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basics:building_physics_-_basics:thermal_comfort:thermal_comfort_parameters [2017/01/31 18:01] kdreimanebasics:building_physics_-_basics:thermal_comfort:thermal_comfort_parameters [2020/08/13 21:18] (current) – [Thermal comfort parameters] wfeist
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 Many subjective perceptions determine living comfort, even the colour of the surroundings plays a certain role – particularly for the mood of person who thereby expresses his or her perceptions.  Living comfort mainly depends on the "thermal comfort". This has been well-researched and the results have been incorporated into international standards (DIN ISO 7730). A large part of the information available to us today is due to the work of the Danish scientist [[http://en.wikipedia.org/wiki/P._Ole_Fanger|P. O. Fanger (Wikipedia Seite)]].\\ Many subjective perceptions determine living comfort, even the colour of the surroundings plays a certain role – particularly for the mood of person who thereby expresses his or her perceptions.  Living comfort mainly depends on the "thermal comfort". This has been well-researched and the results have been incorporated into international standards (DIN ISO 7730). A large part of the information available to us today is due to the work of the Danish scientist [[http://en.wikipedia.org/wiki/P._Ole_Fanger|P. O. Fanger (Wikipedia Seite)]].\\
  
-[{{:picopen:fig._1_air_movement_near_to_a_passive_house_window.jpg?510 | **Fig. 1** Air movement near to a Passive House window: Due to the small temperature difference between window surface and room air, the speed of air sinking at the window is small. At the floor, approximately 10 cm horizontally from the passive house window (U=0.8 W/(m²K)) the maximum air speed is a barely noticeable 0.11 m/s. If the insulating value of the window is worse, then air speed rises to disturbingly high values. Therefore it is recommended, with "normal windows", to position a heating element under the window.(CFD simulation: J. Schnieders, PHI)}}]+In Passipedia we also have a [[phi_publications:pb_25:comfort_criteria_according_to_international_standards_especially_for_use_in_passive_houses|comprehensive explanation of Fangers comfort research and ISO 7730]] for those interested in the scientific background [5],[6].  
 + 
 +[{{:picopen:fig._1_air_movement_near_to_a_passive_house_window.jpg?520 | **Fig. 1** Air movement near to a Passive House window: Due to the small temperature difference between window surface and room air, the speed of air sinking at the window is small. At the floor, approximately 10 cm horizontally from the passive house window (U=0.8 W/(m²K)) the maximum air speed is a barely noticeable 0.11 m/s. If the insulating value of the window is worse, then air speed rises to disturbingly high values. Therefore it is recommended, with "normal windows", to position a heating element under the window.(CFD simulation: J. Schnieders, PHI)}}]
  
  
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     * air temperature     * air temperature
 +
     * the temperature of the surrounding surfaces, this can also be summarised as the "radiant temperature",     * the temperature of the surrounding surfaces, this can also be summarised as the "radiant temperature",
 +
     * air speed and turbulence     * air speed and turbulence
 +
     * air humidity.\\     * air humidity.\\
-There is a complete range of combinations of these four comfort factors where the level of comfort is very good, this is known as the **comfort range**.  It can be determined by Fanger’s equation, documented in ISO 7730.  Furthermore, according to this standard it is essential that+There is a complete range of combinations of these four comfort factors where the level of comfort is very good, this is known as the **comfort range**.  It can be determined by Fanger’s equation, documented in ISO 7730 (see also [[phi_publications:pb_25:comfort_criteria_according_to_international_standards_especially_for_use_in_passive_houses#Appendix: Calculation of the PMV according to DIN EN ISO 7730|Fangers comfort equation]]). Furthermore, according to this standard it is essential that
  
     * the sultriness limit in relation to the air humidity is not exceeded,     * the sultriness limit in relation to the air humidity is not exceeded,
 +
     * air speeds are within closely defined limits (for speeds under 0.08 m/s, the number of dissatisfied due to draughts is less than 6%)     * air speeds are within closely defined limits (for speeds under 0.08 m/s, the number of dissatisfied due to draughts is less than 6%)
 +
     * the difference between radiant temperature and air temperature remains small,     * the difference between radiant temperature and air temperature remains small,
 +
     * the difference in the radiant temperature in various directions remains small (less than 5 °C, known as the "radiation temperature asymmetry"),     * the difference in the radiant temperature in various directions remains small (less than 5 °C, known as the "radiation temperature asymmetry"),
 +
     * the indoor air temperature stratification is less than 2 °C between the head and ankles of a seated person,     * the indoor air temperature stratification is less than 2 °C between the head and ankles of a seated person,
 +
     * the perceived temperatures in the room change by no more than 0.8 °C at different locations.     * the perceived temperatures in the room change by no more than 0.8 °C at different locations.
  
