NCC 2025 Section J6D10 Space Heating
(1) A heater used for air-conditioning or as part of an air-conditioning system must be—
(e) an electric resistance heater if—
- i) the heating capacity is not more than—
- a) 40 W/m² of the floor area of the conditioned space in climate zones 1 or 2; or
- b) the value specified in Table J6D10 in climate zones 3 to 8; or
- ii) the annual energy consumption for heating is not more than 15 kWh/m² of the floor area of the conditioned space in climate zones 1, 2, 3, 4 and 5; or
- iii) the in-duct heater complies with J6D3(1)(c)(iv);
NCC Table J6D10 Maximum electric resistance heating capacity
| Floor Area of Conditioned Space | CZ 3 (W/m²) | CZ 4 (W/m²) | CZ 5 (W/m²) | CZ 6 (W/m²) | CZ 7 (W/m²) |
|---|---|---|---|---|---|
| ≤ 500 m² | 50 | 60 | 55 | 65 | 70 |
| > 500 m² | 40 | 50 | 45 | 55 | 60 |
Thermodynamic Calculation Engine
Dynamic Fluid Properties: Standard calculators assume a static air density of 1.2 kg/m³. This tool utilizes dynamic fluid thermodynamics to determine precise heating capacities based on the exact entering air temperature properties.
Outside Air Pre-Heaters: The engine calculates the exact required OA temperature prior to mixing, utilizing a weighted energy balance equation:
Required OA Temp = ((SA Flow × Desired Mixed Temp) - (RA Flow × RA Temp)) / OA Flow
Density (ρ): 101325 / (287.05 × (T_entering + 273.15))
Capacity (kW): (L/s / 1000) × ρ × C_p × ΔT