Example Data Table
| Case | Area | Outdoor Temp | Windows | People | Estimated Result |
|---|---|---|---|---|---|
| Phoenix bedroom | 220 sq ft | 110 °F | 35 sq ft west glass | 2 | About 0.8 to 1.3 tons |
| Tucson living room | 520 sq ft | 106 °F | 85 sq ft mixed glass | 4 | About 1.8 to 2.7 tons |
| Yuma garage workshop | 650 sq ft | 112 °F | 20 sq ft shaded glass | 2 | About 2.0 to 3.5 tons |
Formula Used
Room volume: Volume = Floor area × Ceiling height.
Temperature difference: ΔT = Outdoor design temperature − Indoor setpoint.
Envelope load: Area × (10 + 0.45 × ΔT) × insulation factor × exposure factor × ceiling factor × Arizona factor.
Window solar load: Window area × direction gain × shading factor × Arizona factor.
Infiltration airflow: CFM = Room volume × ACH ÷ 60.
Sensible air load: BTU/h = 1.08 × CFM × ΔT.
Latent air load: BTU/h = 4840 × CFM × humidity ratio difference.
Total load: Raw load = sensible load + latent load + people load + appliance load + lighting load.
Final load: Final BTU/h = Raw load × duct multiplier × safety multiplier.
Tons: Cooling tons = Final BTU/h ÷ 12,000.
Power: Cooling kW = Final BTU/h ÷ 3412.142. Input kW = Final BTU/h ÷ EER ÷ 1000.
How to Use This Calculator
Enter the Arizona location first. Then add the floor area and ceiling height. Enter indoor and outdoor design conditions. Add humidity values when ventilation or leakage matters.
Next, describe the building. Choose insulation quality, sun exposure, ceiling condition, window direction, and shade level. Add people, appliances, lights, duct loss, and safety margin.
Press the calculate button. The result appears above the form. Review final BTU per hour, tons, airflow, energy use, and cost. Download the CSV or PDF file for records.
Cooling Capacity in Arizona
Arizona Heat Loads
Arizona cooling work is different from many mild regions. The summer air is very hot. Sun exposure is also strong. A room can gain heat through walls, ceilings, windows, air leaks, people, lights, and equipment. This calculator combines those gains into one estimated load. It then converts the load into tons, kilowatts, and airflow. The result helps compare system sizes before a Manual J review.
What the Result Means
Cooling capacity is the rate of heat removal. In the United States, it is often shown as BTU per hour. One cooling ton equals 12,000 BTU per hour. A higher number means the space needs more cooling. Oversizing can short cycle the unit. Undersizing can leave rooms warm during peak afternoons. A balanced estimate is better than a rough square foot rule.
Arizona Design Inputs
Outdoor design temperature matters in Phoenix, Tucson, Yuma, and other hot areas. Indoor setpoint also matters. The difference between those two temperatures drives sensible load. West windows often add large solar gains. Shading, insulation, ceiling exposure, and air leakage can change the answer quickly. Higher elevation can lower air pressure. That affects humidity ratio and ventilation load.
Airflow and Energy Checks
Airflow is included because comfort depends on heat removal through moving air. A common target is near 400 CFM per ton. The calculator also estimates airflow from sensible heat and supply air temperature drop. Energy input is estimated from EER. This is not the same as cooling output. Better efficiency reduces running cost for the same cooling load.
Best Use Cases
Use this tool for early planning, room comparisons, rental upgrades, garage cooling, additions, sunrooms, workshops, and small equipment checks. Enter realistic values. Avoid guessing window area or appliance watts. Try two scenarios. Compare shaded and unshaded windows. Compare tight and leaky rooms. The difference shows which improvement may lower the required capacity. Final equipment selection should still follow local codes and a professional load calculation. The estimate is educational. It does not inspect duct location, refrigerant charge, building orientation, or exact construction layers. Use it as a screening tool. Keep a margin for unusual roofs, large glass, server equipment, and open doors during busy days. Review assumptions often carefully.
FAQs
1. What does cooling capacity mean?
Cooling capacity is the heat removal rate. It is usually shown in BTU per hour or tons. A larger value means the system can remove more heat from the space each hour.
2. Why is Arizona location included?
Arizona cities have different summer design conditions. Phoenix, Tucson, Yuma, and Flagstaff can need different cooling assumptions. The location factor adjusts the estimate for local desert heat severity.
3. Is one ton always 12,000 BTU per hour?
Yes. In cooling work, one ton equals 12,000 BTU per hour. The calculator divides final BTU per hour by 12,000 to estimate cooling tons.
4. Why do west windows raise the result?
West windows receive strong afternoon sun. In Arizona, that sun often arrives during peak outdoor heat. This can add a large solar load and increase required cooling capacity.
5. Should I add a safety factor?
A small safety factor can help cover uncertain inputs. Do not use a very large margin without reason. Oversized systems may cycle often and reduce humidity control.
6. What is EER used for?
EER estimates electrical input power from cooling output. Higher EER means less electricity for the same cooling load. It helps estimate monthly energy and cost.
7. Does this replace Manual J?
No. This calculator is for planning and comparison. Final equipment sizing should use a professional Manual J calculation and local code requirements.
8. Why does airflow matter?
Cooling equipment must move enough air to remove heat. Low airflow can reduce comfort and performance. The calculator gives airflow from tons and from sensible heat.