Ventilation Energy and Environmental Technology
from VEETECH Ltd.
Updated 4th March 2011
|
|
Ventilation Energy and Environmental Technology
|
|
aqres.php - The air quality reservoir time calculator to determine the safety time in a sealed building Click here for toxic gas ingress calculator
Click here for ventilation rate calculator
Click here for transient thermal model calculator
Written by Martin W. Liddament |
For a simple background to ventilation order the Guide to Energy Efficient Ventilation Summary: This algorithm calculates the air quality reservoir time for a closed enclosure. The reservoir time is based on the volume of the enclosure, the number of sedentary occupants and the ventilation rate. For a sealed enclosure, the ventilation rate must be set to zero. Calculation is based on the standard transient dilution equation. Where other pollutants are not present, reasonable air quality approximates to a metabolic carbon dioxide concentration of about 1000 ppm. In the event of the need to seal the building to protect against outdoor toxic contamination, a CO2 concentration of up to 10000 ppm is acceptable. This algorithm displays the time taken to reach 1000 ppm and multiples up to 10000 ppm subject to a maximum time limit of approximately 72 hours. When used in conjunction with the VEETECH algorithm phptoxicgas.php it is possible to determine the period over which occupants can be protected from outdoor toxic fumes.Assumptions The indoor space is assumed to be uniformly mixed. Caution This algorithm provides an approximate solution only. It must not form the basis of critical design or risk assessment. Results cannot be guaranteed. Theoretical Basis: Dilution Equation given in British Standards BS5925. (Site operated by VEETECH Ltd. See main web site: www.veetech.co.uk for contact details and privacy statement.) |