Simulating Thermal Comfort

Because thermal comfort is derived from the flow and heat transfer results computed by Autodesk Simulation CFD, it can be enabled either before running or after the solution is complete.

Basic analysis considerations

Flow

• Breeze (external wind/wake) and/or vent velocity: specify either a velocity or volumetric flow rate
• If buoyancy is a consideration due to thermal gradients, select Variable on the Environment dialog.
• Specify a pressure boundary condition at outlets (vent returns)

Thermal

• Specify the air temperature at all inlets. This is required.
• Specify U-values on windows and walls (as needed) as solid material thermal conductivities.
• Specify known heat generation boundary conditions on lighting, electronics, and equipment. Do not specify temperatures on components that will be solved for in the simulation.
• Specify film coefficients (as needed) to exterior surfaces to simulate heat transfer with the surrounding environment. (External wall surfaces that do not have an applied heat transfer boundary condition are treated as perfectly insulated.)
• Assign a heat generation boundary condition on the human forms. This is needed to simulate the amount of heat each human dissipates. The Metabolic rate table below lists heat generation rates for a range of activities.

On the Solve dialog, enable both Flow and Heat Transfer. Radiation is optional.

Note: For best results, enable Radiation after the simulation has completed, set the Iterations to Run to 0, and click Solve. This allows the Thermal Comfort calculation to use the geometric view factors computed by the radiation solver. If, however, the model size is so large that radiation cannot be reasonably run, view factors are automatically computed using an approximate projection method that is much less resource intensive.

To enable Thermal Comfort prior to running an analysis

1. On the Control tab of the Solve dialog, click the Results quantities button.
2. Check the Thermal comfort box.
3. To define the characteristics of the environment, click the adjacent Factors button.

To enable Thermal comfort for a completed analysis

1. Enable the Thermal comfort result quantity as described above.
2. On the Control tab of the Solve dialog, leave the Continue From field at the last iteration.
3. Set the Iterations to run to be 0, and click Solve.

The analysis will appear to start, but will not solve any additional iterations. The thermal comfort results are then computed and made available for visualization.