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Join Date: Mar 2009
Location: Green Bay, WI
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Power Consumption

07/10/2009 12:14 AM

I am looking for help - ammunition - in an ongoing debate. Since this forum is made up of tons of smart folks, I'll start here.

My wife is on a rampage over the electricity bill. We live in Green Bay, WI, and the Air Conditioning has only been running for three days thus far in 2009. The electric bill for 3500 sq ft of living space and a family of five is about $160 this time of year. She thinks this is way too much, so she has gone on a mission, searching every Ladies Home Journal-linke website for solutions.

The focus of her attention has turned to the parasitic power consumption of things like cell phone chargers. She's pretty bent outa shape over leaving the PC on overnight, too (I have our updates and system scans set tto run while we sleep) - monitors shut down after 5 minutes idle. She's even starting to obsess about having more than one TV on at any given time (I watch NASCAR, son watches Baseball, girls watch Disney and she wants to watch Food Network).

While I am not an engneer, I know that these things all do sap energy. But... I am more inclined to think that the two loads of laundry per day (electric clothes dryer) and cooking (electric oven and range) are more to blame than the iPod and cell phone transformers and midnight virus scans.

Can anyone help point me to some logical resources so that I can demonstrate what the actual power consumption metrics are? (For example, one recent Good Housekeeping article says that by powering off the PC at night, we can save $100 per year. That's only $8 per month - but it is 5% of the current bill. However, my brain has a hard time believing that a PC with the monitor off eats that much cash). Hell, if a PC costs $8 per month to run at night, a dryer must cost, what, $1,000?

If I am wrong, I need to admit it. But I don't think I am...

Can anyone help me with data, metrics, calculators, spreadsheets, anything to help me understand - I need facts...

Thanks.

-Dan

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#1

Re: Power Consumption

07/10/2009 1:38 AM

You can buy some very simple little meters at many electronics stores or on-line, called a "Kill-a-watt" that you plug in to a wall socket, and it has it's own socket for you to plug in your device or appliance (assuming 15A or less). It then records energy consumption.

But here are some facts:

An average 36" LCD TV takes a lot more energy to operate than an old CRT, about 1500W on average. Most people don't realize that. So it looks like Wisconsin residential users pay around 11 cents/kWH, making that TV cost you about $0.17 per hour to watch. 6 hours per day, 30 days per month, comes to about $30 per month per TV. But TVs also have an "instant-on" circuit that keeps the electronics ready and waiting to do their stuff, and that uses as much as 40W 24/7, so adding 40W for the other 18 hours of stand-by comes to another $2.23 per month on top of that. If your TVs have that "Energy Start" logo on them, they have a "green mode" that turns the instant-on feature off after a few hours.

Cooking uses a lot more power, but for a relatively short time, so it doesn't actually add up to much energy. The dryer probably accounts for more than the stove/oven. A/C systems are the biggest consumers by far.

But wall warts? Nah... When plugged in but not actually charging anything, they use maybe 1 watt. So 24/7/30, that means it uses 0.72kWH per month, that amounts to about 8 cents per month. If you have 25 of these little devils, you are still using less than that one idle TV. PCs sittin idel (no crunching numbers), typically about 60W, including the monitor in stand-by mode. So maybe $4 per month to operate.

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#27
In reply to #1

Re: Power Consumption

07/13/2009 3:56 PM

I think you're a little high on the 1500W LCD TV. As far as the new flat screen TVs go, LCD TVs are the most efficient (2-3 times more efficient than plasma). In fact, a really good one (in terms of power consumption) will draw close to 100 W while a really bad one will only pull 300-350 W. In fact, if you match the screen size of an LCD with a CRT the LCD will win in most cases. Below is a link to a chart that lists power consumption from 150 TVs. Based on this chart the idea of saving $100 a month by unplugging your TV sounds crazy unless you have about 30 big screen TVs in your house.

http://reviews.cnet.com/green-tech/tv-consumption-chart/?tag=contentMain;contentAux

A standard PC power supply used to be 200W back in the 90s. Today that has crept up to over 300 W because PC power supplies have to account for all of the power-sucking USB devices. I have actually heard of some that are over 700W. You can assume that when the PC is being used that you're probably drawing about 1/2 what the power supply is rated for (w/o peripherals). In sleep mode though this will drop to less than 10% of that.

