Zoned Energy Rating Label (ZERL): what you need to know

What does ZERL mean?

It stands for Zoned Energy Rating Label and unlike standard energy rating labels the main difference is that it includes energy efficiency ratings for climate zones throughout Australia and New Zealand where the labels are used in a joint initiative. The reason for this is that heat pumps have an external unit which can be affected by outside temperature changes and will perform differently in various climates.

Image: Example of a ZERL.

The new labels take into account the different climates and list the energy efficiency for three zones. On the label, all of New Zealand is one zone - COLD. However, the Gen Less Efficient appliance calculator (see Gen Less Efficient Appliance Calculator) splits us up into different climate regions, so you can see more accurately how a heat pump will perform where you live. It shows that a heat pump performs quite differently in homes in Whangarei and Christchurch.

1. Cooling and Heating capacity

The first figures you’ll see at the top of the ZERL (Zoned Energy Rating Label) are the heating and cooling capacity of the heat pump. This will give you an idea of whether this model is the right size for your home.

The kilowatt (kW) numbers show the model's heating and cooling output power. Cooling is measured when the outside temperature is 35°C, and heating when it's at both 7°C and 2°C. It's important to consider whether heating or cooling is more important where you live, so you choose a suitable model. For many New Zealand homes in areas where the temperature regularly drops below 7°C, the most efficient models have a 2°C heating power that's close to or greater than the 7°C number.

For more information on how to choose the right capacity heat pump for you see our Heat pumps buying guide.

2. Cooling and heating ratings for New Zealand

We may call them heat pumps, but they can also cool your home in summer. Each climate zone has two star ratings and two kWh consumption ratings, one for cooling and another for heating. On the ZERL you can ignore the ratings for the first two climate zones, they are for parts of Australia. New Zealand is part of the bottom zone, COLD.

The star ratings go from 0 to 10 and can include half stars. Like the old energy rating labels, the more stars the better. The number is displayed in the last star.

The kWh per year energy consumption figures are shown to the right of the stars. The blue number indicates how much energy it will use to cool and the red how much it uses to heat. The lower the kWh number, the less it will cost to run.

These new labels are mandatory on all new heat pumps and ducted portable air conditioners. The manufacturers supply them, and retailers must display them.

Gen Less Efficient Appliance Calculator

On the ZERL, New Zealand is listed as one climate zone, COLD, but we all know there can be a big difference in the outside temperature between Auckland and Invercargill. There is a new tool to help you find the most energy efficient model for where you live, the Gen Less Efficient Appliance Calculator.

This calculator helps you compare the energy efficiency of any appliance with an energy rating label. But the real magic is when you compare heat pumps, you get to select where you live in New Zealand from 18 options:
• Northland
• Auckland
• Bay of Plenty
• Waikato
• Rotorua
• Taupo
• Taranaki
• East coast
• Wairarapa
• Manawatu
• Wellington
• Marlborough
• West coast
• Canterbury
• Queenstown
• Otago
• Central Otago
• Southland

The calculator will display the heating star rating, heating annual energy consumption, heating annual running costs and two heating energy outputs in kilowatts (kW) for all models. You can even shortlist models you wish to compare to find out which will be the most energy efficient for you.

The annual running cost is based on 25c kWh, so if you pay a different price you can click the Electricity Price filter at the top and set the cost to be the same as the tariff from your latest power bill.

3. The name of the model

It’s important to know you’re looking at the right energy label, so all ZERLs include the brand and model name. You can find this in the top left corner of the label, just above the image of Australia and New Zealand.

If the model’s name doesn’t exactly match what you’re looking at in store, ask the retailer and check the manufacturer’s website to make sure it really is for that model.

4. Noise

Heat pumps can be noisy beasts, both inside and outside of the house. To help you compare models and see which will be quieter, the ZERL now includes noise readings. This reading is optional in New Zealand, so you may see a mix of labels with and without noise readings.

There's a diagram of a house in the bottom left of the ZERL label. The numbers show the noise level of the heat pump units inside and outside the house. The outdoor reading is especially important if the unit is located near windows, doors or a neighbour’s house.

Portable air conditioning units will only have an indoor figure and ducted systems will only have an outdoor number.

These noise readings are in decibels (dBA) and the lower the number, the quieter it is. To give you an idea of what these readings mean in real-world terms:
• 30dBA – similar to a whisper
• 40dBA – running water
• 50dBA – moderate rainfall
• 60dBA – normal conversation/TV
• 70dBA – a dull roar such as a vacuum cleaner

The old Energy Rating label (ERL)

It’s easy to spot a new heat pump now as products imported before 1 July 2021 will still display the old energy rating label and only new models are required to have the ZERL.

You can’t compare star rating of ERL with ZERL as they're assessed differently.

As the energy consumption of heat pumps varies, depending on whether they’re cooling or heating, on the ERL there are two star-scores – one for cooling (blue) and one for heating (red). But there are no climate zones listed.

Instead of energy consumption figures, the label shows how much heating power you get (capacity output) compared to the electrical power it uses (power input) in kW.

These figures are useful in choosing the correct heat pump for your home. If you’re buying a heat pump, compare the ratio of capacity output to power input. For example, a heat pump that uses 1.8kW but only outputs 5kW is less energy efficient than a model that uses 1.6kW and outputs 5kW.

Note: the ZERL only applies to heat pumps. For more on ERL see our Energy Rating Labels explained article.