The energy sources that may be used for heating a space directly are listed in J6D10(1) which also specifies that all forms of heating described in J6D10(1)(a) to (e) can be used in combination so as not to restrict heating to only one type. This clause recognises a combination of heating options may be the most appropriate and cost effective heating solution and may include a limited amount of electric resistance heating.

J6D10(1)(d) permits reclaimed heat from another process such as from a refrigeration plant, a co-generation plant, and bio-fuels to be used and this reclaimed energy can be used in conjunction with one or more heaters allowed under J6D10.

Electric heating can be used in specific circumstances only as outlined in J6D10(1)(e)(i) which allows a small amount of electric resistance heating, up to 10 W/m2 for climate zone 1 and 40 W/m2 for climate zone 2, for the floor area of the conditioned space. The small allowances recognise the likely limited heating required for these mild climates.

J6D10(1)(e)(i)(C) permits larger electric heating allowances in situations where reticulated gas is not available at the allotment boundary, recognising the likely limited heating options in areas where natural gas is not readily available. The maximum values are specified in Table J6D10 and are again climatezone based to recognise the limited heatingrequired in temperate climates, compared to cool climates.

J6D10(1)(e)(ii) allows a further exemption for relatively small electric heaters in climate zones 1 to 5 if the annual energy consumption for this heating is not more than 15 kWh/m2 of the floor area of the conditioned space.

J6D10(1)(e)(iii) places limits on the amount of reheat allowed for an in-duct heater.

J6D10(2) permits a small 1.2 kW electric heater in a bathroom of a Class 2, Class 3 or Class 9c aged care building. Typically, this would include small electric heaters such as a 3-in-1 heater, exhaust fan and light system. The heater must be fitted with a means to ensure it will not run excessively when the bathroom is not in use.

J6D10(3) is specifically for fixed outdoor heating and cooling appliances and requires that the appliance must be capable of automatic shutdown, which may be achieved by an outdoor temperature sensor, timer, motion detector or the like. This requirement aims to limit energy consumption when the service is not needed.

J6D10(4) specifies the efficiencies required for a gas fired heater that heats a space via water, such as a boiler. The minimum thermal efficiencies are based on the rated gas consumption of the boiler in terms of MJ/hour. There are a number of testing standards that can be used to demonstrate a unit’s gross thermal efficiency, including—

• BS 7190.
• ANSI/AHRI 1500.
• AS/NZS 5263.1.2.

Whatever the test used, it is important that the test conditions mirror the expected typical operating conditions. This is especially important in regard to condensing boilers, where the inlet/outlet temperature of water will greatly impact the overall efficiency.