Clarification of terms room temperature - room temperature
The temperature measured in the room is generally referred to as room temperature or internal temperature. Room temperature is a summarized temperature variable from the local air temperature and the radiation temperatures of the individual surrounding areas. Air temperature is the temperature of the air surrounding people without the influence of thermal radiation. It is measured in degrees Celsius (° C) at a height of 0.75 m above the floor at the workstations with a thermometer protected from thermal radiation with a measurement accuracy of ± 0.5 ° C.
Room air temperature , also room temperature , is a fixed term, even if a room can have different temperatures. It is regularly a temperature that is perceived as comfortable by people who are in the room under consideration ( comfort temperature ). It is assumed that the people wear clothing that is typical for their stay in these rooms and that is not intended for significantly higher or lower temperatures. An environment is considered to be thermally comfortable if air movement (no drafts ), the humidity (not too dry, too humid) and the room temperature (not too warm or too cold) are perceived as pleasant - therefore the perceived temperature depends on the humidity. The target temperature also depends on the radiant surfaces: the more energy is transferred to the body via radiation, the lower the air temperature needs to be in order to achieve a comfortable room climate ( radiant heating , "tiled stove effect"). In addition, it is strongly dependent on the use of space; It is higher in rooms that are primarily used seated (office rooms, living room), and lower when moving (kitchen, utility rooms). Wet rooms (bathroom, toilet) require high temperatures, bedrooms low temperatures (principle of night reduction ).
Use as a reference and guide value
Building technology and everyday life
In air conditioning , the difference between the desired room temperature and a certain averaging of the outside temperature results in all relevant variables, for heating technology such as heating load and heat demand , heating days and heating period , degree days / heating degree days and the resulting heating costs - the terms of cooling technology if the outside temperature If the room temperature exceeds or the solar radiation heats up the building, the cooling load and cooling requirement , summer / hot days and cooling degree hours are analogous .
The problems associated with the desired room temperature values are in the German-speaking countries, depending on the standard in
- 20 ° C (19–21 ° C) for residential buildings, office buildings, schools,
- 22 ° C (21–23 ° C) for hospitals, nursing homes, public baths,
- 18 ° C (17–19 ° C) for business premises or sports facilities and
- 16 ° C (15-17 ° C) for storage.
At high outside temperatures, the room temperature should not exceed a value of around 25–26 ° C (see heat-free ). In many cases, a room temperature of 20–21 ° C is used to calculate the heating output required for living spaces. The ideal room temperature, however, depends on the function of the room. Room temperatures of 16 to 18 ° C are sufficient for the kitchen and bedroom. However, the room temperature should not drop below 16 ° C in any room in order to avoid mold formation due to excessive humidity . The room temperature can be easily regulated and monitored by means of a radiator thermostatic valve , possibly supplemented by a timer , or by means of a room temperature controller.
The room air temperature is also used in the measurement and with regard to information on the shelf life for food and medication . This information must be adapted for different climate zones : If, for example, food is recommended to be stored "at room temperature" (e.g. when specifying the best before date ), a temperature range of 18 ° C to 22 ° C is assumed in Germany.
In the case of red wine , the recommendation is often heard to "chambrier" it, that is, to bring it to room temperature. However, this means a temperature of 17 to a maximum of 19 ° C, as the instruction comes from times when the rooms in Europe were not heated as warmly as they are today. In addition, this only applies to heavy red wines, light red wines are served at 13 to 16 ° C.
Chemical and physical systems
In physics, mostly in statistical physics, a room temperature of 293.15 Kelvin (20 degrees Celsius) is often assumed, which roughly equates to a thermal energy k B T of around 25 m eV (= 4 10 −21 J ) results. However, this value is by no means clearly or scientifically defined; For example, US textbooks mostly use a temperature of 25 ° C (77 ° F ) as a reference value.
On the other hand, there are also systems of standard conditions or normal conditions that have been defined by international commissions according to scientific guidelines; these are, for example, the IUPAC STP system (273.15 K) or the ISO 13443 standard (15 ° C). Dimensions of ( steam ) pressures or the specific weight or density e.g. B. of liquids and chemical reaction rates are related to temperatures in such systems.
- VDI guideline 2067 / DIN 4108 T6 for calculating the heating limit ; ISO 13790 Calculation of energy requirements for heating and cooling ; EN 15265 Thermal behavior of buildings - Calculation of heating and cooling energy consumption ; etc.
- Energiesparmobil Niedersachsen (Ed.): Indoor climate and comfort . ( energiesparmobil.de [PDF; accessed on March 16, 2009]). energiesparmobil.de ( Memento from May 18, 2006 in the Internet Archive )
- room air temperature / rel. Humidity. (No longer available online.) In: Health → Health Protection & Hygiene → Healthy Building → Indoor Climate → Indoor Air Temperature / Rel. Humidity. Health and Environment Department, City of Zurich, archived from the original on March 14, 2012 ; accessed on December 22, 2009 (links to further brochures).
- Expert Advisory Board “ Energy Pass ”: Guide for calculating key energy figures . Ed .: Austrian Institute for Structural Engineering [OIB]. March 1999, 4.2 internal temperature , p. 6 ( gph.at [ MS Word ; accessed on December 22, 2009] number OIB-382-010 / 99).
- Jagnow / Horschler / Wolff, cit. n. Internal temperature characteristics . In: FH Braunschweig / Wolfenbuettel [FBV] (Hrsg.): Qualification for energy consultant TGA . ( energieberaterkurs.de [PDF; accessed on December 22, 2009]).
- Dietrich Beitzke: The heating limit. In: What do the technical terms mean? Heating operation, January 3, 1999, accessed April 3, 2009 .
- This is how food can be stored. Federal Agency for Agriculture and Food, accessed on June 16, 2019 .