Warmth is a valuable commodity and it will seek every possible means of escape from walls, roofs, windows and floors. Most UK buildings make escape easy.

Heat flow through building components can be modified by the choice of materials. The main heat transfer process for solid, opaque building elements is by conduction. Thermal insulation, which provides a restriction to heat flow, is used to reduce the magnitude of heat flow in a 'resistive' manner. Since air provides good resistance to heat flow, many insulation products are based upon materials that have numerous layers or pockets of air trapped within them. Such materials are thus low density and lightweight, and, in most cases, not capable of giving structural strength. Generally, the higher the density, the greater the heat flow. Since structural components are often, of necessity, rather high in density, they are unable to provide the same level of resistive insulation. Warmth is a valuable commodity and it will seek every possible means to escape from a building. Walls, roofs, floors, chimneys, windows are all escape routes.

It may be necessary to provide additional layers of insulation around them to prevent such elements acting as weak links or 'cold bridges' in the thermal design.

Increased levels of insulation are a cost-effective way of reducing heating energy consumption. In several domestic and other small buildings, it has already been demonstrated that the additional costs of insulation can be offset against a much reduced cost for the heating system involving a whole building radiator and central boiler option.

When specifying insulation materials it is important avoid those which are harmful to the environment such as materials involving chlo-rofluorocarbons (CFCs) in the production process and to select materials with zero ozone depletion potential (ZODP). Insulation materials fall into three main categories:

• Inorganic/mineral - these include products based on silicon and calcium (glass and rock) and are usually evident in fibre boards, e.g. glass fibre and 'Rockwool'.

• Synthetic organic - materials derived from organic feedstocks based on polymers.

• Natural organic - vegetation-based materials like hemp and lamb's wool which must be treated to avoid rot or vermin infestation.

For fibrous materials such as glass and mineral fibres there is a theoretical risk of cancer and non-malignant diseases like bronchitis. This is a matter that is still under review (Thomas, R. (ed.) (1996) Environmental Design, E & FN Spon).

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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