3D Building Geometry Creator

Beta Version 1.3 | 07/01/2026

What is this tool?

The Building Geometry Creator is a comprehensive web-based 3D building modeling tool designed for energy simulation workflows. It enables architects, engineers, and energy modelers to quickly create multi-level building geometry with thermal zones, windows, shading devices, and proper formatting for energy analysis software. The tool bridges the gap between conceptual design and detailed energy modeling by providing an intuitive 2D drawing interface that automatically generates 3D geometry.

This tool is provided as a standalone HTML5 application for building geometry creation. It requires no installation and runs entirely in your web browser. For support or feature requests, please contact [email protected] for support or use the Support Ticket system.

Download the tool here: 3D Building Geometry Creator V1.3

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Key Features

• Multi-Level Building Creation: Design buildings with unlimited floors/levels

• Dual Drawing Modes: Rectangle and Polygon tools for zone creation

• Angled Walls: Create tilted walls with configurable lean angles (new in V1.3)

• Sloped Ceilings: Define varying vertex heights for non-flat roof geometry (new in V1.3)

• Shading Mass Drawing: Create adjacent buildings and external shading objects for context

• Window Placement System: Manual and automatic window placement with Window-to-Wall Ratio (WWR)

• Dynamic Shading Devices: Horizontal overhangs and vertical fins with real-time preview

• Zone Management: Split zones into perimeter/core configurations for detailed energy modeling

• Zone Cutting Mode: Automatically cut overlapping zones to prevent geometry conflicts

• Real-time 3D Visualization: Interactive 3D preview with orbit controls

• Reference Levels: Ghost layers showing adjacent floors for alignment

• Multiple Import Formats: PNG/Image (with calibration), DXF (AutoCAD), SVG (Illustrator, Inkscape, Figma)

• Export Format: EpJSON (EnergyPlus)

• Grid System: Configurable grid with snap-to-grid and snap-to-corner functionality

• Level Duplication: Copy entire floors (up to 50 times) to speed up repetitive designs

• Transform Tools: Move, Copy, Rotate, Mirror, Offset, Array, Split, and Fillet operations

• Measure Tools: Distance, Area, Angle, and Perimeter measurements

• Automatic Zone Naming: Smart naming system with customizable prefixes

• Undo/Redo: Full history support for all operations

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System Requirements

Requirement	Specification
Browser	Chromium-based (Chrome, Edge, Brave)
WebGL	Enabled (for 3D visualization)
RAM	4GB minimum, 8GB recommended
Screen Resolution	1280x720 minimum, 1920x1080 recommended
Network	Not required (runs offline once loaded)

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Version History

Version	Changes
1.0	Initial release
1.1	Added dynamic shading and glazing. Resolved polygon glazing identification. Added multi-story duplication.
1.2	Added underlays (PNG/DXF/SVG import), shading masses (adjacent buildings), CFD wind analysis, zone cutting mode, reference level display, transform tools (move, copy, rotate, mirror, offset, array, split, fillet), measure tools, roof type selection, improved ribbon toolbar interface, ortho mode, corner snapping.
1.3	Added angled walls support for rectangle and polygon zones, sloped ceiling geometry with per-vertex height control, window placement on angled walls, shading devices that follow tilted wall geometry, triangulated roof export for EnergyPlus compatibility.

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Quick Start Guide

Basic Workflow (5 Steps)

Step 1: Set Up Your Canvas

• Open the tool in your web browser

• The 3D view appears by default (click "2D" to switch to floor plan view)

• Grid is automatically enabled (toggle with GRID indicator in status bar)

• Current level shows as "Level 0" (ground floor)

Step 2: Draw Your First Zone

• Switch to 2D Floor Plan view

• Select drawing mode:

  • Rectangle Mode (default): Click and drag to create rectangular zones

  • Polygon Mode: Click multiple points, double-click to close

  • Shading Mass Mode: Draw adjacent buildings for context

• Draw your zone on the canvas

• Zone automatically receives a name (e.g., "Zone 1")

• Height defaults to 3.0m (adjustable in properties)