You can download software that will allow you to shut off your USB drives to save a little energy. I have all of my peripherals run through an independent power strip that I can shut off with a switch that I mounted under my desk. When I flip the switch all lights go out except my PC tower and router. The tower goes to sleep unless I want to copy something from the hard drive to my laptop.

A simple method for figuring out where the electrical energy hogs in a house are is to lightly touch your devices close to where the cords go into them. If the power supply of the device feels warm, then it is consuming power. If not, then it's probably not a major concern.

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#2

Re: Power Consumption

07/10/2009 1:43 AM

We need the list of apparatus (like Air Cond Horsepower, TV, chilers e.t.c.) and its rated power that you have in your house including nos of lamps and the watt of the lamps. Power consumption is base on the total load installed and consume.

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#3

Re: Power Consumption

07/10/2009 1:53 AM

Lot of links are available. eg

TV: http://www.crutchfield.com/learn/learningcenter/home/TV-power.html?page=2

http://reviews.cnet.com/green-tech/tv-consumption-chart/?tag=contentBody;nextPage

http://reviews.cnet.com/green-tech/tv-power-efficiency/

Roughly you are consuming 3 x 250 x 6Hrs = 4.5 to 5 units/day on TV = 150 Units/month

The TV on standby mode takes about 15-20 W = 20* 8 hrs = 0.16 Units = 5 Units/ month.

The cellphone chargers are much lesser so may add up to this much only at tha maximum.

Yes you are correct that tha laundry dish washers etc do take much power.

Assuming a washer on average takes 1 KW and washes for 2 Hrs per day then this is 60 Units per month.

May be another 100 Units for the cooking?

here I support of course your wife. . (BTW my wife is like that too )

There are some things where you don't have a choice - Cooking, washing,...

Cut down on the areas where you do have.

BTW there is a link which says that the parasitic powers (mostly the standby equipments and that includes the TV too) account for about 10-15% of residential energy bill.

But look for the culprit that can be controlled and that do look like your TV (and the associates- 3 TVs on includes the 3 lights and the AC/Fan etc on instead of tha good old family viewing) But that is what is controversial- who have to have the remote?

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#4

Re: Power Consumption

07/10/2009 2:12 AM

I like the answers all great. You could check with the power company and see if they have a "Smart meter" on your house. These meters will pro-rate your usage during peak hours. Doing laundry during the supper hour will put you in a higher tax bracket then doing it after 10:00 pm. Your air con running during peak hours is a big bite, limit the usage during 'on peak hours' and save your money. Some power companies have a rebate schedule for off peak hour consumption. Change your light bulbs to lower wattage use types. (Bring in the Christmas lights before she notices)

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#5

Re: Power Consumption

07/10/2009 2:14 AM

hedjhawg - Welcome.

Go to this link and read this book, the link was posted by somone in a previous thread and I think you will find it very helpful. It has more than you have asked for but you only need to read what is of interest.

Some extracts below:

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#6

Re: Power Consumption

07/10/2009 2:20 AM

Hey hedjhawg,

The local power company will do an "energy audit" for free, and give you a written report detailing the consumption by device and the cost of each per month or year. Who knows, perhaps you will discover that one piece of equipment you have not even thought of, like a failing compressor or that beer fridge in the hot uninsulated garage is the major cause of the bill.

Your bill seems fairly average for the loads you have suggested however.

Regards, CJM

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#7
In reply to #6

Re: Power Consumption

07/10/2009 2:30 AM

Enough is enough, we put out the dog, the garbage and the lights, DO NOT put out the "BEER FRIDGE". How low can a person get without actually doing the big one????

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#23
In reply to #7

Re: Power Consumption

07/12/2009 10:49 PM

It is clear that the light in you beer fridge is staying on 24/7. Thaaats the cause of the high consumption.

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#8
In reply to #6

Re: Power Consumption

07/10/2009 3:44 AM

This type of reprehensible attack was not expected. OK it was failing but still the beer was cold wasn't it? why do you have to look at the fridge?

There are so many better things to look at .

Again i am sorry and disappointed at your choice of words objects.

