How Much Insulation Do You Need Before Installing an Air Source Heat Pump in the UK?

Quick Summary

• You don’t need perfect insulation before a heat pump, but it helps.

• Loft insulation (270mm) is the most cost-effective upgrade.

• Poor insulation = £600+ higher bills per year.

• Pipe insulation is small but important.

• BUS (£7,500) + ECO4 can cover both heat pump + insulation.

Introduction

One of the biggest concerns UK homeowners have when switching from gas boilers to air source heat pumps is:

👉 “Do I need to fully insulate my home first?”

This is a fair question. Heat pumps provide steady, low-temperature warmth, which works best in insulated homes. But does this mean older or poorly insulated homes can’t install heat pumps? Absolutely not.

In this guide, we’ll answer real homeowner questions, share minimum insulation requirements, show quick fixes vs long-term upgrades, and explain how Air Source Company helps Midlands homeowners prepare for efficient, grant-supported installations.

Why Insulation Matters for Heat Pumps

• Gas boilers blast short bursts of high heat → less impacted by draughts.

• Heat pumps provide steady low-level heat → insulation prevents heat escaping.

• Better insulation = lower bills, higher comfort, longer heat pump lifespan.

How Much Insulation Do You Really Need?

Loft Insulation

• Minimum recommended: 270mm

• Poorly insulated lofts lose 25% of heat from a property.

Wall Insulation

• Cavity walls: Injected insulation works well.

• Solid walls: Harder, but external or internal insulation helps.

Windows & Doors

• Single glazing = huge heat loss.

• Double glazing or thermal curtains are strong alternatives.

  
  

Floors

• Draughts between old wooden floors can cause big losses.

• Insulation boards or simple draught-proofing strips help.

What Happens If You Don’t Insulate?

• Bills can rise by £600+ per year.

• Heat pump may run constantly to keep up.

• Comfort drops in winter.

• System lifespan can reduce.

  
  

Quick Fixes vs Long-Term Insulation Upgrades

Problem Area	Quick Fix (Low Cost)	Long-Term Fix (Best Results)
Loft	Add thermal rolls	Full loft re-insulation (270mm+)
Walls	Draught-proofing, wall hangings	Cavity/solid wall insulation
Windows	Thermal curtains, film	Double/triple glazing
Floors	Draught-proof strips	Full floor insulation boards
Radiators	Bleed & balance system	Install larger radiators / underfloor

Is Pipe Insulation Important for Heat Pumps?

Yes. Many homeowners overlook this.

• Outdoor pipes exposed to cold can lose heat fast.

• Poorly taped pipes (UV damage, loose wrapping) reduce efficiency.

• Solution: UV-resistant insulation sleeves and professional fitting.

  
  

Cost vs Savings of Insulation + Heat Pumps

Upgrade Type	Avg. Cost (UK)	Annual Savings	Impact on Heat Pump
Loft Insulation	£500–£1,000	£150–£250	High
Cavity Wall Insulation	£1,200–£1,800	£200–£300	Very High
Double Glazing	£3,000–£6,000	£100–£200	Medium
Floor Insulation	£1,000–£2,000	£70–£120	Medium
Pipe Insulation	£100–£200	£50–£100	Medium

Government Support

• £7,500 Boiler Upgrade Scheme (BUS) → lowers upfront cost.

• ECO4 scheme → covers insulation for some UK homes.

• Local council incentives may also apply.

  
  

Conclusion

You don’t need a perfectly insulated home to install an air source heat pump. But the more you improve insulation, the more efficient and cost-effective your system becomes.

From loft rolls to wall insulation and pipe protection, small upgrades add up to major savings. With grants like BUS, now is the best time to future-proof your home’s heating.

👉 Book a free survey with Air Source Company today and check if your home qualifies for grants + insulation support.

Frequently Asked Question(People Commonly Asked)

1. Do I need insulation before installing a heat pump?

No, but insulation makes your system much more efficient and reduces bills.

2. How much loft insulation do I need for a heat pump?

At least 270mm is recommended in UK homes.

3. Can a heat pump work in an uninsulated house?

Yes, but energy bills will be higher, and rooms may feel less comfortable.

4. Is pipe insulation important for heat pumps?

Yes—uninsulated pipes lose heat and reduce system efficiency.

5. How much does insulation cost before heat pump installation?

From £500 for loft insulation up to £6,000 for windows, but grants can help.

6. Does insulation absorb heat?

No, insulation doesn’t absorb or create heat. Instead, it slows down heat transfer, keeping warmth inside during winter and preventing excess heat from entering in summer. This helps your heat pump work more efficiently by reducing energy loss.