Page 1 of 2 12 LastLast
Results 1 to 10 of 13

Thread: Energy audit for your home or office

  1. #1
    Platinum Member Chatmaster's Avatar
    Join Date
    Aug 2006
    Location
    Cape Town
    Posts
    1,065
    Thanks
    107
    Thanked 97 Times in 63 Posts

    Energy audit for your home or office

    In our discussion about the electricity consumption survey thread it became clear to me that I have a huge problem with my current electricity consumption. This will strongly effect my business which I am running from home and the possible growth I will experience during the coming months.

    dsd made the suggestion that we should start a new thread where we can discuss a energy audit for our home or office, lets see what great advice everyone can come up with.

  2. #2
    just me duncan drennan's Avatar
    Join Date
    Jun 2006
    Location
    Cape Town
    Posts
    2,642
    Thanks
    119
    Thanked 94 Times in 77 Posts
    CM, how comfortable are you with posting a list of appliances in your home, and roughly how many hours they are used? (just remember that this is open for everyone, and anyone, to see)

    Do you know what your geyser temperature setting is? Does your geyser have an insulating blanket? Are the pipes coming out of it insulated?
    [SIGPIC]Engineer Simplicity[/SIGPIC]
    Turn ideas into products | The Art of Engineering blog

  3. #3
    Platinum Member Chatmaster's Avatar
    Join Date
    Aug 2006
    Location
    Cape Town
    Posts
    1,065
    Thanks
    107
    Thanked 97 Times in 63 Posts
    Quote Originally Posted by dsd View Post
    CM, how comfortable are you with posting a list of appliances in your home, and roughly how many hours they are used?
    Well if I want to sort out my problem I certainly have to do this, besides I am sure I am not the only person stuck with this issue, so here goes...

    I have made some changes, but this is based on the account I mentioned before.

    House

    Geyser House - Operates 24 hours set at 60°C
    Swimming pool pump - 6 hours a day on timer
    Stove - Once a month for about 3-4 hours. We make food and freeze it, else we braai .
    Kettle - On every hour for at least 12 hours a day
    Microwave - Mornings and evenings for about 5mins a shot plus when baby bottle needs to be warmed.
    Washing machine - Samsung top loader 13kg runs about 24hours a week
    Tumble drier - Runs about 30 hours a week.
    Iron - Runs about 5 hours a week
    Hi-fi - We have 4 in the house, at least 2 are on every morning and evening during the week and probably from 6 to 23:00 over weekends.
    TV - Haven't had one for years
    Vacuum cleaner - At least 3 hours a week
    Lawn mover - At least 4-5 hours a week during summer
    Fridge - Always on
    Computer in the house. On about 4 hours a day. Also has Amplified speakers and 19" wide screen

    Office

    Geyser - Operates 24 hours set at 60°C
    Stove - Never used
    Kettle - On every hour for at least 12 hours a day
    Hi-fi - 1, on 12 hours a day
    Vacuum cleaner - At least 1 hour a week
    Fridge - Always on
    Computers - 4 PC and 2 notebooks, on at least 12 - 18 hours a day (My computer has double screens)
    Speakers - Amplified speakers on 2 PC's
    Printer/fax - 2 on at least 12 - 18 hours a day
    Cordless phones - always on
    Fans - 2 x Desktop 40cm on at least 12 hours a day.

    Well that is of the top of my mind that I can think of.

  4. #4
    Site Caretaker Dave A's Avatar
    Join Date
    May 2006
    Location
    Durban, South Africa
    Posts
    20,980
    Thanks
    3,055
    Thanked 2,463 Times in 2,068 Posts
    Blog Entries
    12
    Quote Originally Posted by Chatmaster View Post
    Tumble drier - Runs about 30 hours a week.
    There's your little guzzler. 30 hours a week?
    The trouble with opportunity is it normally comes dressed up as work.

