Air conditioning was once considered a luxury. These days, it is considered more of a necessity. Conditioned air is common place in our everyday lives, with the majority of Australians (three-quarters at last count) using at least one home air conditioner.
There are also many benefits of air conditioning, some of which you may never have considered. Disease prevention, health promotion, building/equipment protection, economic growth, and lifestyle enhancement are just some of the many AC benefits.
However, air conditioning is rarely free. This is unless you only enjoy it in the workplace or still live at home with generous parents. Even then, someone is paying for it. If you are investing in an air conditioner, you are sure to want the best value for money.
There are many factors involved in the decision-making process when selecting a new air conditioner unit. Energy efficiency is a key consideration as it can help saving money and the environment. The money side is not always so clear, as the relationship between energy efficiency and money saved (initially vs overtime) is not clear cut.
This article outlines some of the things worth considering when looking to choose an energy efficient air conditioner for you home, business or organisation. It also provides some additional information to help explain and give each point some context.
1. Individual Requirements
Do I need air conditioning?
You may still be trying to decide whether or not you need air conditioning. The more you read, research, and chat to people, the more complicated it can become!
Everyone has their own opinion on the matter. Some people rave about the benefits of air conditioning. Meanwhile others make you wonder whether air conditioning can make you ill.
At the end of the day, you need to weigh up the pros and cons, and make a decision based on your individual circumstances, needs, desires, and budget.
How do I buy an energy efficient air conditioner?
Making the decision to have a home air conditioner or commercial HVAC system is just the beginning.
The next step is to decide on which system to purchase. Factors include type, size, brand, and features, just to name a few. Another key factor, which can often be the final decider, is energy efficiency.
People often ask about how to select an energy efficient aircon. To make your life easier, you could choose to contact an expert air conditioning installer in Brisbane and simply ask for their advice.
By doing that, you can skip all the hard work, time-consuming research, and utilise their expertise in finding the right AC system for you.
However, many people love to learn and explore options for themselves. If you would rather do the research yourself, then read on to learn about how to choose an energy efficient air conditioner.
Having some background knowledge also helps converse with an aircon professional about AC units and installation required. By learning some key words and concepts related to air conditioning, and particularly energy efficiency, you can understand the professional and know what questions to ask.
2. Areas to be Served
Which rooms need air conditioning?
Before you can choose an energy efficient aircon, you first must decide which rooms need to be air conditioned. It is best to carry out this assessment before you purchase or install ANY air conditioning in your residential or commercial building if possible.
Forward planning can save time, energy, and money. For example, initially you may think of just installing one unit in a living room to get you started. You may plan to open doors off the living room to help cool surrounding rooms and see how that goes.
Doing this can result in excessive demand on the one AC unit that would be left continually drawing power without achieving the desired results; People sitting in the living room can be left freezing while room/s off the living room are still uncomfortably warm. This is obviously not an efficient air conditioning scenario.
You may then realise you will need an air conditioner unit for every individual room requiring climate control. On reflection, perhaps should have gone with a multi-head split system due to limited outdoor space, or a ducted aircon due to limited indoor wall space and/or overall cost in the first place. Therefore, it pays to consider all rooms upfront, before purchasing any AC Units.
How do you design the most energy efficient aircon?
There is a lot to consider when designing an air conditioning system, especially an energy efficiency one. The key is to design an AC system that ticks the most boxes in the areas you value the most.
Design factors vary depending on whether you are looking to heat or cool an individual room or zone (in the case of DX air conditioning) or a whole building (in the case of central air conditioning). Many of the general factors will be outlined below, so continue reading to find out more.
It is important to consider all factors upfront before making any purchases. That way you can narrow down the best choice for now as well as the future, if your air conditioning investment must be spread over time.
For example, perhaps you want zoned ducted air conditioning with individual temperature control (ITC) sensors for increased efficiency but can’t afford everything at once. At least by considering this upfront, you can be sure to select an aircon brand/model that is compatible with your desired zoning system for later installation.
3. Air Conditioning and Heating
What is reverse cycle aircon?
Reverse cycle air conditioning refers to the provision of heating and cooling by the one device. It is based on the refrigeration cycle with a heat pump controlling the flow of refrigerant in liquid and gas form.
