Friday, January 26, 2007

Taming the peripheral drain

So you know all those handy peripherals for your computer? the printer? the monitor? the speakers? they all draw power even when they are in standby mode (some models more than others). One way around this is to use a power strip that senses when your computer is off and shuts off the sockets that your peripherals are plugged in to. It watches the power draw for the socket designated for your computer, and then disconnects power to the other sockets (effectively like you had turned off the switch on the power strip)

Here's an example of a product: (power strip with one monitored socket and 5 switched sockets -- made for uk)

I bought this one from amazon:

You'll want to get a power strip for connecting multiple things to the switched socket or a power strip liberator (1 foot extension cord) for something with a wall wart

UPDATE: here's a power strip for sale in the US

Charge your cell phone while riding your bike

New gadget enables charging your cell phone while you bike!
[via cnet and gizmodo and ...]

While I don't think it's going to solve the energy crisis, every bit counts!
And for the paranoid, you can use your bike as a charger when doomsday hits (or just a regular old 7 day north carolina ice storm or other power outage)

Plus it enables good fitness by encouraging you to bike!

Though in the trend I'm hoping to create let's analyze this a bit.

Say it's $23 (I have no idea what the price will be), in a pure electricity at market rate trade off (say it's $.23 / KWh) you have to save 100 KWh, which given my cell phone charger using 1 watt for about 4 hours to charge, I'd have to charge my phone with the bike 25,000 times to pay it back. Modifiers: (+ plus indicates a reason that makes this product better - indicates reason it's worse environmentally relative to a pure market rate analysis)
+ Electrical market rates aren't high enough to reflect co2 emissions and running out oil in future and so on
+ body gets benefit, thereby reducing health care costs (health care consumes energy and resources)
- if you have to pedal more or ride your bike to charge your phone you are going to eat more (food production uses energy and resources)
- the actual production of a gadget uses resources and energy (plastic, heat for molding, pcbs have toxic chemicals) which probably aren't reflected completely in the sales price

Note that these modifiers are in now way relative in size in priorities (and in fact some are totally unquantifiable and silly) but I think it's good to explore some of the connected effects

Tuesday, January 23, 2007

compact fluorescent lighting

I read somewhere that lighting is 22% of the US electricity usage (I'll see if I can track down the source of that). So it is a big chunk of our energy usage and replacing traditional light bulbs with compact fluorescent lights (sometimes referred to as CFLs) is an easy way to reduce your electricity usage.

They screw in to normal light sockets
They use approximately 1/5th the energy
They put out less heat

Light is cooler somewhat greenish
not dimmable
upfront cost more than standard lightbulb
it's best to dispose of them as harzardous waste

Regarding the non-dimmability, I'm told there are now 3 way CFL bulbs as well as dimmable bulbs. They are still quite expensive but given that it's just changes to the ballast, I imagine the costs of the dimmable ones will come down significantly.

Sources for dimmable bulbs¤cy=USD&products_id=1238

Now given that lighting does take up a large amount of energy and replacing light bulbs with CFLs is easy, you may be tempted to ignore the 5 watts your router consumes and and the 10 watts of standby your TV uses. But remember those are on 24 hours a day, and even if all lighting was made more efficient we'd still use way too much electricity!!!!

Monday, January 22, 2007

Hidden cost of electrical consumption measurements

As I mentioned in my previous post on lighting, electrical devices generate heat, and in climates that require air conditioning you incur the cost of the air conditioner electrical usage on top of the electrical usage of the device itself.

For example if you were to take a 100 watt lightbulb. Since very little light escapes the house, we'll make the assumption that all the electricity used by the bulb ends up as heat added to the house (more on this assumption later) To convert watts to BTU/hour you multiple times 3.43 and since we leave the light on for 1 hour, we generated 343 BTUs. Say your AC unit is a 10000 BTU unit (meaning it's rated to cool 10000 BTUs/hour) with an energy efficiency rating (EER) of 8.3 which means your A/C unit uses 1200 watts. For now lets assume with the light bulb on your ac unit is running constantly and maintains a stable 75 degree temperature. 343 BTUs of the 10000 it is cooling are due to the light bulb so 3.4% of the work it is doing is cooling the light bulb. 3.43% of 1200 watts is 41.16 watts for a combined total of bulb and a/c of 141 watts. So with the parameters we chose for the air conditioner, you are paying an extra 41% on top of the amount of power you pay for the light bulb directly.

So if you left that light on 10 hours per day for 100 days in the summer, how much would it cost if you pay $.20 per kilowatt hour? $28.32!

The same calculations are applicable to computers where basically all the electricity is converted to heat. This can be very important when designing datacenters, server rooms and offices, where computers can be on all the time, and the air conditioning becomes a huge factor in the cost. Monitors, TVs, DVD players, all convert most of their power used to heat. Some gets converted to light or sound, but this is still energy that gets converted back to heat when it impacts your walls!

Did I get my math right? Don't agree with my assumptions? Post a comment!

Friday, January 19, 2007


Lighting measurements are fairly straight forward. Most lightbulbs have a wattage rating on them, and typically they use around that amount of electricity. So I won't be measuring a lot of lighting and posting them here. However, I'd like to point out that one of the quickest and easiest ways to save energy around the house is to replace your incandescent bulbs with fluorescents. Granted they cost more up front but most places they pay back from between 6 months to 1.5 years which is way faster than just about anything else "environmental" (other than just using less). Also keep in mind that they can't be used with dimmers. But you can get the same light output (yes they do make really high brightness bulbs) at less than 1/5th the energy usage.

There is another hidden advantage to fluorescents, that saves money, they put out less heat.

According to this article over at cnet, 22 percent of the electricity consumed in the US goes towards lighting. They also note that incandescent bulbs are about 5% efficient (ie 95% of the electrricity gets used gets turned in to heat, with only 5% becoming light), so I believe the dept of energy number is actually bigger, given that many people use air conditioning in the summer, they are having to cool their lighting.

Other TV related measurements

Roku Photobridge HD1000 network media player photo viewer 15-16 16-17 (idle at menu) booting 15 slideshow 17

Scientific Atlanta 8300 hd dvr cable box off 21 watts idle 22-23 peak measured (starting up) 31
Scientific Atlanta 8000HD Explorer (HD DVR cable box) off 29 watts on 30 watts (idle, playing, recording all were 30 watts)

Note that cable boxes and media adapters, are also usually "always on".
DVR cable boxes, because of the 30 minute buffer that lets you go back in time, are always on, even if they aren't recording anything.

Networking gear

A lot of networking gear gets left on permanently and people don't remember that they are paying for that.


Cable Modem 3 watts (Motorola Surfboard SB4200 -- Provided by Time Warner)
Router 5 watts (Netgear FVX538 -- vpn router dual wan)
Switch 5 watts (Netgear GS608 8 port gigabit ethernet switch -- measured with 1 link, 4 watts with no links)