Heat Pump vs Gas Cost Calculator

How Does the Heat Pump vs Gas Cost Calculator Work?

The heat pump vs gas cost calculator compares the running costs of two fundamentally different heating technologies by accounting for their respective energy sources, efficiency ratings, and energy prices. A heat pump works by extracting heat from the outside air (or ground) and transferring it indoors, using electricity to power the compressor and fans rather than generating heat directly. A gas boiler burns natural gas to heat water, which is then circulated through radiators or underfloor heating to warm your home. Because these systems use different fuels with different pricing structures and operate at dramatically different efficiencies, a direct comparison requires converting both to a common framework — total cost to deliver a given amount of heating energy to your home.

The key metric for heat pump efficiency is the Coefficient of Performance (COP), which measures how many units of heat energy are delivered for each unit of electrical energy consumed. A COP of 3.0 means the heat pump delivers 3 kWh of heat for every 1 kWh of electricity it uses, effectively making it 300% efficient. Modern air-source heat pumps typically achieve a seasonal average COP of 2.5 to 4.0, depending on the outdoor temperature, the system design, and the heating distribution method. Ground-source heat pumps can achieve even higher COPs of 3.5 to 5.0 because ground temperatures are more stable than air temperatures. In contrast, a gas boiler converts chemical energy in natural gas to heat at an efficiency of 85% to 95%, meaning 85 to 95 kWh of heat is delivered for every 100 kWh of gas consumed. Even the most efficient condensing gas boiler cannot exceed 100% efficiency, while heat pumps routinely deliver two to four times more heat energy than the electrical energy they consume.

The relative cost advantage of heat pumps versus gas boilers depends heavily on the ratio between electricity and gas prices in your area. In the United Kingdom, where electricity costs approximately 30p per kWh and gas costs approximately 8p per kWh, the electricity-to-gas price ratio is about 3.75:1. For a heat pump to be cheaper to run than a gas boiler at this ratio, it needs to achieve a COP of at least 3.75 — which is achievable for well-installed systems but not guaranteed in very cold weather. In countries like France, where electricity is cheaper due to nuclear power generation, heat pumps are almost always more economical. In the United States, where average residential electricity rates are about $0.16 per kWh and natural gas costs about $1.20 per therm (roughly $0.04 per kWh equivalent), the price ratio is approximately 4:1, making high-COP heat pumps competitive but not always cheaper than gas.

Beyond running costs, there are several other factors to consider when comparing heat pumps and gas boilers. Heat pumps produce zero direct carbon emissions at the point of use, and as electricity grids become greener with renewable energy, their total carbon footprint decreases over time. Gas boilers produce CO2 emissions from burning fossil fuel and are subject to potential future carbon taxes or regulations. Heat pumps also provide cooling in summer (reversing the heat transfer cycle), eliminating the need for a separate air conditioning system. Installation costs for heat pumps are typically higher than for gas boilers, ranging from $8,000 to $25,000 for air-source systems versus $3,000 to $7,000 for a new gas boiler, but government incentives and rebates in many countries can significantly offset this difference.

Formulas

Examples

Example 1: UK Average Home
A home needs 15,000 kWh of heating annually. Electricity costs 0.30/kWh, gas costs 0.08/kWh. Heat pump COP = 3.0, gas boiler efficiency = 90%. HP electricity used = 15,000 / 3.0 = 5,000 kWh. HP cost = 5,000 × 0.30 = $1,500. Gas used = 15,000 / 0.90 = 16,667 kWh. Gas cost = 16,667 × 0.08 = $1,333. In this scenario, the gas boiler is $167 cheaper annually because the electricity-to-gas price ratio exceeds the heat pump COP.

Example 2: High-Efficiency Heat Pump
Same home (15,000 kWh), same rates, but with a ground-source heat pump achieving COP = 4.0 and a 90% efficient gas boiler. HP electricity = 15,000 / 4.0 = 3,750 kWh. HP cost = 3,750 × 0.30 = $1,125. Gas cost remains $1,333. The heat pump now saves $208 per year because its higher COP overcomes the electricity price premium.

Understanding COP and Seasonal Performance

The COP of a heat pump varies with outdoor temperature — it decreases as the outside temperature drops because there is less heat energy available to extract from the air. A heat pump might achieve a COP of 4.5 on a mild 10 degrees Celsius day but only 2.0 on a very cold minus 10 degrees Celsius day. The Seasonal Coefficient of Performance (SCOP) averages the COP across the entire heating season, accounting for temperature variations in your climate. When comparing systems, always use the SCOP rather than the peak COP to get an accurate picture of real-world performance. Modern cold-climate heat pumps are specifically engineered to maintain good performance in sub-zero temperatures, with some models maintaining a COP above 2.0 even at minus 25 degrees Celsius.

Environmental Impact Comparison

From an environmental perspective, heat pumps are significantly cleaner than gas boilers. A gas boiler produces approximately 215g of CO2 per kWh of heat delivered (accounting for boiler efficiency). A heat pump powered by the current UK electricity grid (about 180g CO2 per kWh) produces roughly 60g of CO2 per kWh of heat at COP 3.0. As the electricity grid decarbonizes further with more wind, solar, and nuclear generation, heat pump emissions will continue to decrease toward zero, while gas boiler emissions remain fixed. Many countries are planning to phase out gas boilers for new installations — the UK aims to ban new gas boilers in new-build homes, and several European nations have already implemented similar policies. Choosing a heat pump today future-proofs your home against these regulatory changes while immediately reducing your carbon footprint.