New Calculator: Air-to-Air Heat Pump & Split Air Conditioner
A new calculator is now available on pv-calor.com: The Air-to-Air Heat Pump Calculator enables the calculation and sizing of split air conditioners for heating and cooling. The calculator is based on the European standard EN 14825 and uses real climate data from PVGIS.
What is an Air-to-Air Heat Pump?
Air-to-air heat pumps are better known as split air conditioners. Unlike conventional air-to-water heat pumps that heat water for radiators, they deliver heat directly to the room air. This makes them particularly interesting for:
- Single room heating in older buildings without central heating distribution
- Supplementary heating to existing oil or gas boilers
- Retrofitting in buildings where underfloor heating is not possible
- Summer cooling – every air-to-air heat pump can also cool
The system consists of an outdoor unit and one or more indoor units. With single-split systems, one room is supplied, while multi-split systems can connect up to 8 rooms to one outdoor unit.
What Can the New Calculator Do?
Inputs
The calculator guides you through the following steps:
| Step | Input | Explanation |
|---|---|---|
| System type | Single or multi-split | Number of rooms to be supplied |
| Location | Postcode and city | Automatic determination of climate zone according to EN 14825 |
| Equipment | Outdoor and indoor unit(s) | Selection from manufacturer catalogue |
| Rooms | Area and heating load | Room-by-room assignment for multi-split |
| Operation | Bivalence, cooling, electricity price | Configuration of operating mode |
Calculation Results
After input, you receive detailed results in 7 analysis tabs:
1. Overview
- Seasonal heating efficiency (SCOP) according to EN 14825
- Seasonal cooling efficiency (SEER)
- Total heating load and coverage rate
- Annual electricity consumption for heating and cooling
2. System Comparison (with bivalence)
- Share of air-to-air HP vs. existing heating
- Monthly breakdown of heat generation
- Cost comparison of heat sources
3. Annual Profile
- Monthly display from real TMY weather data
- COP curve throughout the year
- Heating and cooling hours per month
4. Efficiency Analysis
- Seasonal performance factor (SPF) for your location
- COP characteristic curve across temperature range
- Efficiency rating compared to reference devices
5. Cost-Effectiveness
- Payback period of investment
- Net present value calculation over 20 years
- Annual cash flow and break-even point
6. Environmental Impact
- CO₂ emissions per year
- Comparison to direct heating and fossil systems
- Scenarios with different electricity mix assumptions
7. Room Details (multi-split only)
- Individual results per room
- Coverage rate per indoor unit
- Room temperature simulation
Special Features of Split Air Conditioners
Heating AND Cooling in One Device
Every split air conditioner is a reversible heat pump. In winter, it extracts heat from the outdoor air and releases it inside. In summer, the process reverses – the unit cools the room and releases heat outside.
High Efficiency at Mild Temperatures
Air-to-air heat pumps achieve excellent efficiency (COP 4-6) at outdoor temperatures above 0°C. However, at low temperatures below -5°C, efficiency drops significantly. This is why bivalent operation often makes sense: The split unit handles the base load, while an existing heating system kicks in during frost.
Bivalence Modes in the Calculator
| Mode | Description | When useful? |
|---|---|---|
| Monovalent | Air-to-air HP only | Well-insulated buildings, mild climates |
| Bivalent Alternative | Only existing heating below bivalence point | Simplest control |
| Bivalent Parallel | Both operate simultaneously | Very cold regions |
| Bivalent Partially Parallel | HP base load + existing for peaks | Best efficiency utilisation |
Refrigerants and Environment
Modern split units use refrigerant R32 (GWP 675) or increasingly natural R290 (propane, GWP 3). The calculator takes this into account in the environmental assessment.
When Does an Air-to-Air Heat Pump Pay Off?
| Use Case | Suitability | Reasoning |
|---|---|---|
| Retrofit single room | Ideal | Quick installation, no pipes |
| Old building without underfloor heating | Very good | Direct air heating, no radiators needed |
| Supplement to gas heating | Very good | Bivalence saves 40-60% gas costs |
| New build as sole heating | Limited | Only recommended for passive houses |
| Office or commercial | Ideal | Heating + cooling, room-by-room control |
| Summer cooling | Ideal | Every unit can cool |
How to Use the Calculator
- Open calculator: Go to Air-to-Air Heat Pump Calculator
- Select system type: Single-split for one room, multi-split for several
- Enter location: Postcode is sufficient – climate data is loaded automatically
- Select equipment: Choose suitable outdoor and indoor units from the catalogue
- Configure rooms: Enter areas and heating loads
- Analyse results: Check SCOP, costs and cost-effectiveness
Heating load unknown? First use our Heating Load Calculator to determine the required heating capacity. You can then transfer the results to the air-to-air calculator.
Integration with Other Calculators
The air-to-air calculator is part of our integrated platform:
- Heating Load Calculator → Air-to-Air: The calculated heating load can be transferred directly
- Air-to-Air → Solar Calculator: The determined electricity consumption flows into PV sizing
- Air-to-Air vs. Air-to-Water: Compare both heat pump types for your building
Conclusion
The new air-to-air heat pump calculator fills an important gap in our offering. Split air conditioners are a cost-effective solution for single room heating, retrofitting old buildings, and summer cooling. With the calculator, you can calculate the cost-effectiveness for your specific project – free and without registration.
Try it now: Open Air-to-Air Heat Pump Calculator
Related Topics
Split Air Conditioners: Heating with Air-to-Air Heat Pumps · Understanding Heating Load · Combining PV and Heat Pump