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My understanding is that yes: for a vertical façade cavity under strictly buoyancy-driven flow (no wind), and with equally-sized and equally-spaced openings at the top and bottom of the cavity, the height scale (in m) should be half the total height of the vented cavity. If cavity openings are neither equally-spaced nor equally-sized, then the neutral pressure level (or NPL), under strictly buoyancy-driven ventilation, would either shift up or down from mid-height. I suggest the following reference (2nd to 3rd page), as well the EnergyPlus Engineering Reference.

My understanding is that yes: In theory, for a vertical façade cavity under strictly buoyancy-driven flow (no wind), and with equally-sized and equally-spaced openings at the top and bottom of the cavity, the height scale (in m) should be half the total height of the vented cavity. If cavity openings are neither equally-spaced nor equally-sized, then the neutral pressure level (or NPL), under NPL) should be at mid-height of the vented cavity. If cavity openings are neither equally-spaced nor equally-sized, then the NPL (under strictly buoyancy-driven ventilation, ventilation) would either shift up or down from mid-height. I suggest the following reference reference (2nd to 3rd page), as well the EnergyPlus page).

In the EnergyPlus, I think there are a few built-in simplifications (see Engineering Reference.). From what I gather, one assumption is that top and bottom openings are equally-sized and positioned, and are coplanar with the cavity façade (or baffle). So the NPL is assumed to be mid-height of the cavity, and the height scale is "defined as the height from the midpoint of the lower opening to the neutral pressure level". So not half the total height of the cavity, but close.

In theory, for a vertical façade cavity under strictly buoyancy-driven flow (no wind), and with equally-sized and equally-spaced openings at the top and bottom of the cavity, the neutral pressure level (or NPL) should be at mid-height of the vented cavity. If cavity openings are neither equally-spaced nor equally-sized, then the NPL (under strictly buoyancy-driven ventilation) would either shift up or down from mid-height. I suggest the following reference (2nd to 3rd page).

In the EnergyPlus, I think there are a few built-in simplifications (see Engineering Reference). From what I gather, one assumption is that top and bottom openings are equally-sized and positioned, and are coplanar with the cavity façade (or baffle). So the NPL is assumed to be mid-height of the cavity, and the height scale is "defined as the height from the midpoint of the lower opening to the neutral pressure level". So not half the total height of the cavity, but close.

I'm assuming (and may be quite wrong) that the lower and upper cavities are assumed to be really near the bottom and top of the baffle, yet the height scale sets in part the geometry of the openings (as "increasing the value [of the height scale] will increase the ventilation rate due to buoyancy"). Hope this helps.

In theory, for a vertical façade cavity under strictly buoyancy-driven flow (no wind), and with equally-sized and equally-spaced openings at the top and bottom of the cavity, the neutral pressure level (or NPL) should be at mid-height of the vented cavity. If cavity openings are neither equally-spaced nor equally-sized, then the NPL (under strictly buoyancy-driven ventilation) would either shift up or down from mid-height. I suggest the following reference (2nd to 3rd page).

In EnergyPlus, I think there are a few built-in simplifications (see Engineering Reference). From what I gather, one assumption is that top and bottom openings are equally-sized and positioned, and are coplanar with the cavity façade (or baffle). So the NPL is assumed to be mid-height of the cavity, and the height scale is "defined as the height from the midpoint of the lower opening to the neutral pressure level". So not half the total height of the cavity, but close.

I'm assuming (and may be quite wrong) that the lower and upper cavities openings are assumed to be really near the bottom and top of the baffle, yet the height scale sets in part the geometry of the openings (as "increasing the value [of the height scale] will increase the ventilation rate due to buoyancy"). Hope this helps.

In theory, for a vertical façade cavity under strictly buoyancy-driven flow (no wind), and with equally-sized and equally-spaced openings at the top and bottom of the cavity, the neutral pressure level (or NPL) should be at mid-height of the vented cavity. If cavity openings are neither equally-spaced nor equally-sized, then the NPL (under strictly buoyancy-driven ventilation) would either shift up or down from mid-height. I suggest the following reference (2nd to 3rd page).

In EnergyPlus, I think there are a few built-in simplifications (see Engineering Reference). From what I gather, one assumption is that top and bottom openings are equally-sized and positioned, and are coplanar with the cavity façade (or baffle). So the NPL is assumed to be mid-height of the cavity, and the height scale is "defined as the height from the midpoint of the lower opening to the neutral pressure level". So not half the total height of the cavity, but close.

