When you consider replacing a gas boiler or switching to low-carbon heating, one of the first questions that will come to your mind is the simple question of how much an air source heat pump will actually cost you to run. The truth of it is it depends, when you know the key variables you will be in a position to determine whether a heat pump is financially viable in your household or not.
Important: This article will teach you how the cost of running is computed, give some realistic cases here in the UK and also provide some helpful tips that you can apply to keep your bills low.
Calculation of the Running Costs
An air source heat pump (ASHP) does not combust any energy it just transfers the heat in the outside air into your house. The coefficient of performance (COP) is the ratio of the amount of heat produced to the amount of electricity consumed, which tends to characterize its efficiency. Therefore, when a heat pump has the COP of 3, it can offer 3kWh of heat per 1kWh of electricity consumed.
You must have three things to estimate what you will pay:
1. The kWh/year of heating of your home: This is dependent on size, insulation and the temperature at which you prefer to keep your house.
2. The average COP of the heating season of the heat pump.
3. Your price of electricity (pence per kWh) — refers to your most recent bill or tariff.
If cost is a major concern, you may be eligible for a £7,500 air source heat pump grant to help reduce your upfront investment.
A simple formula you can use
Annual heat demand/ COP = Annual electricity used.
Annual operating expenses = annual electricity consumed x electricity price.
Real UK Examples: What You Might Actually Pay
Exact figures will vary, but these examples give you a practical way to think about costs. Let’s use an electricity price of 34p/kWh (£0.34) as a recent common benchmark, check your own tariff. Assume two COP scenarios (3.5 and 3.0), which are realistic for modern systems depending on installation and temperatures.
Example 1
Small, well‑insulated home (8,000 kWh heat/year)
COP 3.5 → electricity = 8,000 ÷ 3.5 = 2,286 kWh → cost ≈ £777/year
COP 3.0 → electricity = 8,000 ÷ 3 = 2,667 kWh → cost ≈ £907/year
Example 2
Average UK home (12,000 kWh heat/year)
COP 3.5 → electricity = 3,429 kWh → cost ≈ £1,165/year
COP 3.0 → electricity = 4,000 kWh → cost ≈ £1,360/year
Example 3
Larger or poorly insulated home (18,000 kWh heat/year)
COP 3.5 → electricity = 5,143 kWh → cost ≈ £1,748/year
COP 3.0 → electricity = 6,000 kWh → cost ≈ £2,040/year
To compare, a gas boiler with 85 percent efficiency priced at approximately 10p/kWh of gas will have an effective cost of heating of between 11-12p/kWh. In the case of an average home which requires 12,000 kWh/year, that is about 1320-1440 pounds a year.
As you have seen, even with a fairly good COP an air source heat pump is already a competitor and the benefit is increased should you take advantage of cheaper electricity periods, or your own solar power.
What Influences Your Costs (that which you can control)?
1. Insulation and Heat Demand
This is the largest lever. Pass on a reduced heat demand and all your pounds saved on running costs and compound every year.
2. Right Sizing and Design
With an oversized system, you will be in a position to short-cycle and waste power whereas a system that is undersized will find it hard to perform during cold seasons. Ensure you obtained a proper calculation of heat-loss.
3. Flow Temperature and Emitters
The best conditions are achieved when the heat pumps operate at lower temperatures of the flow. Floor heating or more substantial radiators allow you to have lower temperatures and enhance COP.
4. Outdoor Temperature COP Goes Down in Extremely Cold Weather
In areas with a lower temperature or those with a house that is poorly insulated, you might want to go with a hybrid solution or a unit of the right size.
5. Controls and Tariffs
T tariffs can be time-of-use tariffs, smart controls and weather compensation can be used to pay less by simply shifting consumption to lower priced times of the day.
6. Maintenance
Your system should be maintained (usually between £100 and £200 a year) to ensure it is efficient and prevent expensive repairs.
How to Save Your Heat Pump Bills in Practice
- Insulate first
Loft, wall and floor insulation are more typically the least expensive upgrades to make prior to altering your heating system. Learn how to choose the right insulation for your home.
- Install underfloor heating
This allows the heat pump to operate at lower temperatures and will help conserve more energy.
- Employ a time-of-use tariff and smart controls
In case you have a capability of moving some heating (or a thermal store) to off-peak power, you will reduce operating expenses.
- Install solar PV
Powering the heat pump yourself will save you a significant sum of money in electricity purchase.
- Service every year
COP is maintained by keeping the outdoor unit clean, as well as making sure that refrigerant levels and controls are in place.
Is Your Home Suitable with an Air Source Heat Pump?
The best thing about it is that you can use it well when your home is fairly well-insulated or can be insulated without costing an excessive amount, and when you are comfortable with lower flow temperatures (or with spending more on radiators).
Especially appealing to a combination with solar PV, a smart tariff or in the case of replacement of an old inefficient boiler, heat pumps are especially appealing. The heat pumps may still be used in case of living in a listed building or having a poorly insulated house in which upgrades are not possible, but the costs will be less favourable.
Learn more about the location and suitability rules for air source heat pumps.
Wish to Receive a Personal Estimate?
You will not be certain till you figure out your property. You can have a free estimate of the running-cost with us, (you can skip the postcode and house type (flat, semi, detached), your existing heating system, and an approximation of your annual spending on heating (if you know it).
We will provide you with a basic breakdown of likely electricity consumption, estimated annual running costs and suggested options of the system. Get a free quote today from Home Energy Guide today.
Frequently Asked Questions (FAQs)
Yes. The air source heat pump developed in the modern technological age is made to suit cold climates. They collapse on the least favorable of days, however, and furnish usable heat. It will decrease the use of backup heat because of proper sizing and insulation.
Yes usually but bigger radiators or underfloor will be required to get a heat pump to perform best.
Be prepared to have an annual service and basic maintenance such as ensuring that the outdoor unit is free of debris. Repairing contributes to the efficiency and extends equipment life.
Indeed, not only is the combination of solar PV with a heat pump among the most effective in terms of minimising the running expenses and emissions. Explore how solar panels can benefit your home.
