How Much a Heat Pump Saves Compared to Gas and Electricity
How Much a Heat Pump Saves Compared to Gas and Electricity
The question "how much will a heat pump really save me" is one of the most common questions people ask us when deciding to replace their heating. The answer isn't a single number valid for every house - it depends on what you're heating with now, the house's heat loss, the heating system (radiators or underfloor heating), and current energy prices in your region. In this article we'll go through a real calculation step by step, show why a heat pump can be cheaper than gas even though electricity is more expensive per kilowatt-hour, and also talk about situations where the expected savings don't materialize.
An important note up front: this article does not contain a specific range of heat pumps or prices for specific models - the Heat Pumps category is currently temporarily out of stock. The goal of this text is to give you a tool to calculate for yourself whether, and how much, a heat pump would save you, whenever you decide to buy one, whether from us or elsewhere.
The principle of savings: why a heat pump is cheaper even though electricity is more expensive than gas
The basis for understanding the savings is a simple physical fact: a heat pump doesn't produce heat by directly converting electricity into heat (like direct electric heating or an electric boiler), but pumps heat from the surroundings - from the air, the ground, or water - and for that it only needs a fraction of the energy that direct electric heating would need. The ratio between heat delivered and electricity consumed is called COP (Coefficient of Performance) for instantaneous output, or SCOP (Seasonal COP) for the average over an entire heating season, which is more important for a realistic comparison.
If a heat pump has a seasonal SCOP of 3.5, it means that from 1 kWh of electricity it can produce 3.5 kWh of heat - the remaining 2.5 kWh is "pulled" for free from the surrounding environment. This is exactly why, even at an electricity price of around €0.17-0.19/kWh, the resulting price of heat can be lower than with natural gas at €0.09-0.11/kWh.
With a gas boiler it's the opposite - a condensing boiler's efficiency is high (typically 90-94%), but all the energy has to come directly from the fuel, with no "free" heat gained from the surroundings. That's the core of the whole comparison.
A real calculation example for a typical family house
To avoid abstract percentages, let's take a concrete, typical case: a family house with a floor area of roughly 120-140 m², with an annual heat demand for heating and hot water combined of 15,000 kWh per year. This is a fairly typical value for a moderately insulated older house with ordinary windows - not passive-house standard, but not an uninsulated building either.
The calculation uses these indicative energy prices (an average we use for comparison - your specific case may differ by supplier and region, so it's worth plugging in your own prices from your bill):
- Natural gas: approx. €0.10/kWh including distribution
- Electricity, standard tariff: approx. €0.19/kWh
- Electricity at a tariff suitable for a heat pump (see below): approx. €0.15-0.17/kWh
Variant A - natural gas (condensing boiler, 92% efficiency)
Gas needed = 15,000 kWh of heat ÷ 0.92 efficiency = 16,304 kWh of gas.
Annual cost = 16,304 kWh × €0.10/kWh = approximately €1,630/year.
Variant B - direct electric heating (electric boiler or direct heating, approx. 99% efficiency)
Electricity needed = 15,000 kWh ÷ 0.99 = 15,152 kWh.
Annual cost = 15,152 kWh × €0.19/kWh = approximately €2,879/year.
Variant C - heat pump with a seasonal SCOP of 3.5
Electricity needed = 15,000 kWh ÷ 3.5 = 4,286 kWh.
Annual cost at €0.17/kWh = 4,286 × 0.17 = approximately €729/year.
The result of this specific example:
- Heat pump compared to gas: savings of approx. €901/year (€1,630 − €729), i.e. roughly 55% lower annual heating cost.
- Heat pump compared to direct electricity: savings of approx. €2,150/year (€2,879 − €729), i.e. roughly 75% lower cost.
Why results differ from house to house - what affects real savings the most
The figures above are a model example. In practice we see significantly different results, and we know why - real savings depend on several specific factors that need to be considered when deciding:
1. The heating system's temperature spread (radiators vs. underfloor heating)
A heat pump's SCOP isn't a constant - it depends on what temperature the pump needs to heat the water to. The lower the required heating water temperature, the higher the SCOP and the higher the savings:
| Heating system | Typical temperature spread | Typical SCOP | Annual cost (15,000 kWh, €0.17/kWh) |
|---|---|---|---|
| Underfloor/wall heating | 30-35 °C | 4.0-4.5 | approx. €567-638 |
| Low-temperature radiators (newer, oversized) | 40-45 °C | 3.3-3.7 | approx. €689-773 |
| Older radiators (original, undersized) | 55-65 °C | 2.4-2.8 | approx. €911-1,063 |
You can see that even in the last, worst-case row (old radiators, high spread), the heat pump is still cheaper than gas (€1,630) - but the savings are much smaller than with underfloor heating. If you're planning a heat pump for a house with old, undersized radiators, it's often more advantageous to at least partially oversize the radiators or switch to a lower heating temperature, rather than expecting a miracle from the pump alone.