Refrigerant can transfer heat from inside a building to the outdoors, creating cooling indoors (Cooling Cycle). Alternatively, it can absorb heat via the outdoor unit and transfers it to the indoor space, creating heating (Heating Cycle).
This cannot be done simultaneously; A reverse cycle AC system can run in either in heating mode, or cooling mode, but not both modes at the same time. This makes sense and usually only one mode of temperature control is required at a given time.
Do I need heating and cooling, or cooling only, for energy efficiency?
A reverse cycle air conditioner will have two energy efficiency ratings: one for heating and one for cooling. We’ll discuss the different types of ratings later on.
An air conditioning system is more efficiency in heating, and therefore the heating efficiency rating will be better than the cooling rating. Meanwhile, the cooling efficiency of an AC system would not be any different whether it is a comparable reverse cycle or cool only air conditioner unit.
However, reverse cycle air conditioning can be more energy efficient than other forms of heating, such as portable heaters or built in electric heating. Therefore, if you require heating as well as cooling, it may be worth investing in a reverse cycle AC system.
4. AC Type
What are the different types of air conditioning?
There is a wide range of different air conditioner types to consider. Each system has pros and cons for use in residential and commercial applications. Certain systems can also be enhanced with the use of fans, fresh air intake, and/or ventilation.
Air conditioning based on the refrigerant cycle can be divided into 2 categories depending on how heat transfer occurs with the refrigerant; Direct Exchange (DX) air conditioning (directly with refrigerant) and Central Air Conditioning (first via a cooling medium, then via refrigerant in centralised equipment).
DX units are the most common forms of air conditioning. They include window/box/room air conditioners (RAC’s), portable aircons, ceiling/floor/wall split systems, heat pumps, multi-head units, ceiling-concealed/bulkhead ducted systems, ceiling-suspended/4-way cassettes, and even roof-top packaged units.
Wall split systems and ducted air con systems are the most common types used for home air conditioning. They can also be used for light commercial application, but the range of units found in commercial settings varies dramatically; From a small wall split system in a server room all the way up to central air conditioning plant in large scale buildings such as high-rise office blocks, shopping centres, etc.
What is the most energy efficient air conditioner unit?
Wall split systems are rated as more energy efficient compared to other systems like ducted aircon, but there is more to the story. Overall energy efficient is the result of many things.
For example, kilowatt (kW) rating of an AC system is a major determinant of energy efficiency. Therefore, smaller AC systems such as portable air conditioners, box units, and wall split systems will naturally have a greater energy efficiency comparted to larger AC systems such as ducted or package units.
If you are interested in energy efficiency, you need to consider the efficiency of your home or building as a whole. While an individual split system may be more efficient than a ducted system, you may need to install 4-6 split air conditioners to cool a standard house. If you add up the average power usage of this many split units compared to 1 ducted unit, which is the most energy efficient way to heat or cool your home?
5. KW Rating
What does kW, kWh, BTU and Ton mean in AC?
kW stands for Kilowatts. As the term ‘kilo’ suggests, it refers to 1,000 watts. Watts is a measure of power. In air conditioning, it refers to the how powerful a system is. This is often referred to as capacity in air conditioning.
You will find two kW ratings on a reverse cycle air conditioner; cooling capacity and heating capacity. Heating capacity (ability to heat a room) is typically greater, and therefore the kW rating will be greater for heating.
From kW, you can move onto kWh. kWh refers to kilowatt-hour, which is a measure of energy. It measures the amount of energy used or required to maintain power for 1 hour.
You may also see the term BTU used in air conditioning. BTU stands for British Thermal Unit. BTU/h refers to the amount of heat an aircon system can remove from a room in 1 hour. 1kW is equivalent to approximately 3500 BTU/h (~3,412 to be exact). Therefore a 3.5kW air conditioner is equal to ~12,000 BTUs.
Large central plant, such as chillers, can be measured in ton. Ton is another measure of energy. One ton refers to the amount of heat (288,000 BTU) required to melt 1 ton of ice in a 24-hour period. 1 ton is equivalent to ~3.5kW. As a practical example, the capacity of water-cooled chillers typically ranges from 100’s to 1000’s of tons.
What kW air conditioner do I need for energy efficiency?
