Energy Management

Looking for tips or advice on energy efficiency around the home? See what others are doing or share your experience!

Looking for tips or advice on energy efficiency around the home? See what others are doing or share your experience!

Demand rates



I'm a newbie to this forum.


I dont really understand the AGL's "General Usage Demand Opt-In" rates.  The demand charge is in units of c/kW/day for usage between the hours of 1500-2100.  That doesnt appear to be a unit of enrgy consumption, do they mean c/kWDay or c/kWHr ?   Is it an additional charge on top of the normal c/kWHr rate?  Can anyone give me a simple worked example of how this rate works ? 


thanks  Jan



So, @jaydeny is this the same as the T14 tariff which is described on the canstarblue website ? They say "This is a ‘Demand tariff’, which is new type of tariff only available to customers with smart meters. Essentially, customers receive lower supply and usage charges, however a ‘demand charge’ is incurred in the peak summer months. A demand charge is a daily charge that reflects a customer’s peak time usage in a 30-minute period between 4pm and 8pm. For example, if you’re charged a 20c/kWh demand tariff, and you use a maximum of 3kWh of electricity in a 30 minute period, you will be charged 60c per day. This charge resets every month." 

If so, I'm confused on several counts.  It nominates a four-hour period whereas @Jan05 referred to a six-hour period 1500-2100hrs.  Secondly, like @Electrons I'm confused by your use of kilowatts rather than kilowatt-hours for peak usage.  If it's the former, then I don't understand what's meant by a peak within a 30-minute period.  Hypothetically, if I experience a short-circuit, then just before the circuit-breaker trips I'm likely to have a large instantaneous demand peak.  Would that then determine the demand penalty that I'd incur?

I notice too that according to Canstar the charge resets each month, whereas you're saying it lasts for the entire billing period.

Is it T14 that you're referring to, or am I barking up the wrong tree?

Tags (3)




If you had a short circuit.

1. The breaker would trip

2. If it was a 25amp breaker your instantaneous current would be 25amps for milliseconds

3. No more current would be drawn from that circuit until you reset the breaker.


Now 25amps is 240*25 or 6250 watts (6.25 kW).


Lets make it easy and say that your breaker took 10 milliseconds to trip.


10 milliseconds is 1/100th of a second.


There are therefore 100 of those each second, 60*100 of those in a minute  (6000 per minute), there are 60 minutes in an hour thus 360000 in that hour.


Now as explained above the short circuit expended 6250 watts divide that by 360000 and you will get your consumption of  0.017361111 kW/hour.


In money turns this at (15c per kW) would be $0.002604167 payable.


With rounding the total would be $0.00.





PS I think you will find that Canstar are inferring that the reader has monthly billing.



@ith all due respect, @NeilC, you’re missing the point of this hypothetical scenario.  I don’t doubt the logic of your argument regarding a short-circuit but maybe I should have chosen a different example to illustrate my point.


Supposing on a given day I switch on our ducted air conditioning, clothes dryer, oven and pool filter simultaneously during that peak demand period.  Within half a minute or so I realise that the power usage has shot through the roof so I immediately switch off every one of those devices.  For the sake of the argument, let’s say I’ve consumed 10kW of power for half a minute, which equals 0.083 kilowatt hours.  That would be added to whatever baseload I was running during that half-hour period.


Which number is relevant to the calculation of peak demand - 10 or the 0.083+ baseload?  That’s what I’m struggling to understand.

According to @jaydeny it’s the 10kW figure which matters, because he talks about kilowatts and doesn’t refer at all to kilowatt hours.  If so, I don’t understand where the 30 minute time period comes into the calculations as that 10kW peak demand figure would then stand for the entire one month or (depending on which of the two sources is correct) 90 day period.  Of course there’s a third possible explanation, which is that that almost instantaneous 10kW peak is assumed to have lasted for the entire 30 minutes, ie equivalent to 5 kilowatt-hours of peak demand.  If the peak demand surcharge was 15 cents/kWh then that would equal 75 cents.  Would that then become the daily charge for the entire billing cycle? 


I’m really hoping that we can get some official clarification.



I am not missing any points at all.

You are fixated on kWh and yet have no understanding of them.


A smart meter reports the number of kWh's used in its reporting period (most cases this is a 30 minute period).


Now during your peak hour period (say 15:00 to 21:00) with demand payments your highest usage in any 30min period is deemed to be your on demand peak rate.


