Tuesday, May 24, 2011

Server Energy Consumption

So I have been blessed with a new computer, which begs the question, what to do with the old one? It's a decade-old Pentium 4 1.6A desktop on an Asus P4B266 motherboard that doesn't owe me anything, and is probably worth even less than that on usedottawa.com. I have wanted a home server for some time, mainly to do backup duties, for which I had been using an external drive to date. It worked fine, but it was getting a bit small and it only worked when I dragged it out of the closet. With almost 20GB of family photos among other things, we don't want to lose any of them. I set the old computer in the basement next to the freezer, connected only a power and Ethernet cable to it, and used Windows XP Remote Desktop to access it from the comfort of my desk.

Of course, the idea of a server is to have it run 24/7, but that also means paying for the resulting electricity bill. So I took that old computer and plugged in to my Kill-A-Watt meter - 96 Watts at idle! The cost to run that is about $142 a year, which is more than we pay for a whole month of electricity now. That kind of utility bill increase isn't acceptable to me, so I thought about how to reduce energy consumption. I decided to pull all of the expansion cards and disconnect power to the optical drives that I wouldn't really need with the computer in its new role. I got the power consumption down to 65 Watts.

Pretty good, but could I do better? I wondered if it would boot without a video card. The video card I had was a victim of capacitor plague. While the card's lifetime warranty was useless as the manufacturer went belly up, and although it still worked without any apparent ill affects, I didn't want to keep using it in a production environment. So I pulled the card out, and it still booted right up! Now the power consumption dropped to 46W.

Next, I set the hard disk to spin down after 20 minutes of idle. Now the idle power draw dropped to 36W.

Next I managed to get this server to go into the S3 sleep state during longer periods of inactivity, for example while we are away from home or asleep or just not using another computer on the network. That brings it down to 3W. This page offers comprehensive instructions on how to set this up, using Windows XP anyway.

Oh, in case you're wondering, the new computer, an Intel Core i5-2500, draws 52W at idle. That's quite a power saving right there over my old computer drawing 96W, especially considering it has exponentially more processing power.

Always a day behind

So far, the Hydro One Time-of-Use Portal data is still one day behind, every day. I have to start keeping a journal of what I've done because I can't remember what I did the day before yesterday.

Tuesday, May 17, 2011

Ontario has an electricity oversupply problem

This graph from the Independent Electricity System Operator's website says it all:

Honey, I left the light on

In our garage, we have three 60W incandescent light bulbs. I have chosen not to change these bulbs out because there is no economic reason to do so, since they are on so rarely and for such short periods, and switching compact fluorescent (or any fluorescent for that matter) is a sure way to promote premature bulb failure.

But one night, those lights did get left on overnight. And sure enough, the time-of-use graph told the tale. Since there's 180W of lighting, leaving it on for 10 hours cost us 30 cents, because we're still paying flat rates until the time of use gets activated! Time to get that motion sensor installed in the garage like we had at our previous house.

The ugly truth about wind and solar: $

Parker Gallant has an excellent blog called "Ontario's Power Trip" hosted by the Globe and Mail that is a definite read for the lay person who wants to get to the bottom of and try to understand the energy mess that Ontario is in.

He writes this letter to the Meaford Independent, rebutting a previous editorial that was published in the paper.

Tuesday, May 3, 2011

Dryer deathmatch - electric vs. natural gas

In our home, the electric clothes dryer is by far the greatest consumer of electricity. So naturally, in any energy audit, we target the largest consumer of energy first, because usually it offers the best return on investment, the biggest opportunity to save, and the biggest impact on the bottom line.

Before we can determine which energy source is better and by how much, we need to first figure out how much energy does it take to dry a typical load of laundry? We can't use a plug-in type meter on a dryer because there aren't any for 220V loads, but we don't need one because the Hydro web portal gives us that information.

Let's take another look at a laundry day in the graph. On this particular day, my wife starts the dryer just before taking the kids to school. Then again later in the afternoon at 2pm, and finally in the evening around 7pm. Notice here is that it takes about 4kWh to dry a load of laundry. Your consumption per load might vary depending on things like the ability of the washer to extract water from clothes, the size of the dryer, the amount and type of clothes dried per load, how plugged the lint filter and dryer vent are, etc. It's going to take more energy to dry a load of towels and jeans than it would for some socks and t-shirts. Regardless, the outcome of this exercise will allow us to see the order of magnitude of savings, and then consider the cost of procuring and installing a gas dryer over the electric one currently in service.

To make this fair, a spreadsheet was used to break out the true cost of energy and exclude the fixed monthly customer charge from each utility, since that amount is not affected by the amount of energy consumed. The spreadsheet allows us to run various scenarios depending on how many loads are dried in a week. The average TOU line gives a rough idea of what it would cost to dry clothes if dryer use is somewhat random during waking hours.

The results aren't even close. Gas wins by a wide margin. In this scenario, a gas dryer handling six loads a week would save $143 to $188 annually. On the other hand, a single person running one load a week would only save $20 to $31 annually.

Now let's consider the cost of a new gas dryer, supposing the old one has reached it's end of life and a new one must be purchased anyway. Most gas dryers carry a $50 cost premium over the electric model. A 120V receptacle needs to be installed for the gas dryer, since the electric one uses 240V. An electrician can do this work for something in the order of $200 unless you are able to do it yourself or there is a spare receptacle nearby. And a gas fitter must run a new gas line to the dryer location. Count on $350 to $500 for this work depending on length and difficulty to install. Let's assume your venting is already metal and suitable to vent the lint, moisture, and products of combustion. So total cost premium for gas is in the order of $550 to 750. At a savings of $143 to $188 mentioned above, payback for this is three to five years. This payback will decline rapidly if electricity prices continue to rise rapidly, or you can get the work done cheaply.

So the bottom line is that gas wins, but only if there is a lot of dirty laundry. With smaller laundry demands, electricity, despite the painfully difficult to swallow electricity prices, may still be the better option for you.

Or just put up a clothesline and fight the relentless rain and birds. Hmmm. Maybe $200+ a year to dry clothes worth thousands of dollars isn't such a bad idea after all.