/occupancy-calculator

What it does

Type /as:occupancy-calculator in Claude Code and describe your building. The skill asks where your project is, retrieves the occupant load table from the code adopted there, and calculates the maximum occupant load — the number that drives egress, plumbing fixtures, and ventilation requirements.

Jurisdiction-aware. The skill establishes the jurisdiction, analysis date and adopted code edition before choosing a load factor — the NYC Building Code for New York City, the CBC in California, and the state’s adopted edition of the IBC elsewhere. It works from the original code text retrieved for the task, not a built-in table.

Every calculation shows the math: use type classification, gross vs net area, load factor, resulting occupant count, and a link to the public code source used.

Install

Claude Desktop:

1. Open Customize → Browse plugins
2. Click + → Add marketplace from GitHub
3. Enter AlpacaLabsLLC/skills-for-architects
4. Install Architecture Studio

Claude Code (terminal):

claude plugin marketplace add AlpacaLabsLLC/skills-for-architects
claude plugin install as@skills-for-architects

Or symlink just this skill:

git clone https://github.com/AlpacaLabsLLC/skills-for-architects.git
ln -s $(pwd)/skills-for-architects/skills/occupancy-calculator ~/.claude/skills/occupancy-calculator

Usage

/as:occupancy-calculator 50,000 SF office building, 3 floors

Or describe a mixed-use building:

/as:occupancy-calculator ground floor retail (8,000 SF) + 4 floors office (40,000 SF)

The skill works through four phases:

• Discover — Learns about your building and identifies use types
• Calculate — Assigns IBC load factors and calculates occupant loads per area
• Detail — Lists the egress and plumbing checks the occupant load feeds, each verified against its own code section
• Refine — Handles adjustments with before/after comparison

Demo: Mixed-Use Office Building — 50,000 SF

Real output from a session. The brief: “50K SF office, 3 floors, ground floor has a 2,000 SF café and 500 SF lobby.”

The skill classified each area independently and flagged that the café — only 4% of floor area — drives 30% of the building’s occupant load:

Area	Use Type	SF	Gross/Net	Load Factor	Occupants
Office (Floors 1-3)	Business Areas	44,000	Gross	150	294
Ground Floor Café	Assembly — Unconcentrated	2,000	Net	15	134
Café Kitchen	Kitchens — Commercial	1,500	Gross	200	8
Lobby	Business Areas	500	Gross	150	4
Storage/Mechanical	Accessory Storage	2,000	Gross	300	7
Total		50,000			447

447 total occupants requires 3 exits (>250), 90” minimum stair width, and 67” minimum corridor width.

Workplace Programmer Integration

If a program.json file exists in the working directory (from /as:workplace-programmer), the skill offers to calculate occupancy directly from the room schedule — mapping conference rooms to assembly, open desks to business, kitchens to commercial kitchen, and storage to accessory. The code occupant load is almost always higher than actual headcount.

Where the numbers come from

The skill ships no load-factor table of its own. For each space it records the area, the proposed use, the code’s gross or net basis, the load factor and the exact section it came from, all retrieved from the code in force for your project. Fixed seating, mixed uses and rounding follow that code’s own rules. If a use or measurement is ambiguous, it asks rather than picking a default.