Which Air Conditioning Units are the Most Efficient?

Guest Post by Rebecca Lee

A lot of people fail to read the specs of they’re newly-purchased AC unit before buying it.

It’s new, does its job, and affordable? . . . Might as well be good as sold!

That said, overlooking these crucial factors before securing the appliance can be a costly act.

While any air-conditioning unit can perform its primary function, not all of them are efficient in doing so.

This could be because of deterioration of the hardware, from a blown fuse to dirty filters or coils.

In some instances, it can also be because of the inherent limitations of the appliance itself.

When you leave these limitations unattended, you could inadvertently be causing your electricity bill to spike up quite considerably.

Over time, this could rack in thousands of dollars of extra costs—something no one wants.

If you’re in the market for the top air conditioning units for your home, you’ve come to the right place.

Here are some air conditioning units that are a cut above the rest in terms of energy efficiency.

Let’s begin!

What Makes an AC Unit Efficient?

There are factors to consider when measuring an air conditioner’s efficiency. Let’s look into some of them.

SEER Rating

The primary measuring system for AC efficiency is the Seasonal Energy Efficiency Ratio (SEER). This is a scale of efficiency that starts at 1 and goes all the way to 26 for the top-grade, efficient air conditioning units.

Most A/C units have a SEER rating attached to them. They’re usually found pasted at the back of the A/C unit in the form of a yellow and black EnergyGuide sticker. The rating may also be part of the name of the product model itself in number form.

SEER ratings are given to nearly all types of AC units, including central, mini-split, and window air conditioning units. This rating method has been around since 1987 and is still used today as a standard of measurement for cooling efficiency.

The higher the SEER unit, the less resources and energy the air conditioning unit requires to produce cooling for an area. When an A/C unit uses up fewer resources, it consumes less energy and rewards you with a happier electricity bill

Generally speaking, newer AC models are more energy efficient than older models. This is because they have undergone extensive development over time and the technology has made achieving a higher SEER number more simple.

Nowadays, you can typically find units with a SEER rating of around 13 to 15 at the minimum, which is already serviceable.

That said, some units with a SEER ranking of 19 to 24 are even more energy-efficient, but they typically come with higher upfront costs.

ENERGY STAR® Certification

If the product has an ENERGY STAR® certification, which is a blue sticker with the words ENERGY STAR written on it, you’re dealing with an efficient AC unit.

This symbol is a government-backed sign of energy efficiency, headed by the U.S. Environmental Protection Agency.

As this is regulated by a third-party organisation without business interests, this helps in removing any biases as only credible manufacturers can be given this label.

Energy Saving Features

Besides external labels that label the AC unit as environmentally friendly and cost-effective, a good sign of an efficient AC unit is when they are propped with energy-saving features.

For instance, some AC units, particularly split-type models, can automatically turn off when the surrounding zone reaches a certain comfortable temperature. This is often only the case if the A/C unit has inverter technology. This feature can save up to 50% of a home’s electricity bill if used regularly.

Some machines may also automatically turn the circulation and exhaust fan on or off as necessary, reducing energy consumption. Lastly, most A/C units have a timer feature that can turn the unit off after a set time has passed.

Which Air Conditioning Units are the Most Efficient?

There are four major types of A/C units: split, window, portable, and ducted (or central) A/C units.

Each type varies in terms of efficiency, and choosing the right one can also depend on your household’s size and your own financial capabilities.

But if you want the most efficient one for large houses, ducted A/C units are the way to go.

Want to know more? Here’s a breakdown of each AC type’s efficiency levels:

Ducted (Central) A/C Units

According to the Department of Energy, ducted A/C units are more efficient than room A/C units when cooling a big space.

This is because they come with a network of ducts that retrieve warm air in the house and then convert them using a refrigerant to cool air.

In the long run, having a ducted A/C unit is very efficient for your electricity bills. That said, the installation process can be quite difficult, so it’s best to consult HVAC experts Alliance Climate Control for them to help you safely set up your appliances.

Split A/C Units

Split-type air conditioning consists of two primary units: the indoor A/C unit, and a large outdoor compressor unit to remove air.

This type of AC unit typically has good SEER ratings, an inverter type, and a wealth of energy-saving functionalities. This makes them fairly energy efficient compared to other energy-intensive AC types. They may cost more upfront, but they’re cheaper to run over time.

They also come in other variants, such as mini ductless split AC units, which can make them even more energy efficient. This is because there’s no reliance on ducts for the unit to operate.

Examples of Split Type ACs you can find in the market include the Awoco 36″. Mitsubishi and Fujitsu also offer split-type ACs.