Step 3: Add More Zones and Levels

• Continue drawing zones on current level

• To add a new level: Click the up arrow next to level display

• To duplicate a level: Click "Duplicate Level" button and enter number of copies (1-50)

Step 4: Add Windows

• Select a zone from the zones list

• Use the inline sliders in the ribbon bar for quick window placement

• Or click "Add Window" for detailed configuration including shading devices

Step 5: Export Your Model

• Click "Export" button in the ribbon toolbar

• Choose EPJSON Format for EnergyPlus simulation

• File downloads automatically

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New in Version 1.3: Angled Walls

Overview

The Angled Walls feature allows you to create buildings with tilted wall surfaces, useful for modeling tapered towers, pyramidal structures, or buildings with distinctive architectural forms. Walls can lean outward (positive angle) or inward (negative angle) from vertical.

How It Works

Each wall can be assigned an angle in degrees from vertical:

• Positive angles create an outward lean (the wall tilts away from the zone interior as it rises)

• Negative angles create an inward lean (the wall tilts toward the zone interior, creating a pyramid effect)

• Zero maintains a vertical wall (the default)

The system automatically calculates the roof vertex offsets required to maintain proper geometry where tilted walls meet at corners.

Applying Angled Walls

1. Select a zone (rectangle or polygon)

2. In the sidebar, locate the "Angled Walls" section

3. For rectangle zones: Select which wall to angle (North, South, East, West) from the dropdown

4. For polygon zones: Select which wall number to angle (Wall 1, Wall 2, etc.)

5. Enter the angle in degrees (positive = outward lean, negative = inward lean)

6. Click "Apply" to apply the angle

The 3D view updates immediately to show the tilted wall geometry. You can apply different angles to different walls to create complex forms.

Angled Walls Display

Once angled walls are applied, the current angles are displayed below the input controls. For rectangle zones this shows all four cardinal directions; for polygon zones it shows each wall number with its angle.

Clearing Angled Walls

Click the "Clear" button next to "Apply" to reset all wall angles to zero and return the zone to standard vertical walls.

Technical Notes

• Wall angles are stored per-zone as either an object (for rectangles: {north: 0, south: 14, east: 0, west: 0}) or an array (for polygons: [0, 14, 0, 0])

• The system calculates roofVertexOffsets automatically based on wall angles and zone height

• Angled walls work alongside the existing sloped ceiling feature (vertex heights)

• Properties are preserved when duplicating zones or levels

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New in Version 1.3: Sloped Ceilings

Overview

The Sloped Ceilings feature (also called Vertex Heights) allows you to create zones with non-flat roof geometry by specifying different heights at each corner of the zone.

How It Works

For rectangle zones, you can set the height at each of the four corners (NW, NE, SE, SW). The system interpolates between these heights to create a sloped surface. For polygon zones, each vertex can have its own height value.

Applying Sloped Ceilings

1. Select a zone

2. In the sidebar, locate the "Vertex Heights (Sloped Ceiling)" section

3. Click "Edit" to expand the vertex height controls

4. Enter the desired height at each vertex

5. Changes apply immediately to the 3D preview

EnergyPlus Export

Sloped ceilings are exported with proper triangulation to avoid coplanar surface errors in EnergyPlus:

• Rectangular roofs are split into 2 triangles using the optimal diagonal

• Polygon roofs use fan triangulation for multiple triangle surfaces

• Wall heights are interpolated correctly to match the sloped roof geometry

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Windows on Angled Walls

Automatic Adjustment

When you add windows to a zone with angled walls, the system automatically:

• Tilts the window to match the wall angle

• Positions the window at the correct location on the tilted surface

• Calculates proper vertex offsets for the EPJSON export

3D Preview

In the 3D view, windows on angled walls appear tilted to match the wall surface. This gives you an accurate preview of how the final geometry will look.

Export Accuracy

The EPJSON export calculates the correct 3D coordinates for each window vertex based on:

• The window's position along the wall

• The window's height (sill height + window height)

• The wall's tilt angle

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Shading Devices on Angled Walls

Overview

Shading devices (horizontal overhangs and vertical fins) now correctly follow the tilted wall geometry when applied to zones with angled walls.