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 [{{:picopen:fig._2_stratification.jpg?510 | **Fig. 2** Stratification: The temperature stratification of air is also imperceptible with the passive house window. Therefore the heating element can be placed also at an inner wall while still reaching optimal comfort in accordance with ASHRAE Comfortclass "A". (computation: J. Schnieders, PHI). }}] [{{:picopen:fig._2_stratification.jpg?510 | **Fig. 2** Stratification: The temperature stratification of air is also imperceptible with the passive house window. Therefore the heating element can be placed also at an inner wall while still reaching optimal comfort in accordance with ASHRAE Comfortclass "A". (computation: J. Schnieders, PHI). }}]
  
-[{{:picopen:fig._3_passive_house_practice.jpg?500 |**Fig. 3** Passive House Practice: Infrared image of the interior side of a passive house window. All surfaces (wall structure, window frame, and the glazing) are pleasantly warm (over 17 °C). Even at the glass edge, the temperature doesn't fall below 15 °C (light-green portion)+[{{:picopen:fig._3_passive_house_practice.jpg?510 |**Fig. 3** Passive House Practice: Infrared image of the interior side of a passive house window. All surfaces (wall structure, window frame, and the glazing) are pleasantly warm (over 17 °C). Even at the glass edge, the temperature doesn't fall below 15 °C (light-green portion)
 (Source: PHI, from the Passive House Kranichstein).}}] (Source: PHI, from the Passive House Kranichstein).}}]
  
  
-[{{:picopen:fig._4_typical_practice.jpg?500 |**Fig. 4** Typical Practice: For comparison, here is a typical old building's window. The center of glass surface temperature is already below 14 °C. In addition, there are large installation thermal bridges, particularly where the window meets the concrete wall. The consequences: significant eadiant temperature asymmetry, drafts, and pooling of cold air in the room.+[{{:picopen:fig._4_typical_practice.jpg?510 |**Fig. 4** Typical Practice: For comparison, here is a typical old building's window. The center of glass surface temperature is already below 14 °C. In addition, there are large installation thermal bridges, particularly where the window meets the concrete wall. The consequences: significant eadiant temperature asymmetry, drafts, and pooling of cold air in the room.
 (IR-fotography: PHI, image taken at the office of PHI)}}] (IR-fotography: PHI, image taken at the office of PHI)}}]
  
-[{{:picopen:fig._5_low-e_glazing.jpg?500 | **Fig. 5** low-e glazing (2 panes) already have higher surface temperatures (16 °C in the average). Additionally, the poor insulation of the conventional window frame is remarkable. Passive house frames allow a dramatic improvement in insulating quality. (IR fotography: PHI, in the corridor of the institute)}}]+[{{:picopen:fig._5_low-e_glazing.jpg?510 | **Fig. 5** low-e glazing (2 panes) already have higher surface temperatures (16 °C in the average). Additionally, the poor insulation of the conventional window frame is remarkable. Passive house frames allow a dramatic improvement in insulating quality. (IR fotography: PHI, in the corridor of the institute)}}]
  
  
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   * By improving thermal insulation (regardless of which external building building component, e.g. wall, roof, floor, etc.) the heat flow from the inside to the outside is reduced.   * By improving thermal insulation (regardless of which external building building component, e.g. wall, roof, floor, etc.) the heat flow from the inside to the outside is reduced.
 +
   * Therefore the heat flow of the room area to the interior surface of this external building component is also reduced. That heat flow has to flow through the thermal film coefficinet of the surface (radiation and convection).   * Therefore the heat flow of the room area to the interior surface of this external building component is also reduced. That heat flow has to flow through the thermal film coefficinet of the surface (radiation and convection).
 +
   * The smaller heat flow implies a resultant smaller drop of temperature over this thermal resistance. In other words:   * The smaller heat flow implies a resultant smaller drop of temperature over this thermal resistance. In other words:
 +
   * There is a smaller temperature difference between the room area (the surfaces in the area and the room air) and the interior surface of the well insulated building component.   * There is a smaller temperature difference between the room area (the surfaces in the area and the room air) and the interior surface of the well insulated building component.
  
