There is nowhere in the Room or Room type properties that allow one to change the computational height of the room.
Why would one want to change the computational height? Consider a room that is bound by a slanted wall. What is the area? What is the Volume? What is the shape of the room?
Consider the Room shown below. One wall is slanted. If the walls were all vertical 5m x 5m, then the area would be 25 m^2. With the levels being 4m apart, the levels are 4m apart, so the volume would be 100m.
To change the computational height of a room, one needs to change the computational height of the level. This also alters at which height the room’s cross-sectional perimeter is used to infer the volume.
To change this height, alter the value in the instance property of the level.
Consider the table of values below. Clearly that the computational height determines the level at which the area is calculated, and that this area is used to multiply by the room height to calculate the volume.
Look at how the volume of the room adjusts to the computational height. Here it is shown for 2m.
And here for 3.995m. It is not possible to choose the upper bound of the room as it will fail.
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