Civil Engineering Reference
In-Depth Information
both walls and roof. Noise-regulating properties are dependent upon the
material used, its design, placement and size. Treatment of sound in building
technology is otherwise seldom discussed and will only be touched upon
briefly here.
Certain climate-regulating materials have qualities that put them in two or three
groups. A thermal insulation material can also be airtight, regulate moisture and
even stop noise. Different functions can be combined, e.g. timber can be a mois-
ture-regulator while acting as a structural and surface material.
Thermal insulation materials
The thermal insulation of a building can be done in two ways: as static or dynam-
ic insulation. There are even materials that reflect thermal radiation, thereby
affecting the heat loss of a building and which should be considered as repre-
sentative of a particular method of insulation of their own.
Static and dynamic insulation
In static insulation the insulation value of static air is used. The principle requires the use
of a porous material with the greatest possible number of air pockets. These have to be
so small that no air can move within them.
In dynamic insulation air is drawn through a similar porous insulation material. When
the fresh air is led from outside through the surface of the wall, rather than through small
ventilation ducts, it picks up heat loss flowing out of the building. Besides achieving a pre-
warmed fresh-air flow into the building, the heat loss through the surfaces is reduced to a
minimum. The optimal materials for such a wall should have an open structure with pores
across the whole width, plus good heat exchange properties. A high thermal capacity is
also an advantage, so that sudden changes in the outside temperature are evened out.
Dynamic insulation is still being introduced into construction and has been used in only a
few buildings.
The main part of this chapter considers the properties of different materials in
relation to static insulation.
The technical demands of an insulating material (excluding the reflective layer)
are usually as follows:
1.
High thermal insulation properties
2.
Stability and long life span
3.
Fire resistance
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