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Average Electricity Usage?

Discussion in 'Home Power and Microgeneration' started by Ted Wood, May 30, 2004.

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  1. Ted Wood

    Ted Wood Guest

    I'm trying to take steps to reduce our household energy consumption
    and I'm looking for information on what's "reasonable" consumption for a
    family of our size.

    I've averaged out our monthly electricity consumption over the two years
    we've been in this house and have come up with 653 kWh per month. We are
    a family of 6; two adults, and 4 kids ranging from 14 years down to 6
    years old. We use natural gas for space heating, water heating and stove.
    We have central air, dishwasher, newer (2002) refrigerator, clothes washer
    and dryer. We have replaced all of our incandescent lights with compact
    fluorescent and we try to use switchable plug bars on the entertainment
    centre and computer. We also make an effort to unplug the "wall warts"
    when not in use.

    Is our usage in line with what one would expect from a family of 6 with
    usage as outlined above? If not, what are we doing wrong?

    I suspect that the bulk of our consumption is related to the washer and
    dryer; laundry with 6 people in the house is an almost constant thing.
    What about a front load washer and a gas dryer? We're not allowed to use a
    clothes line in our area.

    Here's a chart of our consumption:

    Month/Year kWh Used
    09/02 614.90
    10/02 807.71
    11/02 717.03
    12/02 701.40
    01/03 710.78
    02/03 612.81
    03/03 605.52
    04/03 551.32
    05/03 565.91
    06/03 531.52
    07/03 694.11
    08/03 915.05
    09/03 594.05
    10/03 622.19
    11/03 632.62
    12/03 608.64
    01/04 741.00
    02/04 630.53
    03/04 554.45
     
  2. m Ransley

    m Ransley Guest

    Your consumption isnt that bad for 6.
    A Kill A Watt meter apx 50$ will help you it logs your power
    consumption. You plug an apliance into it.
    Do you have a gas or electric dryer.
    What is your KWH cost and gas cost per therm.
    What do you use for heat, what brand and efficency. What about water
    heater. Refrigerator, Freezer?
    You are doing alot with CFLs and controling phantom power.
    For most of the U.S. gas is alot cheaper that is why I wonder on your
    electric dryer.
    New refrigerators are much more efficient than they used to be.
     
  3. m Ransley

    m Ransley Guest

    Do your apliances have the yellow stickers that show yearly energy
    consumption and at what KWH or therm cost do they give your total years
    cost.
     
  4. ....

    Most utilities consider an average house to use aprox 24 kWh a day or
    720 kWh a month. Your household sounds like it's right in that range.

    I'll second the comment that if you really want to reduce the amount
    more then you should get a kWh meter like the Watts Up or Kill A Watt.
    These allow you to record how much electricity each appliance, light,
    wall wart or whatever, uses. With this knowledge you can then make
    decisions based on your actual use and not estimates.

    Anthony
     
  5. Hi Ted,

    It sounds like you're thinking along the right lines. One of the simplest
    things to do is to turn things off when you're not using them, but getting
    your kids to do that is another thing altogehter.... :)

    Our family of 5 uses about 7KWh/day (210KWh/month) of electrical energy.
    That's in South-Western Ontario, Canada. Heating is done with a wood stove,
    water heating with a gas water heater assisted by a solar hot water system.
    All lights are fluorescents. We almost never use the dryer, using the
    clothes line in summer and hanging clothes to dry in-doors in winter.
    Although our house came with central AC, we strictly rely on sweat for
    summer time cooling.

    Clothes washers don't typically use a lot of electrical energy. Most of the
    energy goes into heating the water used by the washer. The dryer, on the
    other hand, uses oodles of energy to evaporate all that water. As I
    understand it, most front-loading washers do a better job of squeezing water
    out of the clothes, so there is less water to evaporate in the dryer.

    Since your energy consumption is almost as high in the winter as in the
    summer, it seems that your AC isn't taking much more energy in the summer
    than your furnace fan does in the winter.

    I'm sure that not using your electric clothes dryer would make a big dent in
    your electrical consumption. Maybe you should try hanging clothes to dry
    for a month and see how much difference it makes. You can read the meter
    yourself before and after to get an accurate measurement for the period of
    the experiment.