How It Works

When you add shading to a window on an angled wall:

Horizontal Overhangs:

• The overhang is positioned at the actual tilted wall location at the shading height

• For a wall with angle θ at height z, the overhang is offset outward by z × tan(θ) from the base wall position

• The overhang projects outward from this adjusted position

Vertical Fins:

• Fins follow the wall tilt from bottom to top

• The bottom of the fin is positioned at the wall location at sill height

• The top of the fin is positioned at the wall location at the top of the window

• This creates a parallelogram-shaped surface that follows the tilted wall

3D Preview

The 3D view shows shading devices tilted to match the wall angle, giving you an accurate preview of the final geometry.

Export Accuracy (Fixed in V1.3)

Previous versions exported shading surfaces at the base wall position regardless of wall angle, which caused shadings to appear inverted toward the interior when viewed in EnergyPlus. Version 1.3 fixes this by calculating proper vertex positions that account for the wall tilt.

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Drawing Tools

Rectangle Mode

• Activation: Click Rectangle button or press 'R'

• Usage: Click and drag from corner to corner

• Grid Snap: Automatically snaps to grid when enabled

• Corner Snap: Snaps to existing zone corners

• Real-time Feedback: Shows dimensions while drawing

• Dimension Input: Type exact dimensions after starting to draw

Polygon Mode

• Activation: Click Polygon button or press 'P'

• Usage: Click to place vertices, double-click to close polygon

• Constraints: Minimum 3 vertices required

• Self-intersection: Automatically detected and prevented

• Ortho Mode: Press F8 to constrain to 90° angles

Shading Mass Mode

• Activation: Click Shading Mass button or press 'S'

• Purpose: Draw adjacent buildings, trees, or other external shading objects

• Usage: Click and drag to create rectangular masses

• Visualization: Displayed in purple to distinguish from thermal zones

• Export: Included as shading surfaces in EpJSON export

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Zone Management

Zone Properties

Property	Description
Name	Unique identifier (auto-generated or custom)
Height	Vertical dimension in meters (default 3.0m)
Level	Floor assignment (automatically set)
Base Height	Height from ground (auto-detected or manual override)
Windows	List of associated windows
Area	Automatically calculated floor area
Wall Angles	Per-wall tilt angles in degrees (new in V1.3)
Vertex Heights	Per-vertex ceiling heights for sloped geometry (new in V1.3)

Zone Selection

• 2D View: Click on zone to select

• 3D View: Click on zone geometry

• List: Click zone name in sidebar

• Multi-select: Hold Shift for multiple zones

Zone Operations

Edit Zone:

• Select zone

• Modify properties in sidebar

• Changes apply immediately

Delete Zone:

• Select zone

• Click delete button (trash icon) or press Delete key

• Confirm deletion

Split Zone (Perimeter/Core):

• Select rectangular zone

• Click "Split" button in ribbon toolbar

• Set perimeter depth (typically 3-5m)

• Creates 5 zones: North, South, East, West perimeter zones plus Core zone

Zone Cutting Mode:

• Toggle "CUTTING" indicator in status bar

• When enabled, new zones automatically cut through existing zones

• Prevents overlapping geometry

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Transform Tools

Located in the ribbon toolbar, these tools work on selected zone(s):

Tool	Shortcut	Description
Move	M	Drag zones to new position
Copy	C	Duplicate zones with offset
Rotate	O	Rotate zones by specified angle
Mirror	I	Flip zones horizontally or vertically
Offset	-	Create offset copies at specified distance
Array	-	Create linear or rectangular arrays
Split	-	Divide zone into perimeter/core
Fillet	-	Round corners of rectangular zones

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Measure Tools

Tool	Description
Distance	Measure point-to-point distance
Area	Calculate selected zone area
Angle	Measure angle between three points
Perimeter	Calculate zone perimeter length

