Heat sensation in humans
Wood can absorb moisture from the air and release it again, so it acts as a buffer for fluctuations in humidity. People do not primarily feel the temperature, but the inflow and outflow of heat. Stone and metal are poor insulators and quickly draw heat from our bodies – they feel cold. In contrast, wood insulates well and draws heat from our bodies slowly – it therefore feels warmer at the same surface temperature. This is the core of the U-value. The lower this U-value, the less heat penetrates through the material and the lower the heating costs. Timber components always achieve a lower U-value thanks to the integrated thermal insulation in the load-bearing layer.
Effective thermal insulation in winter
An airtight layer is applied to the inside of the exterior walls to keep the heat energy inside in winter and prevent it from escaping outside. This layer must also block the transport of moisture from the inside to the outside in order to prevent harmful condensation forming in the exterior walls – in other words, it has a diffusion-inhibiting effect. The Minergie-P energy label even requires a blower door test to check the airtightness of the finished house.
Optimum ventilation of rooms
The most effective method of ventilating rooms is during the night. This is followed in winter by the estimated heat radiation from the sun, which should be shielded on hot summer days. Movable shading elements or specially coated glass are available for windows. The heat storage capacity is in fourth place after the influence of internal heat sources. This can be achieved in timber buildings with double plaster panelling.
Effective noise protection
In the construction industry, a distinction is first made between building physics and room acoustics. Building physics focuses on sound insulation by building components, while room acoustics aims to absorb reverberation through surfaces in order to make speech or music clearly and precisely audible. Modern timber constructions offer effective protection against unwanted noise. Impact noise from neighbouring flats must be given special consideration, particularly in apartment buildings.
Focus on airborne noise and structure-borne noise
In building acoustics, a distinction is made between airborne noise and structure-borne noise. Road noise, for example, can penetrate into the living space as airborne sound through the exterior walls. Impact sound is a form of structure-borne noise that must be taken into account, particularly in ceiling constructions. In timber construction, multi-layer constructions can achieve similarly high sound insulation values as single-layer solid components, but with significantly lower mass. A multi-shell construction offers particularly good sound insulation if the coupling of the shells is low. Important factors are a sufficiently large mass per unit area of the shells, a large shell spacing, the avoidance of cavity resonances and an elastic connection between the shells and the structure. Measures to improve the sound insulation of timber ceiling constructions include weighting the bare ceiling with additional mass and using a suitable floor structure with a heavy screed and soft impact sound insulation. A suspended suspended ceiling can also improve sound insulation. In timber construction, secondary sound paths only have a minor influence, as studies in the ‘Sound insulation in timber construction’ project show. Optimised ceiling constructions achieve good results both for secondary sound paths and for direct sound transmission via the storey ceiling. Simple measures can reduce secondary path transmissions in timber stud wall constructions to such an extent that they are significantly lower than direct sound transmission via the storey ceiling.
Room acoustics in flats
In large or heavily occupied rooms, it is important to consider the reverberation time for the room acoustics. A reverberation time that is too long can impair comfort. In the past, room acoustics measures were mainly taken in public buildings and open-plan offices. Nowadays, the focus is also shifting to private homes, as these also have large room volumes and hard, sound-reflecting surfaces. In order to achieve the optimum reverberation time, part of the room panelling should be fitted with acoustically effective panels. Room acoustics can be improved by acoustic panels on suspended ceilings or wall panelling. These often consist of surface-treated wood-based panels that absorb different frequencies due to different perforations or slots.
Effective shielding against electrosmog
Switzerland is increasingly penetrated by non-ionising radiation, also known as “electrosmog”. In heavily polluted areas, measures must be taken regardless of the construction method. Windows can be effectively shielded with heat-insulating glass or solar control film. When designing the frame, a metal mesh can be inserted at the same time to shield the electromagnetic rays from the building’s own electrical installations later on in the interior. As electromagnetic radiation induces electricity, all shielding must be connected to earth.
Influence on the indoor climate
The quality of the air in a room depends above all on the use of low-emission materials and an appropriate exchange of air. While fragrances such as perfume, Swiss stone pine or essential oils are perceived as pleasant, odours from cleaning agents, cigarette smoke or exhaust fumes are unpleasant for people. Volatile organic compounds are diverse and can harm people and the environment in certain concentrations. If a room is not sufficiently ventilated, volatile organic compounds can accumulate to disturbing or irritating concentrations. The substance keratin contained in sheep’s wool acts as a catalyst for volatile organic compounds and is now used to regulate humidity and improve indoor air quality.