The kW air conditioner that you need is a bit like the story of Goldilocks and the Three Bears; you want to find the one that is just right. The correct size will help achieve the best results all around.
Generally, a small/average bedroom room may need a 2.5kW aircon, while a larger open-plan area might need a lager power output of 6kW (5.0 – 7.1 kW range) or more.
If an air conditioner unit is too big (kW-wise), it will consume more energy and be less efficient. It will also cost you more to buy and install initially.
If an aircon is too small, it may continually run, have to work harder to heat or cool a space, and be unable to reach or maintain the required temperature. This results in maximum power usage and wears the AC system out faster.
Ducted air conditioners can sometime get away with being on the smaller side, IF they are paired with a smart zoning system like iZone. This allows individual rooms or zones to be tightly controlled and only heated/cooled when required.
As all zones are rarely used at the same time, a ducted system can be smaller than what may otherwise be required to climate control a whole building. With clever zoning, the energy usage of a ducted system is managed, making the system as energy efficient as possible for a given kW rating.
6. AC Brand
What are the best air conditioner brands?
There are many different air conditioning brands to choose from. They vary in terms of quality, features, technology, and price. At the end of the day, most of us what value for money; The highest quality at the lowest price.
Popular AC brands include Daikin, Mitsubishi Electric (ME), Mitsubishi Heavy Industries (MHI), Panasonic, Hitachi, Temperzone, ActronAir, Toshiba, LG, Fujitsu, Kelvinator, Samsung, Carrier, just to name a few. These name-brands vary dramatically in terms of quality and price, but many represent good value for money upfront.
Some are not necessarily great units but have become popular through clever marketing and successful advertising. One example is Fujitsu who use familiar faces to promote their brand but then have unhelpful customer service behind the scenes and very poor part availability.
Some of the cheaper AC brands on the market save you money upfront but then cost you far more in replacement parts and repairs over the years. For example, Samsung AC units are relatively cheap to buy, but their replacement parts are horrendously expensive.
By comparison, Daikin AC units might cost a little more upfront than other popular brands, but many replacement parts are far cheaper compared to their competitors. This is especially true if you go through a Daikin Dealer.
How do I choose the most energy efficient AC Brand?
In general, higher priced air conditioners tends to be more energy efficient. Higher quality brands also tend to offer Standard and Premium ranges of wall splits and/or ducted aircons. Premium ranges typically offer additional energy savings.
Technology advancements and additions make higher quality/more energy efficient aircons more expensive to produce. Examples include larger heat transfer coils, more efficient motors, energy saving modes, intelligent sensors, etc.
However, as mentioned previously, price doesn’t also correlate with efficiency. Sometimes as you may just be paying for clever marketing and hype.
On the flipside, some brands and models don’t even advertise all their features. For example, when looking at Daikin wall split systems, the indoor coil size increases as you step up from a Daikin Cora to a Daikin Alira. However, this feature isn’t promoted; all you can find is mention of an increase in energy efficiency.
For more information, you can always dig deeper and look at the product brochures and technical specification sheets to compare brands and models. Key ratings to look at include star rating and EER/COP. More on both of these later.
7. Star Rating
What is the star rating in air conditioning?
Star rating refers to the energy rating that all split air conditioning systems in Australia must have. It is an Australian Government initiative designed to help consumers see and compare the energy efficiency of different appliances, such as air conditioners.
The star rating has a base of 6 stars. However, this can be extended up to 10 stars with a super efficiency rating. The first air conditioner in Australia to unlock the super efficiency rating set of stars is the Daikin US7 2.5 kW air conditioner, with a 7-star rating.
You can often find the energy rating label on the AC unit itself (typically on the indoor unit). There are two colours for reverse cycle air conditioners: blue labelling for cooling and red labelling for heating.
In the smaller sized air conditioning category, such as 2-2.5 kW, many of the best air conditioning brands have a star rating between 5 and 6 stars. Some brands, such as Daikin and Mitsubishi Electric, have many different models within this range.
You can find a comprehensive list of different brands and models on the Australian Government website page dedicated to comparing the star rating of air conditioners.
Is a 5 star AC worth it?
Wondering whether or not a 5-star (or 6 or 7 star) air conditioner is worth it? The short answer is: It all depends.
