You might be surprised to know that old fridges and upright freezers are some of the biggest energy users in the home costing up to around $300 a year to run.
Keep reading about the Fridge Buyback Scheme...
Steplight Pty Ltd was founded in 2007 and involved the collaboration of many people and organisations over several years.
Keep reading about Steplight Pty Ltd...
The power consumption of domestic fridges is typically between 100 and 200 watts.
Over a full day they are likely to use around 1 to 2 kilowatt-hours (kWh). Old domestic refrigerators and commercial refrigerators consume much more.
The actual energy consumption of your fridge or freezer will depend on many factors. These include:
Energy efficiency 'star ratings' are a good buying guide, but because of the variable factors described above, the only way to know how much power your fridge is really consuming is to use a plug-in power meter. Some example power meters are shown at the bottom of this article.
To understand how much electricity your fridge is using over time it is best to keep the Power Meter plugged in and running over a 24-hour period. The fridge will not use power constantly and should only be drawing power when the compressor is running, and also when the door light comes on.
Using the Watts Clever Power Meter we found that the small fridge in our office uses between 90 and 100 Watts when the compressor is running.
We found that our fridge used 0.607 kilowatt-hours in a 24 hour period, which equates to around 221 kWh per year. The Power Meter showed that the fridge was drawing power for 6 hours and 10 minutes over that 24 hour period, or 25% duty, which is very energy efficient (a typical duty cycle for fridges is around 30%, or 8 hours per 24-hour period).
This is an office fridge so it's almost empty most of the time. We have also made sure there's at least a 10cm gap around all sides to allow air to move around the unit.
I did the same test with my fridge at home and found that it uses about 1 kWh per day, which is typical for small units under 250 litres capacity.
Commercial refrigeration is more complex to measure but the opportunities for energy savings are greater. Some of the businesses for which we have completed business energy audits initially spent well over half of their electricity costs on refrigeration. In most cases, we were able to identify affordable cost-saving opportunities of 20-40%.
The easiest way to find out how much your refrigerators are using is to use a plug in power meter.
We sell three main options: the Reduction Revolution Power Meter is our most popular and cheapest option. The Watts Clever INPLUG allows you to monitor power usage from your phone or tablet. Finally, the Power Mate Lite is our highest accuracy option used by professional energy auditors.
Other blog posts:
Thermal imaging is an effective way to identify the sources of heat loss within your home or business. You can use a thermal imaging camera to:
If you have just moved to a new rental property or are looking to purchase a new property, a thermal imaging camera is a very useful tool.
A new camera can be pretty expensive, so we have made the FLIR i7 Thermal Imaging Camera available for rent.
The FlIR i7 camera is very simple to use, you can hold it in one hand and operate it as you would a regular digital camera.
The camera is very sensitive and will pick up even the smallest temperature difference. For best results when checking for heat loss, make sure there is a noticeable temperature difference between the inside and outside of the house. It would be best to heat indoors for a while before using the camera.
The photo below is taken from inside a heated house. The darker colours show lower temperatures and the lighter colours show the warmer temperatures. You can see the lowest temperatures are below the door, so this would be a good spot to put a draft stopper.
The images below show the heat loss that can occur through glass. The image on the right shows a wooden door with glass windows. Also note the heat loss occurring between the two doors. The image on the right show the importance of having good curtains that cover the windows properly.
The below images show the ceiling in the living room. I was trying to determine if insulation was present throughout the ceiling. The darker coloured lines are showing the ceiling joists. If insulation were missing there would be darker coloured areas between the joists.
When checking a building for heat loss from the outside, remember to take into account the surface temperature of the wall of the building. The image below of a brick house was taken at night time. It was a cold night, but you can see that the bricks have stored heat during the day.
Other uses of thermal imaging cameras:
Click here to Hire a FLIR Thermal Imaging Camera.
- Holly Lovell-Smith
Most offices have at least one water cooler and many of these have both a 'chilled water' and 'boiling water' function. So how much energy do they actually use?
The actual energy consumption of your water cooler will depend on how it is used, and how many people are using it. The only way to know the actual energy consumption of your water cooler is with a plug in power meter.
Here are our test results...
Most office water coolers are using energy to keep water cool (and hot) continuously. This doesn't make much sense unless the office is open 24 hours a day.
At the Steplight office we use a simple plug in appliance timer so that the water cooler is only on during office hours. The timer is set so that the water cooler will come on an hour before anyone arrives and turn off when everyone leaves. (Timers can be purchased from a hardware store for less than $20.00). We also have the hot water function turned off.
We ran some tests using our appliance power meter to find the actual energy consumption of our water cooler (with and without the timer).
To get an accurate understanding of the water cooler's energy consumption we need to run the test over a 24 hour period. This is because just like a fridge or washing machine, the water cooler won’t be using a fixed amount of electricity (it cycles on and off).