First the garage, you know that those are our personal domain (ask Del) and all the revolutionery things are made there (apple comps, Bows and Arrows...) to be unmade during the garage sales. Why somebody have to look inside it except presumably for patent stealing? It was hot and uninsulated simply because I wanted it like that, so that while relaxing i don't fall asleep, that way i can enjoy my beer and thirdly the products emanating will be proudly exclaimed as the result of my sweat and of course a lot of blood too <Ouch>.

Then the only other interesting area the fridge is invaded.

let us give a battle call now "All the garageers unite"

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#9

Re: Power Consumption

07/10/2009 4:33 AM

The energy consumption that appears on the bill is the sum of the rated wattage of the appliances times the amount of time that the appliances are on. The wattage will be marked on the case of the appliance. So, for example, a load of 1000 watts that is on for 1 hour uses 1000 watt-hours (or 1 "kilowatt-hour"), which is the same amount of energy as a 100 watt load that is on for 10 hours. It is the kilowatt-hours that the utility company charges for, and the fewer of these that are consumed, the smaller the bill will be.

In the first instance, it's lots of small things that together add up to make a big difference, and these should be done first. Here are some suggestions for shaving the bill that cost absolutely nothing:

  • Pull all chargers out rather than let them just sit there plugged in and not charging anything.
  • Switch off and disconnect the PC rather than let it sit there on standby.
  • Likewise the TVs and radios and and Playstations
  • Don't leave lights on at night.
  • Switch off lights in rooms that have no occupants.
  • Minimise the use of electric dryers by leaving washing to dry thoroughly in fresh air.
  • How many electric clocks are in use there? How many are needed (the answer is one at most - they never all say the same time!)?
  • Is there scope to trim existing timeswitches so as to give a shorter on-time?
  • Are showers the preferred method of bathing or does everyone use a tub-full?
  • Are fans going at full tilt or is there scope to change to a lower speed setting?
  • If the water is heated electrically, is there scope to reduce the thermostat setting? 60degC is enough to kill all the bacteria and more than enough to provide bathing water.
  • Is it really necessary to have the water heater start at 7 in the morning, if the household showers and bathes from 7 at night?
  • Is there scope to switch to an economy tariff ("Economy 7" was the brand name in the UK), that charges for power at a lower rate overnight in exchange for a higher unit rate during the day when the home's occupancy is lower, and do the washing and water heating in that low-rate period?
  • Review the need for all appliances. Switch something off without telling anyone. See if it stays off. If it stays on, ask the individual that switched it to justify why it should stay on.
  • Check room thermostats regularly. 19degC is enough!
  • Can the contents of two refrigerators be combined so that one refrigerator is on and the other can be turned off?
  • Bath with a friend!
  • etc.

Next, in terms of modest do-it-yourself investments and improvements inspired by a visit or two to some home major improvement retail outlets:

  • Consider investing in a pressure-cooker. Steaming vegetables and stuff at higher temperatures for a shorter time uses less energy. Some claim it makes the food taste better too.
  • Is there scope to add timeswitches to things so as to trim the on-time? Timeswitches can be fitted to fixed installations like the water immersion heater, and there are plug-in devices for things like table lights.
  • Is there scope to increase the insulation jacket thickness for the hot water storage equipment? It will pay for itself through energy savings in weeks.
  • Review all electric lighting. Is there scope to replace tungsten incandescent lamps with modern high-efficiency light sources? Start with the higher wattage lamps that are on for most time first, and then work down through the list over time - even a 40W tungsten that is on for 15min every day is a worthwhile candidate for replacement with an 8W modern-equivalent light source.
  • Can that tungsten 500W outside floodlight be replaced with something else of a lower wattage? The neighbours might appreciate the gesture too!
  • Is there scope to fit occupancy detectors so that lighting only comes on when it is dark and there is someone there to be lit?
  • Review loft insulation, and thicken it. It stays warmer in the winter as a result, giving the heating less work to do, and it will stay cooler in the summer, giving the aircon less work to do. Take special care with fibreglass/"rockwool" types on installation, as loose fibres can irritate the skin, respiratory tracts and eyes. UK building regulations currently require 250mm fibreglass for loft insulation on new buildings.
  • Is there draught excluder tape applied around the inside of the frames of all external doors?
  • Is there scope to fit the offcuts of draught excluder tape to that rattling window?
  • Is there scope to fit blinds, sunshades or self-adhesive reflective coatings to the underside of that conservatory roof so as to reflect some of the summer sunshine instead of making the aircon do all the work?
  • If the old furnace/heating boiler is approaching the end of its economic life, consider replacing it with a modern balanced flue device that uses less fuel.
  • Is there scope to fit retro-reflective panels behind hot water radiators so as to reflect heat into the room instead of warming the walls?
  • Would it make more sense to have electric heaters that can be easily switched on when needed in low-occupancy rooms rather than heat the room all day from the central heating system?
  • Are hot water radiators all fitted with thermostatic valves, so that the heating system doesn't have to work so hard?
  • etc.