Usage is a key factor to consider. Think about whether the system will be used regularly (e.g. lounge room or master bedroom) or just occasionally (e.g. guest room)?
Special features are another consideration. In the case of the Daikin US7, the initial purchase price of the 7-star 2.5 kW model is over double the cost of the nearly 5-star 2.5 kW Daikin Cora model. Aside from energy efficiency, the US7 offers a wide range of other benefits that prompt people to buy it, including advanced humidity control, air filtration, and fresh air provision into a home.
Size is another factor. As discussed previously, kW rating impacts energy efficiency. You also need to ensure you select the most suitably sized (capacity) air conditioner for the area you need to cool down or heat up.
If an air conditioner is larger than 2 – 3.5 kW, you are unlikely to see a star rating of 5 due to pure physics. Therefore, you need to compare AC units with the same capacity (e.g. 5.0kW Daikin vs 5.0kW Mitsubishi), rather than focus on the star rating itself. It’s important to compare identical kW ratings for a fair and relevant comparison.
What does EER mean? What does COP mean?
EER stands for Energy Efficiency Ratio. It is a measure of the cooling capacity of an air conditioner. The higher the EER rating, the more efficient the AC is and the less it costs to run.
EER refers to the ratio of capacity to power. Capacity for this equation is measured in British Thermal Units (BTU) while power is measured in watts (W):
EER rating = Capacity (in BTU) / Power (in W)
COP stands for Coefficient Of Performance. COP is a term used when rating the heating capacity of air conditioning systems.
This rating factors in the hot temperature outside (Thot) and the cold temperature desired inside (Tcold):
COP = Tcold / (Thot – Tcold)
Finally, the maximum EER from COP can be calculated as follows:
EER = 3.41 x COP
What is a good EER for an air conditioner?
Given that small capacity (kW) air conditioners have a higher energy efficiency rating, we can use them as an example of a good EER.
Let’s take a small 3.5kW air conditioner as an example. This is the equivalent of ~12,000 BTU. Say it is powered by 1000 W. Using the above calculation, EER is equal to 12.
EER rating = 12,000 BTU / 1000 W = 12
An EER rating of 12 tells us that for every watt of energy we provide to the air conditioner, the air conditioner will provide 12 BTU of cooling effect. 12 is a good EER rating for an air conditioner.
Smaller 2.5kW air conditioners and higher quality models can reach more than 12. Meanwhile, larger kW-rated systems will naturally be less, as the energy efficiency of an AC decreases as capacity (kW) increases.
As discussed, when comparing air conditioning systems, fair and meaningful differences can only be detected when comparing units of the same capacity. Comparing apples to apples, as they say.
9. Fan Speed
What is the use of fan speed in AC?
Fan speed in air conditioning typically refers to variation (or not) of the fan motor in the indoor evaporating unit. Fan speed allows greater control over temperature and humidity, as well as power usage.
When a fan is running at a lower speed, components in the AC system have more time to remove humidity from the air. This allows greater dehumidification. Alternatively, when the fan speed is higher, the air can be cooled faster but not dehumidified to the same extent.
Is variable speed AC worth it?
Variable fan speed comes standard in most mid-high range air conditioning systems. This is for good reason. Variable fan speed is a valuable addition to any AC system in terms of ability to climate control the indoor environment.
If an air conditioner unit only has one fan speed (i.e. fixed), then a room can only be heated or cooled at one pace. In comparison, a variable fan speed air conditioner can be set to heat or cool a room quicker. This allows the desired setpoint to be reached quicker, at which time the air conditioner can just tick over to maintain the conditions.
A variable speed fan motor can result in energy savings, as a fixed speed aircon will just continue to draw power for however long it takes to reach setpoint. This can take a long time depending on what the fan motor fixed speed is.
These days, it does not cost manufacturers that much more to include variable fan speed in their AC products, compared to a fix fan speed. This is because of technology advancements and refinements in the manufacturing processes.
10. Inverter Technology
What does inverter mean in air conditioning?
Inverter is a popular term in the world of air conditioning. Inverter in air conditioning typically refers to the variation (or not) of the compressor motor in the outdoor condensing unit.
As the compressor motor is a significant component of an air conditioner, and significant power-user, control over this motor affects energy usage. It also impacts overall system efficiency.
