Impact tool

Background

An online app to calculate indoor pollutant concentrations.

IMPACT means Innovative Modelling of Museum Pollution and Conservation Thresholds. This is the name of the project where the IMPACT tool originated. The current version (2) was coded by Josep Grau-Bove, in order to continue offering access to this useful model. The original research was carried out by Nigel Blades, Declan Kruppa, May Cassar (UCL Institute for Sustainable Heritage), and Terje Grøntoft (Norwegian Institute for Air research).

Instructions

The model predicts indoor concentrations of pollutants. The main otuput is the Indoor/Outdoor ratio (%), which is the percentage of outdoor pollutant concentrations that we can expect indoors. To find this value, the model estimates the deposition flux of pollutants to surfaces. The deposition flux depends on the type of surface, its area, and the air movement in the room. It also depends on a value known as deposition velocity, which has been experimentally determined for a diversity of common indoor surfaces.

To run a simulation, you need to input the volume of the room, the area of every surface where pollutants can deposit, T, RH and the level of ventilation. Ventilation is expressed in Air Exchange Rate (AER, 1/h), which indicates the number of times in an hour that the air in the room is refreshed.

The model shows the indoor concentration at equilibrium. This means that, in a room with no deposition, the internal concentration will eventually be equal to the external, even if it takes a very long time. The time to equilibrium can be explored with the plot Concentration Through Time.

References

A description and the main equation of the model can be found in:

Kruppa, D.; Blades, N.; Cassar, M.; (2002) A web-based software tool for predicting the levels of air pollutants inside museum buildings developed by the EC impact project. 5th EC Conference, Cracow, Poland.

The deposition values determined experimentally for a range of materials are published in:

Grøntoft, T. and Michele R. Compilation of tables of surface deposition velocities for O3, NO2 and SO2 to a range of indoor surfaces. Atmospheric Environment (2004).