Demand Charges: Why Some Bills Punish Short Spikes
A demand charge is a fee based on the highest power draw (in kilowatts) recorded during a billing period — not on total energy consumed. A household that turns on an oven, air conditioner and electric hot water element simultaneously for 30 minutes may trigger a demand charge even if total monthly usage is modest. The dollar impact is tariff-specific, so check the demand line on your own bill. Understanding demand charges matters because reducing them requires managing peak draw, not just total consumption.
- Demand charges bill you for your highest peak draw (kW), typically measured in 15–30 minute intervals during the billing period.
- Common in Queensland via Energex network tariffs; used in other states in specific tariff types. Check your bill for a line labelled "demand" or "peak demand."
- One event sets the charge for the whole billing period — a single afternoon of heavy simultaneous use can determine the demand component for the entire quarter.
- Reducing demand charges means staggering high-draw appliances, not just using less overall.
What triggers a demand charge
A demand charge measures the highest sustained power draw during a billing period, not the total energy consumed. Most demand tariffs measure peak draw in 15 or 30-minute intervals and bill based on the highest single interval reading.
Common household events that create peak demand:
| Simultaneous loads | Approximate peak draw |
|---|---|
| Air conditioner (3.5kW) + oven (2.2kW) + electric hot water boost (3.6kW) | ~9.3kW |
| Air conditioner + EV charging (7.4kW Level 2 charger) | ~10.9kW |
| All of the above simultaneously | ~17kW+ |
For a demand charge based on the highest 30-minute interval, a 9.3kW peak recorded once on the hottest day of summer can set the billing period's demand component, depending on the tariff rules. Treat the load table as an illustrative example.
Who has demand charges on their bill
Queensland residential customers on Energex's network service territory commonly have demand-based network tariffs embedded in their bills through their retailer. The tariff may be called a "demand tariff," "peak demand charge" or similar. It appears as a separate line item.
Other states: demand charges appear in some business and large residential tariff structures in SA, NSW and VIC. They are less common for typical residential customers outside QLD. Check your bill for a line item labelled "demand" — if it is not there, you are on a usage-only structure.
New smart meter deployments are enabling demand tariffs in more states as the grid transitions. This is worth watching on each new billing period if your distributor has recently upgraded your meter.
How to reduce a demand charge
Stagger high-draw appliances. The core strategy is not to run multiple large loads simultaneously during peak hours.
Practical changes:
- Set the dishwasher to run after 9pm rather than immediately after dinner while air conditioning is still running
- Set electric hot water to heat overnight (off-peak) rather than in the afternoon
- Avoid running the oven and air conditioner simultaneously — pre-cool the house before cooking
- If charging an EV at Level 2, set it to start after the household's other loads have reduced (after dinner, after air conditioning has stabilised)
For households with battery storage: a home battery can absorb demand spikes — the battery meets the peak load so the grid draw stays lower. This is one legitimate financial argument for home battery in QLD demand tariff areas.
If your bill shows a demand charge, focus on staggering high-draw appliances rather than reducing total usage — a single peak event drives the charge for the whole quarter. Electric hot water overnight, dishwasher after 9pm, and avoiding simultaneous oven and air conditioning are the practical starting points.
Analyse your bill to identify whether your plan includes a demand charge component.