Ventilation Energy and Environmental Technology
                                     from VEETECH Ltd.              Updated 27th October 2007


PHPCO2VENT - The On-Line Ventilation Rate and Air Quality Calculator (Based on Steady State Carbon Dioxide Concentration) Beta Version Under Test

Click here for ventilation rate calculations based on wind and stack effect

Written by Martin Liddament

PHPCO2 Input Form


Level of Occupant Activity:

  Office Work (100W)   Light Work (240W)
  Moderate Work (400W)   Heavy Work (560W)

Room and Occupancy Details:

Volume of Space (m3)

Number of Occupants

Outside CO2 Concentration (ppm) (Use 380 ppm if no other data available)

Inside CO2 Concentration (ppm)



For a simple background to ventilation order the Guide to Energy Efficient Ventilation

Instructions: The above illustration shows the distribution of CO2 concentration in an occupied office space during the course of a day. The ventilation rate and air quality conditions can be calculated when the CO2 concentration remains approximately constant. In the example above this is late morning, when the concentration peaks at approximately 1500 ppm, and in the middle afternoon, when the CO2 peaks at 2000 ppm. This latter peak is not so obviously steady state but is the best information available. For selected steady state periods enter the data itemised and click send.
Output: Estimated ventilation rate in L/s, air change rate and air quality assessment according to CEN Standards 13779.
Limitations: Approximate solution. Does not allow for other sources of CO2 emissions such as pets and emissions from unvented combustion appliances. Results cannot be guaranteed
Theoretical Basis: Dilution Equation given in British Standards BS5925; Sedentary Occupant emission based on 0.3L/min (.005 L/s) as given in Health Canada: Environmental and Workplace Health. Higher metabolic rates based on energy class intervals given in BS5925.

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