Glossary

Airborne sound Spread in the air sound which is created by speaking, music, transport, etc. The creation of airborne sound inside a room, the associated oscillations and waves can set off oscillations in the adjoining walls and ceilings as well. These construction elements, in turn, can animate/induce the air of the adjoining room to oscillate, thus to create airborne sound.

Building moisture Humidity inside the brickwork and the construction shell of a new building. Building materials such as mortar, screeds (Germany), prepared screed floors (Switzerland), stones, plaster and climate transport considerable amounts of water into the building. It takes about two entire heating periods before the moisture has disappeared from a newly built house. The amount of moisture contained in the building materials already in the construction shell phase and how quickly this moisture is passed to the outside air are therefore of vital importance. A low degree of building moisture means: no increased energy supply during the first two winters, no health impairment to the inhabitants of the new building.

Condensate Condenses on the inside of exterior walls and windows if their surface temperature is below the dew point temperature of the air. The dew point temperature is the temperature at which the humidity contained in the air condenses to water. Remedied through heat insulating measures, avoidance or reduction of air humidity.

Convection Water vapor convection occurs when the humid room air penetrates construction elements through open joints and leaky construction element connections in structures.

Dew point Air has only a limited capacity to store humidity at any given temperature. Air saturated with water vapor has a relative air humidity of 100%. The absolute amount of the humidity which can be absorbed at the most is dependent mainly on the air temperature - warm air can hold more humidity than cold air. If air is cooled down, the relative humidity increases (the absolute amount of humidity contained remains unchanged). At some point, the relative humidity reaches 100% which will lead to the formation of condensate (condensation). This phenomenon can be observed quite often, i.e. when warm room air cools down at a window surface which leads to the condensation of the moisture on the pane. It is especially critical when warm room air seeps/flows through a construction element due to leaks. While passing through, the air cools down, the relative air humidity increases and condensate inside the structural element may occur. This, in turn, may cause structural damage and increased energy consumption.

Diffusion Slow movement of water vapor from areas with higher concentration (iinternal air) to areas with lower concentration (iouter air)

Gross density Identifies the density of a building materials including pores, hollow spaces and the like in kg/m3.

Heat storage capacity The stored heat quantity is that much higher, the higher the specific heat capacity, the larger the mass or the volume- ¥ density and the higher the temperature difference to the surroundings (i.e. the ambient air).

Heat transmission resistances Rsi / R se (m²K/W) The heat transmission resistances Rsi (indoors) and Rse (outdoors) indicate the heat transfer from room air to the interior surface of the construction element, or from the outer surface of the construction element to the outer air depending on the direction of the heat flow (upwards, horizontal or downwards).

Hydrophobic Water resistant, not soluble in water.

Impact sound The sound that is created as structure-borne sound by walking or similar stimulation of a ceiling, stairs or the like and which is partly passed on as airborne sound in an underlying or adjacent room.

Inverted roof A non-ventilated flat roof construction which, as opposed to the conventional flat roof, shows a completely different order of its layers. The insulation is above the roof cladding and thus more exposed to the rain. This is the reason why only insulation materials inured to water, such as cellular glass, polyurethane or extruded polystyrene are used. A weight needs to be placed on the insulation in order to counteract the wind suction forces.

Lignin In addition to hemicelluloses and cellulose, lignin is a main component of wood, accounting for 15% to 35% of the tree, depending on the wood type. It mainly serves to stiffen and hold together the individual wood fibers or cell walls, simi-lar to concrete in reinforced concrete constructions.

Sorption Sorption is the description for the agglomeration of water vapor molecules on the interior surface of the pores of a substance.

Structure-borne sound Sound spread in solid materials as a result of an impact through a hammer tapping a wall or a slammed door, for example.  If structure-borne sound is created in a construction element, it will set off oscillations. These construction elements, in turn, can animate/induce the air of the adjoining room to oscillate, thus creating airborne sound.

Thermal diffusivity Ratio of thermal conductivity and the product of density and specific heat capacity. This effects the non-stationary state. In addition to other properties, the thermal diffusivity is responsible for the behavior of the temperature at a certain point inside the material in light of a temperature change on the surface. The higher the thermal diffusivity, the more sensitive is the reaction of the internal temperature of a material with regard to changes in the surface temperature.

Transmission heat loss Loss of heat energy due to construction elements.

Water vapor Gaseous aggregate state of water. Under normal atmospheric pressure, boiling water evaporates at 100 °C. Depending on the steam pressure of the water, however, water vapor is generated at lower temperatures as well. In the condition of equilibrium, the quantity of the water vapor formed is given by the saturation vapor pressure.