This figure is then used to calculate your demand payment the formulae that you must well know by now.


Now this figure will always be the MAXIMUM amount in your billing cycle, for instance on the first Monday on your billing cycle you got 10kW as your max reading that would be the starting rate, for you, now any max 30min usage in your billing cycle that exceeded that rate would then become your new max rate.


For instance on the last Friday of your billing cycle you drew 13kW for a 30min interval in the peak hours that would now become your demand rate and that what you would be charged for.


Instantaneous power does not matter too much, what you use in TOTAL for that 30min period is what matters.


Now for the life of me I cannot even think why on a demand tariff you would even think of running your pool filter and clothes drier during your peak hours.


10000 watts consumed in 30 seconds is 5000 watts per second. Which in turn is 83.333 watts  per minute. Now seeing you are concerned with kWh that equates to 0.001388889kWh.


Now I don't know about your use of the word baseload. My average daily usage so far for my current billing period is 5.480kW. Now this is not an hour but for the WHOLE DAY.


Yesterday (Wednesday) my MAX demand was .482kW at  19:30 and my daily usage was 5.394kW.


Now according to Energy Made Easy 

Demand tariffs

Plans with demand charges will have the usual usage and supply charges, but will have demand charges added on top.

Instead of measuring your usage over time, demand (measured in kilowatts or kW) is a measure of how intensely you use electricity at a point in time. Therefore, your demand will be high when you have many appliances on at the same time.

You need a smart meter to be eligible for plans with demand charges.

Different retailers have different ways of applying demand charges, for example, you may be charged:

  • for your highest demand in a period of time
  • an average of peak demand over a period of time
  • different demand rates in different seasons.

The same site also states:

Kilowatt (kW)

A measure of electricity equal to 1,000 watts.

Kilowatt hour (kWh)

A measure of electricity equal to 1,000 watt hours. It is the unit measure used on your electricity bill.


Now I presume that your bill will show the same same details as mine and  all meter readings are referred to in kWh.


Therefore your download file from either your Retailer or Supplier always refers to kWh.


Further to confuse you, your Air Conditioner may have a Cooling capacity of 10kW however its kWh usage is much less than this. You need to find the INPUT power listed on the label or manual.


For instance say your AC had an EER (Energy Efficiency Ratio) of 3.8 you would then divide the Cooling capacity by the EER. if your AC had a 10kW capacity then the kWh of your AC would be 2.63 kWh.


Wow this figure is much less than the 10kW that you think you are paying for.


So the end result of this topic is that if your meter reports that your usage is 10kW for a half hour period then it is ACTUALLY 10kWh, but this however does not mean that your usage is going to be 20kWh. (For instance in my peak usage above my, usage for that hour is .878kW).


Hope you work out what you are going to do.


For instance if you run your AC at 25C in summer rather than 22C you can save 20-30% on its power usage (also shut curtains and blinds where possible and close vents / doors in rooms that are not in use).


In Winter run your AC at 20C to reduce your bill.






Thanks @NeilC .  Well, actually I do have a very good understanding of the difference between kW and kWh, so there's no need to lecture me on the basics.  I spend a lot of time analysing and spread-sheeting my usage and studying the output from the smart meter attached to my solar installation.  However your explanation still doesn't clarify the situation.


Let's take your example where I draw 13kW for 30 minutes.  If that were a constant 13kW for the full 30 minutes then it would all make sense.  That's basic.  However, as we well know, power demand fluctuates constantly, so that 13kW might be sustained for some lesser time than 30 minutes.  What happens then?  What say the demand peak lasts 5 minutes, 15 minutes or 25 minutes?


If 13kW is the peak demand for the month, does that then trigger the smart meter to record the actual usage in kWh during that particular half-hour period and use that as the basis for calculating the daily demand charge?  You really haven't provided any explanation as to how a peak demand in kilowatts translates into charge for kilowatt hours in a situation where power demand is constantly fluctuating.  If you can explain that in a clear fashion then I'll be a lot happier.


Finally, I thought it was obvious from my previous post that my example involving the dryer, air-conditioner, pool filter was a purely hypothetical one.  I wouldn't be so stupid as to really run them all at once.  Please give me some credit.




Ok, lets make this simple then.


I will repeat myself.


Between your peak hours there will be one 30min period (if using highest 30min) which is the largest figure.


This figure will be taken EVERY Monday to Friday (excluding public holidays).


