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The Impact of WHEN we Consume Energy (part 2)

Last newsletter we looked at the environmental and environmental and financial motives for managing when and how we use energy in our homes and businesses (see Part 1 of this blog). In this second installment I'll share details on the ways your household can take advantage of the options available, and fine tune  your use of  energy consuming appliances. This will include tips for heating and cooling your home, and getting the most of your solar PV (if you have it).

Heating and Cooling

Heating and cooling are a huge contributor to energy bills / grid demand spikes, so to moderate their use I suggest utilising off-peak periods to get your home to the desired temperature, and then back off during peak times.

And of course, do whatever you can first to improve the thermal performance of your home by making improvements to insulation, drought-proofing, window shading and the like.

A personal example:  On weekday mornings in winter we have an off-peak tariff until 7am, and then suddenly it's peak from 7 – 9am. That results in a jump of over 20 cents per kilowatt hour for the energy we use after 7am.  So, given that I'm motivated to reduce our energy bills,  in winter I get up by 6:30am and turn on the AC to start getting the house warmer. While I’m at it, I boil the kettle to make tea (including a thermos for lunch at the worksite), make toast and so on. Come 7am (peak!) I turn the heater down to very low, just to maintain a reasonable temperature (19-20 degrees C.). Once it gets to 9am (shoulder tariff), if the house is still on the cold side, and it’s even colder outside, I will once again turn the heater up to get back to a comfortable 20 degrees. The double advantage by this time is that our solar PV is now producing well, providing the power we need to run the AC. In warmer months when the house doesn't need heating, I'll try to do all the other activities I mentioned (like making breakfast and tea) before 7am.  Keep in mind that these morning Peak tariffs times may not be the same in your area, and if you have a Smart meter you might only have a night time Peak. However even a jump from off-peak to peak can be significant with some energy companies.

Likewise, on hot summer afternoons if you have air conditioning you might also take advantage of Shoulder tariffs by cooling your house down before the peak tariffs start (in our case, at 5pm).  If you have solar you will also be taking advantage of the solar power available while the sun is still in the sky.


The Time of Use periods for some energy distributors can be quite complicated... this one from Ausgrid. source: https://www.ausgrid.com.au/Your-energy-use/Meters/Time-of-use-pricing?fbclid=IwAR2ECXnIjNZUhyEviPlDOtEFp2zRmBvFEnp-DDT3TsCZllfYCyLIhob-PBY
solar roof

If you have solar pv

The most beneficial times for ‘load shifting’ as I’m describing it here shifts to times of the day when you are producing sufficient power to meet those energy demands. On a sunny day that is likely to be between 9am and 3pm, and particularly between 11-1pm. NOTE: Be careful not to overdo it, if you have a 6kWp solar PV that’s producing say 2.5 kW at 8:30am, if you turn on too many appliances at once you may still be drawing grid power, at Peak rates.

Even a kettle will push you over when added to the base load of a fridge. And yet, come 11am you could probably get away with simultaneously putting on a load of washing and a dishwasher. The good news is that by having solar you are much more likely to have mostly off-peak energy use, with some peak from non-solar hours – unless you also have a battery!

Solar + hot water + timer...

One of my favourite tips for clients with solar PV and an electric hot water system is to 'load shift' that hot water so it heats in the middle of the day and capitalises on excess solar power that's otherwise going to the grid (for peanuts). If you have a standard storage resistance hot water system, this can be done by an electrician taking your HWS off the usual 'controlled load' curcuit, and installing a timer in the circuit board. That time can then be set for what ever times suit you (and your solar) the best, eg 11am - 1pm. And if you have a heat pump hot water system, most brands already contain a digital timer (example in image below), to easily set when it heats. Some models even have multiple timers, so for example you could set it to heat from 11-1pm and then do a quick boost in the morning from 7:30-8am, to make sure you have hot water for your morning showers.

Illustration of a heat pump hot water system, with built in timer
The control panel on a heat pump HWS, with temperature controls and multiple timer settings to control when it heats

Are you on a TIME OF USE (TOU) plan?

If you don’t know if you’re on a TIME Of Use plan, have a look at your energy bill. Check the section which spells out how much energy you used and the price you paid per kWh. If there are 3 or more lines with different prices for peak, offpeak, shoulder you’re most likely on a TOU plan. If there is just one line showing your energy use, plus perhaps “controlled load / CL” for hot water, you are probably on a flat rate.

If you want to make sure, call your energy retailer and ask. If you’re on a flat rate and are considering switching, ask your retailer to work out for you if your previous bills would have been lower if you were on TOU. Ideally, they should check a couple of bills from different times of the year, because the effects on your bill can change. This is also service that I (Seb) provide, using a (quite complex) spreadsheet that I developed a while back.

These are the TOU Times for Essential Energy, but only if you have a Smart meter/ interval meter. https://www.essentialenergy.com.au/.../TimeofUseBrochure.pdf

Learn about the times that count

The times of peak/shoulder/off-peak vary depending on your distributor.

In Australia, Essential Energy’s peak periods are 7-9am and 5-8pm weekdays (unless you have a Smart meter), whereas Ausgrid have a peak of 5-9pm and a longer shoulder period which I suspect is at a higher rate than the shoulder periods of other distributors.

So, the first step is to find out who your distributor is (not always the people who send your energy bills!), and then look up online what their Time of Use periods are. Beware that the times may vary depending on what time of meter you have (eg ‘Basic’ vs smart/interval). If you want to be sure, check with your energy retailer.

What do I do then?

Write those times down, or print it out and put it on the fridge, for the whole household to see and learn. This approach to managing your energy use only needs to be as much work as you’re willing to put in. Over time, it can become habit as your awareness grows and behaviours change, such that it requires very little effort at all.

Hopefully, your motivation will be strong enough to make energy management a part of your daily routine to:

  1. a) REDUCE your energy costs, and

Seb Crangle - Zero Emissions Byron

[a variation of this blog originally published on Seb's website:  www.homeenergyadvisor.com.au ]

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