Window A/C Units

Window units boast the cheapest upfront costs, easy installation process, and highly accessible nature. You don’t have to search far and wide to grab a small box-type window AC, as there’s usually one or more in your local appliance store.

As far as efficiency goes, many window A/C types can be pretty energy efficient, especially if you don’t own a large house. If your living arrangement needs only three or fewer A/C units, window units are generally more efficient to run.

However, if you have a large house and want to bring cool air to all areas of your place, you may want to consider central or split A/C units.

Portable A/C Units

Portable A/C units provide flexibility, as they can be moved from one room to another. They also can come with a wealth of energy-saving features like a timer.

However, in the long term, they’re not as energy efficient as split types or window types. This is because the air in the room gets recycled again and again, leading to hot and humid air over time.

While a large room may seem like it would mitigate this problem given the larger volume of air, portable A/Cs also come with the cost of not having enough power to cool a big space. This makes them the least efficient A/C unit type.

Wood For Heating – Why A Wood Heater Is Better Than An Open Fire

Although wood heating is banned in many urban areas they are still allowed in most country properties

A lot of people think that an open fire gives a better ambiance than a wood heater . . . but I much prefer a woodheater

Here’s why:

  • A wood heater is much more efficient which means you will burn much less wood. As well as greenhouse gas savings that means less cost, or less effort gathering wood.
  • One of the problems of any heater that warms the room by burning is that it needs a source of fresh air to achieve combustion……..this means drafts. The efficiency of the wood heater means that less air is required, so less drafts. Remember the fresh air is cold air sucked into the house by the burning.
  • Control of a wood heater is very effective so you can quickly turn it up or down. This means in winter we usually kept the heater alight from June to the end of August which saves a lot of fire lighting.
  • A fully loaded wood stove if turned down can burn for over 8 hours, unlike an open fire which will need more fuel every couple of hours . Great if you are going to be out all day and want a warm home to come home to.
  • The efficiency and effectiveness of the combustion in a room heater means that removal of ash is much less frequent, typically every couple of weeks.
  • No smoke around the house……especially when trying to light the fire.
  • Much less ash dust floating around the house.

A well designed wood heater with a large window will also give you a good view of those flames anyway.

The following link is to a page on the efficiency of various wood heaters that are available in Australia: Home Heat 

More Heating thoughts and 24 pages of Check Lists in the

‘Selection / Pre-Start Guide’

 

Air Conditioner Placing FAIL

I stopped in a country pub in South Australia this week, in the middle of winter.

Here is a view of the reverse cycle unit, on the wall above the step up of the ceiling, over 3m above floor level.

The room was cold so my wife put the unit on full for the whole time we had the room.

The room never warmed up. . . . but the higher section of the room must have got hot because the unit kept switching off.

A good reminder that hot air rises so in tall rooms the thermostatic control needs to be at the same level you are!

A good job we were only staying one night!

For more Fails and Unusual Houses go to What the………………….?

 

3 in 1 Bathroom Heaters or Separate Units?

In a previous house we had one of those 3 in 1 bathroom light/heater/extraction fan.

I can’t say I was impressed. . . . It suffers from the Swiss Army Knife Syndrome…… doing lots of things, but none of them as well as a purpose designed tool.

It seems more sensible to me to have the fan directly above the shower and extract the steam at it’s source, rather than let it drift across the ceiling and then extract it.

As far as Lighting is concerned it’s easier to see yourself clearly in the mirror if the light is in the area between the mirror and you, rather than behind you. . .

I think that ladies putting on make-up in the bathroom will agree!

For heating I never seemed to get much heat from the heat lights. (One exception was a unit in a hotel bathroom with a low 2.1m ceiling)

The best bathroom heating solution for us has been a wall mounted fan heater

A couple of low price alternatives are:

  1. Leave the door partially open overnight allows enough heat from the ducted heating to flow through to the bathroom in the morning.
  2. Switch the bathroom fan on a few minutes before your shower and it will pull the warm air into the bathroom.

 

Thinking about underfloor heating? . . . Check out this Link : Underfloor Heating

 

For more see Bathroms and Ensuites

 

Ground Sourced Heat Pumps

Did you know you can you use your garden to heat your home?

Many of us use reverse cycle air conditioners to heat and cool their homes.

These unit are are ‘Air Sourced’ heat pump that:

  • Extracts heat from the air and uses it to heat your home; or
  • Extracts heat from the air in your house and disposes of the heat outside.

When the outside air gets very cold the air sourced heat pump becomes less efficient.

