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How this is calculated#

The tool estimates the maximum demand of a commercial or light-industrial building from its floor area. It uses the energy demand method in AS/NZS 3000:2018 App C Para C2.4.3. It reads the VA per square metre from Table C3.

1. Pick the figure. For each area, choose an occupancy and a use. The tool takes the printed average, or the low or high end of the printed range (Table C3). You can type your own figure instead.
2. Work out each area. The tool multiplies the area by the VA per square metre and divides by 1000. The result is kVA.
3. Add EV charging. The NOTE to Table C3 puts EV charging on top of all other energy demands. The tool adds the carpark EV rows to the total.
4. Add special equipment. Table C3 prints no figure for it. You enter its kVA from the load details, and the tool adds it.
5. Total demand. The tool adds every area and the special equipment (Para C2.4.3).
6. Current. On one phase, the tool divides the kVA by the phase voltage. On three phases, it divides by 3 times the phase voltage. That gives the current in each phase.

Worked example#

• Small retail and office building with basement EV charging. Shops of 600 m² at 70 VA/m² for light and power and 30 VA/m² for air conditioning. Offices of 400 m² at 50 and 25 VA/m². A basement carpark of 300 m² at 15 VA/m², plus its EV charging at 20 VA/m². The total demand is 100.5 kVA. The current is 145.65 A per phase at 230 V.
• The Paragraph C2.4.3.2 case. 1500 m² of office at 50 + 50 VA/m². The total demand is 150 kVA. The current is 217.39 A per phase.

Limits#

• Table C3 is for commercial and light-industrial buildings. It is not for homes. Use Table C1 for a home.
• The figures depend on the climate, the hours of use, energy management and how evenly the load spreads.
• The per phase figure assumes an even spread over three phases. Check the heaviest phase where the load is uneven.
• The tool uses the phase voltage. On a 230/400 V supply, enter 230.
• Special equipment has no printed figure. You must know its kVA. The tool does not guess it.
• An own figure outside the printed range gives a warning. Check it before you rely on it.
• To work from a list of loads, use the Table C2 method in the Maximum Demand tool.

See also: The energy demand method and Table C3, Shop and office maximum demand by floor area and the Maximum Demand tool.