Carbon tax, anyone?
Now that the controversial carbon tax is enforced (effective 1st July 2012), I guess I must now wake up to the fact that I will be paying more for my electricity bill….all for a good cause…….I hope.
CatchoftheDay recently has a special offer on a Belkin Conserve Insight energy use monitor. I have always wanted to buy something like this that indicates the energy usage of my electrical gadgets/appliances and since it was on sale, I bought it. It was delivered recently.
The unit has a large LCD display and 3 large buttons – a “$” button that shows the energy cost, a “lightning” button that shows the instantaneous power used and a “earth” icon/button that shows the amount of CO2 generated indirectly by the appliance. The first thing I observed is that the LCD screen on my unit is not as crisp as I would have expected from the product photo. The text display is just not as sharp as other LCD display (eg. my Casio calculator). The only time it looks sharp is when you look at the LCD from an angle. You should be able to see the lack of sharpness in the photos below. Maybe I have a dud unit but not a deal breaker, however. But I wish Belkin would improve on this.
Setting up the energy monitor
The first thing I did was to get the latest tariff from my electricity supplier. This can be found here – Synergy electricity tariff.
So the electricity charge per KWH unit is 24.8866 cents. This already includes a carbon charge of 2.2550 cents.
The next thing is to re-program the energy monitor. This is done really easily. Press the $ button for 3 seconds or so, it will start to flash. Then press the left and right button to adjust the unit rate up/down accordingly. So I adjusted mine to 0.248 since the unit rate on the energy monitor is in dollar, not cents.
The next thing is to obtain the latest Co2/kw rate.
http://www.synergy.net.au/carbon_questions_faqs.xhtml indicates that for each kW of electricity produced, 0.98kg of CO2 is generated. Re-programming the energy monitor is easy too. Press the “earth” icon/button for 3 seconds and adjust the value by pressing the right/left button. Too easy.
The first thing I did is to test it with my table lamp for a primitive “calibration” test so to speak. The lamp has a single 4w compact fluorescent bulb and the energy meter shows this as 4.5w. Considering that all lamp has losses in the control gear, cables, etc, I would say this is fairly accurate. I don’t think this has the accuracy of a commercial power meter (such as the Schneider PM9C, etc) but for home “education” usage, this is pretty good in my opinion.
I then go around the house plugging things into the energy monitor. It is interesting to know that the actual power drawn by an electrical appliance is very often far less than the manufacturer’s declared value.
I guess the reading you get from the energy monitor is really only meaningful if the appliance is running non-stop 24/7, such as a fridge or a home network server for instance. Knowing the energy values of a microwave is fun for education purposes but because the appliance is running for very short duration of time (like heating up a cup of cocoa/milk), knowing the power/energy/CO2 values for these type of appliances is more an academic exercise than anything else.
I have a couple of appliances that are running non-stop 24/7. The fridge is almost the no. 1 candidate here. The next one on the list is my Buffalo Linkstation NAS, 2 notebooks and a desktop (well, it is not exactly running 24/7 but it runs most of the time), and other bits and pieces (TV, network printer, etc) run in power saving mode when these are not switched on. But I am not obsessive enough to know how much my TV is going to draw in its power saving mode so I won’t document this here.
My fridge is a 395 litre Samsung SR394NW (model: RT45MBSW2/XSA) and is indicated to have a 30w interior light and is rated to be 4 stars (out of a max 6 stars rating) and having an energy consumption of 472 kWH per year (IF you can trust the manufacturer’s declared value).
When I first plug the fridge into the energy monitor, it registers 900w as the fridge starts up. It then idle to 0.05w. (see leftmost pic). This appears to me that the fridge is almost drawing no power when the compressor did not kick in. If I open the fridge door, the value jump to 30.1w. (see centre pic), which is in line with my expectations since the fridge has a 30w interior “cabin” light. When the compressor kicks in, the power value shows as 110w (see rightmost pic).
The Co2 figures are 36 kg Co2 per 30 days and 438kg Co2 per year.
Energy cost is indicated to be $9.18 per month and $111 per year.
At $111 per year and at $0.248 per kWH, this roughly equates to 447kWH per year or so. This is surprisingly close to the declared 472 kWH figure by Samsung. The difference is about 5% or so. I guess we can now trust a manufacturer’s declared value on the sticker 🙂
My Buffalo Linkstation Quad Pro
The Buffalo Linkstation Quad Pro has a rated power consumption of about 43w (average), 90w (maximum), 0.85w (standby) as per Buffalo’s website here.
My Quad Pro has 4 x 2TB Seagate Barracuda Green 2TB ST2000DL003 hard drives. Upon startup, the linkstation appears to draw around 45w or so. I almost never power down my NAS so I have no idea what is the standby power usage. This is not a scientific experiment so if you are looking to get more accurate figures, I am sure you can google for more info.
Because none of my disks spin down on idle, the power consumption is fairly consistent. The Seagate Barracuda 2TB Green drive has an average operating power of 5.8w as per Seagate’s website. So running 4 of these disks will use about 23.2w. Add another 10w overhead or so for the CPU, power supply, etc, the power drawn would be in the range of 33w or so….I guess this is pretty consistent with the energy monitor which shows an instantaneous power usage of 31w or so. This, however, tends to fluctuate between 28w and 33w. The energy cost appears to be around $5.57 per month and $67.83 per year based on the latest electricity tariff.
The CO2 generated is indicated to be 22kg Co2 per month and 268kg Co2 per year.
The readings should be self-explanatory from the photos below:
The above readings are taken when the NAS is not under any sort of loads.
I then transferred a 10GB file from one of the PC to the NAS.
I would expect the NAS to draw heavier load but I don’t think this is the case here. The power drawn is around 32.1watt (obviously still fluctuating up and down but generally staying within the 33w level).
NAS = 50% Fridge?
Now here’s the interesting part.
Comparing the power consumption of the NAS to the fridge, the energy cost of the NAS is about 50% of the fridge…… I have never quite expected this kind of figure as the NAS is in my mind, afterall, an extremely lightweight device drawing 32w only. From the reading, it appears that it will cost $67.83 to run the NAS each year and using the latest electricity tariff, this is roughly about 273.5 kWH per year. The fridge, on the other hand, uses about 447 kWH per year. And because the fridge’s compressor does not run all the time, it is therefore my opinion that it is more energy efficient than the NAS. So if energy cost is the highest consideration, perhaps the NAS should really be put on standby/idle mode.
Having said this, there seems to be 2 schools of thought in regards to the pros and cons of putting a hard drive into standby/idle mode. It is a tough question and I don’t have any real good answer for it. My past experience in running home servers is that those hard drives that are set to sleep during idle tend to have a shorter life span compared to those drives which run 24/7. Of course I do not have a scientific proof for these. It is certainly conceivable that the drives that fail are just due to bad sample variations. I have 2 notebooks that used to run 24/7 for 4 years and the hard drives are still perfectly fine, till today. Obviously people will have different experiences.
For my NAS, I find that getting the drives to sleep during idle is not very feasible. I have automated backups from the notebooks and PCs to the NAS via the QtdSync Rsync method and these run automatically unattended. I also have the NAS set as one of the data folder for my bittorrent downloads. Spinning down the drives will not seem very likely for extended periods of time. So it is extremely unlikely that I do this to save a couple of bucks each month. Your mileage will vary of course so please take my comments with a pinch of salt.