How much will I save?

How much will I save?

How much will I save?

There are many different figures quoted for how much money insulation will save you. The answer is - it depends on a number of different factors, such as:


  1. How much insulation is already present
  2. The size of the building
  3. How many external walls there are (i.e. if the property is detached, semi-detached or a flat)
  4. The fuel used to heat (and/or cool) the property


The average savings that can be made by insulating a typical home can be found in the table below.

Measure Annual saving
per year		 DIY cost DIY payback CO2 saving
per year
Loft insulation (if no existing insulation is present – i.e. laying 270mm) Around £175 £50 - £350 Less than 2 years Around 730kg.
Loft insulation (if topping-up – i.e. laying 100-270mm) Around £25 £50 - £350 From 2 years Around 210kg.


Cavity wall insulation and solid wall insulation are also great energy saving measures, however this entails the use of a professional installer.

Measure Annual saving
per year		 Cost Payback CO2 saving
per year
Cavity wall insulation Up to £135 £100 - £350 1 - 3 years Around 560kg.
Solid wall insulation (internal) Around £455 £5,500 - £8,500 Varies Around 1,800kg
Solid wall insulation (external) Around £475 £10,500 - £14,500 Varies Around 1,900kg


Remember - these savings are made every single year, so making an investment in insulation now will save both energy and money, year in, year out.

1 The costs and paybacks shown are approximate, are provided for illustrative purposes only and are based on a gas heated semi-detached house with 3 bedrooms. The savings are the same as those used for CERT, assume a gas price of 4.39p/kWh and include a reduction factor for comfort taking. Installed costs and paybacks assume that installation is undertaken by a professional installer, unless otherwise stated, and both loft and cavity wall insulation costs include a subsidy which can be obtained under CERT. The total, unsubsidised cost of installing either loft or cavity wall insulation is typically around £500. Source Energy Saving Trust, October 2011.