Carbon Dioxide Concentration in Rooms

The carbon dioxide concentration in rooms may be used to indicate the air quality and the efficiency of the ventilation system

The carbon dioxide concentration in a room may be used as an indication of the air quality.

The carbon dioxide concentration in a room with a number of persons can after a time - t - be expressed as

c = (q / n V) [1 - (1 / e^{n t})] + (c₀ + c_i) (1 / e^{n t}) + c_i (1)

where

c = carbon dioxide concentration in the room (m³/m³)

q = carbon dioxide supplied to the room (m³/h)

V = volume of the room (m³)

e = the constant 2.718.....

n = number of air shifts per hour (h^-1)

t = time (hour, h)

c_i = carbon dioxide concentration in the inlet ventilation air (m³/m³)

c₀ = carbon dioxide concentration in the room at start, t = 0 (m³/m³)

Example - The Carbon Dioxide Concentration in a Cinema

When the carbon dioxide emission from a person sitting in an cinema is approximately 0.05 m³/h the emission from 100 people is approximately 5 m³/h. If the pollution concentration at start up and in the inlet air is close to zero, the pollution concentration in a 500 m³ cinema after one hour and with one air shift per hour, can be calculated as:

c = ( (5 m³/h) / (1 h^-1) (500 m³) ) [1 - (1 / e^{(1 h-1) (1 h)})] + (0 + 0) (1 / e^{(1 h-1) (1 h)}) + 0

= 0.006 m³/m³

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