The climate of your area significantly impacts your air conditioning needs. For instance, in Adelaide, where the climate can be both hot in summer and cold in winter, opting for an air conditioning unit with effective heating capabilities is essential. A reverse cycle unit (heat pump) can help minimize energy use, as more energy will likely be used for heating during the colder months than cooling in the hotter months.

Portable air conditioners are a good option for renters or those needing a temporary solution. They are easy to install and can theoretically be moved from room to room (although in practice because you need a vent kit and where you put it is where it will stay). However, they are generally less efficient and powerful than other systems, making them suitable for small spaces or occasional use. They are more effective in the evening and at night.

As one salesman I knew would say:
'What have you got now?' 
The answer would be 'Nothing'
His response would be 'Well this is better than nothing.' 
In other words, only choose a portable air conditioner if it is the only option. 

If buying an air conditioner, you need to consider the energy efficiency as the running costs will exceed the purchase cost after a few years. Check the star rating on the government web site Energy Rating - Air Conditioners - AS/NZS 3823.2 .
Generally you should choose the best heating star rating you can afford and aim for at least 3-stars heating, even if you are actually purchasing it primarily for cooling as you will use more energy for heating than cooling.
It is important to choose the correct star rating as air conditioners assessed to the old rating will appear to have a higher star rating. If you are in Adelaide compare the ‘SEER Heating Star Rating’ for the ‘mixed zone’ see below.

Setting the thermostat correctly is critical to achieving comfort and minimising energy use. Setting the Temperature one-degree cooler than needed in the summer will cause a surprisingly large increase in energy use. Similarly setting the Temperature one-degree warmer than needed in the winter will also cause a surprisingly large increase in energy use.

Some old-style thermostats have a single temperature setting, and the temperature swings around that setting. Most modern ones have separate heating and cooling settings, which allow closer control. Normally it is best to set the temperature at 22 degrees for a single setting thermostat or at 20º for heating and 24º for cooling (possibly higher if you have ceiling fans) with a dual setting thermostat. For most air conditioners this would give a temperature of around 24 degrees for most of the summer and 20 degrees for most of the winter. If you can achieve comfort at a higher temperature in summer, or a lower temperature in winter, use the higher summer setting or lower winter setting as every degree change can save up to 10% of your heating or cooling energy.

In practice there are several factors that may require a different setting. For example, if in winter you get freezing air next to the windows sinking down and pooling at floor level, it may be necessary to set the thermostat at a higher temperature (although a better long-term solution would be to have honeycomb blinds or thick drapes with a pelmet to reduce the heat loss). To find out what the best solution is, it may be worth getting an energy audit as getting the right solution would save a lot more than the cost of the audit.

Often thermostats are not very accurate; this is not really a problem if you can find a single setting that achieves comfort all year round. However, it is probably necessary to occasionally tweak the setting.

You can find a suitable setting by randomly adjusting the thermostat, but if that doesn't seem to work, try the following approach:
1.On a day that is warm (to find the best summer setting) or cool (to find the best winter setting), but not an extremely hot or cold day.
2.Ensure the air conditioner has been running for at least one hour so the temperature is stable.
3.Initially set the thermostat to 22 degrees (for a single setting thermostat) or 24 degrees if you are setting cooling on a dual setting thermostat, or 20 degrees if setting heating on a dual setting thermostat.
4.Wait for a period of time (at least 10-15 minutes) to allow the air conditioner to stabilise again
5.If this hasn’t achieved comfort, set the thermostat slightly higher or lower, as seems appropriate. Don’t adjust it by more than a degree at a time or you will end up overcorrecting and take longer to find the best setting.

In summer, using ceiling fans may enable you to set the thermostat slightly higher. It will also significantly reduce the number of hours you need to operate the air conditioner.

Remember there are some problems that can’t be fixed by adjusting the thermostat. For example, if the air conditioner doesn’t have enough capacity due to the temperature of the day, adjusting the set point won’t make any difference to the room temperature. If this is the case, start with Cleaning Filters below, also see the post Our house is too hot, what can I do? Setting the thermostat also can't generally cure hot and cold spots, (refer Hot and Cold Spots below).
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A future post will address basic troubleshooting of an air conditioner.