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Level System

Level Navigation

• Up/Down Arrows: Move between levels

• Level Display: Shows current level name and elevation

• Level Info: Displays height above ground

• Overview: Shows total number of levels

Reference Levels (Ghost Layers)

• Show Level Below: Toggle to see zones from level below (displayed in light blue)

• Show Level Above: Toggle to see zones from level above (displayed in light orange)

• Purpose: Helps align zones across floors and verify vertical stacking

Level Operations

Add Level:

• Navigate up from highest level

• Creates new level 3m above previous

• Customizable height in settings

Duplicate Level:

• Click "Duplicate Level" button

• Select number of copies (1-50)

• Options: Include windows, Include shading surfaces, Replace existing zones

• Creates multiple copies above current level

Delete Level:

• Navigate to level

• Delete all zones on level

• Level automatically removed when empty

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Window System

Quick Window Controls (Ribbon Bar)

When in 2D view with a zone selected, the ribbon bar displays inline sliders:

Control	Range	Description
Sill Height	0.3 - 1.5m	Distance from floor to window bottom
Window Height	0.8 - 2.5m	Vertical height of windows
Width	10 - 95%	Window width as percentage of wall
WWR Display	-	Real-time calculated Window-to-Wall Ratio

Window Placement Methods

Single Window Placement:

1. Select zone

2. Click "Add Window"

3. Choose wall (North/South/East/West)

4. Set position along wall

5. Define width and height

6. Set sill height

Multiple Windows:

1. Select zone

2. Choose "Multiple Windows" mode

3. Set number of windows

4. Choose distribution (Even Spacing, Full Wall, Fixed Spacing, Custom Start Position)

Window-to-Wall Ratio (WWR):

1. Click "WWR" button

2. Configure scope (Selected/Level/Building), percentage, sill height, window height, layout

3. Windows automatically calculated and placed

Window Properties

Property	Description
Position	X/Y coordinates on wall
Dimensions	Width × Height
Sill Height	Distance from floor
Wall	Orientation (N/S/E/W)
Zone	Parent zone reference

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Shading Devices

Horizontal Overhangs

Setting	Description
Overhang Depth	How far extends from wall (mm)
Overhang Count	Number of parallel overhangs
Height Above Window	Vertical gap from window top (mm)

Vertical Fins

Setting	Description
Fin Depth	How far extends from wall (mm)
Fin Count Per Side	Number on left and right
Fin Width	As percentage of wall length
Fin Spacing	Distance between multiple fins (mm)

Dynamic Shading Controls (Ribbon Bar)

When shading toggle is enabled:

• Choose scope: Zone, Level, or Building

• Toggle Horizontal (H) or Vertical (V) shading types

• Adjust sliders in real-time: Depth (0.01 - 2.0m), Count (1 - 8)

• See immediate preview in 3D view

Shading on Angled Walls

When applied to zones with angled walls, shading devices automatically:

• Position at the correct tilted wall location based on height

• Tilt to match the wall angle

• Export with proper vertex coordinates for EnergyPlus

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Roof Types

For the top level only (selected in sidebar):

Roof Type	Description
Flat Roof	Default, standard horizontal roof
Pitched Roof (Gable)	Sloped roof with configurable pitch angle and overhang

Pitched Roof Settings:

• Roof Pitch: 5° - 60° (default 30°)

• Overhang: 0 - 2m (default 0.5m)

Note: Pitched roofs are exported as shading surfaces in EnergyPlus.

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3D Visualization

View Controls

• Toggle Views: Click 2D, 3D, or CFD buttons in status bar

• Orbit: Left-click and drag to rotate

• Pan: Right-click and drag to move

• Zoom: Scroll wheel or pinch gesture

• Reset: Double-click to reset view

Display Options (3D View Status Bar)

Toggle	Description
WALLS	Show/hide wall surfaces
ROOFS	Show/hide roof surfaces
FLOORS	Show/hide floor surfaces
WINDOWS	Show/hide window subsurfaces

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Import Functions

PNG/Image Import (Background Trace)

