Thermal comfort
The Thermal comfort is the central concept of standard EN ISO 7730 . It describes human well-being as a function of temperature .
The term is also defined as a quality criterion for heating and air conditioning systems. Several parameters apply to comfort , all of which are conditioned and can be changed independently of one another:
- Temperature level and temperature differences
- Radiation intensity and differences in radiation
- thermal currents and thermal stresses
- Melting and rivers, steam formation , sublimation
physiology
Thermal comfort is achieved for human physiology through a constant temperature setting and an even input of energy.
Air conditioning
According to VDI guideline 6030, radiators are to be designed and arranged in such a way that "comfort deficits" such as cold falling air or cold walls are compensated. Radiators should be installed as completely as possible below windows in order to mix cold falling air and rising warm air and to cover the heat sink of the cold window surface with direct heat radiation from this heat source .
A room is perceived as comfortable if the temperature difference between
- Wall surface and room air less than 4 ° C
- Foot to head height less than 3 ° C
- different wall surfaces (radiation asymmetry) less than 5 ° C
and if the air speed and its turbulence is small (no drafts).
The different uses of the room result in the users' individual temperature requirements.
Modeling
The conditions for thermal comfort through space heating were systematically dealt with in a paper by Ole Fanger .
As a result of the thermal room simulation, the thermal room condition is characterized by the air temperature and the radiation temperature of the environment. These temperatures are combined with different weightings (e.g. depending on the workload and the air speed) to form the operative room temperature (perceived temperature). Basic definitions of these quantities and a simulation model that can be downloaded free of charge can be found in.
Ray model and wave model
Thermal radiation is a form of electromagnetic radiation and, like other radiation, can cause damage. Skin damage occurs under thermal radiation similar to that in direct contact with a hot surface. Also known is the radiation damage by the sun.
In electromedicine, not only the superficial effect, but also the effect in deeper tissue layers is considered.
Web links
Individual evidence
- ^ HJ Löffler: Thermodynamik, 2 volumes, Volume 1, Springer Verlag Berlin, Heidelberg, New York, 1969
- ↑ Gerthsen Physics
- ↑ Bernd Glück: Room simulation model and definitions of room temperature, the radiation temperature of the environment and the permissible radiation temperature asymmetry .
- ↑ Physics didactics