The Australian Government first introduced the energy star rating system for residential air conditioners in 1987, and air conditioning systems have been subject to the Minimum Energy Performance Standards (MEPS) since 2004. And thank goodness, as most of us would be bamboozled trying to calculate how air conditioner efficiency works!
The ratings are particularly useful with air conditioners because the difference between an efficient unit and an inefficient one can result in hundreds of dollars worth of electricity being utilised every year. Here is a guide to air conditioner star ratings.
What is an Energy Rating Label?
All domestic single phase, non-ducted air conditioners for household use are currently required to display an Energy Rating Label in both Australia and New Zealand. This label contains the energy star ratings and other information about the air conditioning unit’s capacity output and power input.
What are the Energy Star Ratings?
The energy star ratings represent a standard measure of the heating and cooling efficiency of the system, known as the Co-efficient Of Performance (COP) for heating and the Energy Efficient Ratio (EER) for cooling. In simple terms, they are a measure of the ratio of the output or capacity of the unit divided by the power input, or the ‘energy service per unit of energy consumption’.
Air conditioner labels are different to labels on other products and include product specific information on them. Air conditioners that only cool the air have a scale of blue stars, while reverse cycle systems have an additional set of red stars to represent their heating capacities. Currently, it is a scale of six stars for each (six being the most efficient), with an additional four stars representing a ‘super efficiency rating’. If a product is rated as six stars or less, it won’t show the extra ‘super efficiency rating’ band.
These energy star ratings offer a prospective buyer a simple and fair way to contrast similar products, as long as air conditioners of similar size are compared. Split systems, wall units and window units are all required to have the labelling at the present time, which makes it easy for people who are wanting to compare and install smaller units in their homes.
What Does Capacity Output and Power Input Mean?
Energy rating labels are helpful because they provide a simple, visual way to compare ‘like’ products in what could be an otherwise complicated equation! However, you can also learn more about the efficiency of two similar air conditioners by looking at the ‘capacity output’ figures on the label. These will tell you how much cooling or heating the unit can produce.
The ‘power input’ figures are also helpful – they will tell you the amount of power that’s needed to produce the heating or cooling that’s listed in the ‘capacity output’. A product with a lower power output will be more efficient than one of the same size with the same energy rating and ‘capacity output’.
Some labels may also have a separate figure within the output and input heating box, which shows the heating output capacity of the unit when tested at 2°C (the main figure is tested at 7°C). This is helpful in colder climates where the temperature drops below 5°C, because outdoor units tend to ice up which will impact the capacity of the unit and the area it can heat up.
What Is A Variable Output Compressor?
Some energy rating labels may also show a Variable Output Compressor tick box. This will tell you whether it is what is commonly known as an ‘inverter’ air conditioner, which are air conditioning units that are able to vary the speed at which they operate to suit conditions. So for example, on a milder summer day, they won’t have to work as hard as when it’s 40°C outside.
What Types of Air Conditioners Don’t Carry an Energy Rating Label?
The following air conditioners are not currently required to carry an energy rating label:
- evaporative air conditioners
- ducted air conditioners (carrying the label is voluntary),
- three-phase air conditioners (carrying the label is voluntary in the residential sector)
- multi-split air conditioners
- air conditioners intended purely for commercial applications
- single exhaust duct portable air conditioners
However, even if you are purchasing an air conditioning unit without a star rating label, you can still calculate its energy efficiency performance by supplying a product description on the GEMS Registration Database, by downloading the Energy Rating app, or you can calculate the EER and the COP yourself using the Energy Rating Calculator.
A Final Thing to Consider: Size Matters
When considering purchasing a new air conditioner, probably the most important initial step is choosing the right size. Unlike other products where the size of the product is obvious, air conditioning units typically look similar despite having a wide range of cooling and/or heating capacities. Generally, the sizing for air conditioners is provided as a kilowatt (kW) capacity output figure, which is listed on the energy rating label.
Other things to consider include:
- Whether you’re looking to heat or cool a single room or your entire home
- The size of your room or home
- The external wall materials
- The insulation levels
- How many windows there are, and their glazing, shading and orientation
- Where you live, particularly if the temperature regularly gets down to below 5°C
In a nutshell, undersized units will have to work harder to cool or heat your room, and may not be able to reach and maintain your preferred temperature. Units that are oversized will typically be less energy efficient and will cool, but may not dehumidify leaving you clammy and uncomfortable.
Need some help deciding on the most energy efficient air conditioner for your home? Get in touch with H&H Air Conditioning today on (07) 3276 1800 (Brisbane) or (07) 5477 1777 (Sunshine Coast).