Heat Pump Sizing for 420 m² (4,521 sq ft) — Australia & Mild APAC (Sydney/Melbourne/Tokyo)
Thermal heat loss calculation, recommended heat pump capacity (kW, BTU/h & HVAC Tons), SCOP efficiency, and annual electricity consumption.
Recommended Heat Pump19.1 kW65,172 BTU/h (5.43 Tons)
Annual Electricity Usage5,749 kWh/yrDelivers 25,872 kWh Heat (SCOP 4.5)
Savings vs Direct Electric20,123 kWh/yrSpecific Load: 44.0 W/m²
Electrical Circuit (230V)30 A BreakerPeak Compressor Input: 5.16 kW
Thermal & Electrical Specification Table (420 m² / 4,521 sq ft)
| Heated Floor Area | 420 m² (4,521 sq ft) |
| Climate Zone & Design Outdoor Temp | Australia & Mild APAC (Sydney/Melbourne/Tokyo) |
| Building Insulation Envelope | Standard Double-Glazed Insulation (55 W/m² Base) (44.0 W/m² Peak) |
| Peak Space Heating Load | 18.48 kW Thermal |
| Recommended Heat Pump Output (Incl. DHW) | 19.1 kW (65,172 BTU/h · 5.43 Tons) |
| Seasonal Coefficient of Performance (SCOP) | 4.5 (340%–450% Seasonal Efficiency) |
| Annual Heat Demand vs Electricity Consumed | 25,872 kWh Heat → 5,749 kWh Electricity |
Frequently Asked Questions
What kW size heat pump do I need for a 420 m² (4521 sq ft) house?
For a 420 m² (4521 sq ft) building with Standard Double-Glazed Insulation (55 W/m² Base) in Australia & Mild APAC (Sydney/Melbourne/Tokyo), the peak space heating load is 18.48 kW (44.0 W/m²). Including domestic hot water allowance, a 19.1 kW (65,172 BTU/h / 5.43 Ton) heat pump is recommended.
How many kWh of electricity does a 19.1 kW heat pump use per year?
With a Seasonal Coefficient of Performance (SCOP) of 4.5 over 1400 full-load equivalent heating hours, the heat pump consumes approximately 5,749 kWh of electricity per year to deliver 25,872 kWh of heat — saving 20,123 kWh/year compared to direct electric radiators.
Compare Other Home Sizes & Climate Zones
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