Heat pump vs wood burner: which is cheaper in NZ?

Both options come out close to 10 cents per kWh of useful heat in most of New Zealand right now. Wood is fractionally cheaper than a heat pump per kWh delivered, but not by anything close to the gap the folklore suggests, and the non-cost factors (convenience, air quality, regulations) often matter more than the small difference.

Here is the maths, then the things the maths leaves out.

Cost per kWh of usable heat

Heat pump. At Christchurch's February 2026 MBIE retail rate of 36.6 c/kWh, with a mid-winter COP of around 3.7, you pay about 9.9 cents per kWh of heat delivered into the room. Auckland Central with COP 4.2 and a 39.7 c/kWh rate is similar. Invercargill with COP 3.3 and 37.3 c/kWh comes out around 11.3c.

Modern wood burner. A reasonably dry hardwood log delivers about 3.8 kWh of gross heat per kg. A modern Authorised burner that meets the NES-AQ standard is roughly 70-78% efficient (older non-compliant burners drop to 50-60%, which is one reason they are being phased out). So you get around 2.7-2.9 kWh of useful heat per kg of wood.

Stacked dry firewood weighs roughly 600-700 kg per cubic metre for hardwoods (gum, macrocarpa) and 400-500 kg/m3 for softwoods (pine). At April 2026 NZ delivered prices of $130-180/m3 for standard hotmix and $180-220/m3 for premium hardwood:

• Pine/softwood mix at $140/m3: about 1,250 kWh useful per m3 = 11c/kWh
• Hardwood mix at $160/m3: about 1,800 kWh useful per m3 = 9c/kWh
• Premium gum/macrocarpa at $200/m3: about 1,950 kWh useful per m3 = 10c/kWh

So on a per-kWh basis it is a near tie. A modern heat pump in a temperate region is about 10c/kWh of heat. Hardwood firewood at typical NZ delivered prices is about 9-10c/kWh of heat. Wet firewood, an older non-compliant burner, or paying premium prices for delivered, split, seasoned wood will tip the balance the other way.

The folklore that firewood is "almost free" relies on free wood from a farm or doing the cutting and splitting yourself. The folklore that "heat pumps are way cheaper to run" is from a decade ago when power was 25c/kWh and heat-pump COPs were better than they are in cold-snap NZ winters.

Where wood burners still win

• Free or nearly-free wood. If you have access to fallen trees on rural land and the time to cut and stack two years ahead, your effective cost can be almost zero. This is a real situation for some households and a fantasy for others.
• Power-cut resilience. A wood burner does not care if the network is down, which matters in storm-prone areas.
• Whole-house heating from one source. A 14 kW wood burner heats a much larger area than most heat pumps can manage.
• Comfort. Radiant heat and the visible flame are not the same as warm air from a unit on the wall. This is preference, not economics.

Where heat pumps win

• Convenience. No fuel to load, no ash to clear, no chimney to sweep.
• Air quality. No PM10 emissions in your neighbourhood. NZ has serious winter air-quality problems in Christchurch, Rotorua, Nelson, and Timaru, largely from wood burners. Several airsheds have rules that prevent installing new burners or require replacing older ones.
• Cooling. The same unit handles summer.
• Bedroom and shoulder-season heating. Wood burners are all-or-nothing. A heat pump can take the chill off a single room cheaply.

NZ air-quality rules to check before installing a burner

• Canterbury (Christchurch, Timaru, Rangiora, Kaiapoi, Ashburton, Geraldine): sit inside Environment Canterbury's eight Clean Air Zones. Only Authorised low- or ultra-low emission burners can be newly installed, and many older non-compliant burners must be replaced (or the property switched to a non-burner heat source) by the end of 2027 under the Canterbury Air Regional Plan.
• Rotorua, Taupo, Nelson, Reefton, Arrowtown, Cromwell, Alexandra: airshed-specific emission rules. The Ministry for the Environment maintains an Authorised wood burner list to consult before purchasing.
• Auckland: open fires cannot be newly installed in urban areas, and any new wood burner must meet the National Environmental Standards for Air Quality (NES-AQ) emission and efficiency limits.

Check with your council before assuming you can put a burner in. In air-shed-restricted areas, removing a non-compliant burner and going heat-pump-only is increasingly the path of least resistance.

The honest answer

For most NZ urban households today, the per-kWh costs are essentially tied. A heat pump wins on convenience, air quality, summer cooling, and the ability to heat one room without lighting a whole fire. A wood burner wins on power-cut resilience, comfort and ambience, and economics if you have cheap or free wood.

Run your own comparison: enable the heat pump in the NZ Power Bill Calculator, set realistic winter hours, and see what it costs you per month. Then compare that figure against your delivered firewood cost divided by ~1,800 kWh per cubic metre.

Related guides

• How much does a heat pump cost to run in NZ? - per-kWh and per-month figures
• What temperature should you set your heat pump? - settings that affect running cost
• Insulation or a heat pump: where to spend first - reduces how hard any heating system has to work