Lets talk energy efficiency!

Ok, so I’m an energy efficiency nut. I had a long debate last night about whether I can justify spending £39 on an LED light bulb. Even assuming it lasts the 20 years they claim, and uses 4 watts, I worked out that the effects of compound interest wipe out my savings by the end of that period. I also deduced that the entire energy savings would be obliterated by just needlessly reboiling the kettle once a month, which is frankly inevitable.

But anyway, I got thinking about energy consumption and whats considered high low or average. As I’m in the UK, prices are likely not comparable, but for 2 people, no kids, From November to Feb 2010, my electricity consumption was…

1,157 units at 11.52p each. With a standing charge, thats £139.93 before tax.
(for the pound-impaired, that’s currently $202 for a quarter).

1 unit is 1 kwh, so 1,000 watts for an hour. Meaning over 90 days I’m using 12.8 units a day. Thats seems mad. Over 12 hours, I’m averaging 1kw? wtf?

Does $202 a quarter over winter for electricity sound a lot? or peanuts? I’m pretty obsessive about turning stuff off. We don’t use aircon in sunny Britain, but then we boil water for tea like it’s a fucking olympic sport.
Anyone else sad enough to know their energy consumption?

What kind of kettle do you use? If I remember correctly, there is a huge difference in efficiency between different kind of kettles. Also, do you fill your kettle all the way up, or only enough for how much tea you’re making each time you boil it?

$39 for a light bulb is ludicrous from a energy savings standpoint.

On tea, I see varying answers of what’s the most efficient. I know I use the microwave for boiling water; it theoretically should be far more efficient, in addition to being way faster.

£39, so its even worse. However, if a CFL bulb costs £6, and last 1/5th as long, plus uses double the energy, it can actually (just about) make sense.

Kettle wise, I’ve heard conflicting things about the quantity of water making much difference. Theoretically, it must be cheaper to boil less surely?

I found out today that my home theater gizmo uses 38 watts to just sit there, doing nothing. grrrr.

I’m a nut when it comes to efficiency as well, and I do the same math as you: will it cost me more in the long run to buy more efficient but expensive alternatives, or less? So, here’s my latest experience:

I can pick up 12 Wal Mart-brand CFLs for $10. When we moved into this apartment, we noticed that it had a lot of lights. I mean, a lot. So we counted: 37 bulbs including the two on the outdoor patio (13 just between the two bathrooms!). So we got 24 CFLs, swapped out the lights we used the most (ignoring a dozen or so that we’d never use or couldn’t swap, like the track lighting in the kitchen which has 6 bulbs alone on it). Bought a 3-way fader switch for the kitchen track lighting (it’s so damn bright that we keep it at ~60% brightness usually), and replaced the ancient thermostat with a $20 digital energy star one. Total: ~$50 after tax.

Last month, we didn’t use any A/C. This was pre-CFL, thermostat, and fader switch. Our bill was $116. This month, we ran the A/C anywhere from 3-6 hours a day on the built-in energy star program. We probably had more lights on more often as well, since we had guests over at least a few times a week. The latest bill came out to $106. So, in one month (and more usage!), we already managed to save $10. It’ll likely all pay for itself in 2 more months, as we use more A/C during summer and will have guests over even more often.

LED bulbs are not worth it at all right now, IMO, not when a 60w-equivalent CFL uses 13 watts and costs less than a dollar apiece. LEDs are really damn expensive (the cheapest I’ve found is $10 60w-equivalent bulbs at home depot, which if we decided to go the LED route, would have cost us $240 just for the bulbs and only ~200w extra savings). But remember, CFLs used to be really expensive too. I remember buying a pair of GE CFLs a few years back for something like $12. LED bulbs will come down in price eventually, and then, yeah, I’ll be moving over to them.

I you have a lot of home theater equipment, consoles etc. it’s worthwhile to get a power cord with an on/off switch, since they drain a surprising amount of power just on standby. For example, I have remote controlled power switches, that turn the whole home theater/gaming rack on/off with single button.

And by kettle, do you mean an electric kettle or an actual, old-fashioned kettle? Electric water boilers are a lot more energy efficient.

For comparison’s sake, we have two adults, no kids, no pets and an apartment with five rooms and a sauna. According to my last electric bill, we used 3130kWh during a year, so an average of about 780kWh per quarter.

Since you are in the UK. You should definitely spend the .2KWH to download (for free) Dave MacKay Sustainable Energy without the Hot Air. In addition to being a fantastic book on the macro picture of energy he has lots of detail experiments on how really to safe energy. Since he is in Oxford I’m sure his climate dependent experiments are more relevant for you than for me in living in Honolulu :).

Pretty much any question you have a boiling water is answered in this blog posting.

