Cavity wall insulation
Encyclopedia
Cavity wall insulation is used to reduce heat loss through a cavity wall
by filling the air space with a porous material. This immobilises the air within the cavity (air is still the actual insulator), preventing convection
, and can substantially reduce space heating costs.
During construction of new buildings, cavities are often filled with glass fibre wool or rock wool panels placed between the two leaves (sides) of the wall, but many other building insulation materials
offer various advantages and many others are also widely used. For existing buildings that were not built with insulated cavities, a fibrous material such as cellulose insulation
or glass wool
is blown into the cavity through suitably drilled holes until it fills the entire wall space. Foam can also be used for this purpose. Although some foams used in the past, such as urea-formaldehyde
, are no longer used (some people are allergic to this material, which is very difficult to remove once inside the wall), others, such as polyurethane
, have taken their place.
In the United Kingdom
, grants from the government and from energy companies are widely available to help with the cost of cavity wall insulation.
Cavity wall
Cavity walls consist of two 'skins' separated by a hollow space . The skins are commonly masonry such as brick or concrete block. Masonry is an absorbent material, and therefore will slowly draw rainwater or even humidity into the wall. The cavity serves as a way to drain this water back out...
by filling the air space with a porous material. This immobilises the air within the cavity (air is still the actual insulator), preventing convection
Convection
Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....
, and can substantially reduce space heating costs.
During construction of new buildings, cavities are often filled with glass fibre wool or rock wool panels placed between the two leaves (sides) of the wall, but many other building insulation materials
Building insulation materials
Building insulation materials are thermal insulation used in the construction or retrofit of buildings.The materials are used to reduce heat transfer by conduction, radiation or convection and are employed in varying combinations to achieve the desired outcome .-Categories:Insulation may be...
offer various advantages and many others are also widely used. For existing buildings that were not built with insulated cavities, a fibrous material such as cellulose insulation
Cellulose insulation
The word cellulose comes from the French word for a living cellule and glucose, which is sugar. Building insulation is low-thermal-conductivity material used to separate the internal climate and sounds of a building from external climate and sounds...
or glass wool
Glass wool
Glass wool or fiberglass insulation is an insulating material made from fiberglass, arranged into a texture similar to wool. Glass wool is produced in rolls or in slabs, with different thermal and mechanical properties....
is blown into the cavity through suitably drilled holes until it fills the entire wall space. Foam can also be used for this purpose. Although some foams used in the past, such as urea-formaldehyde
Urea-formaldehyde
Urea-formaldehyde, also known as urea-methanal, named so for its common synthesis pathway and overall structure, is a non-transparent thermosetting resin or plastic, made from urea and formaldehyde heated in the presence of a mild base such as ammonia or pyridine...
, are no longer used (some people are allergic to this material, which is very difficult to remove once inside the wall), others, such as polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
, have taken their place.
In the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, grants from the government and from energy companies are widely available to help with the cost of cavity wall insulation.