Air-to-Air Heat Pump Calculator
Calculate split air conditioners for heating and cooling according to EN 14825
Quick Guide
6 Steps to Calculate
1. Choose System Type Select Single-Split (1 room) or Multi-Split (multiple rooms).
2. Enter Location Enter country, postal code and city. The calculator automatically loads:
- Climate zone according to EN 14825 (Average/Warmer/Colder) for SCOP calculation
- TMY data from PVGIS (8,760 hourly values) for load profiles and monthly details
3. Select Equipment Choose outdoor unit and matching indoor units from the catalog. Watch the capacity ratio (0.8-1.3).
4. Enter Rooms Enter floor area and heat load per room. For Multi-Split: assign rooms to indoor units.
- Heat load unknown? Use our Heat Load Calculator or estimate: 40-50 W/m² (well insulated), 50-70 W/m² (medium), 70-100 W/m² (poorly insulated)
5. Configure Operating Mode Choose bivalence mode, activate cooling, set electricity price.
6. Analyze Results Review SCOP, power consumption, economics and CO2 balance in 7 result tabs.
Key Terms
| Term | Meaning |
|---|---|
| SCOP | Seasonal heating efficiency - higher is better (good: > 4.0) |
| SEER | Seasonal cooling efficiency (good: > 6.0) |
| COP | Instantaneous efficiency at a specific temperature |
| Bivalence | Combination with existing heating |
| Bivalence Point | Outdoor temperature at which existing heating kicks in |
| TMY | Typical Meteorological Year - real weather data for your location |
Bivalence Modes Explained
| Mode | Description | Recommended For |
|---|---|---|
| Monovalent | Air-to-air HP only | Well-insulated buildings, mild winters |
| Bivalent Alternative | Only existing heating below bivalence point | Simplest control |
| Bivalent Parallel | Both operate simultaneously | High heat demand in frost |
| Bivalent Part-Parallel | Air-to-air base load + existing for peaks | Optimal utilization |
Bivalence point recommendation: Switch when COP falls below 2.5-3.0 (typically at -2°C to +2°C).
7 Result Tabs
- Overview: SCOP, heat load, coverage, power consumption
- Comparison: Air-to-air vs. existing heating (bivalence)
- Annual Profile: Monthly heat distribution and COP values from TMY data
- Efficiency: SPF values, efficiency rating, COP curve
- Economics: Payback, NPV, cash flow
- Environment: CO2 balance, electricity mix scenarios, equivalents
- Rooms: Room-by-room results (Multi-Split only)
Sizing: Single-Split vs. Multi-Split
| Criterion | Single-Split | Multi-Split |
|---|---|---|
| Rooms | 1 | 2-8 |
| Outdoor units | 1 per room | 1 for all |
| Costs | Cheaper for 1-2 rooms | Cheaper from 3 rooms |
| Reliability | High (independent) | Lower (all dependent) |
Capacity ratio (Multi-Split only): Sum of indoor units / outdoor unit should be between 0.8-1.3.
Advantages of Air-to-Air Heat Pumps
- High efficiency: SCOP 3.5-5.0 (up to 80% electricity savings vs. direct heating)
- Heating AND cooling in one device
- Quick installation: 1-2 days, no heating system conversions
- Ideal for PV self-consumption: Use surplus solar power
- Room-by-room temperature control: Individual comfort settings
- Low costs: 2,000-8,000 EUR (vs. 15,000-30,000 EUR for air-to-water HP)
Calculation Fundamentals
The calculator uses two data sources:
- EN 14825 climate zones: For SCOP calculation and annual heating demand
- PVGIS TMY data: Real hourly values for load profiles, cooling hours and monthly details
Annual heating demand: Heat load × Heating hours × 0.4 (simplified degree-day method)
Detailed Guide with all calculation formulas, equipment selection tips and FAQ.
Next step: With the Solar Calculator you can cover the power consumption of your air-to-air heat pump with a PV system.