Winterise your home now!
What appliances cause greenhouse gases to be generated and where does the energy go?
Reduce fridge and freezer energy use.
A short newsletter giving practical advice on minimising your energy use and greenhouse gas production, focusing on low cost easily implemented ideas.
A number of recommendations to winterise your home are in last May's newsletter (number 14), which can be read at http://www.coolmax.com.au/coolcomfort-tips/coolcomfort-archive.htm . Please note that the internal links in the archives don't work, so you need to scroll down to see the article.Back to Contents
Before getting into todays editorial, I want to let you know that I have decided to broaden the subject of the newsletter to cover all aspects of household greenhouse gas production and energy use. If you would prefer me to stick to heating and cooling please contact me.
Greenhouse gas emissions, energy use and energy costs vary between different end uses, largely because of different fuel sources. The main greenhouse gas associated with fuel and electricity is carbon dioxide. Burning natural gas produces relatively small amounts of greenhouse gases, because the natural gas (methane) molecule has many more hydrogen atoms than carbon atoms. On the other hand burning coal (which is nearly all carbon) produces lots of carbon dioxide, which means it is a big contributor to greenhouse gas production. The pie charts show greenhouse gas emissions and energy use for different uses. The largest energy users are heating and cooling followed by water heating then other electrical appliances and refrigeration. From a greenhouse gas point of view water heating is the worst followed by other electrical appliances then refrigeration.
So why the difference? Most Australian electricity is produced from coal which (as discussed above) produces lots of greenhouse gases. Particularly in colder locations where heating is a larger portion of energy use, a lot of people use gas for heating. As gas is a relatively low greenhouse gas emitter, this means that on average heating produces less greenhouse gases. If you have an all-electric house your greenhouse gas emissions are likely to be higher than if you use other fuels as well (unless you use some form of green power).
When looking at these issues, it is important to be aware that your own individual greenhouse gas emissions can vary significantly from the average. For example greenhouse gas emissions from cooling could be none if you relied on opening doors and windows for cross-ventilation at night of a well designed home. On the other hand they could be your largest contributor to greenhouse gases if you had a large ducted air conditioner, never bothered to shade your windows in summer and you set the summer temperature as cold as you could get. . Nevertheless it is worth talking about average values as this is an indicator of which areas can have the biggest effect, provided we bear in mind trends which are occurring in society. In fact there are very strong tendencies for increased air conditioner ownership, increased areas of cooling and increased expectations of comfort levels. This means average air conditioner greenhouse gas production from residential air conditioning is going to increase over the next few decades from its current relatively small value. However the question is how much is it going to increase? If everyone follows the advice in this book, the increase will be kept to a minimum. Otherwise it could rise to be one of the largest household sources of greenhouse gases.
We should also think about the ease with which some of these things can be dealt with. For example although standby losses are only about 4% of energy used, they amount to about 7% of greenhouse gas emissions. I recently rearranged my computer and other office equipment, so that those items like the fax machine that need to be on all the time, are on one power board and all the other items are on another power board, plugged into a different socket at the wall. I can eliminate most of my office standby losses by the flick of a switch. (Fortunately my wall switch is readily accessible). If your wall switch isn’t accessible, you may need to wait until a switched power board as recently featured on the new inventors becomes available.
If you have any comments please contact us.Back to Contents
The production of most foods uses a lot of energy so when used properly fridges and freezers can be seen to save energy by reducing waste. They also save energy by reducing the frequency with which you drive to the shop. Of course if you walked or rode a pushbike to the shop you would save even more. Nevertheless unless you have a ducted reverse cycle air conditioner or use electric heating, your fridges and freezers are likely to be the largest single electrical users in your home. This means they may well be your largest contributors to greenhouse gas production. There is a substantial difference in energy use of a poorly operated fridge and an effectively operated fridge so it is worth minimising their energy use.
As with most areas of energy use the first task is to determine how much you need to achieve. A 300 l fridge uses less energy than a 400 l fridge, all other things being equal. (The energy star rating depends on the amount of energy required to keep a given volume cool. In other words, a 4 star small fridge uses less energy than a 4 star large fridge because it is keeping a smaller volume cool). If you only need a small fridge don't buy a big one. Similarly a fridge uses less energy (for a given size) than a freezer, because the freezer is colder (even if they have the same star rating). So if you don't need a separate freezer, don't have one.
Try and store foods in the nearest to room temperature place you can. This is because when you open the fridge or freezer to put the food in, or to get it out the cold air spills out. In addition when the food is put in the fridge or freezer it has to be cooled down. All this takes energy. The least energy is used to store something at room temperature. So check the label on jars and bottles and only store them in the fridge if necessary. Similarly in most climates some fruits and vegetables (for example oranges and potatoes) keep as well as or better at room temperature. Save the fridge for things like apple and lettuce that deteriorate quickly at room temperature. Similarly before opening the freezer to put something in there, think 'does it need to go in there?' if it is a leftover that you will use the next night, the fridge will be fine.
Items which need to be frozen, but are likely to be used up quickly, should go in the fridge's freezer as the smaller volume normally means it will take less energy to re-cool the warm air which enters when you open the door. The exception here is that if you are putting a large quantity in (say 4kg or more) you are probably better off putting it in the deep freezer so that it freezes faster and preserves flavour better. The fridge or freezer needs to be located out of direct sunlight and needs sufficient space around it for air to get to the coils on the back of the fridge. Check the manufacturer’s manual for details. Typically they need to have 80 mm clearance at the back unless they have good clearance on the sides, so don’t push them hard up against the wall.
If the fridge or freezer is manual defrost, defrost it regularly, as the thicker the ice the more energy needed. Think before you open the refrigerator door! If you are going to need a number of items in the next 5-10 minutes get them all out at once. Every time you open the door the cold air flows out, being replaced by warm air from the room. This warm air has to be cooled which uses energy.
Both fridges and freezers should be operated at the correct temperature. If the temperature is too high the food won’t keep as long. If the temperature is too low you use more energy (up to 5% per degree). Deep freezers at 15º C to 18º C and fridges at 3º C to 4º C. Freezers in fridges tend to be intermediate in temperature. If you have a suitable thermometer, test it and adjust. (You may need to check your fridge’s manual, as sometimes it is confusing to get the balance between the fridge and freezer right.)
If you have a dodgy old fridge that appears to be low on gas, replace it if you can, as newer fridges can save up to 2/3 of the energy of some older fridges.
If you are keeping an old fridge in a garage as a drinks' fridge, don’t leave it on continuously. Switch it off, leave the door open and only turn it on when you are about to have a party. If the fridge is so old that there is a latch on the door that could cause a child to be trapped inside throw it out, as it would cost a fortune to run and is a safety hazard. For most people it would cost much less to buy ice whenever you are having a party, rather than to run an old fridge continuously.
Obviously, when buying a fridge, look for a high star rating.Back to Contents
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