Residential Air Conditioning – The Big Green Target

Posted on Tue 12/21/2010 by


This Post details the failure of politicians over a number of years, and how the blame for their failure is now being sheeted home to the people themselves.

Yesterday, I mentioned the incongruous situation where those people who accept that Climate Change/Global Warming is man induced will believe the most complex Science about that, and they will accept that Science on faith, without even beginning to understand it. In the same breath, they will not believe someone informing them of the consequences of that belief, someone who has expertise in his own selected area, because they lack an understanding in that. If you haven’t read that Post, this is the link to it.

The expertise I have comes from a background in the electrical engineering area. My training and the work I carried out for 25 years included work on air conditioning, so I needed a good knowledge of that subject. During my 6 years of teaching that electrical trade, one of the subjects I had to teach was air conditioning, both theoretical and practical teaching, so where I write about air conditioning here, I have expertise in that area.

Here in Australia, Air conditioning has got to the point of almost being a necessity in the Summer months. For 6 months of the year, the daytime temperature in Northern States is in the mid to high 80’s (Fahrenheit) and higher, and for the three Summer months, it’s over 90F, virtually from early morning to almost Midnight. Even in Southern States, air conditioning is a Summer necessity with temperatures in the 90’s on most Summer days.

Most new houses now have air conditioning, and a lot of older houses have been retro fitted with aircon. All the large white goods retailers sell air conditioning units and most of them have a huge range. People will just walk in and buy a unit, and then have an electrician fit it into their home. People without knowledge of how air conditioning works at its most efficient will just buy the unit that their wallet can afford at the time.

Because it has now become so prevalent, it is becoming a drain on electricity consumption, and here’s where it gets complicated on numerous fronts, so I’ll try and cover as many bases here as I can, so readers can get the full picture of why all this can indeed be sheeted home to a failure of politics over many years.


(Keep in mind this is pretty basic, for ease of understanding purposes.)

Air conditioning is the ability to cool a volumetric space by extracting heat and humidity from that space, and using a fan to circulate the air. That space has to be calculated correctly, and from that calculation, then the correct unit can be selected for most efficient usage.

The compressor is the big user of electricity here, and this is basically a large electric motor.

The user selects the desired temperature for the space, (let’s call that the low temperature) and the compressor runs until that lower temperature is reached.

The compressor turns off automatically when that low temperature is reached and the fan circulates the air inside the room, and the temperature slowly rises again. When the temperature reaches a preset level, (worked from the low temperature) the compressor turns on and ‘cools’ the room, (by extracting the heat from it) until that low temperature is reached, and then the compressor turns off again. Correctly calculated the compressor might only run for around 4 to 5 minutes at a time as it cycles, and again correctly calculated, it might only run two or three times an hour, if a few things are kept in mind.

Here’s where some knowledge comes in handy.

If you wait until that room gets exceedingly hot (say 90F, mid morning or around lunch time) before turning on the aircon, then the compressor has to work overtime to get that large volumetric space down to the low temperature, if it achieves this at all, and from that point on, then the unit cycles around the two temperatures.

Buy a small unit to ‘cool’ that large space, one that your wallet can afford, and that small unit will have to run flat out for anything up to two to three hours or more before that low temperature is reached, if it ever is, hence the compressor, that large user of electricity, is chewing up the KiloWattHours (KWH).

Buy a large unit, or one specifically calculated for the space and the unit will still run for a long while before reaching that low temperature.

However, turn the unit on early in the morning when you first get up, when it’s still cool, say not yet 80, and the compressor runs for short periods of time, as designed, and then just cycles around those set temperatures.

So turning it on early is actually a money saver, because instead of running flat out for two hours or more at the start, it is running for considerably less time than it would if you waited for it to get really hot before turning it on, probably only half an hour all up, instead of two to three hours.

Also, a small unit will have to run for longer periods of time when it is cycling between those two temperatures to cool the large volume, hence the compressor works flat out again for longer periods of time.

Closing the windows and partially drawing the blinds also helps, because the inside temperature will be cooler by not letting in the outside heat, and the bright Sunlight. Closing internal doors to rooms not regularly used during the day also assists as well, by lessening the volume to be ‘cooled’. Having your house installed with ceiling insulation would also assist greatly in that house remaining cooler for longer.