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 \\ \\
  
-The practical consequence: With highly insulating external construction components, the temperature of the interior surface is only slightly different from the other temperatures in the area; this applies both in summer and winter. In the winter, the interior surfaces of the external construction components are comfortably warm (external walls, roofs etc. at the most 1 °C under the ambient temperature, window surfaces maximally 3 to 3.5 °C under it [ 1 ]). The definition of "Passive House quality" windows is straightforward: The insulating efficiency of a window suitable for Passive Houses must be so good that under the coldest design conditions, the equation: +The practical consequence: With highly insulating external construction components, the temperature of the interior surface is only slightly different from the other indoor temperatures; this applies both in summer and winter. In the winter, the interior surfaces of the external construction components are comfortably warm (external walls, roofs etc. at the most 1 °C lower than the ambient temperature, window surfaces maximally 3 to 3.5 °C below [ 1 ]). The definition of "Passive House quality" windows is straightforward: The insulating efficiency of a window suitable for Passive Houses must be so good that under the coldest design conditions, the equation: 
-                                       θ area - θ Oberfl ≤ 3.5 °C+
  
-still holds true. These small temperature differences have the following affects on the comfort criteria:+θ<sub>air</sub> - θ<sub>surf</sub> ≤ 3.5 °C 
 + 
 +still holds true. These small temperature differences have the following effects on the comfort criteria: 
 + 
 +      * Indoor air speeds (apart from leaks) are created by free convection at cooler surfaces. Due to the small temperature differences the convective currents, and consequently air speeds, are now very small. Fig. 1 in the left column shows a CFD (Computational Fluid Dynamic) simulation result: There is no draft in the room, even without a heating element under the window.
  
-      * Air speeds in the area (apart from leaks) are due to free convection at cooler surfaces. Due to the small temperature differences the convective currents, and consequently air speeds, are now very small. Fig. 1 in the left column shows a CFD (Computational Fluid Dynamic) simulation result: There is no draft in the room, even without a heating element under the window. 
       * If the external surface temperature is not more than 3.5 °C below the ambient temperature, then the radiant temperature difference in different directions cannot be greater than 3.5 °C. The thermography photographs in Fig. 3 to Fig. 5 show the difference between windows of various insulating quality.       * If the external surface temperature is not more than 3.5 °C below the ambient temperature, then the radiant temperature difference in different directions cannot be greater than 3.5 °C. The thermography photographs in Fig. 3 to Fig. 5 show the difference between windows of various insulating quality.
 +
       * The room air temperature stratification between the head and feet of a sitting person is less than 2 °C - however only under the condition that the effective median U-value of the external building components is under 0.85 W/(m²K). See Fig. 2 in the left column.       * The room air temperature stratification between the head and feet of a sitting person is less than 2 °C - however only under the condition that the effective median U-value of the external building components is under 0.85 W/(m²K). See Fig. 2 in the left column.
 +
       * The percieved temperature varies less than 0.8 °C within the area.       * The percieved temperature varies less than 0.8 °C within the area.
  
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       - Sociological questionings of a sample group of inhabitants revealed good remarks about well insulated buildings. [ 4 ]       - Sociological questionings of a sample group of inhabitants revealed good remarks about well insulated buildings. [ 4 ]
  
 +\\ \\
 ===== See also ===== ===== See also =====
  
  
-[[Planning:thermal_protection:windows:Types of glazing and their specific values]]+[[Planning:thermal_protection:windows:Types of glazing and their specific values]]  {{:picopen:members_only.png?25|}} 
 + 
 +[[phi_publications:pb_25:comfort_criteria_according_to_international_standards_especially_for_use_in_passive_houses| A comprehensive explanation of Fangers theory of "thermal comfort" and the implementation in ISO 7730]] [5],[6]
  
 [[Basics:Summer|Thermal comfort - in summer too]] [[Basics:Summer|Thermal comfort - in summer too]]
  
  
-==== Literature ====+==== References ====
  
 \\ \\
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 [ 4 ] Hermelink, Andreas: Do desires become true? Temperatures in passive houses for tenants; in: AkkP proceedings NR. 25, Darmstadt, 2004 [ 4 ] Hermelink, Andreas: Do desires become true? Temperatures in passive houses for tenants; in: AkkP proceedings NR. 25, Darmstadt, 2004
  
-To in this connection the question of the importance of the heat capacity is often discussedFurther information on this topicDaemmen_oder Speichern.HTML.(German) +[ 5 ] DIN EN ISO 7730: Gemäßigtes Umgebungsklima (Moderate thermal environments); Beuth Verlag, Berlin 1987. 
 + 
 +[ 6 ] Fanger, P.O.: Thermal ComfortAnalysis and Applications in Environmental Engineering; USA: New York 1972, © P.O. Fanger 1970. 
 + 
  
basics/building_physics_-_basics/thermal_comfort/thermal_comfort_parameters.1485882093.txt.gz · Last modified: 2017/01/31 18:01 by kdreimane