🔥 Heat Load Calculator

Manual J Block Load Estimator for Heating & Cooling

✅ Formula verified against standard references • Last Updated: Jan 2026

1. Design Temperatures

Indoor Design Temp (°F)

Outdoor Design Temp (°F)

Summer high or Winter low

Calculation Mode

2. Building Envelope

Wall Area (sq ft)

Net wall area (minus windows)

Wall Insulation

Ceiling Area (sq ft)

Ceiling Insulation

3. Windows & Doors

Window Area (sq ft)

Window Type

Sun Exposure (Cooling Only)

Solar Heat Gain Factor

4. Internal Loads (Cooling Only)

Occupants

Number of people

Appliances/Electronics (Watts)

TVs, Computers, Lights

Kitchen Load?

Total Cooling Load -- -- Tons

Sensible Load --

Latent Load (Est.) --

Delta T --

Component	Load (BTU/hr)	% of Total

Licensed HVAC Contractor, 18 years experience

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