Indoor Air Lab v1.2

Parameters

Room Geometry

Floor Area50 m²

Ceiling Height2.7 m

Volume (computed)135 m³

Radon Source

Rn source S_Rn1.35 pCi/s

Initial [Rn]₀5.0 pCi/L

Outdoor PM₂.₅

PM_out25 µg/m³

Deposition v_dep0.0010 m/s

Initial [PM]₀5 µg/m³

Baseline Infiltration (always on)

λ_inf0.10 h⁻¹

Penetration P0.80

P = particle survival fraction through envelope cracks. Building-shell property, independent of η_in.

Mechanical Ventilation λ_vent

DAMPER CLOSED

λ_vent (when open) 0.5 h⁻¹

Inlet filter η_in0.90

η_in = pass-through fraction. 0 = perfect HEPA, 1 = no filter.

Safe ventilation window

computing…

Indoor PM₂.₅ Source S(t)

SOURCE OFF

Cooking, candles, cleaning. S/V adds directly to PM mass balance.

Recirculation / Air Purifier

RECIRC OFF

dPM/dt =
λ_inf·P·PM_out + λ_vent·η_in·PM_out + S(t)/V
− (λ_inf + λ_vent + k_dep + η_r·λ_recirc)·PM
dRn/dt = S_Rn·3600/V − (λ_inf+λ_vent+λ_d)·Rn
P = infiltration penetration (building shell) | η_in = inlet filter (mech. system)
Integrator: Cⁿ⁺¹ = C_ss+(Cⁿ−C_ss)·exp(−μ·Δt) [exact, unconditionally stable]

Radon (current)

—

pCi/L

SS: —

checking…

PM₂.₅ (current)

—

µg/m³

SS: —

< 15 µg/m³ — OK

Total ACH / τ

—

h⁻¹ (λ_inf + λ_vent)

τ ≈ — h

Outdoor PM / Δ indoor

—

µg/m³ outdoor

Δ indoor: —

Transient Response DAMPER CLOSED

5 min

Forcing Functions — 168 h preview

Room Visualisation

OFF

0 100