Heat Pump Simulator
Calculate efficiency (SPF) and electricity costs based on your building status.
Seasonal Performance Factor (SPF)
3.8
Highly Efficient
Electricity Consumption
3,947 kWh
per year
Electricity Costs
1,184 €
per year
Expert Guide: Understanding Heat Pump Efficiency & SPF
Switching to a heat pump is the most effective way to decarbonize your home's heating system. However, unlike traditional gas or oil boilers, a heat pump doesn't "burn" fuel; it acts as a thermal elevator, lifting ambient heat from the air, ground, or water to a useful temperature level for your home. The efficiency of this process is measured by the **Seasonal Performance Factor (SPF)**, also known in Germany as JAZ. Our simulator helps you estimate this critical value for your specific building and calculates the expected electricity costs, providing a clear picture of your future energy bills.
What is the difference between COP and SPF?
These terms are often confused. The **COP (Coefficient of Performance)** is a
laboratory value—a snapshot of efficiency under specific test conditions (e.g., A7/W35, meaning
outside air at 7°C and flow water at 35°C). The **SPF (Seasonal Performance Factor)** is the
real-world scorecard. It looks at the entire year, including cold winter nights, stand-by
consumption, and defrost cycles. It represents the total heat energy delivered divided by the
total electrical energy consumed over 12 months. Only the SPF can accurately predict your actual
operational costs.
Why is Flow Temperature the "Efficiency Killer"?
A heat pump works like a refrigerator in reverse. The greater the temperature
difference between the heat source and your radiators (flow temperature), the harder the
compressor must work. As a rule of thumb, every 1°C reduction in flow temperature improves
efficiency by about 2-3%. This is why large-surface heating systems like floor heating (ideally
35°C) are perfect matches for heat pumps. However, even with traditional radiators, you can
often reach efficient levels (50-55°C) by upgrading individual radiators or improving
insulation.
Does a heat pump work in an uninsulated old building?
Yes, but the engineering must be precise. In an uninsulated house with high heat
loss, the SPF will inevitably be lower. If the SPF falls below 2.5, heating with electricity may
become more expensive than gas or oil. In these cases, a **bivalent or hybrid system** is often
the best solution: the heat pump handles the heating for most of the year, while a secondary
source (like your old boiler) kicks in only during extreme frost. However, modern air-to-water
heat pumps can often achieve an SPF above 3.0 even in partially renovated buildings, making them
an ecologically superior choice.
Monovalent vs. Mono-energetic Systems
A monovalent system covers 100% of the heat load with the heat pump alone
(typical for geothermal units). Air-source heat pumps are frequently operated
**mono-energetically**: on extremely cold days with temperatures below -7°C or -10°C, an
integrated electrical backup heater (immersion heater) supports the compressor. While not 100%
efficient, this is often more cost-effective than over-sizing the heat pump for events that only
occur a few hours per year. Our calculator factors this in via your building's insulation
standard.
Understanding Financial Incentives and Subsidies
Many countries (like Germany via BEG, or the UK via the Boiler Upgrade Scheme)
offer massive subsidies for heat pump installations. Often, these grants are tied to a minimum
calculated SPF (usually 3.0 or higher). This is to ensure that the installed systems actually
contribute to CO2 reduction and remain affordable for the homeowner. Using this simulator, you
can verify if your planned setup meets these efficiency hurdles by adjusting the flow
temperature and building status.
Strategy Tip: The "Thermal Balancing" (Hydraulic Balance)
To get the best SPF, your system must be "balanced." This means ensuring that
every radiator receives exactly the amount of water it needs. After installation, perform a DIY
optimization: open all thermostats and lower the heating curve on your unit until the coldest
room just stays comfortable. This "flat" curve ensures the lowest possible flow temperature,
which could save you hundreds of euros over a decade by boosting your SPF by 0.2 to 0.5 points.
Noise Mitigation: Location is key
Efficiency and acoustics go hand-in-hand. A heat pump running at high efficiency
usually runs its fans and compressor at lower, quieter speeds. When planning, avoid placing the
outdoor unit in narrow alleys where sound can bounce, or directly under bedroom windows. High
SPF values (resulting from low flow temperatures) lead to quieter operation. Efficient systems
are not just better for your wallet, but also for your neighbor-relations.
Embed this Calculator on Your Website
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