The HVAC Study Module 5

Module 5: Labor & Crew Productivity (Expanded)

👷 Module 5: Labor & Crew Productivity

Labor is your biggest risk — learn to turn baseline units into field-realistic hours with transparent factors, smart crew planning, and finish-date math.

HVAC Estimating & Plan Reading Course

Overview

Use baseline manhour (MH) units (from SMACNA/MCAA/PHCC or company standards) as your starting point, then apply documented productivity factors for height, congestion, access, schedule pressure, and conditions. Convert total hours into a crew plan with realistic throughput, and understand how overtime and learning curves affect cost and duration.

Important: Treat baseline MH tables as neutral lab conditions. Your project realities live in the factors.

🎯 Learning Objectives

Pull defensible MH units from guides and historicals and keep them version-controlled.
Build a composite productivity factor (multiplicative) instead of guessing a single adder.
Translate hours into crew size, duration, and weekly goals — with float and inspections.
Evaluate the tradeoff of overtime: faster calendar vs. higher cost and lower productivity.
Model learning curves for repetitive scopes (e.g., VAVs, FCUs) to sharpen totals.

📚 Sources for Labor Units

SMACNA ductwork install tables (airside).
MCAA / PHCC labor guides (piping/equipment).
Company historicals (closed jobs w/ actuals) and superintendent feedback.

Keep a Units_Log.xlsx with columns: Task, Unit, Source, Date, Notes. Lock the tab and reference it in estimates.

📏 Baseline Manhour Units (Examples — replace with your standards)

Airside

Item	Unit	MH/Unit
Rect duct 24×12 (CL2)	LF	0.25
Spiral Ø18	LF	0.20
Elbow 90° (med)	EA	0.80
Transition (rect-rect)	EA	1.20
Volume damper	EA	0.70

Wet/Equipment/Controls

Item	Unit	MH/Unit
CHWS 2" (std)	LF	0.30
Valve install 2"	EA	1.10
VAV box (w/ reheat)	EA	6.00
RTU set (excl. crane)	EA	10.00
DDC point (avg)	EA	0.40

Note: Values above are examples. Insert your controlled units before using in bids.

🧮 Productivity Factor Library (Typical Ranges)

Condition	Typical Factor	Notes
Work height 12–20 ft	×1.10 – ×1.25	Lifts, staging, fall protection
Congested ceilings/MEP clash	×1.10 – ×1.30	Rework risk & short cuts
Occupied/night work	×1.15 – ×1.30	Access windows, protection, escorts
Seismic bracing spec	×1.05 – ×1.15	Extra hardware & layout
Weather (heat/cold/wind)	×1.05 – ×1.20	Outdoor/roof scope
Security/badging	×1.03 – ×1.10	Check-in time loss
Accelerated schedule	×1.05 – ×1.15	Stacked trades/overtime drag

Multiply factors, don’t add them. Composite = H × Cong × Occupied × … (see tool below).

🧠 Formula — From Units to Crew Plan

Total Hours = Σ( Quantity × MH/Unit ) × CompositeFactor + Supervision + Access/Setup

Duration (workdays) = Total Hours ÷ (Crew Size × Hours/Day) → add Float & Inspection days

🧰 Mini Tools

🧮 Composite Factor Builder

Height factor Congestion factor Occupied/Night factor Seismic/Other factor

Composite Factor: —

Multiply factors (not add). Document the “why” in your notes.

⏱️ Task Labor Calculator

Q1 × MH1

Q2 × MH2

Q3 × MH3

Composite Factor

Supervision (hrs)

Access/Setup (hrs)

Total Labor Hours: —

Replace units with your standards; keep supervision/setup separate.

👥 Crew Planner & Finish Date

Total Hours Journeymen (#) Apprentices (#) Apprentice productivity vs J (0–1) Hours/Day Days/Week Start Date (optional)

Effective Crew Hours/Day: —

Workdays Needed: — | Weeks: —

Finish date shown if start date is provided.

⏳ Overtime Cost & Derate

Base Wage ($/hr) Burden % (taxes/fringe) OT Multiplier (e.g., 1.5) OT Derate % (productivity loss) Weekly Hours (e.g., 60)

Avg Cost/hr (loaded): —

Effective Hours vs. 40: —

OT can shorten the calendar but raise $/installed-hour.

📉 Learning Curve (Wright’s)

First Unit Hours (T₁) Units (N) Learning Rate % (e.g., 85)

Modeled Total Hours: —

Unit time model: Tₙ = T₁ · nᵇ, where b = log(r)/log(2). Sums units 1…N.

📋 Field-Ready Labor Breakdown (Template)

Area/Scope	Baseline Hrs	Composite Factor	Adj. Hrs	Crew	Days	Notes
L2 SA Main	50	1.15	57.5	2J+1A	3.0	Lifts; night access
VAV Set (x6)	36	0.92*	33.1	1J+1A	2.2	*85% learning curve
Roof RTU set	12	1.10	13.2	2J	1.0	Crane, weather risk

Ownership: Who owns crane, bracing, access, fire watch? Call it out here to protect your hours.

🧪 QA/QC — Before You Publish Hours

Units sourced & dated; no mixing different baselines.
Factors listed with rationale (height, congestion, schedule, weather, security).
Supervision, access/setup, travel, and inspections explicitly shown.
Crew plan math reconciles to total hours and calendar.
OT decisions documented (cost/benefit), learning curve applied where repetitive.
Versioned export saved (e.g., 2025-02-Module5_LaborPlan_V03.xlsx).

🧠 Practice & Exit Ticket

Compute total hours for 200 LF rect 24×12 @0.25, 12 El90 @0.80, 6 transitions @1.20 with a 1.15 composite, +14 hrs overhead.
Plan crew with 2J+1A (A=0.75 of J), 8 h/day, 5 d/wk; show days and weeks; if start next Monday, what’s the finish date?
Evaluate OT at 60 hrs/wk with 10% derate and 1.5× pay — what’s the loaded $/hr and effective hours vs. straight time?
Model learning curve for 20 VAVs: T₁=6.0 hrs, 85% rate. Compare to “no learning” total and comment on the delta.