Good insulation saves energy and protects the environment. We explain, What exactly is this difficult subject all about?.
The thermal insulation of houses is becoming increasingly important. Since January 1995 the new thermal insulation ordinance places stricter requirements on thermal insulation, to reduce energy consumption and protect the environment. What actually happens to the heat? Why and where is she escaping to??
In a certain time, a certain amount of heat flows through different building materials at different speeds. You can't "lock them up" somewhere. Because it always flows – from warm to cold.
That means for houses, that heat flows from inside to outside in winter and vice versa in summer. The insulation delays the flow of heat, slows down the flow of heat. The greater this delay is, the longer the heat stays in the building.
There are three types of heat flow: the radiation, convection and conduction. For the thermal protection of a house is the thermal conduction, in which the heat migrates through the building material, particularly important. Insulating material conducts heat less well than e.g. Aluminium, which offers hardly any resistance to the flow of heat.
To get accurate values for calculations, standardized measuring systems were introduced: The basic value is the thermal conductivity X (speak: Small Lambda) but. It indicates the amount of heat, that passes through a cubic meter cube of a substance in one hour, when the temperature difference of the two surfaces 1 Kelvin (1 Degree Celsius) amounts to.
water: enemy of insulation
Now if you know, how much heat can pass through a one meter thick layer of fabric, can also be calculated, how much passes through any given thickness of a material. If you divide the thermal conductivity by the number of the material thickness, the thermal transmittance value A is obtained (speak: Grand Lambda). The thermal conductivity of different substances is different, so they are also distinguished by the heat transmission.
When assessing the thermal properties of building materials, not only is of interest, how much heat a component lets through, but above all, how much resistance it offers to the flow of heat, That means, how much it insulates. This insulating ability is expressed by the thermal insulation value. It is the reciprocal of the heat transfer coefficient: 1/Category. exterior surfaces of houses, d.h. walls and roof structures, consist of several layers of building materials, each having a different thermal resistance. In addition to the materials, the heat must also overcome so-called air boundary layers. Both types of resistance, material and air, are summarized in the calculations for thermal resistance 1/K. The larger this value, the better the thermal insulation capacity of the entire component.
The thermal insulation capacity z. B. of a roof can be affected, if water penetrates the component, because moisture is the greatest enemy of thermal insulation. Water can penetrate the thermal insulation in two ways: due to leaks in the building materials (wall cracks, leaks) or by water vapor condensation. It happens again and again, especially in damp rooms such as bathrooms and kitchens, that the wet, warm internal air penetrates into the components, cools down there due to the lower outside temperature and releases the entrained water vapor to the components. Because water is a dense substance in the physical sense, it then also increases the density of the thermal insulation and reduces the thermal insulation capacity of the insulating material. When constructing such components, the thermal insulation layer must therefore also be provided with a vapor barrier (PE- or metal foil) to be protected, to prevent moisture ingress.