I have a conventional bungalow with cavity wall insulation. What is the
lowest-cost way of massively increasing the wall insulation?
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Most houses constructed after 1920 have a gap between the internal and
external wall, and filling this cavity with insulation can save a typical
gas heated, three bedroom semi-detached house around £140 a year in energy
bills, according to the Energy Saving Trust.
Consumer group Which? said unfilled cavities could be responsible for 35pc of
all heat lost from the home and with the cost of installing cavity wall
insulation at around £500, the expense is effectively paid off after a few
The £500 cost is an average and obviously shifts around for the size of the
home. Expect to pay around £450 for a detached bungalow. For comparison, a
mid-terrace house will cost around £300 and a detached, four-bedroom house
will cost around £700.
To fill the wall cavity, small holes are drilled into the external wall and
specialist equipment is used to blow insulating material – made of recycled
granulated mineral wool fibre or polystyrene beads – into the cavity.
Energy saving website, markgroup.co.uk, also points out: “During the
summer, the insulated cavity will prevent some of the sun’s heat from
entering the walls, therefore, keeping the home cooler.”
If a home already has cavity wall insulation, what is the next best way to
insulate the walls?
Brian Horne, domestic energy expert at the Energy Saving Trust, said: “Once
cavity wall insulation is fitted, although it is technically possible to add
further external or internal wall insulation, this would be expensive and
save very little in energy costs.”
Therefore, one of the best ways to further insulate your home – in the most
cost-efficient manner – would be to add insulation to the loft, roof or
Experts say that loft insulation is the most cost-effective way to improve the
efficiency of your home.
Mr Horne said: “After installing cavity wall insulation, there are other
energy efficiency measures that the homeowner could look to install. These
mainly include lower-cost measures such as topping up the insulation in the
loft (the Energy Saving Trust recommends 270mm of loft insulation),
installing draught excluders in doors and windows, gaps around the floor and
maybe even up a chimney, and installing or upgrading a set of heating
controls on the boiler to control the home temperature.”
He said: “At the same time if your boiler is over ten years old then it might
be worth considering an energy efficient boiler. Replacing an old gas boiler
with an A-rated high-efficiency condensing boiler could save you as much as
£310 a year. Once you’ve had any improvements done to the heating system,
make sure the engineer explains how the system works and how to set the
There are Goverment initiatives in place to encourage homeowners to make
energy-saving improvements to their homes or businesses, by providing loans
to pay for insulation, double glazing or draught-proofing. The Green Deal
scheme, launched in January 2013, provides loans from £5,000 to be paid back
over 10 years, and up to £10,000 to be paid back between 15 and 25 years.
Although the scheme was launched at the beginning of the year, no Green Deal
loan providers have made the details of their finance packages public yet.
The Green Deal also has a cashback scheme running until 2014. To see if you
qualify for the loan, call The Energy Saving Advice Service on 0300 123
1234 (England and Wales) or 0808 808 2282 if in Scotland.
The Energy Company Obligation (ECO) programme was also introduced in January
2013 to reduce the country’s energy consumption and support the poorest and
most vulnerable householders in the UK. Energy suppliers are obligated under
the scheme to subsidise the installation of energy efficiency measures in
low-income hosueholds. The scheme will run until March 2015. To check if
your eligible for the funding, go to gov.uk/energy-company-obligation
or call your energy supplier.
Some households have complained that too much insulation can cause problems
due to the lack of ventilation, although the vast majority of British houses
are a long way from such a problem.
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