Cost of Running Heat Pump

Running costs are the practical result of heat pump efficiency: how much you pay for electricity to deliver the heat your building needs.

A heat pump’s running cost is not determined by the unit alone. It depends on three system-level inputs:

  1. Heat demand (how much heat the building needs over the season)

  2. Seasonal/system efficiency (how many kWh of heat you get per kWh of electricity)

  3. Electricity price structure (tariff, time-of-use, fixed charges)

Technical guidance for heat pump systems commonly highlights that seasonal performance (often expressed as SPF) is one of the main drivers for operational cost, together with electricity consumption measurement and monitoring.

What “running cost” includes

For a heat pump system, running cost typically includes the electricity used by:

  • the compressor (main contributor)

  • fans (air-source systems)

  • circulation pumps (heating side and/or source side, depending on design)

  • controls and standby power

  • defrost operation (air-source systems)

  • backup electric heater use (if present and activated)

  • domestic hot water production (often higher temperature operation)

SEAI notes that overall efficiency is influenced by electricity used by other system components (including circulation pumps and electric heaters during certain operating cycles), which directly affects running costs.

Heat pump efficiency infographic showing that higher COP results in lower running costs and monthly energy bills.

A simple way to estimate running cost

A practical estimate starts with this relationship:

Seasonal electricity (kWh) ≈ Seasonal heat delivered (kWh) / Seasonal efficiency (SPF or SCOP)

Running cost (€) ≈ Seasonal electricity (kWh) × electricity price (€/kWh)

This captures the key point: higher seasonal efficiency means less electricity needed to deliver the same heat. SEAI’s implementation guidance explicitly connects SPF to annual electricity consumption and operational cost.

The biggest drivers of running costs

Electricity price and tariff structure

Electricity prices vary by country, supplier, contract type, and time period. Eurostat reports household electricity prices (including taxes) across the EU and shows that prices can change between half-year periods.

In some markets, time-variable pricing can make costs more sensitive to when a heat pump runs. For example, Austrian utilities have introduced dynamic tariffs tied to market conditions, which can create large differences between off-peak and peak pricing.

Seasonal/system efficiency (SPF in real operation)

In real buildings, running costs are strongly linked to how efficiently the installed system operates. Field monitoring work highlights that measured performance can differ across building types and installations, which affects electricity use and cost.

Flow temperature requirement

Higher flow temperatures generally reduce heat pump efficiency and increase electricity consumption for the same heat output. This is why emitters (underfloor heating, radiators) and building heat loss matter for costs, not just comfort.

Outdoor temperature and defrost (air-source systems)

Cold and humid conditions can reduce efficiency and add defrost-related electricity use. This shows up most in winter periods near freezing, where defrost cycling is more frequent.

Control strategy and part-load cycling

A control strategy that keeps flow temperature higher than needed or causes frequent start-stop cycling can increase seasonal electricity use. Guidance documents emphasize that metering and proper setup are essential to understand and manage performance and running costs.

Backup heater operation (if present)

If an electric backup heater runs often, costs rise quickly because direct electric heating has a much lower “heat delivered per kWh” than a well-performing heat pump. In TOFU terms: backup heat is normal as a safety function, but frequent backup operation is usually a sign the system is operating outside its intended efficient range (design, controls, or extreme conditions).

Why “cheap to run” depends on context

It’s common to hear that heat pumps are cheap to run because they can deliver multiple units of heat per unit of electricity. That principle is correct, but actual cost savings depend on the electricity-to-fuel price ratio, building demand, and achieved seasonal efficiency. The EU JRC report on heat pumps notes operating costs depend on electricity prices and the energy performance of the building and system (including SPF).

This is also why energy labels and standardized seasonal metrics are helpful for comparison, but they do not guarantee identical bills in every home.

Practical checklist

If your goal is to understand or reduce running costs, these are the most useful questions to ask early:

  • What seasonal efficiency level (SCOP for comparison, SPF for real use) is realistic for my building type?

  • Can the system operate at low flow temperatures (emitters + insulation + heat load)?

  • How will the heat pump be controlled (weather compensation, zoning stability, DHW settings)?

  • What tariff will electricity be purchased on (flat rate, time-of-use, dynamic)?

  • Will backup heat run often, and under what conditions?

  • Is electricity consumption being metered in a way that matches the system boundary?

SEAI’s operation and maintenance guidance highlights that measuring electricity consumption is essential for determining performance and establishing running costs.

Key takeaway

Running costs are driven by heat demand × (1 / seasonal efficiency) × electricity price.

So the best way to influence running costs is usually to improve the system conditions that protect seasonal efficiency—especially flow temperature, control strategy, and stable part-load operation—while also choosing a suitable electricity tariff structure where possible.

Frequently Asked Questions (FAQs)

Running costs are the ongoing costs of operating the heat pump system, mainly the cost of electricity used to provide space heating (and often domestic hot water, and sometimes cooling). They include compressor electricity plus auxiliary electricity for pumps, fans, controls/standby, defrost (air-source), and any backup electric heating if it runs.

Running costs depend on how much heat the building needs and how efficiently the system delivers that heat using electricity. Higher seasonal/system efficiency means less electricity is required for the same heating output, which typically lowers running costs.

Common cost drivers include:

  • high electricity prices or an unfavorable tariff structure

  • high heat demand (poor insulation or high heat load)

  • high required flow temperature

  • frequent cycling at part load

  • frequent defrost operation in cold, humid weather (air-source)

  • significant auxiliary electricity use (pumps, standby)

  • frequent backup heater operation (if present)

No. COP is measured at a single test condition and does not represent performance across a full season. Running costs are more closely related to seasonal/system performance (such as SCOP for standardized comparison or measured SPF) and to how the system is designed, installed, and controlled.

Higher flow temperature usually reduces heat pump efficiency because the system must operate with higher temperature lift. That increases electricity consumption for the same heating output, which increases running costs.

Yes. Running costs depend on the electricity price you pay per kWh, and tariffs may include time-of-use or dynamic pricing where the cost varies by time or market conditions. If a tariff has high peak prices, operating patterns can affect total cost even when efficiency is unchanged.

Backup electric heating (direct electric resistance) typically delivers roughly one unit of heat per unit of electricity, which is much less efficient than normal heat pump operation. If backup heating runs frequently, it can significantly raise electricity consumption and costs.