An inverter allows the compressor to be run at different speeds. In comparison, a non-inverter system means that the compressor can only run one of two ways: full speed or off.
Does inverter really save electricity?
Inverter technology has been around for a fair few years now, and has become standard in most mid-high range systems. This is for good reason, as it can save energy consumption by over 50%.
The limited on/off operation of a non-inverter air conditioner caused great spikes in energy usage. These spikes reduce the energy efficiency of an air conditioning system. Like sprinting, then stopping, then sprinting, then stopping; it uses up a lot of energy very quickly.
Meanwhile, an inverter type air conditioner gradually ramps up and down, allowing more even and tightly controlled energy usage. Like going for a leisurely jog; pace can be maintained without wasting energy.
11. Premium or Standard
What is the difference between standard and premium air conditioner?
Air conditioner manufacturers may call a product “premium” for many different reasons; features, style, performance, or just marketing hype. However, in general, “premium” air conditioning models correlate with greater energy efficiency.
There are lots of reasons why this correlation exists. Premium AC units are premium products, as the name suggests. These tend to include physical enhancements including larger heat exchange coils, aerodynamic fan blades, and direct current (DC) motors.
Premium air conditioners may also include energy-saving features, including eco and power-saving modes, adjustable temperature sensors, human-detection technology.
In the case of Daikin Standard vs Daikin Premium inverter ducted systems, the Premium Inverter is ~10% more powerful than the Standard Inverter. When comparing the EER/COP ratio, Premium ducted air conditioners are slightly more energy efficient.
Is a premium AC worth it?
Wondering whether a premium air conditioner is worth it? Unfortunately, there is no simple answer. If the environment is a top priority for you, then a premium energy efficient air conditioning system could be for you. Otherwise, it depends on usage and other factors that are worth considering.
If a premium air conditioner is say 10% more efficient, it’s worth looking at the potential cost savings over time vs upfront investment.
As an example, take a quarterly power bill of ~$750. This equates to ~$3,000 per year in electricity.
Heating and cooling makes up ~40% of typical home energy usage. Therefore, warming up and/or cooling down your home would cost ~$1,200 per year.
If a premium AC system saves you ~10%, then this equates to a saving of $120 per year. Over a conservative 10-year life span of an air conditioner, this equals $1,200 in savings.
So, if conditioning your home with premium model/s is less than $1,200, the initial investment may well be worth it in the long run given this example. This is where the savings really do depend on individual circumstances.
Potential savings could be greater if your power bill is larger than $750/quarter. A home air conditioner can also run beyond the example of 10 years, especially larger systems and where aircon units are maintained regularly.
What are the features of an air conditioning system?
Air conditioners have seemingly endless features these days. Certain features a fairly standard in decent air conditioners. This includes timers, adjustable louvers, and back-lit wireless controllers.
Some features are increasingly popular due to demand. This includes Wi-Fi compatibility, eco and quiet modes, and 0.5 degree temperature adjustment for precision control (for wall splits and ducted aircons).
Then there is a long list of features custom to individual air conditioner brands. For example, Daikin split system features includes an Intelligent Eye to enable power-saving mode when a room is unoccupied for 20 minutes. Another example it the Mitsubishi Electric advanced air cleaning system, Plasma Duo Filter System.
What air conditioner features save electricity?
Aside from comfort and personal preferences, there are a few common air conditioning features that can help you save electricity, including:
- Eco-Settings – Ability to run an air conditioner at a reduce power usage state to maintain indoor conditions. Recommended to be used only after a room has reached the desired temperature.
- Automatic Timers – Allows programming of an air conditioner to turn on/off when you desire. Allows a degree of air conditioning system automation to help facilitate effective usage.
- Wi-Fi – While not immediately obviously, Wi-Fi can enable remote access to pre-heat or cool your home when required. Also very handy if you often leave home and forget to turn the AC off. Also great for checking the status when teenage kids are home alone… and adjust/control the AC as necessary!
13. Ducted Zoning System
What is air conditioning zoning?
Air conditioning zoning refers to dividing a building into separate zones or area that require individual climate control. The control can be temperature, airflow, or simply on/off.
Zoning is typically paired with a ducted air conditioning system. The manufacturers of the zoning system can be, and often is, different to the AC brand.
