Walls

Walls are the primary component of the building envelope, separating conditioned spaces from the outdoors and other unconditioned areas.

You work with walls in Building Model → Envelope, on the Walls tab.

Assigning Wall Types

HVAKR treats every space edge as a potential wall. An edge on the building perimeter is exterior; an edge shared between two spaces is interior. You assign wall types to those edges either automatically or by hand.

Auto Create Envelope

The fastest way to assign walls is Auto Create Envelope (the ✨ button in the toolbar). It finds unassigned exterior edges and spaces and applies the wall type you choose — along with roofs and slabs — across All Levels or the current level. Automations never override existing assignments, so it’s safe to run again as you add spaces.

Assign walls manually

1. On the Walls tab, click Assign Walls.
2. Choose Simple Wall (a single Wall Type) or Multi-Segment Wall (wall types stacked bottom to top, each with a height — the top segment auto-fills the remaining space height).
3. Under Options, leave Limit wall assignment to exterior on to ignore interior line segments, or turn it off to assign interior walls too. Optionally enable Separate wall load between ceiling and space.
4. Click Assign Walls.
5. Click walls on the canvas to toggle the wall type on each segment.
6. Click Done when finished.

Edit a wall

Select a wall from the Walls list, or click it on the canvas, to open the Wall Data panel.

Wall Data

Selecting a wall opens Wall Data, where you can set:

• Simple Wall / Multi-Segment Wall — switch between a single assembly and a stack of wall types by height.
• Wall Type — links to the wall type definition from Basis of Design, which supplies the U-value, mass, and surface absorptance used in the calculations.
• Wall Angle — the surface tilt, defaulting to 90° (vertical).
• Separate wall load between ceiling and space — splits the wall load between the ceiling and the space based on the slab-height-to-space-height ratio.

Orientation and area aren’t set here — HVAKR derives them automatically from the wall’s geometry and the building’s Plan Rotation, and uses them for the transmission and solar calculations.

Interior vs. Exterior

Exterior Walls

Walls separating conditioned space from outdoors:

• Subject to outdoor design temperatures
• Include solar absorption effects
• Affect both heating and cooling loads

Interior Walls

Walls between conditioned spaces:

• Usually no heat transfer if spaces are at the same temperature
• May need to account for temperature differences between spaces

Below-Grade Walls

HVAKR has no dedicated below-grade wall mode. To model a basement wall against soil, use a wall type whose Summer and Winter External Temperature Override are set to the ground temperature. Both are advanced fields on the wall type in Basis of Design → Building Data.

Modeling Considerations

Thermal Bridges

Account for structural elements that bypass insulation by setting an effective U-value on the wall type:

• Steel studs through insulation
• Concrete slab edges
• Window frames and mullions

Common Issues

No Wall Types Defined

If a project has spaces but no wall types, the project Check warns that walls won’t contribute to load calculations. Define at least one wall type in Basis of Design → Building Data, then assign it.

Unassigned Exterior Walls

Exterior edges without a wall type don’t transmit heat, which understates loads. Run Auto Create Envelope or Assign Walls so every exterior edge is covered.

Incorrect Orientation

Because orientation is derived from geometry, make sure the plan is oriented correctly — the Plan Rotation dial sets the building’s north, and an incorrect rotation skews the solar calculations.