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The air-conditioning dilemma

When I first moved to Brisbane from New Zealand I arrived in late January. I firmly believed that air conditioning was a waste of energy, so when I stepped off the plane to 30degC heat (coming from a summer that had barely hit 20degC) I was determined to acclimatise as quickly as possible, even though I felt like I was melting. When I got to my hotel I tried sitting on the balcony with a cold drink, to begin adjusting to the heat. I don’t think I lasted more than ten minutes before my resolve crumbled and I was back inside trying to work the air conditioner! I have come a long way since then. I can now work outside in 30degC or hotter, in jeans, long sleeve shirt and boots, but I still can’t sleep if its too hot.

eight acres: the cost of air conditioning
you know what an air-conditioner looks like.....

Our house at Eight Acres came with an older style ducted reverse cycle split system air conditioner installed in the lounge. On very hot days, we would turn it on and lie on the couch to try to cool down, but the cold air never quite made it to the bedroom at the other end of the house. On the first day of the heat waves we had in December 2013, the air conditioner stopped working. Although Pete tried his best to fix it, he admitted defeat and set up an old “window rattler” system that we had used in the previous house. It was loud, but effective, so we lived with it for nearly a year.

Late last year, we decided to install a new air conditioner in our bedroom. I was still not totally comfortable with the idea of using air conditioning, but I told myself that this is a house that we intend to sell, so we won’t be using it forever. Since it has been installed (and Pete got the lounge one fixed at the same time), and we still had all three air conditioners set-up, we used our energy meter to get an idea of their energy use. I was very surprised to see that the new air conditioner used far less energy (it worked out to be about 10c/hr, compared to 50c/hr for the lounge one and $1/hr for the window one, the lounge one is about twice the size, but uses 5 times the electricity).  Apparently this is because the new system includes an inverter, which better matches the machine's energy consumption to the activity in the room.  It is good to know that at least the technology is improving.

I recently read an article in Grass Roots that said new houses, even the ones with good energy star ratings, are really just insulated boxes designed to keep hot air in (winter) or cold air in (summer), but not really designed to take advantage of passive solar opportunities. And this makes sense from my own observations.  This made me feel a little better about using air conditioning. Our house is pretty cheaply built, but it is insulated and well-sealed, it was designed to be air conditioned, and not naturally cooled. When we run the air conditioner we do our best to keep the cold air in the room, using an old mattress protector as a second curtain, and keeping the door closed.

eight acres: the cost of air conditioning
.... so here's two hot dogs instead.

At our house at Cheslyn Rise we made a huge effort to set up the house to be naturally cool. Firstly we orientated the house to have verandas facing north and most of the windows facing south. We are lucky to have great air flow, with plenty of windows, breeze ways, high ceilings, fans and a windy hill-top position. Finally we tried to prevent heat entering the house by choosing a light roof colour and insulating the ceiling cavity (curtains will help further when I get around to sewing them). So far we have found this house to be perfectly comfortable on even the hottest days. We are going to try to avoid installing air conditioning if the inside temperature remains cool enough.

Although its nice to think that an older house, built before air conditioning, is better suited to our climate, in its original position it would have been relatively hot, as we spun it around 90 degrees when we moved it to our property.  One of the verandas is built in and mostly windows, previously it would have had full afternoon sun heating up that room, but now that is on the south side and very cool.  If old houses have been renovated without consideration for passive solar, they may not be ideal either.  If you live in a hot house, don’t feel bad for using air conditioning! There are a few things you can do to make your house more comfortable, but at the same time, its difficult to overcome the original design. Some suggestions in order of least to most expensive:
  • Improve curtains and sealing of rooms to be air conditioned
  • Keep doors closed and only cool small areas at a time
  • Install shading (trees or awnings) outside the windows to reduce heat coming into the house
  • Improve insulation in ceiling and walls
  • Install ceiling fans to improve circulation of air
  • Change roof colour to as light as possible (can be painted if roof is in good condition)
  • Add ceiling space ventilation to remove hot air
  • Move windows and doors around to improve airflow or change how rooms are used to make use of cooler rooms for sleeping

Do you use air conditioning?  Do you live in an insulated box?  A badly designed house or make use of passive heating and cooling?


  1. I was the same about air conditioning, Liz. We actually did with out it for many years but knew that once the farm stay started our guests would expect it.It is surprising how your body acclimatizes to things-for people coming from the city that work in air conditioned offices, the heat outside is Summer here really knocks them around.. One thing we have found that makes a huge difference is an ornamental grape vine we have growing on one of the verandas- it grew really quickly and the coolness in that section of the house is so different to the rest of the house- so we are going to try and get it going around the whole house eventually.

    1. That's great that you notice the difference. My only worry with growing plants too close to the house is termites.... so I prefer shade structures or trees that are a good distance away! Unfortunately I spend my time (freezing) in an air conditioned office during the week, and I do think it makes it harder for me in the weekend (although its impossible to work at a computer when your fingers are sweating, so I'm glad that they do air condition the building!).

  2. a/c is our biggest expense... our house is not effective at all and my hubs refuses to be hot at nite. during the day i work outside in the heat and i really dont like going in and out of the ac during the day. we need to find a better system but our house really holds the heat! we learned that keeping the curtains drawn really makes a difference so i scamper around during the day blocking out the sun. we also are careful with cooking and try and do as much in my smallest oven or outside on the grill.

    1. Yes, good point, we have most of the curtains and blinds closed all day in our house in summer, and it does make a huge difference. I hate going in and out too, best to stay at one temperature :) We use our BBQ and slow cooker for everything in summer, rather than heat up the kitchen.

  3. At our farm we do have window units in two windows (one in each bedroom window) but more often than not, we keep the curtains drawn and we have a set of roller shades under and we pull those down as well. It's sort of a two step way to block out the heat and it works pretty well. Ceiling fans help as well.

  4. Our house faces due west so on hot days I run the air conditioner for a few hours in the afternoon to keep the place cool. One tip for when you come to make your curtains is to go for a three-pass lining, which is the best to block out the sun. Most lining sold is one-pass, so be sure to specify it. More expensive but definitely better st keeping rooms cool.


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