Macroware Technology
Standby Power
posted Wednesday, 30 May 2007
I saw a small blurb in my recent Kiplinger's magazine about the waste of standby power from devices like TV's, VCR's and computers when they are not being used. These devices consume a little bit of power when they are plugged in and off, and that adds up to quite a bit of wasted power when you consider that they are not being used most of the time. There was mention of a device from Smart Home USA called the Smart Strip that cuts power off to devices that are not in use.
That made me wonder how much standby power my house is using and what the biggest consumers of it are.
I turned everything off all the lights in my house and went to my circuit breaker panel and measured the current on both incoming 120 V feeds to my house with a Tenma True RMS AC/DC Clamp Current meter. Here's the results.
left feed = 1.98 A
right feed = 1.59 A
Total current consumption = 3.57 A
At 120 V rms, the total power is 428.4 W rms.
Assuming that everything is off and not used an average of at least 15 hours per day (probably an under estimate), the total power used per day would be:
6426 W hr / day
Total power wasted per year would be:
2345.49 KW hr / year
At a cost of about 0.10 per KW hr, that would be a waste almost $235 per year.
That made me wonder how much standby power my house is using and what the biggest consumers of it are.
I turned everything off all the lights in my house and went to my circuit breaker panel and measured the current on both incoming 120 V feeds to my house with a Tenma True RMS AC/DC Clamp Current meter. Here's the results.
left feed = 1.98 A
right feed = 1.59 A
Total current consumption = 3.57 A
At 120 V rms, the total power is 428.4 W rms.
Assuming that everything is off and not used an average of at least 15 hours per day (probably an under estimate), the total power used per day would be:
6426 W hr / day
Total power wasted per year would be:
2345.49 KW hr / year
At a cost of about 0.10 per KW hr, that would be a waste almost $235 per year.
| Description | Standby Current Measured (A) | Standby Power (W) |
| Total Standby for my House | 3.57 | 428.4 |
| Basement TV + DVD / VCR combo | 0.29 | 34.8 |
| Basement Computer (in standby) + Printer (Printer alone was 0.13 A) | 0.143 | 17.16 |
| Cable modem and router (with no network activity) | 0.153 | 18.36 |
| Living room TV | 0.0119 | 1.43 |
| Living room entertainment center (including cable box) | 0.57 | 68.4 |
| HDTV 1 | 0.02 | 2.4 |
| Radon fan | 0.414 | 49.68 |
| Office Computer (in standby) + Printer | 0.243 | 29.16 |
| Office speaker amplifier (on but not being used) and external USB hard drive (off) | 0.065 | 7.8 |
| Aquarium | 0.2 | 24 |
| Garage door opener | 0.035 | 4.2 |
| Bedroom TV / VCR | 0.094 | 11.28 |
| Sunroom TV / DVD VCR Combo | 0.146 | 17.52 |
(1) This is in low power mode. The TV is a DLP and it takes longer to power on in lower power mode (20 s vs. 1 s). In fast power on mode the TV has a standby power of 0.48 A or 57.6 W
The total standby power that I have accounted for is:
2.385 A
286.2 W
That leaves the following amount unaccounted for:
1.185 A
142.2 W
I'm a little surprised at how much I didn't account for yet. I believe some of it can be explained by various night lights and clocks that we have around the house, but the majority remains a mystery. Larger items that I haven't checked yet are the oven, microwave, furnace, water heater, washer, and dryer. The next step of this project is to figure out how to reduce some of this standby power loss.
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