Heat Pump Sizing for 74 m² (797 sq ft) — UK & Temperate Maritime (-5°C Design, UK/IE/NZ)
Thermal heat loss calculation, recommended heat pump capacity (kW, BTU/h & HVAC Tons), SCOP efficiency, and annual electricity consumption.
Recommended Heat Pump3.1 kW10,578 BTU/h (0.88 Tons)
Annual Electricity Usage1,080 kWh/yrDelivers 4,428 kWh Heat (SCOP 4.1)
Savings vs Direct Electric3,348 kWh/yrSpecific Load: 33.2 W/m²
Electrical Circuit (230V)6 A BreakerPeak Compressor Input: 0.94 kW
Thermal & Electrical Specification Table (74 m² / 797 sq ft)
| Heated Floor Area | 74 m² (797 sq ft) |
| Climate Zone & Design Outdoor Temp | UK & Temperate Maritime (-5°C Design, UK/IE/NZ) |
| Building Insulation Envelope | Modern / New Build Insulation (35 W/m² Base) (33.2 W/m² Peak) |
| Peak Space Heating Load | 2.46 kW Thermal |
| Recommended Heat Pump Output (Incl. DHW) | 3.1 kW (10,578 BTU/h · 0.88 Tons) |
| Seasonal Coefficient of Performance (SCOP) | 4.1 (340%–450% Seasonal Efficiency) |
| Annual Heat Demand vs Electricity Consumed | 4,428 kWh Heat → 1,080 kWh Electricity |
Frequently Asked Questions
What kW size heat pump do I need for a 74 m² (797 sq ft) house?
For a 74 m² (797 sq ft) building with Modern / New Build Insulation (35 W/m² Base) in UK & Temperate Maritime (-5°C Design, UK/IE/NZ), the peak space heating load is 2.46 kW (33.2 W/m²). Including domestic hot water allowance, a 3.1 kW (10,578 BTU/h / 0.88 Ton) heat pump is recommended.
How many kWh of electricity does a 3.1 kW heat pump use per year?
With a Seasonal Coefficient of Performance (SCOP) of 4.1 over 1800 full-load equivalent heating hours, the heat pump consumes approximately 1,080 kWh of electricity per year to deliver 4,428 kWh of heat — saving 3,348 kWh/year compared to direct electric radiators.
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