Heat flows through thermally conductive materials by a process generally known as 'gradient transport'. Gradient heat transport depends on properties: the conductivity of the material, the cross-sectional area of the material, and the spatial gradient of temperature. The larger the conductivity, gradient, and / or cross-section means that the faster the heat flows. In the home radiators are excellent radiators of heat because they also absorb their own heat. Radiation in the house is necessary for keeping the house and room’s warm, electrical equipment is usually fitted with some kind of extracting device to remove the heat, an example of this is a cooling fan, so that all of the radiated heat does not over heat the equipment.
The economic reason houses are insulated to mainly reduce costs of heating bills, so that the heat lingers in the house/building for longer periods of time, so that the occupant dose not have to have the heating or some heat producing machine does not have to be turned on at all times, and does not cost as much.
How heat losses can be prevented.
Loft Insulation
Loft insulation works because heat rises. It is the same as wearing a big heavy hat on a cold day - it makes a big difference. By insulating your loft to a depth of 250mm (10") you can save 25% of your heating costs. You should have the 100mm of mineral fibre blanket. It should insulate the sides and over the top of the water cisterns. The loft space above the insulation should be ventilated, usually through the eaves, to prevent condensation
Without insulation in place, the only barrier between you the occupier and the outside world is 12.5mm (½") of plasterboard. That is why rodents and birds like to live in unheated roof spaces during the winter. They are provided with free warmth that you are putting into the home and it is escaping as fast as you are putting it in. Although extremely expensive to heat, it will also keep the pipes that run through warmer and prevent freezing. On an extremely cold day not even this offers complete protection.
Wall Insulation
Most heat (up to half the total) is lost through the walls of an un-insulated house. Wall insulation can reduce this loss by two-thirds and make your home more comfortable. If there are cavity walls they can usually be safely filled with insulating fibre, beads or foam.
If the walls are solid, internal insulation (often applied in the form of an insulated board fixed to the wall) is highly effective, but means rooms have to be redecorated and may lose architectural detail. This can be done by competent do it them selves people and may be done on a room by room basis at the same time the home is redecorated. External insulation usually needs planning permission and should only be carried out by specialist companies.
Window and Door Insulation
Draughts are the most uncomfortable and obvious signs of a badly insulated house and can be fixed easily with either draught proofing, secondary or double glazing. Polypropylene tubes are expensive but last longer than most bog standard insulation devices and are more effective. Fires need a good flow of air to burn safely and there is a danger of being poisoned by Carbon Monoxide fumes if a room is too tightly sealed.
Double glazing is the UK's most popular energy saving measure, although it actually saves less from a typical fuel bill than putting in (much cheaper) cavity wall insulation. If your windows need replacing, make sure that you specify "Low-e" glazing, which has a special heat-reflective coating between the two panes of glass. This will reduce heat loss through the glass by nearly half. You can also get Argon gas filled windows: argon is a gas found naturally in ordinary air, but it transmits heat much less readily than the other gases in air, so helps you save even more money.
Floor Insulation
You can lose as much as 10% of heat through un-insulated floors. There are a number of ways of solving this problem, including insulating blankets under suspended floors and laying boards over concrete floors. When your roof and walls are well insulated the loss of heat through a floor becomes more significant. It is difficult and usually uneconomic to insulate a floor that has already been laid. However, a good quality underlay beneath your carpet can improve your comfort levels considerably.
Draught Excluders
Draught proofing can be very cost effective because its cheap to install and can save 15% of the heat loss from your home.
Draught excluders are usually a self adhesive foam profile, which is soft and flexible, available for use all around the house in gaps located in windows and doors, for example a gap underneath the window that you believe is allowing a low amount of air draught through it. You would apply this foam substance to the area. This would then seal the affected area.
Hot Water Tank Insulation
Insulating hot water tanks and pipes will help to keep your hot water hot. Polyurethane foam insulation in thicknesses up to 2" are applied to the sidewall and dome top. The foam is covered with a protective weather resistant covering.
The most popular insulating product for hot water tanks is
Polyurethane Foam
Is a two component sprayed coating that expands and hardens to about two inches thick, for about an R16 insulation value. When cured, it is coated with 25 mils of semi- rigid white acrylic weatherproof coating.
Bibliography
Source’s used:
Internet sites
*www.thermalite.com
*www.leeac.org.uk
*www.google.com (for diagrams)
*www.altavista.com (for diagrams)
*www.natenergy.org.uk
*www.encyclopedia.com
Software
- Microsoft Encarta 2003
- Britannica 2004 Deluxe Edition
Books
- Physics (higher), Heinemann
- The Hutchinson Encyclopaedia
