How many kW heat pump do I need per square metre?

Roughly 50-80W per m2 for well-insulated homes, 80-120W per m2 for average insulation, and 120-160W per m2 for poor insulation.

Does my location affect the size needed?

Yes. Northern and Scottish locations use colder design temperatures (-5 to -7°C vs -3°C in southern England), which increases the size needed slightly.

Should the heat pump also size for hot water?

Yes. The heat pump must handle both space heating and hot water. Most domestic cylinders (200-250L) add 2-3 kW to the requirement.

Heat Pump Sizing by House Size UK

Q: Is bigger always better?

No. An oversized heat pump costs more and may cycle inefficiently. Correct sizing from a proper heat loss calculation is essential.

By Home Heat Pump Guide Published 18 March 2026

This is the definitive UK heat pump sizing reference — covering every property type from 1-bed flats to 5+ bed country houses, adjusted for three insulation levels. Use these tables to estimate what you need before getting a proper heat loss survey from an MCS installer. Getting the size right saves money upfront and delivers lower running costs for the system's 20+ year lifespan.

Heat pump sizing research and data analysis for UK properties by house size and insulation level — Correct sizing is the foundation of an efficient, affordable heat pump installation.

Get a personalised size and cost estimate

Free heat pump calculator

Instant estimate based on your specific property details.

Complete Sizing Tables by Property Type

Property	Well-insulated (EPC C+)	Average (EPC D)	Poor (EPC E+)
1-bed flat	2-3 kW	3-4 kW	4-5 kW
2-bed flat/terrace	3-5 kW	4-6 kW	6-8 kW
2-bed semi	4-6 kW	5-7 kW	7-9 kW
3-bed semi	6-8 kW	7-10 kW	10-13 kW
3-bed detached	8-10 kW	9-12 kW	12-16 kW
4-bed semi	8-10 kW	9-12 kW	12-15 kW
4-bed detached	10-13 kW	12-16 kW	16-20 kW
5-bed detached	14-18 kW	18-24 kW	24-30 kW
Bungalow (2-3 bed)	5-8 kW	7-10 kW	10-13 kW

Indicative ranges only. A proper MCS heat loss survey is mandatory for BUS grant claims. For bigger properties, see our guide to heat pumps for large houses (5+ bedrooms).

Watts Per Square Metre Guide

Heat Demand Per m2 by Insulation Level

Well-insulated (EPC C+)

50-80 W/m2

Average (EPC D)

80-120 W/m2

Poor (EPC E+)

120-160 W/m2

Improving insulation before installation dramatically reduces the size and cost needed.

MCS installer measuring room dimensions for room-by-room heat loss calculation and heat pump sizing — Room-by-room heat loss surveys provide accurate sizing that these tables can only estimate.

Adjustment Factors

Location: Add 5-10% for northern England and Scotland (colder design temperatures). Exposure: Add 5-10% for exposed/hilltop locations. High ceilings: Add 10-20% for rooms above 2.7m (common in Victorian homes). Hot water: The heat pump must also heat your cylinder — add 2-3 kW for a 200-250L cylinder. Homeowners using solar panels to offset electricity costs do not need a different size but benefit from lower running costs.

UK semi-detached houses representing the most common property type for heat pump sizing calculations — Semi-detached houses are the most common UK property for heat pump installations.

Homeowner viewing positive heat pump sizing calculator results for their UK property — Our free calculator provides personalised sizing estimates based on your specific property details.

Check your home's suitability

Free suitability checker

Includes estimated sizing for your property type.

Check if a heat pump suits your home

Request a heat pump quote

Answer a few questions about your home and request a quote.

Frequently Asked Questions

How many kW per square metre?

Roughly 50-80 W/m2 well-insulated, 80-120 W/m2 average, 120-160 W/m2 poor insulation.

Does location affect size?

Yes — northern/Scottish locations add 5-10% due to colder design temperatures.

Should it size for hot water too?

Yes — add 2-3 kW for the hot water cylinder.

Is bigger always better?

No. Oversized pumps cost more and cycle inefficiently. Correct sizing from a proper calculation is essential.

About This Topic

Heat pump sizing depends on property type, insulation level, and location. MCS-certified installers use room-by-room calculations mandated by the Boiler Upgrade Scheme. Both air source and ground source systems must be correctly sized. Solar generation offsets running costs without changing sizing.