The highest figure is then used to calculate your demand charge using the formula,

          max use * number of days in billing cycle * cost per kWh.


There it is simply.


So if you are tracking it yourself you must get that figure every working day and when your bill is due find the HIGHEST value in you list and use that.


Now you must realise that THIS FIGURE IS SUPPLIED TO YOU in the CSV file that AGL allows you to download. It does not matter how you use the power, the figure is calculated for you (same as your bill at the end of your cycle).


The formula for your final bill  is:

            (end meter reading - start meter reading) * no of days in billing cycle * cost per kWh


You do this for all your meters


Add them all together plus add the cost of your supply charge.


If you have not used the GST price then you must add GST to the appropriate amounts.


How Smart Meters Work 


Above is a link, all it says is that a smart meter accumulates your usage over a 30min period and then reports it to your provider.


Then end result is you must trust what the meter says.


You may be able to find the correct manual for your meter so you can read the instantaneous current, wattage and voltage occurring on each of your meter circuits at any time.


If you want to spend $5000 or more  you can get a system installed that can measure and report usage on any device in your residence.


You don't appear to have solar otherwise you would have asked question about the effects of solar on your system.


Just remember that is you find the consumption figure for a device (say an AC), it is a sample figure and may not occur under your usage conditions.


I have two programmes and two spreadsheets that I use to keep track of my usage.


AGL2NEM.EXE grabs the file that I have down loaded from AGL and converts it into a NEM format file.


METERREAD.EXE converts create NEM file into reports (up to 24 of them) and also tells me my meter readings for the last day in the file, my usage for that same day and my average usage in the current billing period and if I wanted too my highest 30 min usage between two times.


ElectUsed.xls, keeps track of my daily usage and is divided up with a sheet for each billing period and then monthly results on that sheet.


BillingCalculator.xls, this sheet keeps track of all my bills.


Has separate sheets for all standard bills (Council rates etc etc).

Each sheet, where appropriate, tells me how much I should pay each fortnight off my bill.

My water and electricity bills keep track of the water usage and by taking the current consumption, dividing it by the number of days since.


(current reading - start reading) / number of days)

Gives me my daily usage.


Then multiplying that by the number of days in my pay-cycle I get a figure that I have to pay each fortnight


So happy calculating.





  Actually I finally have it worked out, but the problem lies with your explanation.  Basically, it omitted one vital step which I have bolded below.  Try this for an alternative:

The meter will detect the 30 minute period between 4pm and 9pm when the usage (in kWh) within the month is highest. This value then gets doubled to arrive at a figure which represents the average power demand in kW over that time interval. That is the figure which the retailer multiplies by the demand tariff to arrive at the daily surcharge.


There are still a few unanswered questions. 1) Is the 30-minute period according to the clock, ie on the hour and half-hour, or is it a rolling 30 minutes? 


 2)  I understood that the peak demand gets calculated for each month on a quarterly bill, rather than one fixed amount for the for the entire 90 days or so.  Your explanation seems to suggest otherwise.  Which one is correct?  Surely they can’t allow a situation where someone who receives monthly rather than quarterly bills gets an advantage 


3) Does a month mean a calendar month?  If not, then how does it work? Is it based on the anniversary of when you started with the supplier?


You’ve said that peak time is measured only Monday to Friday excluding public holidays.  Presumably you aren’t in SE Queensland.  Here, where it’s being introduced to most households in a couple of months’ time, Energex, our wholesaler, will apply 365 days a year, which I believe to be totally unreasonable.  You can imagine someone living on their own who has family staying over the Xmas holidays.  They might well have air conditioning, oven and clothes dryer all working flat out for a couple of low electricity demand days and they get penalised for the entire month.


Overall, there seems to be very little information out there, with worked examples, about how this is going to work.  The average punter certainly won’t understand it, and certainly isn't going to be in a position to interpret .csv files.


Oh, and by the way, I do have solar power, and have a Fronius smart meter which provides me with plenty of data that I frequently look at and analyse.  I’m assuming that the demand figure is looking only at the nett power drawn from the grid, so it should provide some advantage to have solar power.  Of course, here in Queensland we don’t have daylight saving, so the solar power will be of less benefit.



@Spydah, @jaydeny, @David_AGL 


Well, I am sorry, it's the official response to this question from AGL that gave that formula not me.


You were the one having the issue trying to work out how they got the figure.


