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❄️ Heat Pump & HVAC Thermal Load · EN 12831 & ACCA Manual J Reference

Heat Pump Sizing for 436 m² (4,693 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 Pump15.1 kW51,523 BTU/h (4.29 Tons)
Annual Electricity Usage6,357 kWh/yrDelivers 26,064 kWh Heat (SCOP 4.1)
Savings vs Direct Electric19,707 kWh/yrSpecific Load: 33.2 W/m²
Electrical Circuit (230V)25 A BreakerPeak Compressor Input: 4.58 kW

Thermal & Electrical Specification Table (436 m² / 4,693 sq ft)

Heated Floor Area436 m² (4,693 sq ft)
Climate Zone & Design Outdoor TempUK & Temperate Maritime (-5°C Design, UK/IE/NZ)
Building Insulation EnvelopeModern / New Build Insulation (35 W/m² Base) (33.2 W/m² Peak)
Peak Space Heating Load14.48 kW Thermal
Recommended Heat Pump Output (Incl. DHW)15.1 kW (51,523 BTU/h · 4.29 Tons)
Seasonal Coefficient of Performance (SCOP)4.1 (340%–450% Seasonal Efficiency)
Annual Heat Demand vs Electricity Consumed26,064 kWh Heat → 6,357 kWh Electricity

Frequently Asked Questions

What kW size heat pump do I need for a 436 m² (4693 sq ft) house?

For a 436 m² (4693 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 14.48 kW (33.2 W/m²). Including domestic hot water allowance, a 15.1 kW (51,523 BTU/h / 4.29 Ton) heat pump is recommended.

How many kWh of electricity does a 15.1 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 6,357 kWh of electricity per year to deliver 26,064 kWh of heat — saving 19,707 kWh/year compared to direct electric radiators.