2. Quality of insulation and the house's actual heat loss
If the house's heat loss is higher than we assumed (e.g. 22,000 kWh/year instead of 15,000 kWh/year for an uninsulated house with old windows), the savings in euros will increase proportionally, but it's generally worth investing in insulation alongside or before installing the heat pump - cheaper heat doesn't mean it's worth using carelessly.
3. Electricity rate and tariff
Many electricity suppliers offer a discounted rate for connection points with a heat pump (often combined with dual-tariff metering, where part of the day has cheaper electricity suitable, for example, for heating the hot water tank). The difference between the standard and the discounted rate can make a difference of up to €100-150 a year in our model example. It's therefore worth arranging a suitable tariff product with your electricity supplier at the same time as installing the heat pump.
4. Outdoor temperature and the type of heat pump
An air-source heat pump (air-water) has a lower COP on frosty days (at -15 °C, COP can drop to 1.8-2.2), while a ground-source (ground-water) or water-source pump has more stable output throughout the winter, because the source temperature (ground, groundwater) changes far less over the year. The SCOP stated by the manufacturer already averages this seasonal variability, but in exceptionally cold regions (mountainous areas of Slovakia) the real SCOP may be somewhat lower than the catalogue value for the Central European climate zone.
Payback period - when a heat pump "pays for itself"
Running-cost savings are only half the equation - the other half is the upfront investment. The purchase price of a complete air-water heat pump installation (unit, installation, any modification to the heating system, DHW tank) on the Slovak market typically ranges roughly from €8,000-16,000 depending on output, brand, and installation complexity; ground-source pumps with a ground collector or borehole tend to be more expensive due to the cost of earthworks or drilling. These figures are only an indicative range - the exact price will always be given by a specific quote from an installation company for your house.
Comparing with gas (savings of approx. €900/year from our example) and, say, a €12,000 investment, the simple (undiscounted) payback period comes to roughly 13-14 years without a subsidy. Compared with direct electricity (savings of approx. €2,150/year), the payback period is significantly shorter, roughly 5.5-6 years. The real payback period can also be shortened by state support - in Slovakia, programmes such as Green Households or subsidies via Renovate Your House have operated in the past and are periodically renewed, and can cover on the order of thousands of euros of the investment. Since the conditions and amounts of subsidies change over time, always check the current status directly on the website of the Slovak Innovation and Energy Agency (SIEA) or with your supplier before signing a contract.
Heat pump vs. direct electricity - why this difference is so big
Many people who currently heat with direct electric heaters, storage heaters, or an electric boiler are surprised that the difference compared to a heat pump is even bigger than compared to gas. The answer is simple - direct electricity has a "SCOP" of practically 1 (1 kWh of electricity = just under 1 kWh of heat after losses), while a heat pump delivers 3 to 4.5 times more heat from the same kilowatt-hour of electricity. So if you currently heat directly with electricity, a heat pump is, from an economic point of view, almost always by far the strongest argument of all the comparisons in this article.
When savings may not turn out as expected
To keep this article honest, we should also mention situations where real savings fall short of the theoretical calculation:
- Undersized heating elements - if the heat pump has to run at a high water temperature (60 °C or more) because of old, small radiators, the SCOP drops significantly and the savings compared to gas can shrink to 20-30%.
- Incorrectly sized pump output - a pump that's too small will more often rely on the built-in electric backup heater (bivalent source), which has a SCOP of practically 1 - this can significantly worsen the annual average.
- Neglecting hot water preparation - if a household has high DHW consumption (a large family, frequent baths), you need to reckon with hot water preparation generally having a lower SCOP than space heating, because the tank has to be heated to a higher temperature (at least 50-55 °C to prevent legionella).
- High electricity prices in a given region/from a given supplier without a discounted rate - if you're paying significantly above average for electricity without a heat pump tariff, part of the savings is lost.
None of these points means a heat pump "isn't worth it" - they just show that real savings always depend on the quality of the design and implementation, not just on the catalogue SCOP number on the box.
What happens to the savings when energy prices rise or fall
The model calculation above uses prices valid at the time of writing, but both gas and electricity prices change over the years - sometimes significantly. The good news is that a heat pump is surprisingly resilient to this risk, because it consumes only a fraction of the energy compared to direct heating. Let's look at what happens to the annual cost difference if both energy prices moved by the same percentage upward:
- If both electricity and gas get 20% more expensive equally, the gas cost rises from €1,630 to approx. €1,956, and the heat pump cost from €729 to approx. €875. The absolute savings grow from €901 to approx. €1,081 a year - so a heat pump not only maintains its advantage as energy prices rise together, but typically increases it in euro terms too, because it consumes a smaller absolute amount of energy.
