IRCR Explained: What Is It, How Is It Calculated and How Can You Reduce It?

If you operate a large electricity customer in Western Australia, you may have come across a charge called IRCR on your electricity bill.

IRCR stands for Individual Reserve Capacity Requirement. It is a WA electricity market charge that can represent a significant cost for larger electricity customers, particularly when their electricity use coincides with periods of high demand across the Western Australian electricity system.

The calculation can look complicated. There are peak intervals, median demand, different load classifications, ratios and Reserve Capacity prices all working together.

The good news is that the basic idea is much simpler:

Why has IRCR become such a big issue?

For some businesses, the most noticeable thing about IRCR is not the calculation itself but the size of the cost.

A tenant can have relatively stable electricity consumption throughout the year and still see a substantial increase in its IRCR-related costs if its demand during the relevant peak periods increases, or if the underlying Reserve Capacity costs and IRCR factors change.

This is why IRCR can sometimes produce a surprisingly large year-on-year change in electricity costs. It is not simply a matter of using more kilowatt-hours.

A business may use only slightly more electricity overall but still have a much higher capacity cost if it contributes more heavily to the system peaks used in the IRCR calculation.

First: what is the WA Reserve Capacity Mechanism?

Western Australia operates a different electricity market structure from the National Electricity Market used in the eastern states.

In the WA Wholesale Electricity Market (WEM), the electricity system needs enough generation and other capacity to be available to meet periods of high demand.

This is managed through the Reserve Capacity Mechanism.

Capacity providers are paid for making capacity available, and the cost of that capacity ultimately needs to be allocated to electricity market customers.

IRCR is one of the mechanisms used to allocate that Reserve Capacity cost to Market Customers.

The important point is that IRCR is therefore not a Western Power network charge. It is a cost associated with the WA Wholesale Electricity Market and the Reserve Capacity Mechanism.

Why are large customers charged IRCR?

The reason large electricity customers are exposed to IRCR is relatively straightforward.

A large customer can have a meaningful impact on the amount of capacity the electricity system needs during periods of very high demand.

For example, a large shopping centre, warehouse, industrial facility or commercial building may have hundreds or thousands of kilowatts of demand.

If that demand occurs when the WA electricity system is experiencing its peak conditions, the customer is contributing to the amount of capacity required across the system.

IRCR attempts to allocate a proportion of the Reserve Capacity cost based on that contribution.

Smaller customers are generally treated differently and do not face IRCR in the same way as large contestable customers.

IRCR is about demand, not just energy consumption

This is one of the most important things to understand.

Your normal electricity bill is largely driven by how much electricity you consume, measured in kWh or MWh.

IRCR is different. It is concerned with your contribution to peak demand.

Think of it this way:

• Energy consumption: How much electricity did you use?
• Peak demand: How much electricity were you using at the critical times?

A business can therefore have relatively modest annual energy consumption but still have a significant IRCR exposure if its demand is high during the relevant peak periods.

The Capacity Year runs from 1 October

One point that often causes confusion is the timing.

For the WA Reserve Capacity Mechanism, the Capacity Year runs from 1 October to 30 September.

This is different from the Australian financial year, which runs from 1 July to 30 June.

So when looking at an IRCR calculation, it is important to understand which Capacity Year and which Hot Season data are being used.

The IRCR applied to a customer is linked to its contribution to system peak demand during the relevant periods, rather than simply the customer's electricity consumption over the previous financial year.

The 12 peak intervals

One of the most important parts of the calculation is the 12 Peak SWIS Trading Intervals.

These are the 12 half-hour trading intervals identified by AEMO as the relevant system peak intervals for the IRCR calculation.

Importantly, they are not simply "the 12 highest half-hours for your business".

They relate to the WA electricity system peak.

This means a customer's demand during those particular intervals can have a much greater impact on its IRCR than demand at other times.

AEMO publishes the current and historical 12 Peak SWIS Trading Intervals, so businesses do not need to guess when these intervals occurred.

What does "median" mean?

AEMO uses the median consumption across the relevant peak intervals.

In simple terms, the median is the middle value once the relevant demand readings have been put in order.

This is important because IRCR is not simply calculated by taking the single highest demand reading.

Instead, the calculation considers the customer's demand across the relevant peak intervals and uses the median to determine its contribution.

TDL and NTDL – what do they mean?

Another part of the IRCR calculation is determining whether a load is a Temperature Dependent Load (TDL) or a Non-Temperature Dependent Load (NTDL).

Temperature Dependent Load (TDL)

A TDL is broadly a load where electricity demand is significantly influenced by temperature.

Air conditioning is the obvious example.

A large commercial building may have substantially higher electricity demand on a very hot day because its cooling systems are working harder.

Non-Temperature Dependent Load (NTDL)

NTDL is broadly electricity demand that is not considered to be temperature dependent.

For example, equipment or processes that operate at relatively consistent levels regardless of whether the weather is hot or mild may be treated as NTDL.

The distinction matters because different ratios are applied to TDL and NTDL in the IRCR calculation.