1. Click Import → PNG/Image (Trace)

2. Select image file (PNG, JPG, JPEG, GIF, WEBP)

3. Calibrate scale: Click two points on image, enter known distance

4. Adjust position and opacity

5. Trace over image in 2D view

DXF Import

1. Click Import → DXF File

2. Select DXF file

3. Configure options: Scale Factor, Zone Height, Closed polylines only, Clear existing zones, Merge adjacent cells

4. Select layers to import

5. Click Import Zones

SVG Import

1. Click Import → SVG File

2. Select SVG file

3. Configure options: Scale Factor, Zone Height, Closed paths only, Clear existing zones

4. Select elements to import

5. Click Import Zones

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Export Functions

EPJSON Format Export

Purpose: EnergyPlus energy simulation

Contents:

• Building geometry

• Zone definitions

• Surface constructions

• Window subsurfaces

• Shading surfaces (overhangs, fins, masses, pitched roofs)

• Zone names and properties

• Boundary conditions

• Air walls for split zones

Compatible Software:

• EnergyPlus 9.0+

• OpenStudio

• Other EpJSON-compatible tools

Export Improvements in V1.3

• Sloped roofs are triangulated to avoid coplanar surface errors

• Wall heights are interpolated for sloped ceiling geometry

• Angled wall vertices are calculated correctly

• Shading surfaces follow tilted wall positions

• Windows on angled walls export with proper tilt

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Grid System

Grid Controls

Control	Description
GRID Toggle	Show/hide grid (G key)
SNAP Toggle	Cycle snap modes (click to cycle)
Grid Spacing	Input field in status bar (meters)
ORTHO Toggle	Constrain to 90° angles (F8 key)

Snap Modes (Cycle with click)

• Grid + Corners: Snap to grid and zone corners

• Grid Only: Snap only to grid intersections

• Corners Only: Snap only to zone corners

• Off: Free drawing

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Keyboard Shortcuts

Shortcut	Action
R	Rectangle mode
P	Polygon mode
S	Shading Mass mode
G	Toggle grid
F8	Toggle Ortho mode
M	Move tool
C	Copy tool
O	Rotate tool
I	Mirror tool
Delete	Delete selected zone
Ctrl+Z	Undo
Ctrl+Y	Redo
Ctrl+D	Duplicate selected zone
Space	Toggle 2D/3D view
↑/↓	Navigate levels
Escape	Cancel current operation
Enter	Confirm dialog
Tab	Switch input fields

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Workflow Examples

Example 1: Tapered Tower with Angled Walls

Goal: Create a tower that tapers inward as it rises

Steps:

1. Ground Floor (2 minutes):

   • Draw 20m × 20m rectangle

   • Set height to 4m

   • Apply 40% WWR to all walls

2. Apply Angled Walls (1 minute):

   • Select the zone

   • In Angled Walls section, select "All Walls"

   • Enter angle: -5 (negative for inward lean)

   • Click Apply

   • 3D view shows tapering effect

3. Duplicate Floors (30 seconds):

   • Click "Duplicate Level"

   • Enter 9 copies for 10 floors total

   • Include windows option

4. Add Shading (1 minute):

   • Enable shading controls

   • Add 0.5m horizontal overhangs

   • Shading follows the angled walls

5. Export (30 seconds):

   • Export as EPJSON

   • All angled geometry exports correctly

Result: 10-story tapered tower with proper window and shading geometry

Example 2: Building with Sloped Roof

Goal: Create office building with sloped ceiling on top floor

Steps:

1. Create Typical Floors (3 minutes):

   • Draw floor plan

   • Duplicate for 4 floors

   • Add windows

2. Apply Sloped Ceiling (1 minute):

   • Navigate to top floor

   • Select zone

   • In Vertex Heights section, click Edit

   • Set NW and NE corners to 4.0m

   • Set SW and SE corners to 3.0m

   • Creates south-sloping roof

3. Export (30 seconds):

   • Roof triangulates automatically

   • No coplanar surface errors

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Best Practices

Angled Walls

• Keep angles moderate (under 20°) for realistic building geometry

• Verify 3D preview before export

• Use consistent angles across a level for uniform appearance

• Combine with sloped ceilings for complex roof forms

Sloped Ceilings

• Set vertex heights before adding windows on walls that will change height

• Use interpolated heights consistently (the system calculates wall heights automatically)