    Not being allowed a clothes line sounds like an issue ripe for brining
    before your local council. Hopefully more people will start to wake up to
    the need for energy conservation, so that rules like this can be revoked.

    Good luck. Let us know what you find out.
     
  6. daestrom

    daestrom Guest

    Hi Ted,

    You don't mention your gas usage, only the electric. A bit higher than
    mine, but not very bad. I have a family of five (although my kids are older
    than yours) and we run about 500 kwh/month. I don't have A/C
    (northern/central NY doesn't really need it as much probably as where you
    live) or dishwasher. We have a gas clothes dryer. Other than that, we are
    setup similar to you (gas forced air, gas HW, fair number of CF's).

    I'm always looking for ideas too. One is try to see if you can wash laundry
    in *cold* water and be sure loads are full size. If the Mrs. works during
    the day, be sure to have a set-back thermostat that can turn down the heat
    whenever the kids are in school. And always turn back at night if at all
    possible.

    How high do you have the A/C set? In some areas, the humidity is a major
    part of the A/C load, so opening the windows in the evening when it's cooler
    (thinking this helps reduce A/C usage) can actually let in humid air and can
    actually raise your usage.

    daestrom
     
  7. Guest

    Lovely. I wish more people thought this way, did this.

    I have a book, _Homemade Money_ by Richard Heede, pub. Rocky Mountain
    Institute, which covers home energy conservation quite well. My favorite
    Albuquerque bookstore says it is out of print, though Backwoods Solar
    continues to list it in their catalog, at $15.
    For what it's worth, my daily consumption is around 2 1/2 KWH from a solar
    system capable of producing around 5 KWH a day. Largest consumer is
    refrigeration. Heaviest intermittent load is my small machine shop. (I
    live alone.)

    And yes, a wattmeter will give you much valuable information. Mine is a
    Brand model 4-1850, bought 5 years ago. It works well. When I objected to
    some design/construction practices I think are shabby, Brand's reply was
    pretty arrogant. I don't recommend his products, assuming he's still in
    business.

    Tom Willmon
    Mountainair, (mid) New Mexico, USA

    Only the mediocre can always be at their very best.

    Net-Tamer V 1.12.0 - Registered
     
  8. Guest

    The AC energy needed to remove a houseful of humid air seems negligible
    compared to the potential coolth gain, as long as condensation does not
    occur inside the house.

    Nick
     
  9. daestrom

    daestrom Guest

    If the house is 'cool' during the day, and then you open the windows in the
    evening, you *don't* gain any 'coolth'. But you do raise the humidity level
    from a nice 50% back up to 90%. And so the A/C has to run to remove that as
    well as maintain the house cool tomorrow.

    Leave the windows closed at night and the A/C doesn't have to remove the
    moisture, just the heat conducted/radiated into the house tomorrow. A much
    lower number amount of energy.

    daestrom
     
  10. Roland Mösl

    Roland Mösl Guest

    That's crazy

    I use with 3 adult and 2 children an average from 150,6 kWh a month

    I bet most of this energy wasters have a smaller living standard,
    they waste only energy sensless
     
  11. m Ransley

    m Ransley Guest

    150 kwh Mo , must be no tv,computer a few lights, little laundry No
    Fun. You did say 5 people and you do laundry , cook and have a frige ,
    right. Heat ? AC ?
    I use 125 Kwh mo and have the most efficient stuff. But I computer or
    tv 18 hrs a day
     
  12. Guest

    By opening windows in the evening, you can keep the house and its thermal
    mass closer to the average daily min than the 24-hour average temp (or
    higher, given some internal heat gain and sun in the windows.) This seems
    obvious, but...
    Possibly. 'Pends on where you live. Of course that's relative humidity,
    with no condensation.
    Maybe, but the energy required to dehumidify a houseful of humid air (once)
    is small compared to the potential coolth gain. It could be large if water
    vapor condensed inside a house, but that would be Bad Thermal Management.
    Not necessarily. With no night venting, the AC has to remove more heat...