We're a pretty small office of up to six people. In larger offices expect the savings to be much greater than below.
The water cooler used 0.2 kilowatt-hours in a 24 hour period, which equates to around 81 kilowatt-hours ($19.00) per year. The water cooler was using power for 2 hours and 15 minutes of the 24 hour period.
The water cooler used 0.3 kilowatt-hours in a 24 hour period, which equates to about 109 kilowatt-hours ($26.00) per year. The water cooler was using power for 3 hours and 5 minutes of the 24 hour period.
The water cooler used 1.9 kilowatt-hours in a 24 hour period, which equates to about 693 kilowatt-hours ($166.00) per year. The water cooler was using power for 6 hours and 28 minutes of the 24 hour period.
The water cooler used 2.8 kilowatt-hours in a 24 hour period, which equates to about 1022 kilowatt-hours ($245.00) per year. The water cooler was using power for 10 hours and 43 minutes of the 24 hour period.
As shown above, using a timer switch is a simple and cost-effective change, no matter how much the cooler is used.
If you have a water cooler with a hot and cold option, consider deactivating the hot water option. This will yield the biggest savings. A kettle used only when needed would be a better option.
If you already have a fridge, why not switch the water cooler off completely, and a keep a filtered water pitcher in the fridge.
If you are still considering getting a water cooler then keep in mind the energy rating. Energy star qualified water coolers are about 50% more efficient than typical water coolers. To qualify for the energy star label, units that cool only must use less than 0.16 kilowatt-hours per day. Hot and cold units must use less than 1.2 kilowatt-hours per day. If you are leasing the water cooler, ask your supplier about energy efficient options.
When buying any new equipment a good site to check out is the E3 energy rating website. Unfortunately, it doesn’t rate water coolers yet. It does state that there are an estimated 450,000 water dispensers in use in Australia, consuming approximately 350 GWh of electricity every year (this includes bottled water and mains connected water). Since the market for these products is steadily increasing, annual energy consumption by water dispensers is projected to reach 570 GWh by 2020 without intervention.
And that's just the humble water cooler!
- Holly Lovell-Smith
We keep seeing the Arlec Energy Cost Meter at Bunnings, Coles and other shops. It costs about the same as our power meter, so we thought we'd give it a comparative review.
The Arlec Energy Cost Meter is not particularly user friendly - the biggest problem is the size of the screen. When you compare this with Steplight's Power Meter (pictured below) it is difficult to read the numbers, especially the time. Neither screen is back-lit but the larger size does make the Steplight unit much easier to read.
Arlec Energy Cost Meter (left) and Steplight Power Meter (right)
The Arlec Power Meter will display:
Power factor and the current time is displayed on the Volts, Amps and Watts screens. It is helpful to be aware of power factor as you scroll through the screens.
Overall the manual is reasonably easy to follow. It has a helpful glossary of terms at the back which includes an explanation of power factor.
Setting the cost takes time and is quite tricky, but the manual explains it fairly well.
The Arlec Energy Cost Meter allows you to set 2 different prices for electricity. The manual suggests setting one to your ‘normal' rate and one to your 'off peak' rate. This will work to varying degrees depending on where you live and how your electricity supply is set up.
Once you have set the cost you then need to set the time of day or days that these rates apply to. This can be set in several different combinations of days or blocks of days. These include individual days, Monday through Friday, Monday through Saturday, weekend and the entire week. An example of how to set the cost would be one price set for Monday through Friday, and one price set for the weekend. Or one price could be set for night time and one price could be set for day time over the whole week. So, it is not comprehensive enough to handle the NSW time of use tariff which has 3 prices for Peak, Off peak and Shoulder which happen over 4 time periods.
The total cost and total time that the appliance has been on is displayed on the cost screen (separate from the clock). You can also see total cost and length of time the appliance has been on for each cost separately.
Steplight's power meter is more accurate when displaying the kilowatt-hours (kWh), which is what you pay for. The picture above shows the Arlec and Steplight Power Meter kWh screen, which shows the total energy use over a period of time. I plugged each power meter into a kettle and boiled it twice. Steplight's power meter is very accurate showing kWh to 3 decimal places. The Arlec only shows one decimal place and so it has not registered any electricity use.
- Holly Lovell-Smith
The power consumption of an appliance in watts is often said to be equal to current multiplied by voltage.
Unfortunately, it's not that simple.
This conventional wisdom or 'rule of thumb' will have you calculating Apparent Power rather than Real Power (what you get billed for).
Amps (A) x Volts (V) = Volt-Amps (VA)
The formula above can be used for calculating apparent power consumption in volt-amperes (VA). This equation will give you a rough idea of power use in watts but is not strictly correct. For this you need to take into account power factor.
Amps (A) x Volts (V) x Power Factor = Watts (W)
This formula takes into account power factor, and therefore shows accurate power consumption (what you are billed for).
