New MEPS Testing Coming for Heat Pump Water Heaters

Australia’s heat pump water heater (HPWH) market is approaching a significant change in regulation.

A new HPWH test method — AS/NZS 5125.1 Appendix H, developed by Standards Australia/NZ committee CS-028 — is soon expected to be finalised and published in preparation for use.

Following a public consultation and public forum in October 2025, the Energy and Climate Change Ministerial Council (ECMC) announced that they will introduce minimum energy performance standards (MEPS) for HPWHs in Australia and New Zealand as soon as practicable.

Why This Change Is Happening

Water heating accounts for roughly 25–33% of household energy use in Australia and New Zealand, making it one of the largest residential energy loads. Governments are moving toward regulated minimum performance benchmarks to ensure consistent efficiency and consumer outcomes.

Historically, HPWH performance in Australia has largely been driven by incentive schemes (SRES, VEU, ESS), which effectively created a market efficiency floor based on 60% modelled energy savings determined using AS/NZS 4234, but did not impose a formal MEPS requirement.

As STCs decline toward 2030, regulators are replacing incentive-driven performance with mandatory standards. The new framework will introduce MEPS for HPWHs and provide comparable consumer performance information.

What Level Will MEPS Be Set At?

The short answer is that we do not know yet. Based on the recent CRIS announcement, the MEPS will be set at the equivalent of the current minimum requirements for STCs in Australia (equivalent to 60% energy savings in Zone 3). The level will be reviewed after three years.

What the Appendix H Test Method Involves

AS/NZS 5125.1 Appendix H introduces a new laboratory test that replicates household operation under controlled conditions. The method measures:

• Maximum deliverable heated water volume
• Recovery performance (reheat time and energy consumption)
• Energy consumption
• 24-hour tapping cycle (COP test) including both operational and standby periods

These tests are undertaken in climate-controlled test laboratories, repeated for three ambient conditions: cold, average, and hot.

An important aspect: the minimum delivery temperature is increased to 50 °C, differing from the 45 °C minimum used in AS/NZS 4234 modelling.

How Does the 50 °C Requirement Impact Results?

The maximum hot water delivery test will end when outlet temperature drops below 50 °C. This means control logic for products optimised to AS/NZS 4234 requirements (minimum 45 °C) may produce unfavourable Appendix H performance results.

Products with small tanks and low set points will show relatively small maximum hot water delivery results, and underpowered compressors will show long recharge rates.

What Manufacturers Should Do Now

Manufacturers should review product ranges to understand expected performance under new Appendix H testing, and decide which products will undergo MEPS testing to stay compliant.

Designs should be optimised to have ample hot water delivery above 50 °C while maintaining efficient reheating after large draw-offs. This might involve a review of compressor and evaporator sizing, control logic settings (set point temperature, deadbands), and tank aspect ratio.

How EnergyAE Can Help

EnergyAE can assist manufacturers in the following ways:

• Product range review: High-level advice about how products may perform in Appendix H testing
• Predictive modelling: Modelling products against Appendix H to optimise designs before physical testing — saving time and cost
• Testing project management: Streamlining third-party laboratory testing as capacity may become constrained once MEPS requirements come into place

Get in touch with us if you would like EnergyAE to assist you with this transition.

Final Thoughts

MEPS for HPWHs has been a long time coming. Manufacturers will have a new challenge to balance historical incentive-scheme optimisation with performance outcomes under the new MEPS testing framework.

We believe these updates will have a positive impact on the HPWH industry and consumers by ensuring a minimum level of thermal performance across both Australia and New Zealand. Manufacturers who start to prepare now will be in the strongest position when GEMS legislation comes into place.