- The opposite case - if electricity got significantly more expensive than gas (for example due to a change in distribution tariffs), the difference could narrow. It's therefore worth monitoring current price lists and, if the gap grows, contacting your electricity supplier about a more favourable tariff product for a heat pump.
- Historically, the volatility of natural gas prices on wholesale markets in recent years has been significantly higher than the volatility of electricity prices for households, which is another (non-financial, but related) argument in favour of a heat pump - lower dependence on a single, price-unstable fuel.
For long-term decisions (payback is calculated over 10-20 years), it's therefore sensible not to look only at the current price difference, but also to factor in that a heat pump reduces a household's sensitivity to fluctuations in individual fuel prices, since it consumes substantially less primary energy for the same amount of heat.
Comparison with other heat sources - where a heat pump wins and where it doesn't
For completeness, it's good to place a heat pump in a broader context alongside gas and electricity, even though these aren't the main comparisons of this article:
- Solid fuel (wood, coal, pellets) - the cost of heat from a quality automatic pellet boiler tends to be roughly comparable to, or somewhat higher than, a heat pump, but with significantly higher demands on operation, fuel storage, and combustion chamber maintenance. Wood in a stove is the cheapest in terms of fuel, but the most demanding to operate and the least convenient.
- District heating (central supply) - the price varies from town to town and supplier to supplier; the comparison needs to be made individually based on the specific heat price list in a given location.
This comparison is only for orientation - the main topic of this article, i.e. the comparison with gas and electricity, remains the most relevant for most households in Slovakia, since these are the two sources most often replaced.
How to calculate your own savings estimate
If you want your own, tailored estimate, follow these steps:
- Find out your house's annual heat consumption - most easily from your gas bill (consumption in m³ × 10.55 kWh/m³ × your boiler's efficiency) or from your electricity bill if you heat directly.
- Find out or estimate the expected SCOP for your type of heating system (radiators vs. underfloor heating) using the table above - an installation company can give you a more precise estimate after visiting your house, based on the project documentation and heat losses.
- Divide your annual heat demand by the expected SCOP - you get the estimated annual electricity consumption of the heat pump.
- Multiply by the electricity price you'll actually pay (including any discounted tariff) - you get the estimated annual cost.
- Compare with your current annual cost for heating and hot water.
Summary
In our model, but realistic, example of a family house with a heat demand of 15,000 kWh/year, a heat pump with a SCOP of 3.5 comes out to a cost of approximately €729 a year, compared to €1,630 for natural gas (savings of approx. 55%) and €2,879 for direct electricity (savings of approx. 75%). The real savings in your specific house may differ depending on the heating system's temperature spread, the quality of insulation, the electricity price and tariff, and how precisely the pump is sized and set up. That's exactly why it's worth using your own figures from your bills, not just a general example - and having a professional site visit and design done by an installation company before deciding.
Frequently Asked Questions
Is a heat pump worth it even in an old, uninsulated house?
Yes, but the savings compared to gas will generally be lower than in an insulated house, because the higher required heating water temperature reduces the SCOP. In most cases it's still cheaper than both gas and direct electricity, but if financially possible, combining at least partial insulation (roof, windows) with a heat pump brings the biggest effect.
Is a heat pump always cheaper than gas?
In most typical cases, yes, as long as the pump has a reasonable SCOP (at least 3.0 or more) and electricity isn't significantly more expensive than average. With an extremely high temperature spread (old, undersized radiators without modification) and an unfavourable electricity rate, the difference can narrow to tens of euros a year - in that case a more precise individual calculation is needed.
How long does it take for a heat pump to pay for itself?
Compared with gas, in our model example it comes out to roughly 13-14 years without a subsidy; compared with direct electricity, roughly 5.5-6 years. With a state subsidy, the payback period shortens. The lifespan of a quality heat pump (15-20 years) is longer than this payback period, so the investment generally pays for itself many times over during its operating life.
Does a heat pump make sense with old radiators, or do I need underfloor heating?
Underfloor heating isn't a requirement, but if the radiators were originally designed for a high heating temperature (60 °C or more), it's worth oversizing at least some of the radiators or switching to a lower heating temperature to keep the SCOP as high as possible. An installation company can best assess the specific condition of your system on site.
Does hot water heating affect the savings?
Yes - preparing hot water requires a higher temperature (typically at least 50-55 °C) than most modern heating systems, so the SCOP for DHW tends to be lower than for space heating. Households with high hot water consumption need to factor in this lower efficiency when estimating total annual savings.
Where can I check the current level of state subsidy for a heat pump?
The conditions and amounts of support (for example programmes like Green Households or Renovate Your House) change over time, so we recommend always checking the current status directly on the website of the Slovak Innovation and Energy Agency (SIEA) or asking an installation company before signing a contract.
Related topics
- How to choose a heat pump
- What heat pump output do I need
- Heat pump air-water vs. ground-water
- Heat pump with underfloor heating or radiators
- Subsidies and support for heat pumps
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