Knauf Insulation » Solutions » 1.0 Introduction » 1.1 Buildings and Energy » Saving costs by saving energy

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In a typical home, approximately half of the heat generated internally is lost through the walls and loft, making them the two biggest causes of heat loss. Insulating these two elements is the most efficient way of reducing energy costs. The amount of heat wasted in homes annually in the UK through poorly insulated lofts and cavity walls is enough to heat 1.8 million UK homes. If these un-insulated homes instatlled cavity wall insulation it would cut CO₂ emissions by approximately 6 million tonnes and save over £700 million a year.

Walls

Over 30% of the heat lost in an un-insulated home is lost through un-insulated external walls.

Cavity wall insulation

Cavity wall insulation is a highly effective and efficient way to significantly reduce the amount of energy needed to heat a home: the average house could reduce its heating costs by approximately 15% and could save around £90 a year on fuel bills by installing cavity wall insulation. Many existing houses can easily have their cavity walls upgraded. By extension, if all of the houses with empty cavity walls had them filled with insulation, the energy saved could heat a staggering 1.4 million homes each year.

External wall insulation

External Wall Insulationis more expensive than cavity wall insulation but it could save around £300 a year on energy bills and could pay for itself in around six years. It has the added benefit of providing a new external appearance. A three bedroom semi-detached house, therefore could save up to 2.6 tonnes of CO₂ a year.

Internal lining

Internal lining is an economical option and could save around £300 a year on energy bills. A three bedroom semi-detached house could save up to 2.4 tonnes of CO₂ a year.

Wall insulation costs, savings and paybacks

Measure	Annual saving per year (£)	Installed cost (£)	Installed payback	CO₂ saving per year
Cavity wall insulation	£90	Around £500	Around 5 years	750kg
External wall insulation	£300	Around £1,900	Around 6 years	2.6 tonnes
Internal wall insulation	£300	From £42/m²	-	2.4 tonnes

Source: The Energy Saving Trust, June 2008 (www.energysavingtrust.org.uk)

All costs are approximate and exclude VAT

Lofts

A house with no loft insulation having had the recommended thickness of glass mineral wool loft insulation (270mm) installed, will not only save approximately £110-worth of heating bills per year but also nearly 1 tonne of CO₂ each year.

The lofts in many houses already have some loft insulation in place, but not the recommended thickness. If all houses in the UK had the recommended thickness of insulation, it is estimated that the annual saving would be £380 million, which is equivalent to the annual fuel bills of over 400,000 families.

When a loft with 50mm of glasswool loft insulation is increased to 270mm, it pays for itself in about 8 years* and the annual saving in CO₂ is 250kg.

* Estimated cost of loft top up, if work is carried out under a energy company subsidised scheme or DIY installation.

Loft insulation costs, savings and paybacks (professional versus DIY)

Loft insulation	0-270mm	50-270mm
Annual saving per year	£110	£30
Professionally installed cost	Around £500	Around £250*
Professionally installed payback	Around 4 years	Around 8 years
DIY cost	From £250	Around £180
DIY payback	From 2 years	Around 6 years
CO₂ saving per year	Around 1 tonne	250kg