Standby Power Consumption
Monday, 15. October 2007, 15:04:10
As I'd promised back in March and with the prompting of Blog Action Day, I've finally gotten around to doing a "standby energy audit" of my house.
I suspected that I'd be a bit surprised at the varying amounts of power consumed by devices on standy in my home, and I wasn't dissappointed. First, some notes.
I was only interested in electronic devices that had a standby mode where they could conceivably have had a "fully off" mode instead. I ignored devices such as fridges/freezers where turning them off negates their usefulness. Given that, in total my home uses over 300W continuously.
For measuring the energy used by devices, I used an Energy Meter kit I built (I'd provide a link, but the place I bought it from doesn't list it anymore). It measures about +/-0.02W, but it hasn't been checked against an accurate reference. It did measure a 60W incandescent light globe at almost exactly 60W, though.
My first survey was the kitchen where there was a microwave (2.73W), clock radio (1.32W) and cordless phone (3.31W). Total: 7.36W. There's also an electric oven, but it's hard-wired to the main switch board, so no way of measuring its standby. It has a clock, so there's really no reason for the clock radio (we almost never listen to the radio). The microwave clock is wasted too.
Next was the living room: VCR (0.98W), DVD (7.00W), TV (3.50W), turntable (0.02W), CD stacker (5.36W), amplifier (2.11W), cassette deck (1.02W). Total: 19.99W. There was also a fish tank with a filter and aerator consuming 9.76W, but that's not really optional, is it!
Laundry: washing machine (5.21W).
Bedroom1: clock radio (2.67W).
Bedroom2: DVD (3.20W), TV (15.05W), VCR (12.65W).
What was interesting was the difference between the TV+VCR in the living room (3.50+0.98=4.48W) versus the TV+VCR in bedroom2 (15.05+12.65=27.7W). The living room items are much more recent in design. There have been some obvious improvements.
The next stop was the home office. We seem to have collected an amazing number of computers. Plus we also run a server 24/7 that hosts various personal web sites. I knew that would consume a bit of power, but was curious about precisely how much.
PC1: Compaq 1.8GHz P4 (3.01W), 19" LG LCD (0.86W), 20" ADI CRT (5.79W).
PC2: HP desktop + 17" CRT + UPS (combined 19.82W).
PC3: this was the server mentioned above, this is always on, so rather than measure the standby I measured its operating power. Note that it doesn't have a screen or keyboard/mouse. 1GHz Athlon + ADSL modem/router + UPS: 116.30W. This is about one third the total continuous household power consumption right there. During the day there's usually at least two, sometimes four or five other computers operating! Spin that wheel!
PC4: AMD64-3500 + 19" CRT + 15" CRT + UPS (combined 22.80W)
PCs5,6,7 are all ancient models that don't have any of the fancy soft-starting PSUs found in modern PCs. Their on/off switches are all switching the mains power. Total "standby" power consumption: 0W.
The office has several other miscellaneous items: PoE enabled ethernet switch, powering 3 wireless APs (32.27W), cordless phone (2.36W), intercom (1.85W), GPS-NTP server (5.31W, however, its plugpack consumed 2.10W without being plugged into anything! maybe I need more energy efficient plugpacks?), integrated stereo system (14.32W), doorbell + 9V plugpack (0.28W - the plugpack is a fancy switch-mode variety), clock radio (2.12W), TV (8.82W), HP all-in-one + LAN print server (12.97W), Epson photo printer (0.24W), external hard drive enclosure (0.82W), 4-port KVM switch plugpack (3.01W), two other plugpacks (7.63W).
Total office standby power: 260W. However, this counts our 24/7 server, which is nearly half the total. Clearly, finding ourselves a more energy efficient server computer might save some money, not to mention the greenhouse gases.
In general I think it's safe to say that recent consumer items such as TVs, DVDs/VCRs etc have become a lot more energy efficient. That's great. However, there are still an awful lot of little devices around powered by plugpacks - typically not very efficient plugpacks either!
An idea that's been bouncing around my head has been the fact we need a better way to power low-voltage, typically DC, devices. The PoE switch I recently bought provided a fairly obvious solution. We need to wire all our houses for PoE ethernet! Right next to each set of mains power outlets should be an RJ45 PoE ethernet port. That provides 48V DC. Efficient DC-DC converters are readily available.
The VCR in my living room is proof that it's possible to run a clock in standby off mains power for less than 1W. All devices should be able to do that. Folks should also consider if they really need all those clock radios. After my little audit, we've now turned off the clock radio, stereo and TV in the office, saving over 25W.