I mean an electric kettle, although in winter, now we have a wood-burning stove heating the living room, we use an old fashioned kettle on top of it to boil water. I know in theory that this energy is not really ‘free’ but it feels like it :D
So far, I’m concluding that heating the home with the wood burner is way way more efficient than the oil-fired central heating, and likely more efficient than gas too.

It seems the real power draws in my house are the PCs, which is a bit unavoidable. That, and heat leaking out through 200 year old windows I’m not allowed to replace :(

  1. Switch to using laptops. Plug in to charge, once topped off, unplug the charger completely. Bonus points if you charge your phones/media devices from the USB charge of your laptop. Get used to using the laptop monitor, even a low end additional LCD can pull 20W pretty easily.

  2. Consider space heating only the room you are in with a fairly efficient space heater. Drop the temp you keep your home at a bit and simply space heat the room you are in as you move around the house.

I’ve turned off all of my PC rigs at this point unless I need them for something in particular. Three years ago I had substantial power bills here in the American south due to the need for A/C, multiple PC’s running, an in-window A/C just to keep up in the PC room, a lingering CRT monitor, and normal lighting. I’m now using mostly laptops, have retreated to the bottom floor of the house in the summer (cooler overall.) I’ve also replaced all my lighting with CFL’s and put all my vampire charge devices on power strips that I turn off. I am -amazed- at the difference it’s made in my power bill.

$202 over three months in the winter for 2 people sounds fairly reasonable to me. We get billed monthly and for a household of four (me and a trio of renters) have gone as high as $200-ish during one winter month. Though, admittedly, it can get down to around -15-30 Fahrenheit around here during the winter - usually not consistently, thankfully. But 0-20 isn’t uncommon at all.

No offense, Skipper, but that’s the stupidest thing I’ve heard in a while. You realize you’ll kill your battery in no time if that’s your usage pattern? What good is saving a few bucks on the laptop power draw if you’re replacing your battery annually?

So leave it plugged in? You are still using less power than a PC. I don’t unplug constantly but I have a two year old work laptop and two home laptops that are frequently off power with no substantial battery life issues. Batteries today a hell of a lot better on charge cycles than they used to be. However, you are correct, running it daily on nothing but battery would be bad and I probably shouldn’t have stated it that way. Thank you for the correction.

Yeah, leaving it plugged in as much as possible will keep battery life at the longest, and odds are good it’ll sip power better than anything short of a nettop with a tiny LCD.

You’re right about the newer batteries being more forgiving; the batteries for my 5-year old Dell only last me about 12 months before they start to seriously degrade. I’ve got a 3rd party battery that started with about 4.5 hours of charge when I bought it less than a year ago that’s down to 2 hours on a full charge. Makes me sad.

But, I run that thing down almost to empty on a daily basis, sometimes more than once, so I’m definitely a fringe case.

I started thinking about it a bit and the battery I charge up the most happens to by my work laptop which is an extended battery, meaning I rarely drain it fully. Perhaps that is what’s adding life to my charge cycles?

Energy is gay


Microwaves are incredibly inefficient.

It will boil faster, though.

laptops arent an option for me, due to my day job (indie game developer), as well as enjoying big screen gaming.
I’m surprised we don’t have more of a push for energy efficiency in home electronics. My TV has this big ‘energy meter’ thing onscreen if you toggle it on, but when I was shopping for a TV, you had to be really anal to find the power consumption stats for them. Where are the ads that boast about how little power a new TV or PC or dishwasher uses?

I’ve read the complete opposite to this. Believe me, nothing bugs me more than laptop batteries that hold less charge over time. My previous laptops were left plugged in nearly all the time, and all lasted around 3 years before the battery failed to hold more than about a minute of charge. So I read up on it, and switched to full charge / full discharge. So far my current laptop is 18 months old and still holds about 95% of the charge it did when new. I’m convinced… unless of course it’s purely a reflection of improving battery tech.

I note my iPhone manual advises the same thing, incidentally - cycle the battery constantly is better than half cycles or keeping it plugged in continuously (it sez so right 'ere!).

But I ain’t no expert, I just do what I’m told, y’know.

On energy, we have a solar hot water system which must save us thousands on electricity to heat the water. Of course, the climate here suits it so there’s that. We’re thinking of switching totally to solar in our next house, just waiting for the tech to catch up to our requirements.

Looking into it, it seems there is some debate. The current consensus is that you want to discharge it occasionally, but never below 15% charge, and leaving it plugged in 24/7 and not discharging is pretty bad for it.

So straightforward use as a DTR is out unless you do pull the plug a couple times a week for a couple hours.

hugely jealous grinding of teeth

Oh for a decent amount of sunshine in wiltshire + a really friendly planning department (yeah right)…