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CONTAM

Submitted by Christa Cornelis on Tue, 2009-05-26 09:17
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The Indoor Air Quality model CONTAM (CONTAM Multizone Airflow and Contaminant Transport Analysis Software) is a multizonal indoor air quality and ventilation analysis computer program designed to determine the airflow in a building, chemical contaminant concentration in various rooms of the building, and personal exposure to chemical contaminants present in building.

The CONTAM model was developed by the American National Institute of Standards and Technology (NIST). CONTAM exists of 2 parts, namely (1) the CONTAMW module, referring to the user-interface of CONTAM and (2) the numerical solver CONTAMX.

CONTAM can be useful in a variety of applications. Its ability to calculate building airflows, is useful to assess the adequacy of ventilation rates in a building, to determine the variation in ventilation rates over time and the distribution of ventilation air within a building, and to estimate the impact of envelope air tightening efforts on infiltration rates. The prediction of contaminant concentrations can be used to determine the indoor air quality performance of a building before it is constructed and occupied, to investigate the impacts of various design decisions related to ventilation system design and building material selection, and to assess the indoor air quality performance of an existing building. Predicted contaminant concentrations can also be used to estimate personal exposure based on occupancy patterns in the building being studied. Exposure estimates can be compared for different assumptions of ventilation rates and source strengths.

Model description
Purpose: 

The CONTAM model aims to provide a tool to calculate building airflows, to determine the variation in ventilation rates over time and weather conditions, and to provide insight in the effect of design of ventilation systems, in the distribution of ventilation air within a building, and to estimate the impact of envelope air tightening efforts on infiltration rates. In a subsequent step, the CONTAM model enables the calculation of contaminant concentration in the indoor environment, based building airflows and contaminant emission patterns from various indoor sources (building materials, consumer products, human activities,…). In a last step, CONTAM allows (personal) exposure calculations based on occupancy schedules.

Boundaries: 

Fields of model:  indoor air, exposure

Spatial Resolution:  the CONTAM model assumes homogenous concentratrion distribution within each room of the building enveloppe
Temporal Resolution: the CONTAM model allows a time resolution starting from 5 minutes time steps, up to long term calculations
Pollutants/Stressors/Agents covered: chemical pollutants; user-defined (the model is a toolbox, without preset chemicals defined)
Source type of emissions/sectors: CONTAM covers a wide spectrum of emission type and pattern modelling including:
-        Constant coefficient model
-        Pressure driven model
-        Cut-off concentration model
-        Decaying source model
-        Boundary layer diffusion model
-        Burst source model
-        Deposition velocity sink model
-        Deposition rate sink model
-        Super source/sink model
Input: 

Data input for the airflow module: building dimensions and design, layout and parametrization of ventilation system, leakage surfaces and location, weather conditions (wind speed, temperature,…)

Data input for the contaminant concentration module:  contaminant name + properties, emission rates of the various indoor sources + location of indoor sources, deposition/adsorption rate and outdoor concentration.

Data input for the contaminant exposure module: occupancy schedules in the various rooms in the building envelop and outside the building

Output: 
Data output of the airflow module : infiltration, exfiltration, and room-to-room airflows in building systems driven by mechanical means, wind pressures acting on the exterior of the building, and buoyancy effects induced by the indoor and outdoor air temperature difference.
Data output of the contaminant concentration module: the prediction of indoor concentration in the various room in the building (time-dependent concentrations, with 5 minutes interval as the smallest interval)
Data output of the contaminant exposure module:  the predictions of exposure of occupants to airborne contaminants for eventual risk assessment.

Data output : output files are either text files or binary files; they can be converted for import into spreadsheet programs (optional with Contam Utility Software)

Description of processes modelled and of technical details: 

For further information and CONTAM model and manual download, we refer to the following website: http://www.bfrl.nist.gov/IAQanalysis/index.htm.

Time required for a typical run: depends on the complexity of the user-defined model (< 1 second - > 1 minute)

Operating system: Windows 98, NT/2000, XP and Vista, Contam can be run as a command line programme and can be run in a TCP/IP socket communication mode (Windows or Linux)

Degree of mastery:  intermediate expertise

Developed by: NIST (National Institute for Standards and Technologies)

Cost for using the model: free