Validation #4 - ASHRAE Eight-Story Condominium Summer Example

Reading Time: 4 minutes

Created with software version: 2024.2

To follow along with this post, download the link: condo_validation_summer.zip file.

Introduction

The eight story condominium summer conditions problem is the fourth example taken from the ASHRAE Handbook of Smoke Control Engineering, Klote et al., 2012. Chapter 14 - Network Modeling and CONTAM gives background to modeling and includes four CONTAM-W examples.

You can build off of the third ASRHAE example to run the eight-story condominium model with summer conditions in Ventus (Figure 1), and add tags to the stairwell zones. We also present several examples of results processing that you may find helpful to developing a workflow. All notes and all conditions from our Validation #3 tutorial apply to this document.

Setup

Save the condo validation.vnts Ventus file with a new name for the 'summer' conditions. After you create a copy of the condo validation.vnts file, it may be helpful to delete the results of the winter conditions simulation in the tree view. Alternatively, you can easily overwrite them later when you run the simulation. Either way, we recommended that you hide any out-of-date results when looking at the model in Ventus.

Figure 1. The building retains flowpath and zone definitions that you will use for the summer condition simulation.

Change the ambient temperature to 92 °F.

To change ambient temperature:

In the Model menu, click Weather and Wind. Click edit to enter a new Ambient Temperature of 92 °F.
Click OK to close the Ambient Temperature dialog and then click OK to close the Weather and Wind dialog.

Change the stair temperatures to 89 °F

Select all the zones for which you want to specify summer temperatures, as shown in Figure 2. Make sure to avoid selecting the stair zones on Level 54.0 ft, since the stair zones on that level are ceiling type areas above stairwell shafts. It may help to hide flowpaths and AHS zone points.

Figure 2. Selected zones in the condo building.

With appropriate zones selected:

Tag them: In the ribbon, click the + icon next to Tags: and enter stairwell. We recommend the use of tags to highlight certain volumes of the building, as done for the stairways in this example. For more information on Object Tags see the Ventus user manual.
In the ribbon, click on Temperature and enter the value 89°F. Leave the setting Constant.

Change the AHS Supplies to 3300 SCFM

Change the AHS supply settings to match the specifications of ASHRAE Example 14.4; for each supply, enter a design flowrate of 3300.0 scfm.

Simulation Preferences - Variable Air Density

This has minute effects for our scenario; we recommend that you leave that feature turned off for this validation. For more information on Variable Density, see the Ventus user manual.

Run the Simulation

Run the simulation:

On the Analysis menu, click Run Simulation.
Click OK to close the Run Simulation dialog.

Process the Results

There are several methods you can use to validate the results of this model.

Compare with CONTAM-W, as done for ASHRAE example 3

Click a flow path to display the pressure difference and flow rate; compare to CONTAM-W. Notice that the results are identical to the fifth significant figure. The small difference is due to different precision when writing the input .prj file. In most cases, Ventus uses more significant figures.

Figure 3. Compare results from the Ventus model with CONTAM-W.

Results - Door Pressure Plot - Summer

Like CONTAM-W, Ventus is designed to support the creation of shaft reports. Recall that in our validation #3 tutorial, you named the door between the stair and the hall Door1_Hall. You can use the name to search the results.

Note that whether the pressure difference is reported as positive or negative depends on the direction used when defining the flow path; the display of the results is always drawn showing the direction of pressure difference or flow.

Because the building is symmetrical, the flows and pressure differences should be the same for both stairs. Data is interchangeable for stair1 and stair2.

excel-scrn-view-plot-summer-dp-door-stair2-ashrae-4.png — Figure 4. Spreadsheet plot of door pressure difference for stair2.

The same plot data can be obtained in CONTAM-W through the "generate shaft report" tool.

Results - Stack Effect

Seasonal stack effect flow behavior is key to smoke control. Since data is symmetrical for stair1 and stair2, you can compare the stair2 and stair1 data interchangeably and plot both summer and winter stack effect together shown in Figure 5.

excel-scrn-view-plot-summer-dp-door-stair-summer-winter-ashrae-4.png — Figure 5. Spreadsheet plot of door pressure difference for winter and summer conditions.

Conclusion

If desired, you can also work with zone and flow path data in a spreadsheet, as described in detail in the Basic First Model tutorial. The ZIP file linked at the top of this document contains a complete CONTAM-W file and Ventus solution file to check your work.

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