Then some more substantial investments can be considered on the basis of longer-term payback and adding to the value of the home:

  • Is there scope to upgrade the windows with low-emissivity glass and double-glazing? Triple-glazing is done in Switzerland, among other places.
  • Is there scope to generate some power at the home, reducing grid consumption and even feed it back into the grid ("making the meter run backwards") by:
    • fitting wind turbines to some high point on the building?
    • fitting solar voltaic harvesting to the roof of the building or to a stand-alone installation out in the garden/yard?
  • Is there scope to capture some solar heat for hot water generation using some form of heat pump? (CR4's Del the cat has done a blog or two on a home-brew system installed in Harlow, UK, and there is plenty of information to be had from, oh, say the Centre for Alternative Technology at Machynlleth in Wales, which has a website, among many other places.)
  • Is there scope to install ground-source heat pumping arrangements that refrigerate the garden/yard to provide warmth for the building in winter? Most systems operate with a coefficient of performance of around 2.5, which means that for every 1kW consumed (and that can be dissipated within the building!), an additional 2.5kW is pumped into the building from outside.

Happy savings!

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#10

Re: Power Consumption

07/10/2009 8:03 AM

I'm the power miser in my house. My wife would leave everything running all day. I simply turn off what we are not using use. I have all the modern conveniences, extra fridge for beer and soda in the garage, Freezer, electric dryer, laptops and cell phones, AC, Blah blah blah...

The big screen TV does not need to be on when nodbody is watching. We use a radio for background noise, it is amazing how much more faster kids get things done when the radio is on instead of the TV.

We use one TV - it is good to work together to select shows. People have to loose and win and get along. It also will cut the E-bill.

The dryer is not an Iron. Took me a while to teach people to take care of their laundry right away but it was good. We almost never even need to use the dryer or a regular iron to de-wrinkle clothing.

Shut off the computer - you can configure updates to be down at shutdown. The computer will stay on long enought to update then shut down.

Use energy efficient bulbs - they use much less energy and they don't generate nearly as much heat that the AC has to compensate for.

Unplug the clocks and such in spare bedrooms.

look around the house - I am sure you can find waste if you want to.

Most of it comes down to common sense and wether or not your care. But the point is if you saw a dollar on the ground each day would you bend over to pick it up or just leave it. Most of us would pick it up. That is about how much effort it takes to save a dollar a day by shutting off the things you don't need.

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#11
In reply to #10

Re: Power Consumption

07/10/2009 8:14 AM

Very good short and to the point. In fact as per the few reports that I have seen, the energy wasted on the standby mode is aprroximately 15-20% of the total electricity produced.

Add the wasted energy (as per your advice) and you almost solve the energy crisis. But that means more unemployment and recession .

We wash the clothes and put up in the sun to dry during the day. Of course we have to resort to iron to remove the wrinkles. But the advantages are keep the steam off, and the semi-wet cloth out of the washing machine are dried faster and better in ironing.

And the end line is

Most of it comes down to common sense and whether or not your care

This deserves a GA but that would be wasted on You

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#13
In reply to #10

Re: Power Consumption

07/10/2009 9:13 PM

Most of it comes down to common sense and wether or not your care.

And keep "double-dipping" in mind, my sons used to run the game computers 24/7, which generate heat, which in the summer means more cooling.

So you start with a 900 watt power supply, presume you are throwing half off as heat, so that is 450W.

That 450W is felt at the thermostat, but the A/C is only about 50% efficient. So you have to run 900W of A/C to control the temp.