I'm assuming (and may be quite wrong) that the lower and upper openings are assumed to be really near the bottom and top of the baffle, yet the height scale sets in part the geometry of the openings (as "increasing the value [of the height scale] will increase the ventilation rate due to buoyancy"). Hope this helps.

In theory, for a vertical façade cavity under strictly buoyancy-driven flow (no wind), and with equally-sized and equally-spaced openings at the top and bottom of the cavity, the neutral pressure level (or NPL) should be at mid-height of the vented cavity. If cavity openings are neither equally-spaced nor equally-sized, then the NPL (under strictly buoyancy-driven ventilation) would either shift up or down from mid-height. I suggest the following reference (2nd to 3rd page).

In EnergyPlus, I think there are a few built-in simplifications (see Engineering Reference). From what I gather, one assumption is that top and bottom openings are equally-sized and positioned, and are coplanar with the cavity façade (or baffle). So the NPL is assumed to be mid-height of the cavity, and the height scale is "defined as the height from the midpoint of the lower opening to the neutral pressure level". So not half the total height of the cavity, but close.

I'm assuming (and may be quite wrong) that the lower and upper openings are assumed to be really near the bottom and top of the baffle, yet the height scale sets in part the geometry of the openings (as "increasing the value [of the height scale] will increase the ventilation rate due to buoyancy"). Hope this helps.

EDIT: See original NREL report.

In theory, for a vertical façade cavity under strictly buoyancy-driven flow (no wind), and with equally-sized and equally-spaced openings at the top and bottom of the cavity, the neutral pressure level (or NPL) should be at mid-height of the vented cavity. If cavity openings are neither equally-spaced nor equally-sized, then the NPL (under strictly buoyancy-driven ventilation) would either shift up or down from mid-height. I suggest the following reference (2nd to 3rd page).

In EnergyPlus, I think there are a few built-in simplifications (see Engineering Reference). From what I gather, one assumption is that top and bottom openings are equally-sized and positioned, and are coplanar with the cavity façade (or baffle). So the NPL is assumed to be mid-height of the cavity, and the height scale is "defined as the height from the midpoint of the lower opening to the neutral pressure level". So not half the total height of the cavity, but close.

I'm assuming (and may be quite wrong) that the lower and upper openings are assumed to be really near the bottom and top of the baffle, yet the height scale sets in part the geometry of the openings (as "increasing the value [of the height scale] will increase the ventilation rate due to buoyancy"). Hope this helps.

EDIT: See original NREL report.

EDIT 2

While I agree with @Aaron Boranian that your follow-up question should be an edit to your initial question (or instead broken down as multiple comments), I can quickly provide a short answer: Based on your description, the height scale should be approximately (or slightly less?) than 1.35m for a 2.70m compartmentalized cavity.

EnergyPlus will take care of the change in wind speed based on the 3D position of the referenced BuildingSurface:Detailed.

In theory, for a vertical façade cavity under strictly buoyancy-driven flow (no wind), and with equally-sized and equally-spaced openings at the top and bottom of the cavity, the neutral pressure level (or NPL) should be at mid-height of the vented cavity. If cavity openings are neither equally-spaced nor equally-sized, then the NPL (under strictly buoyancy-driven ventilation) would either shift up or down from mid-height. I suggest the following reference (2nd to 3rd page).

In EnergyPlus, I think there are a few built-in simplifications (see Engineering Reference). From what I gather, one assumption is that top and bottom openings are equally-sized and positioned, and are coplanar with the cavity façade (or baffle). So the NPL is assumed to be mid-height of the cavity, and the height scale is "defined as the height from the midpoint of the lower opening to the neutral pressure level". So not half the total height of the cavity, but close.

I'm assuming (and may be quite wrong) that the lower and upper openings are assumed to be really near the bottom and top of the baffle, yet the height scale sets in part the geometry of the openings (as "increasing the value [of the height scale] will increase the ventilation rate due to buoyancy"). Hope this helps.

EDIT: See original NREL report.

EDIT 2

While I agree with @Aaron Boranian that In response to your follow-up question should be an edit to your initial question (or instead broken down as multiple comments), I can quickly provide a short answer: (1.35m vs 14.35m) under "Update": Based on your description, the height scale should be approximately (or slightly less?) than 1.35m for a 2.70m compartmentalized cavity.

EnergyPlus will take care of the change in wind speed based on the 3D position of the referenced BuildingSurface:Detailed.