What Happens During AS/NZS 4234 Modelling
AS/NZS 4234 modelling estimates annual hot water system performance using climate data, load profiles, product test evidence, tank geometry, and control settings. The results are used by Australian schemes to calculate energy savings and certificate quantities.
What the model represents
The model represents the product or system configuration being submitted. For residential work, this may be an integral HPWH, a separate HPWH, or a solar water heater with auxiliary boosting.
For commercial work, the model may represent a heat pump connected to one or more storage tanks, or a larger system with multiple heat pumps and tanks. In every case, the model should match the product that will be supplied to market.
Inputs EnergyAE uses
For residential HPWHs, EnergyAE uses AS/NZS 5125.1 performance test data, tank heat loss evidence, tank geometry, fitting heights, and product control settings.
For commercial HPWHs, EnergyAE uses EN 14511 test data to build the heat pump performance map. The model also uses tank drawings, system schematics, pump flow rates or variable flow logic, control setpoints, legionella control settings, boost settings where applicable, and the climate zones and load profiles required by the target scheme.
What the simulation calculates
The simulation estimates annual performance across the required climates and load conditions.
The main outputs are annual electricity consumption, energy savings compared with the reference electric water heater, minimum delivery temperature, and the values used for SRES, VEU, or ESS certificate calculations.
For commercial systems, the model also determines the commercial peak load that can be served while still meeting scheme criteria.
Why controls matter
Control settings can change modelling results materially.
A higher heat pump setpoint can improve delivered temperature but may reduce COP. A wide deadband can reduce cycling, but it may also risk lower delivery temperature.
Electric boost settings can improve delivery temperature while increasing electricity consumption. Variable flow control affects heat pump outlet temperature and tank stratification.
EnergyAE needs settings that reflect the real product configuration.
What happens before results are issued
Before results are issued, EnergyAE checks that the input documents are internally consistent and that the model configuration matches the evidence pack.
EnergyAE also checks that simulations complete without obvious numerical or physical errors, minimum delivery temperature criteria are met where required, energy savings criteria are met where required, and certificate quantities are plausible for the product size and configuration.
What EnergyAE needs from you
Provide complete test evidence, drawings, manuals, data plates, and control settings before modelling starts. If you want EnergyAE to test alternative control settings or configurations, confirm that those settings can be supplied in the market product.