An Alternative – Ground Sourced

These are sometimes incorrectly called geothermal heat pumps but they don’t use energy from hot deep rock strata.

They take advantage of the fact that the soil at a depth of around 1m is generally at a temperature around 15 degrees all the year round.

By pumping water around a network of pipes under your garden they extract this heat.

In cold conditions this water being warmer can give up more heat than the air for use in the home.

Are ground sourced heat pumps worth it?

Ground source heat pumps can be a bit more efficient than air source, but not by a whole lot in most Australian locations.

The problem is they are very expensive to install as they involve burying long pipelines deep below your garden.

The units being less common are also more expensive than the standard units you may be familiar with.

In my opinion the additional expense is just not worth it for the few days when the temperature drops below zero.

You would be better to put some additional solar panels on the roof to cover any additional power needed for an air sourced unit.

Bathroom Heating

If you have following this blog you will know I am a big fan of reverse cycle air conditioning for room heating due to its amazing efficiency..

That however doesn’t apply to our bathroom.

This might look like a reverse cycle unit but its actually a rather smart looking fan heater.

So why am I happy with the 100% efficiency for this heater rather than the 300% efficiency of reverse cycle.

Well there are a few reasons:

  1. The unit was fairly inexpensive at less than $100 as opposed to around $2,000.
  2.  It doesn’t actually use much power as it runs for less than 10 minutes a day over the winter months only. (we are 3 minute shower people) That’s probably no more than 12 kw hours per year (Power cost of under $4 a year)
  3. Being a fan heater it starts to warm up the room within 30 seconds whereas a reverse cycle unit will need to run for several minutes meaning that there really isn’t a power saving benefit for short term heating.
  4. The fast response is more convenient.

This just shows the most ‘efficient’ heater isn’t always the best solution, particularly if the heating is only for short periods. .

 

Where Is Your Fireplace

One thing I have never understood is why Australian Houses nearly always seem to have their fireplaces, and chimneys, on an outside wall.

I was brought up in an English terraced house, and a significant source of heat in winter was the heat radiating from the wall against next door’s fireplace and chimney.

Even the cat knew which was a nice warm spot!

If you are planning to build a detached house with a fireplace don’t position it on an outside wall.

There is going to a lot of heat you have paid for that will be lost to the outside.

Historically

A hundred years ago, when all cooking was done on a wood stove, there was a good reason for the kitchen fireplace to be on an outside wall.

Cooking on a hot Australian summer day meant that you wanted to minimise the heat going into the home, so an outside wall could be a good choice.

These days with almost all of us cooking using electric, or gas, that reason no longer applies.

Planning a house

Check this link to see how I designed a house with a central fireplace:   Bubble Diagrams

Three Reasons Why Natural Gas Isn’t Better Than Electricity

With all the publicity about rising gas prices the gas networks must be feeling the heat. (AAAARGH what a shocking ‘Dad’ Joke)   

Why else would I find an article on my Facebook feed entitled ‘Three Reasons Why Natural Gas Is Better Than Electricity’   

Like a lot of advertising there is a fair bit of Bull Dust around so lets look at what they say, (with my comments in Italics afterwards)

1. It’s always there when you need it

Natural gas infrastructure allows distributors to deliver gas to customers on demand, without the supply and reliability issues associated with electricity. In fact, when it comes to reliability, Australia’s natural gas network experiences only one unplanned outage, on average every 40 years.

But when it happens it can be a big one!  After the Longford Gas Disaster in 1998 the Whole of Victoria had no gas for more than 2 weeks. Daily cold showers over that one period was worse than the total of around 50 hours (say 2 hours a year) of power cuts over the last 25 years!   We were just happy that we didn’t have gas cooking.

Also what about these articles on the upcoming   Gas Shortage   that forced Malcolm Turnbull to step in

 

2. It’s up to 40% cheaper than electricity to use

Natural gas has always been consistently affordable and is likely to continue to be so well into the future. Unlike electricity, where increased consumption drives your tariffs higher, generally the more gas appliances you install the more you can save. This is because in most cases, the cost per unit of gas decreases as consumption increases.
While gas appliances may cost a little more to install initially, running costs are generally lower. This means that using natural gas almost always works out cheaper in the long run.
For example, take one cook top and hot water system running in an average Australian household for one year:

  • Running on electricity, the cost would be $1,156 p.a. in South Australia and $1,235 p.a. in Victoria.
  • Running on natural gas, the cost would be $782 p.a. in South Australia and $725 p.a. in Victoria.

Installing a heat pump would save 50 – 60% of the electricity costs. That would bring electricity costs down to below gas.   A solar hot water system with electric boosting could save more . . . . and think of the savings if you could get rid of the gas standing charge!