AEMO determines and publishes the relevant ratios used in the calculation.

Where do the IRCR ratios come from?

The ratios are not something a retailer simply chooses.

AEMO publishes the IRCR ratios used in the calculation.

The relevant ratios include the NTDL Ratio, TDL Ratio and Total Ratio.

These ratios are updated and published by AEMO and are used to ensure that the total IRCR allocated across Market Customers corresponds with the Reserve Capacity Requirement.

A Simplified IRCR Calculation

The easiest way to understand the calculation is to break it into stages.

This is a simplified explanation rather than a replacement for the WEM Rules. The actual AEMO calculation contains additional steps and provisions for different types of loads, new meters and other circumstances.

Why can IRCR increase so dramatically?

There are several reasons a customer's IRCR cost can change significantly from one period to another.

1. Your peak demand changed

If your demand during the relevant peak intervals increased, your contribution to the IRCR calculation can increase.

2. The system peak intervals changed

The relevant peak intervals are determined by the WA electricity system, not by an individual customer. A change in when the system experiences its peak can therefore change which periods are important.

3. The IRCR ratios changed

AEMO publishes the ratios used in the calculation. Changes in these ratios can affect the resulting IRCR allocation even if a customer's own electricity usage has not changed substantially.

4. Reserve Capacity costs changed

The underlying cost of Reserve Capacity can also change.

This is one reason why comparing IRCR purely against a customer's kWh consumption can be misleading. IRCR is a capacity-related cost, not simply an energy usage charge.

IRCR is not a network charge

This distinction is worth making very clearly because IRCR is sometimes confused with network charges.

IRCR is not a Western Power network tariff.

Network charges relate to the cost of operating and maintaining the electricity network infrastructure. IRCR is associated with the WA Wholesale Electricity Market's Reserve Capacity Mechanism.

The purpose of the Reserve Capacity Mechanism is to ensure sufficient capacity is available to meet system demand.

IRCR is the mechanism used to allocate a customer's share of that capacity requirement based largely on its contribution to system peak demand.

Why should businesses care about IRCR?

For a large electricity user, IRCR can become one of the more significant components of its electricity costs.

The important thing is that, unlike some electricity costs, there may be opportunities for a business to actively manage its exposure.

The key is understanding when your business is using electricity, rather than looking only at how much electricity it uses over the entire year.

Can you reduce your IRCR?

Potentially, yes.

IRCR management is essentially about reducing your contribution to the relevant system peak periods.

Depending on the type of business, strategies may include:

• Identifying equipment that can be switched off or reduced during likely peak periods.
• Changing operating schedules for high-load equipment.
• Pre-cooling or adjusting HVAC operation before a potential peak period.
• Managing refrigeration and other large electrical loads.
• Using battery storage to reduce grid demand when appropriate.
• Coordinating EV charging so multiple chargers do not operate at full capacity at the wrong time.
• Implementing automated demand management or load-control systems.
• Monitoring the customer's interval data against the published AEMO peak intervals.

The right strategy depends heavily on the individual site. A strategy that works well for a shopping centre may not make sense for a warehouse, supermarket, office building or industrial facility.

Don't just look at the bill – check the data

One of the most useful things a business can do is check whether its IRCR calculation appears reasonable.

This means looking at the underlying interval data rather than simply accepting the dollar amount shown on an electricity invoice.

The review can include:

• Checking the customer's meter data during the relevant peak intervals.
• Confirming the correct meter and site have been used.
• Checking the TDL or NTDL classification.
• Checking the AEMO-published ratios.
• Recalculating the relevant IRCR quantity.
• Comparing the result with the amount charged by the retailer.
• Reviewing historical IRCR results to identify unusual changes.

This can be particularly valuable where a business has experienced a large unexpected increase in IRCR costs.

How Energy Intelligence can help

IRCR does not have to be a number that simply appears on your electricity bill without explanation.

At Energy Intelligence, we can help businesses and tenants understand how their IRCR has been calculated and whether the amount being charged appears reasonable.

We can review the underlying interval data, check the relevant AEMO peak intervals and ratios, and investigate the customer's TDL/NTDL treatment.

More importantly, we can look beyond the calculation and help identify practical strategies to minimise future IRCR exposure.

This may involve analysing load profiles, identifying avoidable peaks, reviewing operating schedules, assessing battery or load-management opportunities, or developing a broader energy management strategy.

AEMO information and IRCR data

AEMO publishes information relating to IRCR, including the current and historical 12 Peak SWIS Trading Intervals and the IRCR ratios.

AEMO's published information can be used by Market Participants to reconcile their IRCR calculations. AEMO also publishes the relevant data files and supporting information.

For businesses wanting to understand the detailed calculation, the AEMO information is a useful starting point. However, the underlying WEM Rules and calculation methodology can be difficult to navigate if you are not familiar with the WA electricity market.

That is where an independent review can be valuable: rather than simply looking at the final dollar amount, the calculation can be worked backwards to understand why the cost has changed and what can be done about it.