Last month, when I opened my electricity bill, I was modestly surprised by the lower than average amount due. I didn’t give it too much thought; after all, energy prices and usage fluctuate. I paid the charges and went about my day.
Today, though, when looking at this month’s bill I did a double-take. The bill was lower than it had ever been.
In our old building on New York’s Upper West Side, heat and and hot water are provided by the building’s boiler, so those charges would not have affected the electricity bill. The only items powered by electricity are lights, appliances and … computer hardware and peripherals.
Aha! Regular readers of this blog will recall that, a couple of months ago, I replaced my bulky 2008 Mac Pro “cheese grater” tower with the new 2013 Mac Pro “trash can” model. I couldn’t think of any other changes I had made in recent months to lighting, appliances or computers. Could the Mac Pro be the cause of the savings? I had to find out.
Luckily I was able to research electricity bills for the past three years without too much trouble. Unsurprisingly, I found that my energy usage peaks in July, when the air conditioning runs the most; I use the least energy in December, when I typically close up shop for a few days during the holiday season.
On average, prior to this year, I had used 15.6 kWh per day during the months of February and March. Yet in February and March of this year, my KWh per day usage averaged just 12.4. And it was mid-way through February this year when I replaced my computer; had I replaced it at the beginning of the month, it’s likely that number would be even lower.
I figure that the new Mac Pro is saving at least 3.2 kWh per day — a savings of more than 20% off of my total electric usage. The cost of one kWh in the expensive local market, on average over the past three years, has been 28 cents. So that works out to a savings of about 90 cents per day.
That’s about $328 per year. I had my previous Mac Pro for six years, so if the current one matches that tenure, that will work out to $1,968 in energy savings over the life of the Mac.
Apple helpfully provides power consumption data for its entire Mac Pro line going back to the original model in 2006. In an idle state my 2008 Mac Pro consumed 112 watts more than the 2013 Mac Pro – the equivalent of more than 8 energy efficient light bulbs. Over a period of 24 hours (I had often left my Mac Pro on overnight to run background tasks) that would work out to 2.7 kWh per day. Factoring in the greater efficiencies of the OS and hardware, the new Mac Pro is idle and sleeping more, and so my estimate of a 3.2 kWh per day savings seems reasonable.
Of course, replacing the old 2008 Mac Pro with just about any modern computer (like an iMac) would have resulted in a cost savings. And I realize that this is but an infinitesimal drop in the ocean of energy issues that our planet faces. Still, we tend to just flip on a light switch or boot up a computer without often thinking about what it takes or costs to make that happen, so knowing that the new computer saved some green – and, saved some green – is a good feeling.