ASK THE EXPERT
Cutting the cost of
heating your home
ou may have seen the rising fuel prices and
you are thinking of using re-newable
energy, solar panels and the like to reduce
your fuel bills.
Before you consider the various alternative
systems for providing the heat or power, first you
must consider the efficiency of the property in
the first place. Making improvements to the
basic fabric of the building will ensure that
whatever energy source you use to heat it, that
you are not losing the heat through the walls,
windows and roof.
Anybody who has bought or sold a house since
August 2007 will be aware of the energy
performance certificate (EPC) the multi-coloured
chart similar to that of a washing machine that
tells the purchaser how efficient the house is
likely to be currently, and after improvement
how much better it should be. Usually rated very
efficient A grade (green) through to not very
efficient G grade (red). Improvements can be
made to older properties by focusing on
insulation and airtightness (draughts). Newly
built houses since 2006 have been tested for air
leakage (draughts) as part of process to
determine the energy efficiency of the building.
Once you start talking about improving the
insulation of a property, you will no doubt be
introduced to the ‘U’ value. Every element of a
building – walls, roof, windows, doors etc is
measured using U values in terms of the thermal
efficiency. A ‘U’ value is a measure of heat lost
through the element (for example a window) in
watts per square meter of the element for every
degree cooler outside (W/m2K). You should be
looking for the lowest ‘U’ value to give the best
insulation value. For example a single pane of
glass you can expect to lose about 5 watts of
energy through a square metre of glass for every
degree colder outside. This means on a cold
night about freezing temp 0°C outside and 20°C
inside you would lose about 100 watts of heat
through a window 3 feet wide x 4 feet tall. A
double glazed window around 15 years old would
Y
42 Leek Life January/February 2014
have a better ‘U’ value of around 2.2w/m2k
would lose only around 44 watts for a similar
sized window, this is about the same as the
insulation value of a solid 9inch brick terrace
house wall, or house built before around 1920. A
more recent A rated double glazed window
however could half that heat loss again, to
around 20 watts heat lost and have better
thermal insulation than an un-insulated cavity
wall.
A house built in 1985 would be expected to
have about 100mm (4 inch) deep insulation laid
between the ceiling joists in the loft space. A
newly built house would have multiple layers of
insulation laid across the lower layer to equal
around 300mm (12 inch) in total (say 150mm
laid between the joists, with a second layer laid
at 90 degrees over the top.
Be wary when reducing the draughts,
especially to rooms with gas or solid fuel fires.
Fires need air to burn, sealing a room of all
draughts reduces the efficiency of the fire, and it
will soon start using your air supply!! New
houses have air bricks dedicated and ducted to
the fire to ensure this isn’t a problem.
Article supplied by
Andrew Dukesell
DBD Architectural
Consultancy
01538 383 118
[email protected]
www.dbdconsultants.co.uk