All in all, this was an interesting exercise. Now I know for certain just how much power that server is consuming. I think searching for a low-power server might be a good idea.
I suspected that I'd be a bit surprised at the varying amounts of power consumed by devices on standy in my home, and I wasn't dissappointed. First, some notes.
I was only interested in electronic devices that had a standby mode where they could conceivably have had a "fully off" mode instead. I ignored devices such as fridges/freezers where turning them off negates their usefulness. Given that, in total my home uses over 300W continuously.
For measuring the energy used by devices, I used an Energy Meter kit I built (I'd provide a link, but the place I bought it from doesn't list it anymore). It measures about +/-0.02W, but it hasn't been checked against an accurate reference. It did measure a 60W incandescent light globe at almost exactly 60W, though.
My first survey was the kitchen where there was a microwave (2.73W), clock radio (1.32W) and cordless phone (3.31W). Total: 7.36W. There's also an electric oven, but it's hard-wired to the main switch board, so no way of measuring its standby. It has a clock, so there's really no reason for the clock radio (we almost never listen to the radio). The microwave clock is wasted too.
Next was the living room: VCR (0.98W), DVD (7.00W), TV (3.50W), turntable (0.02W), CD stacker (5.36W), amplifier (2.11W), cassette deck (1.02W). Total: 19.99W. There was also a fish tank with a filter and aerator consuming 9.76W, but that's not really optional, is it!
Laundry: washing machine (5.21W).
Bedroom1: clock radio (2.67W).
Bedroom2: DVD (3.20W), TV (15.05W), VCR (12.65W).
What was interesting was the difference between the TV+VCR in the living room (3.50+0.98=4.48W) versus the TV+VCR in bedroom2 (15.05+12.65=27.7W). The living room items are much more recent in design. There have been some obvious improvements.
The next stop was the home office. We seem to have collected an amazing number of computers. Plus we also run a server 24/7 that hosts various personal web sites. I knew that would consume a bit of power, but was curious about precisely how much.
PC1: Compaq 1.8GHz P4 (3.01W), 19" LG LCD (0.86W), 20" ADI CRT (5.79W).
PC2: HP desktop + 17" CRT + UPS (combined 19.82W).
PC3: this was the server mentioned above, this is always on, so rather than measure the standby I measured its operating power. Note that it doesn't have a screen or keyboard/mouse. 1GHz Athlon + ADSL modem/router + UPS: 116.30W. This is about one third the total continuous household power consumption right there. During the day there's usually at least two, sometimes four or five other computers operating! Spin that wheel!
PC4: AMD64-3500 + 19" CRT + 15" CRT + UPS (combined 22.80W)
PCs5,6,7 are all ancient models that don't have any of the fancy soft-starting PSUs found in modern PCs. Their on/off switches are all switching the mains power. Total "standby" power consumption: 0W.
The office has several other miscellaneous items: PoE enabled ethernet switch, powering 3 wireless APs (32.27W), cordless phone (2.36W), intercom (1.85W), GPS-NTP server (5.31W, however, its plugpack consumed 2.10W without being plugged into anything! maybe I need more energy efficient plugpacks?), integrated stereo system (14.32W), doorbell + 9V plugpack (0.28W - the plugpack is a fancy switch-mode variety), clock radio (2.12W), TV (8.82W), HP all-in-one + LAN print server (12.97W), Epson photo printer (0.24W), external hard drive enclosure (0.82W), 4-port KVM switch plugpack (3.01W), two other plugpacks (7.63W).
Total office standby power: 260W. However, this counts our 24/7 server, which is nearly half the total. Clearly, finding ourselves a more energy efficient server computer might save some money, not to mention the greenhouse gases.
In general I think it's safe to say that recent consumer items such as TVs, DVDs/VCRs etc have become a lot more energy efficient. That's great. However, there are still an awful lot of little devices around powered by plugpacks - typically not very efficient plugpacks either!
An idea that's been bouncing around my head has been the fact we need a better way to power low-voltage, typically DC, devices. The PoE switch I recently bought provided a fairly obvious solution. We need to wire all our houses for PoE ethernet! Right next to each set of mains power outlets should be an RJ45 PoE ethernet port. That provides 48V DC. Efficient DC-DC converters are readily available.
The VCR in my living room is proof that it's possible to run a clock in standby off mains power for less than 1W. All devices should be able to do that. Folks should also consider if they really need all those clock radios. After my little audit, we've now turned off the clock radio, stereo and TV in the office, saving over 25W.
All in all, this was an interesting exercise. Now I know for certain just how much power that server is consuming. I think searching for a low-power server might be a good idea.
WIDGETIZE
scipio # 15. October 2007, 21:31