Some brands, such as Daikin, have a popular zoning system that consumers choose to use with their new Daikin ducted aircon. However, there is a wide range of other compatible zoning systems available, such as iZone, MyAir, AirTouch, and ZoneMaster, just to name a few.
How can zoned ducted air conditioning be energy efficient?
A zoned air conditioning system is more energy efficient than a non-zoned system. With a non-zoned system, the whole system is either on or off, regardless of which areas require climate control at a given time. In comparison, zoned systems allow only the relevant areas to be heated or cooled at a given time.
Furthermore, zoning allows for a smaller ducted system (capacity) to be installed. For example, you may choose to install a Day/Night system, which means all the living areas are served at once OR all the bedrooms are served at once.
With a Day/Night system, the ducted system would only need to be half the size of one required to cool the whole house at one time. Saying that, this type of system does have its limitation as it is not designed to cool bedrooms during the day. Not ideal if you have little ones or shift workers trying to sleep during the day while the rest of the household hang out in the living room.
Smart zoning systems also allow for individual temperature control (ITC) of zones with sensors. This can come standard with the system (e.g. iZone) or be an optional extra (e.g. MyAir or AirTouch). ITC sensors allow occupants to control the degree of hot or cold air coming into an individual space, rather than everyone having to experience full heating or full cooling at any one time.
Some smart zoning systems also have a return air bypass, which means air can recirculate back to the indoor unit without the need for a constant zone somewhere in the building. A contact zone means that air must always enter that area when the ducted air conditioning system is running. This prevents pressure build up and damage to the AC unit. Obviously having one area always open, even when not in use, can be a waste of electricity.
How is air conditioning installed?
Air conditioners are installed as per manufacturer’s instructions. All AC units come with an installation manual that sets out requirements and recommendations to an aircon installer for that particular system.
There is a range of materials and extras that must be installed along with the air conditioner units themselves. This includes pair coil (pipework), interconnect cable, capping, drain, isolation switch, power run, support structures (wall bracket or polyslab), etc. These materials don’t come with an air conditioner as standard.
An air conditioning installer typically supplies and installs the new air conditioner and associated materials. An installer (or install team) installs the indoor and outdoor units, runs the pipework between them, runs power to the isolator, installs all remaining materials, then commissions and tests the AC system. Normally, all the logistics are pre-assessed and offered as one complete quote, including outlining unit locations.
How can air conditioner installation affect energy efficiency?
Air conditioner installation can affect energy efficiency in a number of ways. It is recommended to select a professional aircon installer to carry out the install to ensure your AC system is as energy efficient as possible.
- Indoor Unit Location – For room air conditioners, the indoor evaporator unit should be installed in the most suitable location in the room. Somewhere that air is not going to be unnecessary blown out of a room or into wasted space. It also requires a degree of clear space around it.
- Outdoor Unit Location – The outdoor condensing unit also requires a degree of clear space around it to function efficiently. Furthermore, the unit should be kept out of the sun where possible. While they are designed to sit in the sun, constant exposure to sunlight makes it work slightly harder to reject heat during the day. Ultraviolet light (UV) also breaks down the insulation on the connecting pipework over time.
- Pair Coil – The pipework carrying refrigerant between the indoor and the outdoor units must be insulated for maximum efficiency. The correct pair coil/pipe size must also be selected for installation to ensure the AC works efficiently.
The chosen air conditioner and subsequent installation is the beginning of the energy efficiency journey. Usage and maintenance also affect AC system efficiency in many important ways.
Whichever system you decide to go with, for whatever reasons, routine maintenance cannot be forgotten. Things like dirty air filters affect energy efficiency. If a system is not cleaned and serviced regularly, the energy efficiency may not be what it should be, and the initial investment may be wasted.
It pays to learn about the key concepts of air conditioning energy efficiency before making any purchase decisions. During some research can help you make the best decision, or at the very least allow you to have a more comprehensive discussion with an air conditioning contractor.
With many factors to take into account, the most efficient way to choose an air conditioner may well be to contact an expert for advice and arrange a free quote. After all, it is their job to know and understand all the variables involved. Their years of experience and wealth of knowledge allows them to tailor an air conditioner supply and install package just for you.
If you have any question or would like an obligation-free quote, please don’t hesitate to contact us.