    Say you live near Phila, like me, and it's an NREL average 71.8 June day
    with an 81.7 average daily max and a 61.8 average daily min and a constant
    (day and night) absolute humidity ratio w = 0.0080 pounds of water per
    pound of dry air. Suppose the house has a 200 Btu/h-F thermal conductance
    and 2000 Btu/h of internal heat gain (adding 10 F to the outdoor temp) and
    you want to keep it at 75 F max. Suppose (arguendo) the outdoor temp is
    61.8 all night and 81.7 all day.

    The 1992 ASHRAE-55 standard comfort zone has an upper 68 F wet bulb temp.
    At 68 F and 100% RH has Pw = e^(17.863-9621/(460+68)) = 0.699 "Hg, so
    (using Bowen's equation) we are in the zone if 100(0.699-Pa)/(68-75) = -1,
    ie Pa <= 0.229 "Hg, ie w = 0.0080 <= 0.62198x0.629/(29.921-0.629) = 0.0134,
    so no dehumidification is needed.

    Consider two scenarios:

    1. AC all day, with 24h(2000-(71.8-75)200) = 32.6K Btu, about 6 hours
    of window-rattling.

    2. Open the windows at night, cool a thermal mass C to 65 F, and let it
    warm to 75 F over 12 hours, so 75 = 91.7+(65-91.7)e^(-12/RC), which makes
    RC = -12/(ln(75-91.7)/(65-91.7)) = 25.6 hours = C/200, so C = 5114 Btu/F,
    with 0.00 Btu of air conditioning.

    Nick
     
  13. Pete C

    Pete C Guest

     
  14. More of Nick's theoretical bullshit that doesn't actually
    work.



    Paul ( pjm @ pobox . com ) - remove spaces to email me
    'Some days, it's just not worth chewing through the restraints.'

    HVAC/R program for Palm PDA's
    Free demo now available online http://pmilligan.net/palm/
    Free Temperature / Pressure charts for 38 Ref's http://pmilligan.net/pmtherm/
     
  15. Guest

    But Paul disagrees :)

    But Paul disagrees :)
    An assertion demands no more than a counterassertion. To effectively
    disagree with basic physics, you need to talk about basic physics...

    Nick

    Tired of Iraq? Do something about it. Learn to halve your energy use
    while having fun with math and science.

    Join solar guru Steve Baer and PE Drew Gillett and PhD Rich Komp and
    me for an all-day workshop on solar house heating and natural cooling
    strategies ("HVAC Nonsense") on July 9 in Portland, OR--see page 25 of
    http://www.ases.org/conferences/2004_call_for_papers/SOLAR2004_prelim_program.pdf
     
  16. Steve Spence

    Steve Spence Guest

  17. Ted Wood

    Ted Wood Guest

    Our average gas usage is 242 cubic metres (I live in Canada) or about 8200
    cu. ft (1 m3 is about 34 ft3) per month for water heating, space
    heating and cooking. Our greatest usage (559 m3) was in Jan/Feb 2003 when
    it was COLD!!. Our lowest was 23 m3 in July 2003.
    We already wash in cold water (except the very dirty white socks!!).
    There's usually always someone home during the day, but we set the 'stat
    at 22C or about 72F during the winter and set that back to 17C (63F) at
    night.
    I live London, Ontario, Canada. We've got Lake Huron to the north/west
    and lake Erie to the south, so we've got humidity in the summer. During
    July and August the temp can be (32C/90F) with 100% humidity for weeks at
    a time.
     
  18. Ted Wood

    Ted Wood Guest

    No kidding!! ;)
    Me too! I'm in London.
    We're thinking of getting a front loading washer, but don't like the idea
    of getting rid of an appliance that is still in good working order. Is
    it worthwhile to wait until the current one breaks down or get a front
    loader now and donate the top loader to charity?
    I'll investigate further about the clothes line issue. I was taking the
    word of a neighbour about the clothes line ban, but he's the type that
    doesn't like things like clothes lines, rain barrels, and other things
    that just don't fit with his world view.
     
  19. Ted Wood

    Ted Wood Guest

    Our kWh cost is 4.7 cents (Canadian) kWh for the first 750 kWh and 5.5
    cents for anything above that. Subsidized to heck by our provincial govt,
    masking the true cost. Gas is 19 cents per cubic metre (34 cubic feet)
     
  20. Don Ocean

    Don Ocean Guest

    So What? Nick doesn't actually work either! ;-p
     
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