Some of the technical ‘stuff’ I mentioned is not really common sense, because people don’t have that sort of knowledge base to start with. As long as it feels cooler than outside, then it must be working as designed.

Not so in fact.


While not a residential application, this Commercial area is well worth looking at in conjunction with the use of air conditioning in that residential sector.

Next time you go into a big city, look at the skyline as you drive into that city. Every building higher than 2 stories has to have aircon units, usually large units mounted on the roofs of all those buildings. You just can’t open the windows in them because they are sealed. Calling it air conditioning is actually a misnomer really, because those huge units actually provide breathing air into those buildings, conditioned breathing air. So, those units are set at a constant temperature year round. It just seems that they are cool in Summer and warm in Winter. They are actually providing circulated breathing air into those buildings, and because of that, the temperatures remain set all year round give or take a degree or two. They cannot be turned off overnight, or else the air in that building becomes stale, hence they run 24/7/365. When the low temperature is reached the fans circulate the breathing air throughout the building, so while running in the cool of the night, basically, the huge fans are just circulating the air through the building, and adding outside fresh air to the mix, as they do even while the compressors are running during the heat of the day. These units are specifically designed for those buildings, and again, the compressors just cycle around those two temperatures.

So, why have I mentioned commercial applications when the title specifically mentions residential air conditioning?

Electrical power is consumed in three sectors. The Residential Sector consumes 38% of all electricity being generated, the Commercial Sector 37% and the Industrial Sector 24%. Those percentages have changed very little over the years. True, the Residential sector has risen by about 2% over the last decade or two. However the biggest change has been in the Commercial and Industrial Sectors. That Industrial sector has fallen by 10%, and the bulk of that has resulted in a rise in the Commercial sector. So taking out the Residential Sector, those other two consume around 60% of all power being generated. Those two sectors are where people work, and work has not got to the stage of being done on a 24 hour basis, with different shifts working. As they are places of work, then a constant, regulated supply of electricity is critical for them to stay in operation, as without electricity, there is no work, and with no work for people to go to, the result would probably be chaos on a grand scale for everyone. Commerce also entails everywhere you shop, all you do outside the residential environment, so without electicity, then nothing would work at all.

All of this very closely relates to this much maligned term, and specifically this little referenced diagram, Base Load Power, the diagram being a Load Curve of power consumption. This curve is basically the same across the Western World where there is a constant and regulated 24/7/365 availability of electrical power.


There’s no real need for a title for the vertical axis, as this is basically percentage. See that dark line there. That’s around 65% and as you can see all the power being consumed below that line is needed for 24 hours of every day, all year round. Below that line IS the Base Load, electrical power that is required all the time. Now, refer that line there at around 65% back to the power consumption in the sectors I mentioned above, especially the areas where people work, the Commerce and Industrial sectors that consume 61% of all power being generated.

Above the line is Peaking Power, starting around breakfast time and going right through to around midnight, in the main home life in the AM, then off to work, and home life in the PM, that extra being workplaces that only work on the 9 to 5 basis.

There are two humps on the blue line, Winter, and notice where they are, around breakfast time, and mid afternoon till midnight when people come home from work, turn on the heat, lights, cook and do all the things you do at home.

In Summer, the orange line, that main peak is around 8AM till 10PM, again, all on top of the Base Load, and see how close it gets to 100% around midday till 4PM.

So, the bulk of Residential power consumption is Peaking Power, above the line.

The Residential air conditioning factor in the Summer months on that orange line kicks in around mid morning, Peaking Power, on top of that Base Load.


So, here’s where that political failure kicks in.

Up until the 60’s and 70’s governments constructed large scale power plants, in the main all coal fired, and these, because of their nature, can run 24/7/365 supplying huge amounts of power. Overkill probably, and, as it turns out now, quite lucky really. There was always plenty of power there on tap.

To cover Peaking Power demands, smaller units that can run up to speed quickly come on line to top up what is being consumed, and in the main, these are Natural Gas fired plants, and most will only be running for a few hours a day, now a lot longer.