3. It produces significantly less greenhouse gas emissions than electricity

Yes, natural gas is a fossil fuel, but it is also far more environmentally friendly than electricity. Its chemical structure is quite different to coal, meaning its emissions are much lower.
Here are some quantifiable examples of why natural gas is a better environmental choice:

  • In South Australia, a gas powered hot water system emits 67% less CO2 than an electric equivalent
  • In Victoria, a gas powered hot water system emits 83% less CO2 than an electric equivalent
  • The emissions from a natural gas powered hot water system is on par with those produced by a system using 50% renewable energy and 50% coal electricity mix.
  • Gas currently delivers 44% of Australia’s household energy, but only produces 13% of household greenhouse gas emissions
  • Gas has a higher yield rate* from extraction to delivery (90%) compared to electricity, making it far more efficient.

With either of the alternatives mentioned in my response to Point 2 above the CO2 for electricity drops dramatically.   I also have 3kw of solar panels on the roof of my 2 bedroom unit,  on current performance it looks like I will be generating more power than I consume* . . . . Net effect no CO2 generated.

Although gas does have a higher yield rate what they don’t say is gas appliances have a lower efficiency typically 70 – 90% compared to electricity. Even the most basic electricity heater is 100% efficient. Some heat pumps are better than 300% efficient (for every kw going into the unit it delivers 3kw of heat)

Conclusion

If you want good advice on hot water, cooking, and heating your property don’t rely on the gas networks (or the electricity networks) . . . . find some independent advice, like this blog.

 

* Between when my solar system was switched at the end of January 2017, and 15th May 2015, I have generated 510kwhrs more power than we have used. I know I won’t be generating as much for the next few colder months, but I did miss out on a peak generating month of January.

 

Multi Head Split System Air Conditioners May Not Be Best

Reverse cycle split system air conditioners are a popular choice for cooling.

They are also one of the cheapest heating systems to run.

Single Head Split System

These are the most common units, that you will see in most big box electrical stores, consist of a matched outdoor unit and an indoor unit.

Fine if you want the cooling in one room, but it can look a bit messy with lot’s of outdoor units if you have got several rooms to cool

There is however an alternative

Multi Head Split System

Multi Split systems consist of one outdoor unit running multiple indoor units.

In some cases up to 8 indoor units to be run off a single outdoor unit.

The indoor units don’t have to be all the same KW capacity so they can be matched to the room size

The outdoor unit can also be a little smaller than the sum of the indoor units

For instance if you had a 3 bedroom house you may have 2 x 3.0kw indoor units in family rooms and 3 x  2.0kw units in the bedrooms a 10.0kw outdoor unit may be adequate/

If all 5 indoor units are running at maximum, the out door unit will only deliver 11kw of output rather than 12kw.

However the indoor units are rarely all running at full capacity,

Also most people are unlikely to run all 5 units at the same time.

Advantages and Disadvantages of Multi Split system

Advantages

  • Good for people who have limited space
  • Much neater than having several units

Disadvantages

  • If the outdoor unit fails all the indoor units stop and you have no cooling.
  • Usually costs more to buy and install.

Why are Multi Head Systems more expensive?

Although it seems that having less out door units should save on cost there are a few reasons why that isn’t the case.

  • With the majority of systems being single head systems that makes multi head systems a special order.
  • Multihead systems are normally sold by specialist companies rather than the big box stores so there is less competition.
  • Longer pipe runs and cable runs are required rather than the typical back to back installation of the single head systems.
  • In some cases the indoor units might also require drainage pumps rather than a simple gravity drain through the external wall.

Air Conditioners – Why The Star Rating Is More Important Than Price

I’m currently in the market for a Split System Reverse Cycle Air Conditioner.

I went round a couple of the big box electrical stores last weekend and saw several models in the 3.5kw range, with prices ranging from $650 to $1,000.

But is the higher star rating of the more expensive models worth the extra dollars?

Finding Out The Savings

Well I went to www.energyrating.gov.au website to do a little investigation

I used their calculator and based my search on:

  • A 3.5kw Unit.
  • Heating for 5 months at an average of 10 hours per day.
  • Cooling for 7 hours a day for 2 months.
  • Power at $0.287 per kW hour.

The results were:

  • The best  6 Star unit would cost around $236/year to run.
  • The worst 2 Star unit would cost around $551/year to run.

That’s a huge difference of $315/year!

In other words buying the more expensive unit would be cheaper after less than 2 years!

When I decide to buy; I’m only going to be looking at the 6 Star units.

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