Summary 

Sefaira does not currently support zones which span multiple levels (stories). Multiple level zones can occur in a building for a multitude of reasons, but the most common is when an atrium is a part of the design.

In this article, we will look at two different examples of an atrium; one which contains a mix of interior and exterior walls (left), and one where all of the walls are interior (right) and how Sefaira modifies each for analysis for EnergyPlus. 

1. Mix of Interior and Exterior Walls

Looking at the section of the model below, the atrium spans all three levels of the building and has a mix of interior walls and exterior glazing.

To prepare the model to run for EnergyPlus, Sefaira automatically makes simplifications to the model. These simplifications result in the multiple level zone being truncated to match the height of the first level. The interior walls will automatically be changed to exterior walls.

This is obviously a significant simplification of the intended geometry and not always obvious from within the plugin or zoning diagrams of the web application.

Workaround 

You can add floor plates to the atrium area and mark those zones as either "unconditioned" or create a custom atrium Space Use. However, this would not allow solar gains or daylight into the first or second floors.

This workaround does not provide the same results as the intended geometry so should be used with the full understanding that the dynamics of a multi-height space are not being simulated. It does however allow an envelope area which is closer to the intended geometry.

2. All Interior Walls

Looking at the section of the model below, the atrium spans all three levels of the building and is comprised of all interior glazing walls, and exterior roof glazing. 

Similar to the other example, the zone is truncated to the first level, however, the walls of the base floor are set to internal wall instead of glazing.