Power Factor is a measure of effectiveness with which an electrical device converts volt-amperes to watts. Power factor is represented as a dimensionless number between 0 and 1.
The closer the number is to one the 'better' the power factor. The higher the power factor, the more effectively electrical power is used. Resistive loads, such as most electric heaters, will have a power factor of 1 as they convert all electrical power supplied into heat. Equipment with motors, such fridges and air conditioners will have a lower power factor.
Power factor is important if you want to know the real power consumption of an appliance (real power is what you are billed for). See below for a demonstration of how power factor is used with our power meter to calculate the real energy consumption of my TV.
It is particularly important for larger businesses to have a power factor close to 'unity' (1) as they may be charged a fee if they have a low power factor. This is because the utility has to supply more current (amps) to the site than is actually required. In so doing, they incur more transmission losses. The good news is that businesses can take steps to increase their power factor. This is something we investigate in our energy audits.
The compliance label of my TV shows the power use as 130 Watts.
The problem is that compliance labels often show maximum power rather than actual power. The only way to know the actual power is to measure it with a plug-in power meter. Over a two hour period the power meter showed a power draw of between 70 and 110 Watts - substantially less than indicated on the label.
At one point the power meter showed the TV to be using 243 volts and 0.421 Amps. If we follow conventional wisdom and just multiply Volts and Amps together without power factor, we'd work out the apparent power draw as follows:-
...then falsely present it as 102.3 W
When we add power factor into the calculation, we get a very different figure. Since the power meter showed a power factor of 0.65 at that time, the calculation becomes:
Hopefully you can see why it's important to get this calculation right.
Thankfully, our plug-in power meters will do these calculations for you. Be aware that some cheap power meters do not perform these measurements accurately and do not always display real power.
Our power meters display real power (Watts) as well as Amps (A), Volts (V), and power factor so you can verify the calculation if you need to.
- Holly Lovell-Smith
A new bed can be expensive and an old mattress is often difficult to dispose of.
Please Note: we DO NOT recycle mattresses. Click the links in this blog post for the contact details of some mattress recycling companies.
Here are some companies I found that are offering mattress recycling services - read on for further links:
Dilemmas arise at both ends of the life cycle of a bed. Australian householders usually replace their mattresses every 10-15 years, resulting in over a million mattresses ending up in landfill every year.
Mattresses contain a variety of materials such as: foam, wood, metal, filler, matting, plastics and mixed fibre fabrics. Once separated these materials can be recycled into other products, including: carpet underlay, wood and coconut fibre mulch, and fabric stuffing in a variety of products. All metals removed can be sent to scrap metal recyclers. Some mattresses still in good condition can be cleaned and refurbished ready for reuse.
I have just been through the process of acquiring a 'new' bed for my guest room. Brand new off the showroom floor was not an option. I wanted to find the most sustainable option for my pocket, my guests' comfort and very importantly for the environment.
I considered accepting a second hand bed through freecycle (local groups where people give unwanted stuff away to others who can use it rather than send their stuff to landfill), only what I needed was not available within my time limit.
I was also concerned about the issue of hygiene and the condition of the bed when considering a second hand mattress.
I'm an avid op-shopper, and had noticed Vinnies selling new mattresses. A closer look revealed the mattresses and ensemble bases are made with new and recycled materials by Land Saver exclusively for welfare organisations.
The outer covers are made from new materials while the inner sprung mattress contains recycled wadding and foam padding which has been cleaned, sanitised and ozone treated (removing any bacteria and odours).
All three of my original considerations of cost, comfort and environment were met, the bed arrived in time for my guest and they attest to having slept very comfortably.
After this success I did a bit of research for you to find where mattresses and bed bases are being collected for recycling and who in Australia is manufacturing recycled beds.
I am always excited when I find useful products made from recycled materials. We are living in a time of change and transition where waste is becoming valued as a resource and innovation is helping to reduce our consumption of the Earth's finite resources.
- Marta Lett
The "people’s watchdog" CHOICE magazine recently reviewed 11 plug-in Power Meters.
The review included testing the accuracy of a high power reading (over 1,000 watts) and a very low reading (about 1 watt). We're pleased to report that our power meter (pictured on the left) scored well (the highest of the low cost power meters). You can purchase the full article here.
Power meters are a handy educational tool for consumers. By monitoring your energy consumption you can use these devices to your advantage. You’ll discover the power hungry appliances in your home... CHOICE put 11 power meters to the test ranging in price from $15 to $395. Each power meter was tested to see how accurately it records high power usage and very low power usage and was compared to CHOICE’S calibrated power meter. Power meters are generally easy to use – you simply plug your appliance into the meter (which needs to be plugged into the power point) and clear readings are given to you on a LCD screen. You don’t need to spend top dollar, most of the cheaper models will do the job. [...]
- CHOICE 8 June 2011. Full article can be viewed here.
See our full range of energy meters and monitors.