Some homes have hot and cold spots, usually caused by an air conditioner serving areas that:

• Have windows facing different directions. 
  
• Differences between the old and new parts of a home.
• Upstairs and downstairs

It is possible to get ducted air conditioning controllers to give individual temperature control in each room, however this is still quite expensive. Most people must use judicious control of curtains or blinds to control temperature differences.
To save randomly trying different ideas, it may be worth getting an energy audit as getting the right solution first off, would likely save a lot more than the cost of the audit.

To keep informed of my latest posts, sign up for the Energy Saving Newsletter and as a free bonus, get  a 14 page extract from the forthcoming second edition of the book:

'House Taming, How to reduce greenhouse gases in comfort'

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If you need personalised advice or you are thinking of spending some real money on air conditioning or improvements to the house, get an energy audit. I guarantee I can cost effectively save you the cost of the audit or the audit is free.

Feel free to leave a comment or question below.

Keeping warm is usually the largest energy user (and cost), especially in Southern Australia. Accordingly, it is a good place to start for saving money, improving comfort and reducing greenhouse gas emissions.

If you were outside and you wanted to keep warm on a cold day, you would wrap yourself up in warm clothes, stand out of the wind and try and catch the sun if there is any. As a last resort you would light a fire. Fundamentally, this is what you do to a house to keep warm. For a house the warm clothes are the insulation (ceiling insulation, curtains etc), standing out of the wind is weatherstripping the home so cold drafts don’t come in, catching the sun is having north facing windows to get warmth from the winter sun and lighting a fire is having some form of heater. As in my analogy, lighting the fire is the last resort because that produces greenhouse gases and is an ongoing expense.
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Note that the above figures differ from the MyHome figures as they are for South Australian homes. For example, in South Australian homes, window losses can be up to 41% or more of losses, whereas in Australia as a whole they are rarely more than 35%. This illustrates the importance of getting local advice, and not relying on generic advice, or worse still recommendations from a sponsored home improvement show.

Let’s look at these elements. The first is insulation. If you have an older existing home, it is unlikely that your home is well insulated. The order of importance of insulation is generally:

1. Appropriate clothing
2. Ceiling
3. Windows
4. Walls
5. Floors

Your options may be limited by renting or financial constraints. However, look at your insulation needs in the above order.

For your clothing in winter, ensure you have long sleeves and either long pants or tights to keep your legs warm. More on this in Winter Comfort

If the insulation in the ceiling doesn’t at least come up to the ceiling joists, I recommend that you add more. In cathedral ceilings or flat rooves, consider blown in insulation if lifting the roof to get batts in is too hard.

More on ceiling insulation including faults that may be reducing the performance of the insulation you have, can be found in Get Insulation Right 

Window insulation options are extensive, and should be considered with both summer and winter in mind and depend a lot on the direction the window faces. Basically, in winter you want to keep the heat in, but let sunlight in when it is available, but in summer you want to keep heat out, in particular direct sunlight and at night allow built up heat to escape. Window options can include blinds, curtains, add on glazing and even replacing windows with double glazing if the frames are deteriorated. More on this in Winter Comfort

Insulating walls is generally something that can only be done by a professional unless you are replacing either the external cladding or the internal lining. This means it can be expensive and it may be worth getting a professional energy efficiency report before committing any money to verify if that is the most cost-effective approach.

Floor insulation also tends to be expensive and whether it is worthwhile depends on the performance of the rest of the house, so again I recommend a professional energy efficiency report if you are contemplating it.

For information on weatherstripping, refer stop-air-leaks-in-your-home

Winter comfort is influenced by a variety of factors beyond just temperature. While obvious factors like temperature affect comfort, there are also subtler ones that play a role.

For instance, many Australian homes suffer from the "hot head/cold feet" syndrome, which can be exacerbated by several factors. One of the primary culprits is poor insulation in the walls and windows of homes. As cold air sinks, it accumulates on the floor, resulting in a pool of cold air at feet level.

