Is a wood burner or heat pump cheaper to run?

It depends on firewood and power prices in your area. Heat pumps are very efficient, delivering several units of heat per unit of power, while a wood burner's cost depends on what you pay for firewood. Cheap or free wood can make a burner cheaper; bought firewood is often comparable to a heat pump.

How do I compare firewood and heat pump costs?

Work out the cost to deliver the same heat each way: firewood by the cord allowing for the burner's efficiency, and the heat pump by the power it uses, helped by its high efficiency. This calculator does both for a season.

What else matters besides cost?

Wood burners give a strong, cosy heat and work in a power cut, but need wood handling and meet clean-air rules in some areas. Heat pumps are easy and also cool in summer. Cost is one part of the choice.

Firewood vs Heat Pump Calculator

This calculator works out whether a wood burner or a heat pump is cheaper to run in a New Zealand home, based on delivering the same amount of heat over a winter season. Heating is one of the biggest running costs in an NZ household, and the cheaper option is not obvious: heat pumps are highly efficient, turning one unit of electricity into several units of heat, while a burner's cost depends on what you pay for firewood and how efficient it is. You enter the heat you expect to need for the season in kilowatt-hours, the price of a cord of firewood, your burner's efficiency, your power price per kilowatt-hour, your heat pump's efficiency (its COP), and the heat a cord delivers. The calculator returns the wood cords needed and their seasonal cost, the heat pump's power use and seasonal cost, and a verdict on which is cheaper for you. Cheap or free firewood tips the result toward the burner, while a high power price or efficient heat pump can flip it back. Cost is only part of the decision: burners give a cosy heat and work in a power cut but need wood handling and must meet clean-air rules, while heat pumps are effortless and cool your home in summer. Treat the figures as an indicative estimate only, since firewood energy content and burner efficiency vary.

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Heat needed per season (kWh)

Firewood per cord

Wood burner efficiency

Power price (per kWh)

Heat pump efficiency (COP)

Heat energy per cord (kWh)

cheaper to run over the season

Firewood, season$0

Heat pump, season$0

A cord's heat energy and burner efficiency vary with wood type and the unit; the defaults are rough. Cheap or free wood shifts the result toward the burner. Beyond cost, weigh convenience, clean-air rules and power-cut resilience. Estimate only.

How it works

The calculator works out how much usable heat a cord of firewood gives once the burner's efficiency is applied, then the cords and cost needed to meet the season's heat. For the heat pump, it divides the heat needed by the heat pump's efficiency, its COP, to find the power used, then costs that at your power price. The high COP means a heat pump delivers several units of heat per unit of power, which is why it competes well with firewood.

Worked example

To deliver 4,000 kWh of heat, a burner at 65% efficiency from cords giving 5,000 kWh each needs about 1.2 cords, roughly $220 at $180 a cord. A heat pump with a COP of 3.5 uses about 1,143 kWh of power, about $320 at 28 cents. Here firewood is cheaper, though cheaper power or pricier wood could flip it.

Related calculators

Electricity Cost Calculator: power costs.
Gas vs Electric Cooking Calculator: cooking costs.
Room Heat Pump Sizing: what kW your room needs.

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