Reference

Glossary

Power-industry vocabulary is full of acronyms. This page collects the terms you will see across this calculator, on your bill, and in retailer plan descriptions, with a one-line plain-English explanation for each.

Where these terms appear in a blog article, you can also tap or hover the underlined word to read the short version inline.

Pricing & bills

amortised: When the MBIE retail rate is described as "amortised", it means the daily fixed charge has been spread across each kWh that a typical household uses. This makes a single c/kWh number that already includes both the variable and fixed parts of the bill, useful for quick estimates but a bit hidden if you want to model your bill structure precisely.
blended rate: A single c/kWh figure that already includes both the variable rate and the daily fixed charge spread across typical usage. The MBIE QSDEP figure is a blended rate.
c/kWh cents per kilowatt hour: How much you pay per unit of electricity used. NZ rates in 2026 range from about 36c/kWh in cheaper areas to 50c/kWh in the most expensive.
Day/Night plan: A two-rate power plan: a higher rate during the day (typically 35-45c) and a lower rate overnight (typically 18-25c). Worth it if you can shift a chunk of your usage to night.
fixed daily charge: The flat amount your retailer charges you per day, regardless of how much power you use. Covers metering, billing, and a share of the network cost.
Free hour of power: Several NZ retailers now offer a daily free hour - you pick the hour and any electricity used during it is free. The catch is you have to actively shift consumption into that window: running the dishwasher, kettle, oven, dryer, or charging your EV during that hour. A typical household shifts 1-2 kWh into the window, worth around $9-$18 per month at current NZ rates. The calculator has an optional free-hour input in the advanced rates panel - enter the kWh you realistically shift and the saving is credited back at your day rate.
Free Power Day: Mercury Free Power Day gives eligible customers one free power day per month - midnight to midnight, everything used is on the house. Unlike a free hour, you don't need to shift consumption; the entire day counts. The calculator models this as a rebate of one day's share of your monthly appliance spend per free day claimed. Combined with a free hour of power, total credits are capped at your appliance bill so the number can never go negative.
GST Goods and Services Tax: NZ's 15 percent value-added tax. All electricity rates and figures on this site are GST-inclusive, the way they appear on a residential bill.
low user tariff: A type of NZ power plan with a very low daily fixed charge (capped at 30c historically) and a higher c/kWh rate. Suited to small households that use under 8,000 kWh a year. Being phased out 2022-2027.
off-peak: The hours of the day when electricity demand is lowest, usually overnight (11pm-7am). Some plans charge less for power used at off-peak times.
standard tariff: A NZ power plan with a higher daily fixed charge ($1.50 to $3 per day) and a lower c/kWh rate. Suited to larger or higher-use households.
tariff: The pricing plan you are on with your retailer. Two main shapes in NZ: standard (lower fixed cost, higher per-kWh) and low user (higher fixed, lower per-kWh).
time of use TOU: A pricing plan with different rates at different times of day. The most common form in NZ is Day/Night, but newer plans split into peak, off-peak and shoulder windows.
variable rate: The cost per kWh you actually use. Adds to your daily fixed charge to make up your total bill.

Technical

COP Coefficient of Performance: Coefficient of Performance is the efficiency rating of a heat pump. A COP of 1.0 means 100 percent efficient (you get out exactly what you put in, like a plug-in heater). Modern heat pumps in NZ winter conditions run at COP 3.0 to 4.5, meaning they deliver three to four-and-a-half times more heat than the electricity they consume. The colder it is outside, the more the COP drops.
COP derating: Manufacturers rate heat pumps using a standardised test at 7°C outdoor temperature, which flatters them. At 2°C a typical split system drops to COP 2.5-3.0, and below 0°C (common on Canterbury and Southland winter mornings) it can fall below 2.5. The calculator uses a conservative winter COP, not the rated figure, because that is what actually shows up on your bill. If your unit is new, well-sized and in a mild region like Auckland, you can safely override the COP upward.
heating degree days HDD: A measure of how cold a place is, used to estimate heating demand. Higher HDD = colder climate = more heating needed. NZ's southern regions have roughly twice the HDD of Auckland.
kWh kilowatt hour: A kilowatt hour is the standard unit of electricity consumption. If you run a 2,000-watt heater for one hour, it uses 2 kWh. If you run a 100-watt fridge for 24 hours, it uses 2.4 kWh. Your power bill multiplies your total kWh by your rate (in cents per kWh) to calculate the variable part of your bill.
PM10: Tiny airborne particles smaller than 10 micrometres. Wood burners are the largest source in NZ winter air, especially in Christchurch and Rotorua. Linked to respiratory and cardiovascular illness.
ripple control: Ripple control is a low-frequency signal injected into the local power grid by the lines company (your network owner). A small relay near your hot water cylinder listens for the signal and switches the heating element on or off. In practice, most NZ cylinders heat overnight via ripple, which is why hot-water heating is often eligible for the night rate even if the rest of your house is on the day rate.
smart meter: A digital electricity meter that records your usage in 30-minute intervals and sends it to your retailer automatically. Almost all NZ homes have one as of 2026.
wattage: How much electricity an appliance draws when running. Listed on the rating plate (often on the back or underside). A 2,000-watt heater running for 1 hour uses 2 kWh.

Regulation

Authorised burner: A wood burner that has passed the NES-AQ emission and efficiency tests and appears on the Ministry for the Environment's Authorised list. Required for new installations in most NZ urban areas.
Healthy Homes Standards: NZ regulations that require landlords to provide rentals that meet minimum standards for heating, insulation, ventilation, moisture and draughts. Heating must be capable of warming the main living room to 18C on a cold morning.
NES-AQ National Environmental Standards for Air Quality: NZ-wide rules covering emissions from wood burners. Any new burner must be on the Authorised Wood Burner list to be installable in an urban area.
ULEB Ultra Low Emission Burner: A wood burner that meets the strictest NZ emission limits. Required for new installations in many Canterbury Clean Air Zones, including Christchurch.
Warmer Kiwi Homes: EECA's grant scheme that pays 50-90 percent of the cost of ceiling and underfloor insulation, and (for the most disadvantaged households) up to 90 percent of the cost of a heat pump up to $3,450.

Organisations

BRANZ Building Research Association of New Zealand: NZ's building-research institute. Source for figures like "30 to 35 percent of heat is lost through the ceiling".
EECA Energy Efficiency and Conservation Authority: A NZ government agency that promotes energy efficiency. Runs Warmer Kiwi Homes (insulation grants) and publishes household heating advice via Genless.
MBIE Ministry of Business, Innovation and Employment: The NZ government department that publishes the QSDEP electricity-pricing survey every quarter. The pricing data on this site comes from MBIE.
QSDEP Quarterly Survey of Domestic Electricity Prices: MBIE's survey of typical NZ household power costs in 42 locations. Published mid-Feb, May, Aug and Nov. The numbers in this calculator come straight from the latest QSDEP release.