So you brought the heat into the house so you could use another inefficient machine to take it back out. Right up there with having the refrigerator inside.

Except it all turns around in the winter

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#18
In reply to #13

Re: Power Consumption

07/12/2009 9:42 AM

Edignan,

Actually, most AC and heat pumps are better than that. They will use 1/2 to 1/3 of the energy they transfer to outside.

You are correct that most energy losses inside the house will be evacuated by the AC in the cooling period, your 450W of waste hear should need approximately 200W of electricity.

In the heating season, all these losses in the house are cancelled by the reduction in heating requirement. So during the heating season, leave the lights on, its free. You will be happier because we are often affected by the reduction of light in the winter.

One way to reduce the impact of an AC, if to add a de-super heater coil on it and use it to produce hot water. It is easier than solar panels. Your central AC can probably produce all the hot water you need.

This is what I do at home. I also have a second coil that heat up the swimming pool with the heat that would normally "trow out". That is what I call "recycling where it counts".

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#19
In reply to #18

Re: Power Consumption

07/12/2009 4:26 PM

Simply brilliant. CJM

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#22
In reply to #18

Re: Power Consumption

07/12/2009 9:22 PM

I LIKE that idea!

I knew a fella ran a heat exchanger on well water - 65 degree water provided most the cooling he needed.

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#26
In reply to #22

Re: Power Consumption

07/13/2009 9:33 AM

If you can do it, it is even better since you only need a recirculating pump. The problem is that in most areas, ground water is a controlled resource. While you can easily get a permit to pump it out, it is difficult to get the permission to return it in the ground and dumping it in the nearest river seems to be a waste of good naturally filtered water.

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#24
In reply to #13

Re: Power Consumption

07/13/2009 3:32 AM

So you start with a 900 watt power supply, presume you are throwing half off as heat, so that is 450W.

Where do you think the other half goes?

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#28
In reply to #24

Re: Power Consumption

07/16/2009 11:53 PM

Hah!

Very good point - I was going to start with "inconvenienced electrons" but heh, same answer we started with, hunh?

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#12

Re: Power Consumption

07/10/2009 8:19 AM

A couple more points.

I don't think that shutting of the water heater (as I think somebody else indicated) is worth it unless you are going to be away for several days. The warm water will cool and have to be reheated. I also don't think instant hot water heaters are worth it unless you will still take the same lebgth shower. Most people I know that have instant hot water use much more hot water - 30 minute showers etc...

Keep the fridge full - The air in the fridge exchanges rapidly when the kids stare into it. If it is full you will exchange much less air and the fridge will do less work. Remind the kids that staring into the fridge will not change what is their :-)

If you have laptops with week or bad batteries as many of us do. They will suck power even when they are off if they are plugged in. They will try to charge the battery but the energy will just be lost in the battery leakage. I had one that would get quite warm when it was off unless I unplugged it.

Warmth can be a good indicator - touch some idle things. My cable box is realy warm when not in use - what does the cable company care :-)

Not everything that is wasting energy will feel warm but if it is warm the heat is comming from somewhere.

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#14

Re: Power Consumption

07/11/2009 1:38 AM

Run some common sense numbers before going crazy or spending money on power measuring gadgets. The small power "vampires" people freak out over may not be as bad as advertised.

A typical vampire group consisting of charger wall-warts, AV equipment, and standby PC hardware may reach a total of 100 W. If you pay $0.10 per kW-hr (kiloWatt-hour)...

0.100 [kW] * 0.10 [$/kW-hour] * 24 [hours/day] * 30 [days/month] = $7.30 [/month]

A central AC unit could be 10x more significant.
4.8 [kW] * 0.10 [$/kW-hour] * 6 [hours/day] * 30 [days/month] = $86.40 [/month]

A newer normally operating refrigerator may be around
1.0 [kW] * 0.10 [$/kW-hour] * 4 [hours/day] * 30 [days/month] = $12.00 [/month]

An OLD poorly operating refrigerator could be
1.0 [kW] * 0.10 [$/kW-hour] * 16 [hours/day] * 30 [days/month] = $48.00 [/month]

Also, $20-$30 of your electric bill is probably delivery, taxes, and fees that you cannot reduce without completely disconnecting from the local grid. Not a realistic option for most people. Use the basic calculations to make a list. When your list $ is close to your actual bill $, you got it right and can then pick out the best places for YOU to conserve.

