Energy audit for your home or office

[Chatmaster]

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.

[duncan drennan]

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?

[Chatmaster]

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.

[Dave A]

Tumble drier - Runs about 30 hours a week.

There's your little guzzler. 30 hours a week?

[Chatmaster]

Yep, with 3 kids you get to do a lot of washing

[Dave A]

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.

[duncan drennan]

How many litres is each geyser?

[duncan drennan]

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?

[Chatmaster]

How many litres is each geyser?

It doesn't say anywhere on either of the geysers

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.

3. What kind of computer screens are they? (LCD, CRT)

All screens are LCD

4. How old are your two fridges?

Well they are the same KIC fridges we bought them together in 1998.

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.

6. Are you computer peripherals always on, even when not in use? (e.g. amplified speakers)

Yes

7. Do you hot or cold wash your clothes in general?

Cold wash always

[duncan drennan]

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.

[Chatmaster]

I phoned the Municipality and according to the lady I spoke to our gate is locked every time they want to take a reading so they worked on estimated figures for my account! Now does that make sense out of the 4,000 + account? lol

Apparently I can phone them the numbers in future, so I guess I will be doing that from now on... Mmmmmmmm I wonder how much money they owe me by now!

[duncan drennan]

I phoned the Municipality and according to the lady I spoke to our gate is locked every time they want to take a reading so they worked on estimated figures for my account! Now does that make sense out of the 4,000 + account? lol

Well, there are still quite a few ways you can shave some kWh off of your account, but I'll post more about that tonight.

What is their last reading for your meter, and what is your current reading?

[duncan drennan]

0.8kW * 6hrs * 30 = 144kWh (swimming pool pump)

You can try to figure out whether it is possible to run for fewer hours per day. It not, you can try to make sure this happens outside of peak hours (doesn't save energy, but helps Eskom). Also check out alternatives, such as salt chlorinators, and the Floatron.

3kW * 4.3hrs * 30 = 387kWh (tumble drier)

As Dave said, consider using a washing line. You'll save a lot of money.

0.005kW * 24 * 30 * 4 = 14.4kWh (4 hi-fi's - on standby 24hrs a day)

Make sure your hifi's (and anything else) is off at the wall plug when not in use.

50kWh (fridge)

I'm assuming that people use the fridge reasonable (i.e. open and close quickly - no starting for hours). You could probably save a little by upgrading your fridges to more modern energy efficient ones, but no need for this.

0.2kW * 4 * 30 = 18kWh (computer @ 0.15kW + screen @ 0.05kW)
0.04kW * 24 * 30 = 28.8kWh (computer, screen and peripherals while "off")
0.85kW * 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)

Make sure your computers and peripherals are off at the wall plug when not in use. Also make sure that they are set for the highest energy saving (sleep after 15 minutes, no screen saves, power screen off after 15 minutes, hibernate after 30-60 minutes, power usage set to Minimal Power Management)