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Cavity Wall Insulation

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ROI
2.2-Years

If you have cavities in your walls which are not already filled with insulation then you have a great opportunity to save quite a lot of money. Most household heat is lost through the walls and anything to slow this down helps. The story is similar to loft insulation, you can reduce your energy bill for heating by up to 25%, but again more realistically 20%. The table below calculates the effect of only insulating your cavities considering several main household fuels and estimates a payback time for the investment. For a larger house cavity wall insulation will cost £ 500 and for the smaller house about £ 350.


  Approx % energy saving Approx energy saving per year
Gas                      
Electric  (Std) Economy 7 LPG                      
Fuel   Oil        
3 bed house 20% 4000 kWh £ 180 £ 580 £ 292 £ 308 £ 264
Payback time with cavity wall insulation costing £ 400 (3 bed house) 2.2 years 0.7 years 1.4 years 1.3 years 1.5 years
5 bed house 20% 6000 kWh £ 270 £ 870 £ 438 £ 462 £ 396
Payback time with cavity wall insulation costing £ 550 (5 bed house) 2 years 0.6 years 1.3 years 1.2 years 1.4 years
Calculations assume the energy required to heat an un-insulated 3 bed house is 20000 kWh and a 5 bed house is 30000kWh.

Is it worth doing?

Yes.  This measure is on a par with insulating the loft as one of the most effective thing you can do to your house to save money and protect the environment.  And like loft insulation there are grants available to many of us to completely pay for the insulation, check for grants from the warm front scheme (this is now gone), energy companies and local authorities and check with your local energy advice centre.



 
Comments (6)
U-values?
6 Wednesday, 30 January 2013 20:53
LL
Average U-value for cavity wall insulation? and what would you say is the average payback time for houses in general then?
5 Tuesday, 27 November 2012 10:54
Jane
While I would agree generally that cavity wall insulation is a good thing please point out that it isn't appropriate for all properties. Houses that are exposed to wind driven rain, such as those on the west coast of the UK, may end up with significant problems from having cavity wall insulation. The rain is driven into the cavity and soaks the filling this can cause damp and condensation problems internally as well as then freezing and causing problems with external rendering etc.

So generally a good thing but not always. It is a shame that it is pushed so hard without consideration being given to the site and exposure to extreme weather that a property may have.
4 Thursday, 20 October 2011 21:44
Richard
As my wife would say to me "you are a sad and lonely man, I pity you".... Who said that then?????
I can honestly say I never have a dull moment, but thanks for the concern and your kind comment regarding the site! My latest endevour is an app for android phones on energy. good fun! don't worry I do drink beer and other more normal stuff.
comment
3 Saturday, 15 October 2011 14:38
commenter
thank you whoever made this website. It is very helpful. But you have no life- why do this for fun
2 Friday, 13 August 2010 12:34
Thanks justin, looks useful.
1 Wednesday, 28 July 2010 09:43
Hi - you can quickly and easily apply for insulation grants by going to http://www.insulationgrants.info. As your article rightly says, this can save you hundreds of pounds off your energy bill and help to create a more energy efficient home.

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Site Guidance

All calculations on this site are based on current fuel prices they are checked regularly are automatically updated and were last changed on:-
19th February 2013
For complete clarity, all calculation using current fuel prices are coloured red.
The costs calculated based on these fuel prices should be regarded as 'good estimates', given that fuel prices vary in different parts of the county and at different time of the year.
The calculations also have different levels of accuracy depending on the nature of the calculation. For example calculating the energy use of a known power output TV is very easy compared to calculating the effect on energy savings when insulating a cavity wall.

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Icons are also used throughout the site to indicate the level of saving or the relative cost implications associated with an choice you might make, or a tip you read or related to how your house is currently configured. These icons below.
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£ 10+ Think twice, perhaps you should focus elsewhere first
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£ 1000+ Focus your effort here to save as much money as possible

In some areas there are some substantial investments you may choose to make, in sections describing these we indicate with two icons, thumbs up or down, if the investment is a good one. Payback in less than 15 years is regarded as reasonable, but longer that that poor. These icons are below.
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More than 15 years to payback the investment

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kW Kilowatt 1000 watts
kWh Kilowatt hour Measure of Energy
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Best Investment table

Measures to reduce fuel bills ROI*
Lagging 1
Loft Insulation 1.9
Cavity Wall Insulation 2.2
Underfloor Insulation 4.2
Solid Wall Insulation 15.1
Solar Hot Water 34
Double Glazing 55.6

*ROI is the time it takes in years to return the investment in fuel savings for an average gas heated 3 bed semi-detached house. The table assumes no government incentive schemes are used.

Renewable Energy Measures ROI**
Heat Pumps
- Replacing Electric
4 to 8
Heat Pumps
- Replacing LPG
15 to 30
Wind Power 14 to 55
Solar Photovoltaics 24 to 64

**ROI is the time it takes in years to return the investment in electricity savings. The table assumes no government incentive schemes are used.

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Comments, category: "Heat Loss and Insulation"


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