• Check that roof triangulation looks correct in 3D view

Shading on Angled Walls

• Add shading after applying wall angles

• Verify in 3D view that shadings project outward correctly

• For complex angles, check exported geometry in EnergyPlus

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Troubleshooting

Issue: Angled Walls Not Appearing

Symptoms: Applied angle but walls appear vertical

Solutions:

• Ensure angle value is not zero

• Click Apply button after entering angle

• Check 3D view (angled walls may not be visible in 2D)

• Verify zone is selected

Issue: Shading Appears Inside Building

Symptoms: Shading devices face interior instead of exterior

Solutions:

• Update to V1.3 or later (this was fixed in V1.3)

• Re-apply shading after updating

• Verify wall angle direction (positive = outward lean)

Issue: EnergyPlus Coplanar Surface Error

Symptoms: Export fails validation with coplanar surface error

Solutions:

• Update to V1.3 (sloped roofs now triangulate automatically)

• Check for very small height differences at vertices

• Simplify complex sloped geometry

Issue: Windows Not Tilting with Angled Walls

Symptoms: Windows appear vertical on angled walls

Solutions:

• Delete and re-add windows after applying wall angles

• Verify wall angle is applied (check Angled Walls display)

• Update to latest version

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Glossary

Term	Definition
WWR	Window-to-Wall Ratio - percentage of wall area occupied by windows
CFD	Computational Fluid Dynamics - simulation of fluid flow
EPW	EnergyPlus Weather file format
EpJSON	EnergyPlus JSON format for building models
Sill Height	Distance from floor to bottom of window
Perimeter Zone	Zone adjacent to exterior wall
Core Zone	Interior zone not touching exterior walls
Air Wall	Internal boundary with no thermal resistance
Shading Mass	External object providing shade (adjacent building, etc.)
Ortho Mode	Drawing constraint limiting to horizontal/vertical lines
Wall Angle	Tilt of wall from vertical in degrees (new in V1.3)
Vertex Height	Height at a specific corner for sloped ceiling (new in V1.3)
Roof Triangulation	Splitting sloped roof into triangles for EnergyPlus export (new in V1.3)

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Data Structures

Zone Object

{
  id: number,
  name: string,
  type: 'rectangle' | 'polygon',
  level: number,
  x: number,      // For rectangles
  y: number,
  width: number,
  depth: number,
  height: number,
  baseHeight: number,
  points: [{x, y}],  // For polygons
  windows: [],
  wallAngles: {north: 0, south: 0, east: 0, west: 0},  // For rectangles (V1.3)
  // or wallAngles: [0, 0, 0, 0]  // For polygons (V1.3)
  roofVertexOffsets: [{dx, dy}, ...],  // Calculated from wall angles (V1.3)
  vertexHeights: [h1, h2, h3, h4]  // For sloped ceilings (V1.3)
}

Window Object

{
  id: number,
  zoneId: number,
  wall: 'north' | 'south' | 'east' | 'west',
  position: number,
  width: number,
  height: number,
  sillHeight: number,
  shadings: []
}

Shading Mass Object

{
  id: number,
  name: string,
  x: number,
  y: number,
  width: number,
  depth: number,
  height: number
}

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Export Specifications

Geometry Precision

Element	Precision
Coordinates	3 decimal places (mm precision)
Angles	1 decimal place
Areas	2 decimal places
Volumes	2 decimal places

EPJSON Structure

• Compliant with EnergyPlus 9.0+

• Includes all required objects

• Validates against schema

• Proper surface matching

• Automatic boundary conditions

• Air walls for split zones

• Triangulated sloped roofs (V1.3)

• Angled wall vertex calculations (V1.3)

• Tilted window coordinates (V1.3)

• Correctly positioned shading surfaces (V1.3)