I can tell you that SA Power Networks on their site states.


Maximum Demand (sometimes referred to as Capacity) is calculated by identifying the highest half hourly interval usage that occurs during each “To Date” period and multiplied by two to obtain the maximum demand expressed in kW.

For 15 minute intervals, the highest 15 minute interval usage that occurs during each “To Date” period is identified and multiplied by four to obtain the maximum demand expressed in kW.


This does not corresponds with the AGL official response stated by Jayden.


So I used his AGL quoted formulae in my responses to you.


Please also note the above regarding 30 and 15min readings (the usage is re-calculated to kWh) thus this answers about how you get charged.


So in Jayden's response which was:


For example, if your highest 30 minutes of usage for a 90-day billing period was 9.6KW with a demand charge of 15c, this'd be calculated as follows: 9.6 x 90 x 15 = $129.60 (excl. GST).


Maybe, Jayden, had already converted the 4.8 kW into the 9.6 kW?


The correct statement should have been 2*(9.6*90*15)=$259.20   PLUS a further $25.92 for GST.


You will notice that the 2* converts the stated usage into kWh!


So the answer to your next question is:


If your peak time is between 15:00 to 21.00 then it would be the RESULT from highest 30min period  from 15:30 till 21:00 every weekday that is NOT a public holiday through the whole of your billing cycle.



The AGL file supplied to me for SA  (briefly) is below


28/04/2019 00:0028/04/2019 00:290.1910A

 The above is if you open the CSV directly with Excel.


"Generalusage","28/04/2019 12:00:00 AM","28/04/2019 12:29:59 AM","0.191","0","A",

While, as above, the actual file lists the above in AM / PM format if you use a text editor.


So to SIMPLY matters I have opted to use 24 hour format so there is no confusion about what time I am referring to.



Why 15:30 you ask because that is your consumption from 15:00 for the first 30 min and last reading would be the 21:00 reading.


If you feel that a person on a monthly billing cycle gets an advantage then simply log onto your AGL account and request a change to monthly billing.


My understanding is a month is from one date in that month to the same day the next month (ie from the 20th to the 20th), if you are on quarterly billing and have a smart meter then the end date  is specified on your most recent bill. (Typically from 90 to 93 days).


According to the internet, Energex is not a wholesaler, they are a supplier, this means that they provide the poles and wires that enable your retailer, (I presume this is AGL), to charge you for the power you consume.


You can see more information about Energex on their website HERE .


The portion of your bill that Energex receives is listed as your supply charge.


In SA (we only have one supplier SA Power Networks), I have a log-in to their web site and I can see my consumption for the previous day by about 0600 most days and also download the industry standard NEM format file from them.


They have had for some considerable time, a DOT on the daily graph for our usage showing our PEAK half hour consumption however this is not for, peak hours usage, but your peak consumption anytime during the day. (See their explanation listed above)


Which for me happened at 18:00 yesterday (Saturday) with 1.6kw , the day before (Friday) it is listed at 06:00 as .5kw??


I have directly notified Jayden in this conversation, so he may come forward with any more information regard the exact times that AGL would be using in your area and any further updates in thus subject.


My understanding is that this is still an Optional Plan and is one of the MANY that AGL offers for its QLD customers.


By the way in the 731 days that I have data for, our highest  ½ hour reading  we have is 1.37 kW so for a 90 day period if we were silly enough to take this option we would have paid $93.71 but if we were charged half as much for our normal rate the total would have cost me $179.21 for our peak usage instead of the $171.00 we would have to have paid if we paid it normally. Only a mere $8.21 more.

But when you take into consideration the $468.00 that we average in solar for a 90 period we still would not pay a bill, even considering the $81.90 that we have to pay for my supply charge.


So our bill for this average 90 day period would be $468.00-($81.90+$179.21+$81.90)

or a Credit of $124.99 towards our account if we had Demand....


In the 2.25 years since we have had solar payback we once paid an $11.16 bill for electricity.





@NeilC @jaydeny@David_AGL

Now we're starting to get somewhere and are beginning to understand each other on this topic. 


I joined this forum largely so that I could figure out how the charges were calculated, bearing in mind that at this moment most consumers, me included, aren't yet on a demand tariff.  Clearly you have the advantage(?) of being on it already, so are familiar with it.  The SA Power Networks explanation which you provide states it clearly and succinctly.  Why are AGL unable to do likewise when someone like me asks a basic question on their forum?


