Where to put attics, knee walls, slopes, vaults, cheek walls, etc…

[Gamaliel Lodge]

There seems to be some confusion among our Vermont users as to where all these components get modeled in OptiMiser. Here’s a quick primer:

Walls:

• The Walls page is used to model any wall above the foundation that forms a boundary between the conditioned space and the outdoors. Including:
  1. Main floor exterior walls
  2. Gable walls of conditioned attics
  3. Cheek/gable walls behind knee walls (but only if they are insulated)
• Be sure to hand calculate exterior wall area, when the building has finished attic space, lots of vaulted ceilings, or other unusual geometry
• When moving the thermal boundary behind a knee wall, use the second wall section to add the new cheek wall area on the improved side, while leaving the base area set to zero.

Attics:

• On the Attics page the Attic Areas are used to model any ceiling that forms a boundary between a conditioned space and an unconditioned buffer space such as an unconditioned attic. Including:
  1. The floor of standard full unconditioned attics
  2. The flattened peak of a conditioned attic
  3. The floor of the unconditioned space behind a knee wall (which forms the ceiling to the room below)
• When moving the thermal boundary behind a knee wall, use a separate attic section section to model the floor of that space and remove it by setting the improved area to zero.

Knee Walls:

• Knee walls are vertical boundaries between a conditioned space and an unconditioned buffer space that is also bounded by roof slope and the ceiling of the floor below.
• Knee walls are modeled using special Knee Wall sections on the Attic page.
• It is preferable to model a knee wall in association with the attic area that represents the floor of the space behind the knee wall.
• When moving the thermal boundary behind a knee wall, set improved area of that knee wall to zero.

Ceilings:

• The Ceilings page is used to model any ceiling that forms a boundary between a conditioned space and the outdoors (i.e. roofs). Including:
  1. Standard vaulted ceilings
  2. Roof slopes of a conditioned attic space
  3. Roof slopes of the space behind a knee wall (but only if insulated)
• When moving the thermal boundary behind a knee wall, use a separate Ceiling section section to add the newly insulated roof slope, leaving the base area set to zero.

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