One of my household projects the past few weeks has been to profile my home power usage with the goal of seeing where I can reduce it with small investments of time and money. The $20 Kill-a-Watt tool has been invaluable in this exercise. So far, I've managed to reduce my estimated power usage by around 10% ($190/year) with another 3% of quick-wins yet to do as well as some future projects that could yield another 20-30% savings. For the full details, here's the spreadsheet that I've been using.
Here are some interesting facts that I've learned along the way:
- Massachusetts has some of the most expensive electricity in the contintental US.
- In my house, just the three computers (office desktop, router, mediacenter pc) and three TiVos that were turned on 24/7 account for 425W 24x7 (and that's not counting laptops, and even with the monitors and 170W Windows box turned off). This is around half my electric bill! I suspect that many of you are in similar situations... Over time, I think that I'll start to replace some of these with low-powered Via Eden or AMD LX800 boxes with solid-state-drives. Even when buying new desktops, low-power CPUs will likely pay for themselves in MA.
- Computer processors use up lots of power, but so do hard drives. Across my desktop computers and TiVos, I have 12 hard drives in the house. That's around 100W just by themselves! Configuring drives to spin-down when not in use can save 4-10W per drive. Taking the second CPU out of my router was also a quick-win.
- For TiVos and other similar devices, the power costs can be a significant portion of the cost-of-ownership. For example, my Series3 TiVo draws 40W which costs about $5.50/month or $200 over three years. This is about half the cost of the service subscription!
- Those power bricks do add up (at 500mW-2W each), but a few individual turned-off-but-plugged-in devices may dwarf those at 10-15W each. Finding those and putting together mitigation strategies for those few devices are faster wins than dealing with power bricks. For example, my subwoofers use 10-20W even when in "power-saving mode". Two Yamaha stereos that I have from \~1993 use 16W even when turned off. By contrast, my newer Yamaha receiver in my home theater only uses 1W when turned off.
- There are some dimmable compact florescents that play nicely with X10/SmartHome dimmer switches. In particular, the Philips Marathon Alto bulbs seem to work ok so far, although it takes them a little time to warm up.
- Plasma TVs use *lots* of power when they're turned on. My 42" 480p display uses around 220W when turned on, but 1080p plasmas are rated to use 2-3x as much. I guess this means that I should get an LCD when I eventually upgrade to 1080p.
These are the highlights of the audit along with example actions taken (or planned) to save power:
|**Approx Pct**||**Monthly Kwh**||**Average (W)**||**Example Savings (W)**||**Actions to achieve savings**|
|**Home office computers**||21%||176||240||14||Remove unused power bricks, configure drives to spin-down when not in-use, set Windows machine to go into standby when idle, eventually migrate apps off of desktop server to lower-powered machine|
|**Lights (total)**||15%||128||175||54||Replace selected lights with compact florescents|
|**Home theater (total, with tivo+computer)**||14%||116||159||19||Used trigger cable from receiver to power supply to shutoff subwoofer and DVD player when not in-use|
|**Electric clothes dryer**||11%||89||122||Planned: replace with energy-efficient gas dryer|
|**Home router/server**||10%||82||112||18||Removed a CPU, configured drives to spin themselves down when not in-use|
|**Refrigerator**||7%||64||87||33||Could save \~33W by replacing with more efficient fridge|
|**Bedroom A/C (amortized)**||6%||49||67|
|**Air purifier**||6%||47||64||50||Don't keep always-on|
|**Kitchen lights**||4%||36||49||18||Replaced two 90W R40 bulbs with dimmable 20W Philips Marathon CF bulbs|
|**Halogen torchiere in office**||3%||29||40||28||Planning to replace with compact florescent|
|**TiVo Series1 w/ 2 drives**||2%||20||28||28||Retired since I don't really need three TiVos|
On a related note, is anyone interested in my old Hacked Series1 TiVo (with ethernet and extra storage) before I try to sell it? I also have a bunch of incandescent R30 bulbs for ceiling canisters that are left-over from my old house. I also have an old CRT TV stand from Ikea that I'd like to get rid of to make room for a breakfast nook table.