  5. #5
    Platinum Member Chatmaster's Avatar
    Join Date
    Aug 2006
    Location
    Cape Town
    Posts
    1,065
    Thanks
    107
    Thanked 97 Times in 63 Posts
    Yep, with 3 kids you get to do a lot of washing

  6. #6
    Site Caretaker Dave A's Avatar
    Join Date
    May 2006
    Location
    Durban, South Africa
    Posts
    20,980
    Thanks
    3,055
    Thanked 2,463 Times in 2,068 Posts
    Blog Entries
    12
    Sure, but we're talking about the drying here. Invest in a washing line or two, or more if needed. Stuff dries so fast up on the highveld anyway.
    The trouble with opportunity is it normally comes dressed up as work.

  7. #7
    just me duncan drennan's Avatar
    Join Date
    Jun 2006
    Location
    Cape Town
    Posts
    2,642
    Thanks
    119
    Thanked 94 Times in 77 Posts
    How many litres is each geyser?
    [SIGPIC]Engineer Simplicity[/SIGPIC]
    Turn ideas into products | The Art of Engineering blog

  8. #8
    just me duncan drennan's Avatar
    Join Date
    Jun 2006
    Location
    Cape Town
    Posts
    2,642
    Thanks
    119
    Thanked 94 Times in 77 Posts
    Some questions:

    1. What kind of lights do you have? (incandescent, CFL, fluorescent tubes)
    2. How do you use your lights? How many hours a day would you estimate they are on? Are your office lights normally on?
    3. What kind of computer screens are they? (LCD, CRT)
    4. How old are your two fridges?
    5. How many cups of coffee do you make on a single kettle boil? Do you boil more water than necessary?
    6. Are you computer peripherals always on, even when not in use? (e.g. amplified speakers)
    7. Do you hot or cold wash your clothes in general?
    Last edited by duncan drennan; 19-Feb-08 at 01:10 PM. Reason: added question
    [SIGPIC]Engineer Simplicity[/SIGPIC]
    Turn ideas into products | The Art of Engineering blog

  9. #9
    Platinum Member Chatmaster's Avatar
    Join Date
    Aug 2006
    Location
    Cape Town
    Posts
    1,065
    Thanks
    107
    Thanked 97 Times in 63 Posts
    Quote Originally Posted by dsd View Post
    How many litres is each geyser?
    It doesn't say anywhere on either of the geysers

    Quote Originally Posted by dsd View Post
    1. What kind of lights do you have? (incandescent, CFL, fluorescent tubes)
    My office has 2 fluorescent tubes
    House has 3 single 6ft tubes outside front,side and back.
    I only use energy saver globes except at my front door where it doesn't fit. All the outside lights has day night sensors except the tubes.
    Lapa has a double 4 ft tube but I almost never use it.

    During the evening we are very focused on switching lights of when we leave a room, so we hardly leave lights on if we are not in a room.

    My office lights burn all day and until at least 11 at night
    My outside lights are on the entire night for security purposes.

    Quote Originally Posted by dsd View Post
    3. What kind of computer screens are they? (LCD, CRT)
    All screens are LCD

    Quote Originally Posted by dsd View Post
    4. How old are your two fridges?
    Well they are the same KIC fridges we bought them together in 1998.

    Quote Originally Posted by dsd View Post
    5. How many cups of coffee do you make on a single kettle boil? Do you boil more water than necessary?
    Difficult to say, but we drink a lot of coffee, the kettle are normally filled with the exact amount of water necessary.

    Quote Originally Posted by dsd View Post
    6. Are you computer peripherals always on, even when not in use? (e.g. amplified speakers)
    Yes

    Quote Originally Posted by dsd View Post
    7. Do you hot or cold wash your clothes in general?
    Cold wash always

  10. #10
    just me duncan drennan's Avatar
    Join Date
    Jun 2006
    Location
    Cape Town
    Posts
    2,642
    Thanks
    119
    Thanked 94 Times in 77 Posts

    Post

    Okay, let's start by trying to sum the usage up and see if we can get close to the amount on your bill. I'm making a lot of assumptions, and approximations. Mainly I'm guessing the kilowatt rating of different devices. Where you specified hours/week I've used the hours/7 to get an average per day. I've worked on a 30 day month.