Yes, I now realise that the half-hour periods go by clock time.  It's not a rolling 30 minutes, which would have been another possibility.


I'm not going to get into the semantics as to whether Energex should more accurately be described as a wholesaler rather than a supplier, but the fact remains that they are the ones calling the shots regarding the tariff structure.  See 


At this moment the demand plan is optional for most people, though not for much longer.  I understand that everyone with a smart meter, which includes me, will be changed over on 1 July whether they like it or not.  But it gets worse.  A member of my family, who isn't with AGL, got solar panels installed about six weeks ago.  As part and parcel, Energex exchanged her old spinning disc meter for an EDMI smart meter.  However, nobody bothered to tell her that anyone who gets swapped over like that will immediately and automatically go on to the demand tariff.  We uncovered it purely by chance.


I don't think we'll be as fortunate as you when it comes to the finances.  Firstly, Queensland doesn't have daylight saving so we'll be feeding very little solar power into the grid even in summer during the peak demand period.  Secondly, and far worse, is the fact that for residential customers the peak period assessment applies 365 days a year.  Hence my earlier example of someone who lives on their own but has family staying with them over the Xmas holidays being heavily penalised.  As an aside, small businesses are assessed only Monday to Friday.  Go figure.


Certainly, if AGL continue to offer monthly billing as an option I'll be swapping to it.  That's a no-brainer.






I am hoping that either David or Jayden will respond to this.


It has been in, for a while, that when you get Solar you will be getting a smart meter.


In SA and VIC, I know that it the responsibility of your RETAILER to arrange the install of the smart meter and also for the on going rollout of smart meters to replace the outdated meters.


There are many good reasons for this.

1. The meter is readable remotely.

2. A physical meter reader is not required and thus eliminates the home owner for some liabilities

3. The meter can be read on the due date and a final meter read can be undertaken without a visit.

4. The meter is much more accurate (3 decimal points).

5. Readings can be undertaken at either 15min or 30min (30 min being the norm).

6. Latest meters can be remotely isolated thus saving site visits when customers request disconnect.

7. Attempts by home owners to bypass meters can be detected.



The Energex document is not meant for consumers but is directed at RETAILERS as to how and why they create their network supply charge (which your RETAILER) collects from you.


ONCE AGAIN Energex only make their money from the SUPPLY CHARGE hence the different charge depending on what services the client (the end consumer) wants.


For instance the document talks about a standard flat, a house a building complex etc.


I will again iterate that AGL has a large number of plans that are available for customers in each state. Was looking one day and reckon that I saw at least 15 that are available for QLD customers.


Look at the Energy Made Easy Australian web site to see what plans are available. (This is the site that AGL sends you after you make a decision from the THREE basic choices that are shown on their site).


I have yet to see any DEMAND price deals that are 7 days a week, I will leave it up to you now to show me a RETAILERS plan that is  not a MON - FRI (less public holidays).


I also challenge YOU to show me (and this community) the plan that your family member is now on.


If your family member does not like their current plan then they should change, their are very few plans available these days that have locked in contracts.


It is the decision of the QLD, NT and WA residents not to have Daylight Savings.


You the users, in these states need, to adjust your usage to either minimise your usage costs or to maximise your solar returns.


With the max 13c - 15c  feed is offered by RETAILERS, at this time, you should be using your solar to gain benefits. Rather than running your pool pumps in peak hours, you should be using your solar power to run dishwashers, washing machines etc when you are generating solar.


Look at strategies that involve using OFF PEAK / Controlled Load tariffs for pool pumps etc.


Cool your house down in the morning and then run cooling at 24 or 25 in the house, don't even try and tell me that you walk out side on a 25C day in the afternoon and rush inside and turn you RC cooler on.


I am going to give up on this discussion now.


I spent three years trying to assist SENIORS in developing strategies to reduce their BILL SHOCK's but they would say, BUT I HAVE ALWAYS USED TELSTRA, BLAH BLAH Electric company have always done me right, but after being shown 10 plans that would save them money they said they didn't want to waste their time on the phone.


I suggest you look at all the plans that are available to you, from all the companies, do an analysis, using all of your available data, then find the right plan for you and your family.


Think that your family member also needs assistance in getting the right plan for them.


is a site  where you can see information regarding fees and tariffs.


Any way had enough of this, good luck in your life.


One thing though, I always put my name to the end of my messages, and besides that put a greeting with it.