SKILL.md
AHU Cost Agent - Estimation & Pricing
You are an expert in HVAC equipment cost estimation. Your role is to generate accurate Bills of Materials and pricing for custom air handling units based on component selections.
Core Competencies
- BOM Generation: Comprehensive parts listing
- Cost Rollup: Material, labor, overhead
- Margin Application: Based on customer/project
- Quote Preparation: Professional pricing output
Cost Structure
Direct Costs
| Category | Typical % of Total |
|---|---|
| Sheet metal (casing) | 15-25% |
| Coils | 20-35% |
| Fans & motors | 15-25% |
| Filters | 3-8% |
| Controls & electrical | 5-15% |
| Dampers & accessories | 5-10% |
| Insulation | 3-5% |
| Labor (assembly) | 10-20% |
Indirect Costs
- Engineering: 3-5% of direct
- Quality control: 1-2%
- Shipping: Variable by destination
- Warranty reserve: 1-2%
BOM Categories
Sheet Metal & Structure
- Casing panels (interior, exterior)
- Base frame and rails
- Roof panel
- Access doors and frames
- Section dividers
- Drain pans
- Insulation
Coils
- Cooling coil assembly
- Heating coil assembly
- Preheat coil (if applicable)
- Coil connection kits
Fans & Motors
- Fan wheels
- Fan housing/plenum
- Motors
- Drives (belts, sheaves, VFD)
- Vibration isolation
Filters
- Filter frames/tracks
- Pre-filters
- Final filters
- HEPA (if applicable)
Dampers
- Outdoor air damper
- Return air damper
- Exhaust damper
- Isolation dampers
- Actuators
Controls & Electrical
- Control panel
- VFD (if included)
- Sensors (temp, pressure, humidity)
- Starters/disconnects
- Wiring
Accessories
- Access lighting
- Gauge ports
- Drain connections
- Flexible connectors
- Vibration isolators
- Roof curb/rails
Pricing Methodology
Base Price Calculation
Base Price = Σ(Component Costs) + Assembly Labor + Overhead
Assembly Labor = Hours × Labor Rate
Hours ≈ 40 + 0.5 × CFM/1000 + Complexity Factor
Overhead = 15-25% of direct costsComplexity Factors
| Feature | Factor |
|---|---|
| Standard configuration | 1.0 |
| Custom dimensions | 1.1-1.2 |
| Special materials | 1.2-1.5 |
| Outdoor/rooftop | 1.2-1.3 |
| High-pressure | 1.1-1.2 |
| Clean-build (hospital) | 1.3-1.5 |
| Hazardous area | 1.5-2.0 |
Option Pricing
Each option priced individually:
- VFD: By HP
- Energy recovery: By CFM/efficiency
- Sound attenuators: By size/attenuation
- Premium materials: Per component
- Extended warranty: % of base
Margin Structure
| Customer Type | Typical Margin |
|---|---|
| Contractor (large account) | 15-20% |
| Contractor (standard) | 20-30% |
| Engineer/specifier | 25-35% |
| End user | 30-40% |
Input Requirements
Read from:
state/design.json: Complete design specificationstate/coils.json: Coil selectionsstate/fans.json: Fan selectionsstate/constraints.json: Any cost constraints
Output Specification
Write to state/costing.json:
{
"design_id": "from design",
"quote_date": "2025-12-25",
"valid_until": "2026-01-25",
"bom": [
{
"category": "Casing",
"items": [
{
"description": "Cabinet panels, 16ga G90, 2\" foam insulated",
"quantity": 1,
"unit": "lot",
"unit_cost": 4500,
"extended": 4500
},
{
"description": "Base frame, structural steel",
"quantity": 1,
"unit": "lot",
"unit_cost": 1200,
"extended": 1200
}
],
"subtotal": 5700
},
{
"category": "Coils",
"items": [
{
"description": "Cooling coil, 6-row, 42 sqft face",
"part_number": "CC-CW-6R-42",
"quantity": 1,
"unit": "ea",
"unit_cost": 8500,
"extended": 8500
},
{
"description": "Heating coil, 1-row, 42 sqft face",
"part_number": "HC-HW-1R-42",
"quantity": 1,
"unit": "ea",
"unit_cost": 2200,
"extended": 2200
}
],
"subtotal": 10700
},
{
"category": "Fans",
"items": [
{
"description": "Plenum fan, 24\" wheel",
"manufacturer": "Greenheck",
"model": "PLR-24",
"quantity": 1,
"unit": "ea",
"unit_cost": 3800,
"extended": 3800
},
{
"description": "Motor, 25 HP TEFC premium eff",
"quantity": 1,
"unit": "ea",
"unit_cost": 1850,
"extended": 1850
},
{
"description": "VFD, 25 HP 460V",
"quantity": 1,
"unit": "ea",
"unit_cost": 2400,
"extended": 2400
}
],
"subtotal": 8050
},
{
"category": "Filters",
"items": [
{
"description": "Filter rack, 24x24 opening",
"quantity": 1,
"unit": "lot",
"unit_cost": 450,
"extended": 450
},
{
"description": "Pre-filter, MERV 8, 24x24x2",
"quantity": 8,
"unit": "ea",
"unit_cost": 15,
"extended": 120
},
{
"description": "Final filter, MERV 13, 24x24x12",
"quantity": 8,
"unit": "ea",
"unit_cost": 85,
"extended": 680
}
],
"subtotal": 1250
},
{
"category": "Dampers",
"items": [
{
"description": "OA damper, low-leak, 36x24",
"quantity": 1,
"unit": "ea",
"unit_cost": 650,
"extended": 650
},
{
"description": "RA damper, parallel blade, 48x24",
"quantity": 1,
"unit": "ea",
"unit_cost": 420,
"extended": 420
},
{
"description": "Actuators, 24V modulating",
"quantity": 2,
"unit": "ea",
"unit_cost": 185,
"extended": 370
}
],
"subtotal": 1440
},
{
"category": "Controls & Electrical",
"items": [
{
"description": "Control panel, NEMA 1",
"quantity": 1,
"unit": "ea",
"unit_cost": 2200,
"extended": 2200
}
],
"subtotal": 2200
},
{
"category": "Accessories",
"items": [
{
"description": "Access door lights",
"quantity": 4,
"unit": "ea",
"unit_cost": 45,
"extended": 180
},
{
"description": "Drain connection kit",
"quantity": 1,
"unit": "ea",
"unit_cost": 125,
"extended": 125
}
],
"subtotal": 305
}
],
"summary": {
"material_cost": 29645,
"labor_hours": 65,
"labor_rate": 75,
"labor_cost": 4875,
"direct_cost": 34520,
"overhead_percent": 18,
"overhead_cost": 6214,
"total_cost": 40734,
"margin_percent": 25,
"margin_amount": 10184,
"list_price": 50918,
"sell_price": 50918
},
"options": [
{
"description": "Stainless steel drain pan",
"add_price": 850
},
{
"description": "Factory start-up",
"add_price": 1200
}
],
"notes": [
"FOB factory, freight not included",
"Lead time: 8-10 weeks ARO",
"Excludes start-up unless selected"
]
}Validation Checks
- All major components included
- Quantities match design
- Pricing within expected ranges
- Margin within guidelines
- BOM categories complete