Kitchen exhaust hoods: BTU and CFM for F&B people

I’ve conceptualized, designed, and operated kitchens and back-of-house systems across luxury hotels and restaurants for almost 3 decades. One thing I’ve noticed: F&B professionals feel inadequate around engineers and consultants. Ventilation specs, BTU, CFM—treated like black boxes. You sit in meetings nodding, uncertain if you’re being sold something or if you’ve missed something fundamental.

I became a GM at 28. The buck stopped with me. Engineers tested me. Finance tested me. Everyone had leverage. I couldn’t afford to be ignorant, and I couldn’t afford to pretend expertise I didn’t have. So I became a real expert generalist—someone who could sit in the conversation, ask the right questions, and push back when specs didn’t make sense.

Here’s what I learned: the fundamentals are straightforward. Not mysterious.

WHAT IS BTU?
British Thermal Unit. The amount of heat required to raise one pound of water by 1°F (0.556°C). In kitchens, it measures the heat output of cooking equipment.

A 6-burner gas range outputs approximately 180,000 BTU/hour. A flat griddle: 60,000 BTU/hour

WHAT IS CFM?
Cubic Feet per Minute. Volumetric airflow. Think of it as the fan’s breathing capacity—how many cubic feet of kitchen air the exhaust system pulls out per minute. (Metric: CMM = Cubic Meters per Minute)

A 1,200 CFM (570 CMM) hood moves 1,200 cubic feet of kitchen air per minute. A 2,400 CFM (1,136 CMM) hood moves twice as much.

THE CORE CALCULATION:
CFM = Total Equipment BTU/hr ÷ 100

That’s it. Industry standard for gas kitchen equipment.

Worked Example:

• 6-burner range: 180,000 BTU
• Flat griddle: 60,000 BTU
• Total: 240,000 BTU
• Required CFM: 240,000 ÷ 100 = 2,400 CFM (1,136 CMM)

WHY THIS MATTERS:

Once you know CFM, you validate it against:
• Sensible Heat: Q = 1.08 × CFM × ΔT where ΔT is temperature difference in °F (standard cooling: 20°F or 11°C). Can this hood handle the temperature rise?
• Latent Heat: Q = 0.68 × CFM × ΔW (will it remove moisture without condensation?)
• Air Changes/Hour: ACH = (CFM × 60) ÷ Room Volume (is kitchen air turning over often enough? Target: 12-15 ACH)
• Fan Power: Determines motor size and annual electricity cost—often 30-40% of HVAC budget

WHEN VENDORS PITCH YOU, DEMAND:
✓ CFM/CMM calculation (show the math)
✓ Ductwork schematic with friction loss
✓ Static pressure analysis (in inches of water column or Pa)
✓ Makeup air strategy (must be 85-95% of exhaust CFM/CMM)
✓ Sound rating at design CFM (luxury spaces: max 70 dBA at 21°C/70°F)
✓ Annual energy cost projection

A credible vendor will provide all of this.

The goal isn’t to become an HVAC engineer. It’s to understand enough to ask intelligent questions, catch when specs don’t make sense, feel adequate.

Because you are adequate. You just needed the language.

Expertise comes with time. Start here. :)