + Q11 +Q+Q22 )Ci )Ci

For t = 0 , Ci = CFor t = 0 , Ci = C R = E x CiR = E x Ci Also t tends to infinityAlso t tends to infinity Ci,ss = ((k x [QCi,ss = ((k x [Q00 x C x C00 (1 – F (1 – F00) + Q) + Q22]C]C00) + S) / ) + S) /

((Q((Q00 + Q + Q11 +Q +Q22) + E)) + E) Where, Ci,ss = Steady State concentrationWhere, Ci,ss = Steady State concentration

NotationsNotations

QQ0 0 = Make up air= Make up air QQ1 1 = Indoor air Recirculation= Indoor air Recirculation QQ2 2 = Infiltration from outdoors = Infiltration from outdoors QQ3 3 = Exfiltration= Exfiltration QQ4 4 = Exhaust= Exhaust F0 = Filter efficiencyF0 = Filter efficiency F1 = Filter efficiencyF1 = Filter efficiency Co= Outside ConcentrationCo= Outside Concentration

NotationsNotations

Ci = Indoor ConcentrationCi = Indoor Concentration V = Room VolumeV = Room Volume K = Mixing factorK = Mixing factor S = Source emission rateS = Source emission rate R = Decay of PollutantR = Decay of Pollutant