    House:

    0.8kW * 6hrs * 30 = 144kWh (swimming pool pump)
    3kW * 1.5hrs = 4.5kWh (stove - I assumed 3 plates on half the time of cooking)
    2.2kW * 1hrs * 30 = 66kWh (kettle - assumed 5 minutes 12 times per day)
    0.9kW * 0.2hrs * 30 = 5.4kWh (microwave - assumed 12 minutes per day @ 900W)
    0.9kW * 3.4hrs * 30 = 51kWh (washing machine on cold wash - guess for top loader)
    3kW * 4.3hrs * 30 = 387kWh (tumble drier)
    1.2kW * 0.35hrs * 30 =12.6kWh (iron - assume heating element on for half of usage time)
    0.05kW * 5.7hrs * 30 * 2 = 17.1kWh (2 hi-fi's - running 40hrs/week)
    0.005kW * 24 * 30 * 4 = 14.4kWh (4 hi-fi's - on standby 24hrs a day)
    1kW * 0.43 * 30 = 12.9kWh (vacuum cleaner)
    1.5kW * 0.57hrs * 30 = 25.7kWh (lawn mower)
    50kWh (fridge - approximate 600kWh/yr, based on this)
    0.2kW * 4 * 30 = 18kWh (computer @ 0.15kW + screen @ 0.05kW)
    0.04kW * 24 * 30 = 28.8kWh (computer, screen and peripherals while "off")
    0.04kW * 10 * 30 * 3 = 36kWh (3 fluorescent tubes on a night)

    The geyser is hard to approximate, but we'll come back to that a little later...

    Total kWh for house/month = 873kWh (approx, without geyser)

    Office:

    2.2kW * 1hrs * 30 = 66kWh (kettle - assumed 5 minutes 12 times per day)
    0.05kW * 12hrs * 30 = 18kWh (hi-fi)
    0.005kW * 24 * 30 = 3.6kWh (hi-fi - on standby 24hrs a day)
    1kW * 0.15 * 30 = 4.5Wh (vacuum cleaner)
    50kWh (fridge - approximate 600kWh/yr, based on this)
    0.85kW * 16 * 30 = 408kWh (4 computers @ 0.15kW + 5 screens @ 0.05kW)
    0.04kW * 8 * 30 * 4 = 38.4kWh (4 computers, screens and peripherals while "off")
    0.05 * 16 * 30 = 48kWh (2 laptops)
    0.1kW * 16 * 30 * 2 = 96kWh (2 printer/fax)
    0.003kW * 24 * 30 = 2.16kWh (1 cordless phone)
    0.06kW * 12 * 30 * 2 = 43.2kWh (2 fans)
    0.04kW * 17 * 30 * 2 = 40.8kWh (2 fluorescent tubes)

    Total kWh/month for office = 768kWh (approx, without geyser)

    The geysers are tough, as they are very usage dependant. I've read in a couple of places that geysers make up about 40% of your total electricity usage (typically). You didn't mention a dishwasher, so I'm guessing all those coffee cups are washed by hand.

    For the office I guess about 150kWh, and the house about 400kWh for the geysers (guesstimate based on number of people and how many coffee mugs need to be washed).

    So that makes it

    Office: 918kWh
    House: 1273kWh
    Total: 2191kWh

    Now the major problem is that the final figure is about half of what your bill was. Here are a couple of reasons I can think of for that,

    • Over estimate by municipality on most recent bill (check back and see what your average was over the last few months)
    • Underestimate on usage you gave
    • Underestimate on power consumption estimates I made
    • Underestimate of geyser consumption
    • Appliances missed from list
    • Faulty appliance or geyser element


    As I've said, the numbers are estimates, so please feel free to make suggestions for changes.
    Last edited by duncan drennan; 20-Feb-08 at 09:30 PM.
    [SIGPIC]Engineer Simplicity[/SIGPIC]
    Turn ideas into products | The Art of Engineering blog

Page 1 of 2 12 LastLast

Similar Threads

  1. Simple ways to improve your energy efficiency
    By duncan drennan in forum Energy and Resource Conservation Forum
    Replies: 14
    Last Post: 27-Aug-08, 07:49 AM
  2. Integer Home Loans
    By QUINN in forum Business Finance Forum
    Replies: 5
    Last Post: 15-Apr-08, 11:32 PM

Tags for this Thread

Did you like this article? Share it with your favourite social network.

Did you like this article? Share it with your favourite social network.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •