Monday, January 6th, 2014

Cutting the cost of heating your home

You 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 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 of 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.

Leave a Reply

Your email address will not be published. Required fields are marked *