NIST Multizone Modeling Website
Simulations
CONTAM allows you to perform several types of simulations. The type of simulation you wish to perform depends on the goal of your analysis. You can perform simulations to determine just interzonal airflows and pressure differences, or you can also have CONTAM solve for contaminant concentrations within each zone of a building. CONTAM provides the ability to perform several combinations of steady state, transient and cyclical simulations of both airflow and contaminant dispersal.
The following table shows the different combination of simulation methods you can apply using CONTAM.
| Airflow Simulation | Contaminant Simulation | Purpose |
|---|---|---|
| Steady State | None | Used to obtain airflows and pressure differentials under constant building system and/or weather conditions. |
| Steady State | Steady State | Used to obtain equilibrium contaminant concentrations under conditions of steady airflow. |
| Steady State | Transient | Used to obtain a time history of contaminant concentrations under conditions of steady airflow. This is similar to the previous table entry but will allow you to observe the contaminant concentrations for each time step leading up to the final time step. |
| Steady State | Cyclic | Used when it's important for initial contaminant concentrations to match the final concentrations under steady airflow conditions. This provides a method of simulating a typical pattern of operation by simulating only a representative time period (e.g. one day). |
| Transient | None | Used to obtain a time history of airflows and pressure differentials under changing building system and/or weather conditions. |
| Transient | Steady State | Not allowed |
| Transient | Transient | Used to obtain time histories of airflows, pressure differentials and contaminant concentrations under changing building system and/or weather conditions. |
| Transient | Cyclic | Used when it's important for initial contaminant concentrations to match the final concentrations under transient airflow conditions. This provides a method of simulating a typical pattern of operation by simulating only a representative time period (e.g. one day). |
| Steady State OR Transient | Short Time Step Method (Transient OR Cyclic) | The short time step contaminant solution method is available beginning with version 2.4. This is an explicit solution method useful when interested in rapidly changing conditions that require short time steps to capture. It is required when using the 1D zone and duct models. |
| Duct Balance | n/a | Use this feature to have ContamX adjust duct terminal balancing coefficients to provide user-defined design airflow rates at each balancing terminal. This does not perform a simulation per-say; it balances the system for upcoming simulations. |
| Building Airflow Test | n/a | Generates a set of data, mostly related to building ventilation, that enables you to review the reasonableness of your building model and the input values. |
| Pressurization Test | n/a | Performs an automated, idealized fan pressurization test to determine building envelope tightness of your building model. |
To perform a simulation, you set the simulation parameters, run the simulation, and view simulation results. Simulation parameters are categorized by Run Control, Weather, Output, Airflow and Contaminant Numerics. Run control properties include the simulation methods, simulation dates and times and time steps, Weather enables the selection of type of weather to use (steady or transient). Output properties are used to set the type and amount of data you wish to have sent to the simulation results files. Numerics properties include convergence criteria, maximum iterations and relaxation coefficients for equation solvers. ContamW provides default settings for these parameters. However, you will probably work more with the Run Control and Output parameters than any others.
