Office Project Inputs
The default values create a practical early estimate for a 3,600 square foot office. Change every value to match your project assumptions.
Example Data Table
| Input | Example value | Purpose |
|---|---|---|
| Floor area | 3,600 sq ft | Sets the base envelope, lighting, equipment, and ventilation area loads. |
| Occupants | 30 people | Adds people heat and the person-based outside air allowance. |
| Lighting density | 0.80 W per sq ft | Creates internal electrical and cooling load. |
| Equipment density | 1.20 W per sq ft | Represents computers, printers, and normal plug equipment. |
| Summer conditions | 20°F and 25 grains/lb | Estimates sensible and latent outside air cooling load. |
| Safety factor | 10% | Adds a transparent planning allowance to thermal totals. |
Formula Used
Outdoor ventilation
Outdoor air CFM = (Occupants × CFM per person) + (Area × CFM per sq ft)
Cooling load
Cooling = [Envelope + Lighting watts × 3.412 + Equipment watts × 3.412 + Occupants × 450 + (1.08 × CFM × Summer ΔT) + (0.68 × CFM × Humidity difference)] × Safety factor
Heating load
Heating = [Area × Heating factor × Height multiplier + (1.08 × CFM × Winter ΔT)] × Safety factor
Electrical current
Single phase amps = Watts ÷ (Voltage × Power factor); Three phase amps = Watts ÷ (√3 × Voltage × Power factor)
The height multiplier adds two percent for each foot above nine feet. The solar adjustment applies to the cooling envelope allowance. These formulas provide early planning figures, not final engineered loads.
How to Use This Calculator
- Keep the 3,600 square foot default or enter your actual conditioned area.
- Set occupancy, lighting, and equipment inputs for the busiest normal period.
- Enter local summer and winter design differences.
- Set ventilation rates from the project basis or applicable requirements.
- Choose the service voltage, phase, and heating equipment type.
- Submit the form and review cooling, heating, ventilation, and electrical results above.
- Export the displayed results for preliminary project records.
Planning a 3,600 Square Foot Office Load
A 3,600 square foot office can have very different loads. Location, glass area, ceiling height, people, equipment, and operating hours all matter. This calculator gives a planning estimate. It does not replace a detailed engineered design.
Start with the floor area. The preset is 3,600 square feet. Then enter the expected occupancy. A small office with thirty people has a different internal load than a crowded call center. People add sensible heat, latent heat, and ventilation demand.
Lighting is another major source. Enter the installed lighting power density in watts per square foot. Efficient fixtures reduce cooling demand and electrical demand. Computer stations, printers, servers, kitchen equipment, and other plug loads also create heat. The calculator converts those watts into cooling load.
Ventilation supports indoor air quality. The tool combines outdoor airflow per person and outdoor airflow per square foot. It then estimates summer sensible and latent ventilation loads. Adjust the outdoor temperature difference and humidity difference for local design conditions. These inputs can change the result significantly.
Ceiling height helps reveal whether a standard area factor is reasonable. Tall spaces can increase air volume and stratification. Large south-facing glazing can add solar gains. Use conservative inputs at first while plans remain incomplete or uncertain.
The cooling result includes envelope allowance, internal heat, occupants, and ventilation. A safety factor is then applied. The output appears in Btu per hour, kilowatts, and refrigeration tons. Use it only as an early sizing check. Equipment selection needs manufacturer data and local design requirements.
Heating is estimated from a selected area factor and winter ventilation load. Tight buildings may need a lower factor. Older buildings, large windows, and exposed roofs may need a higher factor. The heating output is shown as delivered heat. Gas input or electrical heating demand is also estimated from the selected system type.
The electrical section adds lighting, plug loads, and estimated HVAC demand. It applies the selected demand factor, voltage, phase arrangement, and power factor. The recommended protective-device size is a planning value. It is not a final electrical service calculation.
Review every assumption before using the numbers. Compare the results with drawings, climate records, equipment schedules, and local rules. Ask a qualified mechanical and electrical professional to verify final equipment sizes, duct design, circuit protection, and code compliance.
Frequently Asked Questions
1. What does this calculator estimate?
It estimates ventilation airflow, cooling load, heating load, internal electrical demand, HVAC electrical demand, service current, and a planning protective-device value for an office project.
2. Is 3,600 square feet fixed?
No. The floor area starts at 3,600 square feet because that matches the example office. Replace it with any positive conditioned area.
3. Why are lighting and equipment separate?
They often change independently. Efficient lighting can lower lighting heat. Dense computer use can raise plug load. Separate entries make the estimate easier to adapt.
4. How is ventilation airflow calculated?
The tool adds a people component and an area component. Enter the rates used by your project or the applicable ventilation basis.
5. What does the safety factor do?
It increases the calculated thermal total by a selected percentage. It is useful for early planning, but it should not hide missing project information.
6. Does this select HVAC equipment?
No. It provides a preliminary capacity target. Final selection also needs climate data, equipment performance, zoning, ductwork, controls, and design review.
7. Why does ceiling height matter?
Taller rooms can increase air volume and stratification. This tool adds a modest height allowance above nine feet for planning purposes.
8. How should I set the solar adjustment?
Increase it for broad exposed glazing, strong sun exposure, or limited shading. Reduce it only when project shading and envelope details support that choice.
9. How are service amps estimated?
The tool converts estimated kilowatts to watts. It then uses voltage, phase type, and power factor to estimate current.
10. Is the output code compliant?
No. Codes and project requirements differ by location and occupancy. Use the results as a planning reference, then complete formal calculations.
11. Who should confirm the final system sizes?
A licensed engineer or qualified designer should review final plans. Always confirm readings before final equipment selections and installations.