Because of the large initial cost, only Governments could afford to construct them. They collected the cost of producing the power plus some extra, and things went along smoothly, because there was always plenty of power there. The money coming in might only amount to $130 to $150 a month (much more now) at the residential level, but you have to take into account all those residences, and then add on the take from the Commercial and Industrial sectors, so the overall amount is in fact quite considerable, and a rough estimate, say for the State of Queensland, in Australia with a population of around 4.6 million (U.S. equivalent, Alabama) would be in the vicinity of, and wait for it, $5 Billion per year, (probably a conservative figure too) and I’m willing to bet a lot of you will go back and read that total again. Incidentally, Residential consumers pay more per KWH for electricity than those other two sectors, so the total Residential take is a considerable proportion of that total, much greater than the actual power consumption rate of 38%.

Did those Governments sink all that back into constructing new power plants to cater for the increase in population, or infrastructure to better improve transmission and delivery of that power to consumers? Well some of it perhaps, but you can bet the vast bulk went in other directions, say a pot for spending in the next election campaign.

Now we have got to the stage where electricity allocation to consumers is reaching a critical stage. All that overkill from the construction of those large scale plants decades ago is now actually being consumed, because no new major plants are even being considered, and all those older ones are getting long in the tooth, and rapidly closing in on their use by date, and are older technology, and, need I go on.

Now even the thought of constructing a large scale power plant is the absolute farthest thing from the collective mind of any Government. For all those years they collected the money and it went into Government coffers.

Now, especially here in Australia, those Governments have sold off electrical power. Not the plants themselves, but the bill collection side of things. Those Governments sell the power to those private providers, and they charge the consumer, adding on their own profit margin. This is pretty clever really, because if they need to increase the cost of electricity, it’s not the fault of the Government, but of those dirty money grubbing private providers. Win win for Governments.

Governments then use the money they get from the electricity charges, not to construct more power plants, but in the main to build up a great big wad of money to give away in the form of promises at the next election.

They have consistently failed to even consider new power plants on the scale required. Rake the money in, and spend it on something else.

Never mind that the population base has increased, requiring more houses to provide electricity to, more places of work for those people, more big buildings in cities to cater for that population increase.

Now, with more people, those really old power plants are reaching their use by dates, so instead of providing more power for that population increase, there will actually be less power as those plants inevitably close down.

Now we come back to that maligned Load Curve above.

See how the top of those lines is approaching the full 100%.

Existing power plants are now working harder, and those Peaking power plants, designed to run for a few hours a day, are now also running for a lot longer time.

So, to have power available for the two main sectors, places of employment, everything below the solid black line, Base Load Power, then actual consumption has to be decreased. I mean, it’s political suicide to consider constructing a new large scale power plant.

So, the blame for extra consumption is now being mentioned by those politicians as being the (vast) increase in residences fitting air conditioning units into their houses. It’s mentioned almost in passing, because after all, a politician cannot be seen as actively blaming the voters people they are supposed to working for, so it’s mentioned politely, but insistently.

Governments have even brought out TV advertisements saying as much, mentioning Peak Power demands, and how we all need to do our bit, usually sweetened with the addition of the ‘save the Planet’ from CO2 emissions to make it sound like they actually are doing something constructive.

Even the Companies who now on sell the electricity to consumers are advertising on TV about air conditioning and how we should be using it responsibly, ‘for the sake of the Planet’.

They’re telling us we should be waiting until it gets almost unbearably hot to turn them on,  set the low temperature higher, and turn them off early.

Hey! Wait a minute!

Go back to the basic theory I mentioned above.

All those things mean that the compressor runs for longer and consumes more electricity. So, without actually checking first, what they are effectively doing is leading people to believe they will be doing something good, and in actual fact, they are only making things worse.

Sometimes you really have to wonder about politicians.

Still I suppose it does achieve one thing.

With a greater consumption of electricity, they will be making more money from it.

Win win for the Government, and also the providers.

Think about this.

One or two new large scale power plants will alleviate the problem in each State, and while the cost might be considerable, it would amount to the take from just one year of collection of money from the sale of electricity.

It’s been coming in for decades now without the construction of one new large scale plant.

However, now it’s getting to the stage where biting the bullet and building a new plant will take too long for it to get to the stage of delivering power, and any new plant is not even on the Radar of any politicians thoughts, because even the suggestion would be political suicide at the next election.

Naah! Better off finding someone and something to blame.

Like the people and their need for a comfortable life in their home with air conditioning.