Calculate heating and cooling loads for proper HVAC system sizing
Based on ASHRAE climate zone map
Walls & Roof: 0%
Windows: 0%
Occupants: 0%
| Factor | Value | Unit |
|---|---|---|
| Design Temperature Difference | -- | °F |
| Building Volume | -- | ft³ |
| Insulation Factor | -- | - |
| Solar Gain Factor | -- | BTU/sq ft |
| BTU/hr | Tons | kW |
|---|---|---|
| 12,000 | 1.0 | 3.5 |
| 18,000 | 1.5 | 5.3 |
| 24,000 | 2.0 | 7.0 |
| 30,000 | 2.5 | 8.8 |
| 36,000 | 3.0 | 10.6 |
| 48,000 | 4.0 | 14.1 |
| 60,000 | 5.0 | 17.6 |
| Building Type | Cooling (BTU/sq ft) | Heating (BTU/sq ft) |
|---|---|---|
| Residential | 20-25 | 30-40 |
| Office | 25-35 | 25-35 |
| Retail | 30-40 | 30-35 |
| Warehouse | 10-20 | 35-45 |
| Restaurant | 45-55 | 40-50 |
| Zone | Description | Example Cities | Cooling Factor | Heating Factor |
|---|---|---|---|---|
| 1 | Very Hot | Miami, Honolulu | +30% | -40% |
| 2 | Hot | Houston, Phoenix | +20% | -30% |
| 3 | Warm | Atlanta, Las Vegas | +10% | -20% |
| 4 | Mixed | New York, Denver | Baseline | Baseline |
| 5 | Cool | Chicago, Boston | -10% | +10% |
| 6 | Cold | Minneapolis, Burlington | -20% | +20% |
| 7 | Very Cold | Duluth, Fairbanks | -30% | +30% |
Recommendation: 5-ton central AC system with 60,000 BTU/hr heating capacity.
Recommendation: Commercial rooftop unit, 10-ton cooling with modulating gas heat.
Recommendation: High-efficiency rooftop unit with economizer, 15-ton cooling capacity.
Recommendation: Heat pump system, 3.5-ton with backup heat to 80,000 BTU/hr.
Recommendation: Commercial package unit, 15-ton with kitchen makeup air and exhaust considerations.
Manual J is the ACCA (Air Conditioning Contractors of America) standard for residential load calculations. It provides a systematic method for determining the heating and cooling loads of a building by considering:
| Component | Cooling Impact | Heating Impact | Description |
|---|---|---|---|
| Building Envelope | 25-35% | 35-45% | Heat transfer through walls, roof, and foundation |
| Windows & Doors | 25-35% | 25-35% | Conduction and solar heat gain through glazing |
| Internal Gains | 20-30% | Reduces load | Heat from occupants, lighting, and equipment |
| Ventilation | 10-20% | 15-25% | Outside air requirements for indoor air quality |
| Infiltration | 5-15% | 10-20% | Uncontrolled air leakage through building envelope |