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​This happens because the window loses heat to the outside air (1), causing the air next to the window to get cold and sink to the floor (2). This causes a pool of cold air to collect at your feet (3). If no heat is added and the air isn’t stirred up by a fan, the pool of cold air will gradually thicken (4).

From this we can see that we can reduce this problem by reducing the heat loss through the window with curtains, double glazing, roller shutters or preferably a combination of these. Drafts caused by air leaks under doors can also contribute to this issue. Flued gas room heaters can worsen the problem by dragging cold air across the floor as they take air from the room. (An unflued room gas heater is an even bigger problem, because you need to ensure your home is sufficiently leaky so that carbon dioxide, carbon monoxide and other pollutants from the burning gas are kept to a safe level.)

Additionally, radiation from cold windows can make one side of the body cold while the other remains hot. Despite the size of the heater used, these issues can still prevent you from feeling comfortable.

There are some obvious actions you can take to reduce these issues, for example, install high performance curtains and/or change to double glazing, insulate your walls, install door and window seals etc. However, these can be expensive, and an energy audit can ensure you get the best value from your expenditures.

If you have an unflued room gas heater, changing it to a reverse cycle air conditioner is generally a priority.

These actions should be supplemented with wearing the right clothes for the season. Wear comfortable but warm clothes. Generally, the thicker the clothes, the warmer they will be. Wearing lots of layers also helps because they stop direct transmission of the heat and allow you to change your clothing level, by say putting on a jumper in the evening.

However, other than the door and window seals (which are unlikely to eliminate the problem by themselves) all these items are expensive. The most effective items may not be obvious. To make sure you are getting the best bang for your buck, it is worthwhile getting an energy assessment by an experienced energy assessor.
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Stopping air leaks in your home can help you save money on heating and cooling bills and increase your home's energy efficiency. Here are some ways to stop air leaks in your home:
1.     Identify the leaks: Check for air leaks around windows, doors, and vents.
2.     Caulk: Use caulk (no more gaps or similar) to seal any gaps or cracks around windows, doors, and other areas where air may be leaking in or out. Make sure the sealant is appropriate for the location (e.g. exterior, interior, wet area as appropriate)
3.     Weatherstripping: Install weatherstripping around doors and windows to prevent drafts. If using self-adhesive weatherstripping, choose one with a plastic backing (rather than paper) as they are much easier to apply. Raven weatherstripping has a plastic backing.
The problem with self-adhesive weatherstripping is that if the gap in the door or window frame is too small the weatherstripping gets over compressed, and the door or window won't close properly.
An alternative style is available from Ecomaster ecomasterstore.com.au/. They have a range of sealing options for different applications, which tend to work better than what is available at your local hardware store.
If you can't afford weatherstripping, at least get yourself a door snake for each outside door and for the room you spend most time in of an evening.
​4.     Seal air ducts: Make sure air ducts are sealed and insulated to prevent air from escaping. Assuming you have an attic roof, check your airconditioning ducts and if necessary use duct tape to seal them. Any leaks from the ducts are particularly significant as the air in the duct is either hot or cold and under pressure so you can lose a lot of heat. Furthermore this reduces the amount of air entering the room compromising your comfort. If there are problems that you can't rectify yourself it will probably be worth paying to rectifying them.

By following these tips, you can significantly reduce air leaks in your home, which can help lower your energy bills and make your home more comfortable.
Stopping air leaks in your home can improve comfort in several ways:

• First, by sealing air leaks, you can reduce drafts and cold spots in your home, which can make your living spaces more comfortable. Under door leaks are among the worst for this as in winter they exacerbate the cold feet, hot face syndrome that many people experience in their homes.
• Second, air leaks can allow outdoor pollutants, such as dust, pollen, and other allergens, to enter your home. By sealing air leaks, you can help reduce the amount of these pollutants that enter your home, which can improve indoor air quality and reduce allergy symptoms.
• Third, by reducing air leaks, you can help your heating and cooling systems work more efficiently, which can help maintain a more consistent and comfortable indoor temperature.

Overall, sealing air leaks in your home can help improve your comfort and quality of life.