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#15

Re: Power Consumption

07/11/2009 6:38 AM

Dear friend, Check up how many light connections you have?Are they on even if not reqd. or no body is there.?Install PIR sensors to switch off lights when no one is there.TVS do consume reasonable power.If you CRT type TVs .pl. change over to flat LCD/LED types. Washing M/C is another big consumer.Switch over to CFL lamps for normal lighting equirinments.You have to definately check proper use of every element. regards SPA

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#16

Re: Power Consumption

07/11/2009 10:23 AM

I applaud every energy saving tips that don't simply exchange four quarters for a dollar.

If the objective is to reduce energy consumption, most of the above suggestions will work .

If the objective is to reduce home expenses, most people have bigger money wasting area than energy consumption.

1-Look at your cell phone bills... A hundred dollars a month is almost your energy bill. Do you need all the optional services at $10-$20 each?

2-Cable TV. Same as cell phone. Even less justifiable as most of what is on TV is garbage.

3-Fast foods and snacks. Reduce them, save money, and live better. You can eat a home cooked steak and salad for the price of a restaurant burger and fries + pop.

4-Replace the monster SUV by a reasonable car. (also better for the planet and as safe)

5-Minimize the insurance covering on the older vehicles. Most people that I know have full coverage on 6-10 year old cars hoping for a new one if something happen. Unless you get a total loss accident every few years, you should keep the money for yourself. At least increase the deductible. You don't need to repair each scratch on the old car.

6-Life insurance is similar, how much coverage do you really need once the kids are grown up? Do you really need to pay a lot to transform your death into a jackpot for your spouse? Paying your debts would certainly be a better use of your hard earned money.

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#17

Re: Power Consumption

07/11/2009 6:07 PM

Here in New Hampshire our electric bill is complicated by peak usage billing. If we just run lights, TV, and the dryer, our bill will be about $75 - $80 for the month. Should I be doing some welding while the dryer is running and the air compressor comes on, I'm going to hear my wife shouting about a $120 bill. Even though I only ran the welder for say 15 - 20 minutes, I'll be billed at a higher rate for the entire month because of the peak demand.

If this sounds like you, then do what I do and try to run the heavier demand items by themselves to hold the demand down.

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#20

Re: Power Consumption

07/12/2009 6:19 PM

Jerry quote"Here in New Hampshire our electric bill is complicated by peak usage billing. If we just run lights, TV, and the dryer, our bill will be about $75 - $80 for the month. I'll be billed at a higher rate for the entire month because of the peak demand."

Jerry

Would you explain the rate structure in your area. I have never heard of a utility billing a residential customer using a peak demand as part of his bill.

Thanks

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#21
In reply to #20

Re: Power Consumption

07/12/2009 6:37 PM

I'm guessing he means the 'on peak' period of a time-of-use metering tariff. I have been metering for 1/4 century and have yet to see 'peak demand' registered for residential with the exception of raw data collection for analysis only. CJM

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#29
In reply to #20

Re: Power Consumption

07/17/2009 8:31 PM

I have spent a couple of days looking for some old bills to quote as examples, and the latest one hasn't come in yet, so;

If my bill for the month is 500kw, I'll get billed $.10 per kw.

If my bill for the month is 700 kw, I'll get billed $.12 per kw.

This is why I was looking for the bills; I don't remember if the higher rate kicks in after we exceed a particular level of use, or if it is applied as a blanket over all use if a certain threshold is crossed. It has been awhile since I've reviewed the rate structure with all the new fees and taxes.

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#25

Re: Power Consumption

07/13/2009 8:44 AM

The only suggestion that I did not see above was a programmable thermostat. The largest power consumer in homes is the heating and air conditioner. Here is a list of files on energy use from EnergyStar: https://www.energystar.gov/index.cfm?fuseaction=publications.showPublications&view=all&st=Program&pub_cat_code=ESHI&CFID=2266309&CFTOKEN=24931457

Here is a cost calculator for you to determine what is causing your greatest usage: http://www.wisconsinpublicservice.com/home/appcalc.aspx

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