Accurate Load Calculation & Stable System Operation
Proper equipment selection is the foundation of an efficient HVAC system. This article provides a professional and practical reference for calculating cooling/heating loads and determining system margin, helping you choose the right fan coil units or air-side terminals.
1. Accurate Cooling & Heating Load Calculation: The First Step in Equipment Selection
1.1 Practical Method: Load Estimation by Area
In real-world projects, although accurate load calculation involves many variables, using empirical data or simplified formulas is a fast and effective way to estimate equipment capacity.
Cooling Load Reference Table:
| Application Area | Indoor Design Temp. | Cooling Load Index |
|---|---|---|
| Hotel Room(Standard)/Bedroom | 25℃ | 90–145 W/m² |
| Study Room | 25℃ | 80–145 W/m² |
| Restaurant, Bar | 25℃ | 230–350 W/m² |
| Concert Hall, Ballroom, Entertainment Hall | 25℃ | 260–380 W/m² |
| Foyer | 25℃ | 130–280 W/m² |
| Corridor | 25℃ | 70 W/m² |
| Living room / Lobby | 25℃ | 210–320 W/m² |
Residential Heat Load Reference (Based on Building Type):
| Building Type | Heat Load per m² (W/m²) |
|---|---|
| Energy-Efficient New Housing | 60–80 |
| Standard Housing | 80–100 |
| Old Buildings | 100–150 |
| Commercial Buildings | 120–180 |
How to use: Compare the total estimated load with the rated cooling/heating capacity of the fan coil unit at high speed to determine a suitable model. This method is simple and widely applicable.
1.2 Precise Method: Air Circulation Volume Calculation
Recommended for environments with strict temperature requirements, such as laboratories or constant-temperature rooms.
Formula:
Air Circulation Volume = Room Area × Ceiling Height × Air Change Rate
| Application Type | Recommended Air Changes |
|---|---|
| General Residential | 5–8 ACH |
| Commercial Spaces | 8–12 ACH |
| Special Environments | Based on actual demand |
Accurate air volume calculation helps maintain stable and uniform temperature distribution—essential for sensitive applications.
2. System Margin: The Key to Long-Term Stability
When selecting fan coil units or air duct systems, it is recommended to allow a 20%–30% system margin, to ensure stable performance under various conditions.
Recommended System Margin Reference:
| Application Scenario | Suggested Margin | Key Considerations |
|---|---|---|
| Standard Residential | 20% | Temperature fluctuations, occasional window use |
| Commercial Spaces | 30% | High foot traffic, frequent door opening |
| Special Environments | 40% | Constant temp requirements, no fluctuation allowed |
Why Add Margin?
- Cold Weather Readiness: Outdoor temperatures may drop below design values.
- Load Fluctuation: Changes in occupancy and door usage affect load.
- System Aging: Long-term use may degrade equipment performance.
While additional margin may increase upfront investment, it offers lasting benefits:
- Ensures stable system performance
- Prevents overload during peak demand
- Extends equipment lifespan
- Maintains temperature even under extreme weather conditions
📌 For any HVAC project, accurate load calculation and proper system margin are essential to achieving comfort and operational reliability. Tailor your selection approach based on the project type to ensure optimal performance.
📞 Need help selecting a suitable fan coil unit for your project?
Contact the HanTherm Engineering Team for customized system solutions.