If you are planning on doing more to reduce energy use, I suggest you consider creating a plan to ensure you achieve an optimum insulation level and consider what options you should do when. See Energy Audits.

If 10% of the ceiling is bare due to insulation being tossed aside or being incomplete, the heat loss can double.

I have rarely gone into a roof space (even a new one) and found the insulation properly distributed. Since I have bought a thermal imager, I have not found a ceiling without an insulation fault of some sort.

The most common issue is ceiling batts tossed aside by a tradesman and not replaced. (Although there are many good tradies, there are too many electricians, air conditioning installers and plumbers who don’t make a habit of checking that the insulation has been returned to the correct place after they have finished their work). If you are employing someone who will be working in the roof space, let them know that any insulation that needs to be removed, needs to be replaced properly (for example trimmed around a fan)

Some of the worst examples of failure to replace insulation occur with down lights. If you have down lights you might have a dozen in the room and if a ceiling batt is tossed aside at each light, you would have 12 displaced ceiling batts, which may well more than double the heat loss or gain through the ceiling.

Often this can be readily improved if this is in an attic roof space. Do bear in mind that depending on the type of downlight you may need to give a gap, which depending on the light and insulation may need to be up to 100mm clear around the light. Check the make and model of the downlight to determine the clearance required.

Although I prefer surface or pendant lights to downlights, some of them, particularly the newer IC4 LED downlights can be safely covered with insulation, however check the manufacturer's instructions. (The light should be labelled as IC4 but it can be difficult to read so take a bright light if you are checking yourself in the ceiling. 

Another common issue is exhaust fans. they need a clearance around them to avoid jamming the blades, but often a whole batt is tossed aside. Ideally the exhaust fan should be a ducted fan and discharged above the roof. If the ceiling space is well vented, e.g. an un-sarked tile roof, depending on your climate you may get away with it discharging into the roof until you replace it. However, it is preferable to install a DraftStoppa  so that you can safely insulate to the DraftStoppa and also so that when the fan is not working you don't get air leakage and lose the heat or cool in your house.

When improving the insulation, gaps in the insulation, for example around framing timbers or at edges, should be filled with offcuts.
 
Insulation that has been wetted or compressed doesn’t perform as well as it should and should be replaced.

Ceiling access covers are often uninsulated. Sometimes the insulation contractor leaves a loose piece to be placed over the access cover, but I have often found that the next contractor doesn't replace it. If the insulation is thick fiberglass it won't glue to the access cover very well. Other options include using a construction adhesive (liquid nails) to glue one of the following:

• Foilboard 25 x 2400 x 1200mm Cathedral 25 Insulation - Bunnings Australia
• Bastion 1200 x 600 x 50mm XPS Multi Use Foam Board - Bunnings Australia
• A cheap alternative would be to glue some bubble wrap (using a liberally spread sealant) to the access panel

Another issue with insulation is often the extent is insufficient.  Ideally the insulation should extend over the top of the walls. 

If you intend doing the insulation yourself there are a number of considerations:

• Downlights may need clearance to avoid overheating (check the manufacturers recommendations for the model) (not required if they are IC4 LED downlights.
• Fans opening direct to the ceiling space need a DraftStoppa so you can insulate directly up to them.
• As with any DIY project, consider safety, e.g. safe access, don't work in the roof space in the heat of a summer afternoon etc.

Insulation can be installed deeper than the ceiling joists, however you need to:

• ensure you don't cover electrical cables unless an electrician has confirmed that the cable is safe (cables clipped to the structure can have the insulation butting up against it, if it is modern wiring.) If there is any doubt, get it checked by an electrician.
• consider whether it is safe to move about the ceiling space. If there are appliances in the ceiling (air conditioners, hot water services etc.), you need to ensure safe access for maintenance. This can be achieved by laying the insulation between ceiling joists so the gaps correspond to the location of the joists. Consider installing permanent crawl boards for safe access.) 

If you are planning on increasing the insulation thickness, I suggest you consider creating a plan to ensure you achieve an optimum insulation level and consider what options you should do when. See Energy Audits.