basics:building_physics_-_basics:thermal_comfort:local_thermal_comfort
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basics:building_physics_-_basics:thermal_comfort:local_thermal_comfort [2014/02/07 07:01] – anna.czerwinska_passiv.de | basics:building_physics_-_basics:thermal_comfort:local_thermal_comfort [2019/02/28 11:03] (current) – cblagojevic | ||
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+ | ====== Local thermal comfort ====== | ||
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+ | It is interesting that all comfort criteria are automatically fulfilled in an optimum way with the requirements of the Passive House Standard - Improved thermal insulation simultaneously improves thermal comfort. This can be explained as follows: | ||
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+ | * By improving thermal insulation (regardless of the external building component to which it is applied) the heat flow from the inside to the outside is reduced. | ||
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+ | * Therefore the heat flow from the building’s interior to the internal surface of this external building component is also reduced. The heat flow overcomes the so-called thermal resistance of the surface (radiation and convection). | ||
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+ | * The smaller heat flow results in a smaller temperature loss at this surface, in other words: //the temperature difference between the inside (the surfaces in the room and the indoor air) and the interior surface of the component with improved insulation decreases.// | ||
+ | \\ | ||
+ | The practical consequences are that with very well-insulated external building components, **the temperature of the interior surfaces varies only slightly from the surrounding temperature in the room**; this applies both in summer and winter. This means that the inner surfaces of the external components are pleasantly warm even in winter (external walls, roofs etc. not more than 1 °C below the indoor air temperature, | ||
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+ | > **θ < | ||
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+ | still holds true. These small temperature differences have the following effects on all comfort criteria: | ||
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+ | * Air speeds in the room (apart from leaks – which do not occur in the airtight Passive House anyway) are due to uplift at surfaces which have differing temperatures. Because of the small temperature differences the **lifting forces are very small**. As a result, air speeds also remain very small. __**Fig.1**__ shows a CFD (Computational Fluid Dynamic) simulation: even though there is a heater under the window, no draughts occur in the living area.\\ | ||
+ | \\ | ||
+ | |{{ : | ||
+ | |//**__Fig. 1:__ Air movement near a Passive House window: Due to the small tempe-\\ rature difference between window surface and room air, the speed of air\\ descent at the window is very low. At the floor level, the air is diverted: the\\ maximum air speed is still 0.11 m/s at a distance of approximately 10 cm\\ from the Passive House window (U< | ||
+ | \\ | ||
+ | * The radiant temperature difference in various directions cannot exceed 3.5 °C if the external surface temperature is not more than 3.5 °C below the indoor temperature. The thermographic images in __**Fig.2 to Fig. 4**__ show the difference between windows with various insulation qualities.\\ | ||
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+ | |//**__Fig. 2:__ Infrared image of a Passive House window\\ from the inside. All surfaces (window frame,\\ casements, and glazing) are pleasantly warm\\ (above 17 °C). The temperature doesn' | ||
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+ | * The indoor air temperature stratification between the head and ankles of a seated person is less than 2 °C - but only if the ** effective average U-value of the external building component is less than 0.85 W/(m²K)**. See. the illustration on the [[basics: | ||
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+ | * The perceived temperatures at various locations in the room differ by less than 0.8 °C.\\ | ||
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+ | > ** All the comfort criteria have been ideally fulfilled, without the need for a compensating heating surface. That is why the Passive House room " | ||
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+ | **Findings from three independent research projects** have confirmed that these characteristics of well-insulated building envelopes can be observed **in practice**: | ||
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+ | - Thermographic images, air temperature and air speed measurements in Passive Houses experimentally confirm the results presented here ([[basics: | ||
+ | - Physiological measurements by Bernhard Lipp objectify the perception of comfort ([[basics: | ||
+ | - Sociological surveys of a representative number of residents gave high marks for well insulated buildings ([[basics: | ||
+ | \\ | ||
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+ | ===== See also ===== | ||
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+ | [[Planning: | ||
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+ | [[basics: | ||
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+ | [[Basics: | ||
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+ | ===== Literature ===== | ||
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+ | **[Pfluger 2003]** Pfluger, R.; Schnieders, J.; Kaufmann, B.; Feist, W.: Hochwärmedämmende Fenstersysteme: | ||
+ | (**Highly insulating window systems: inspection and optimisation in the installed state**, Appendix to Sub-report A)\\ | ||
+ | \\ | ||
+ | **[Schnieders 2002]** Schnieders, J.; Betschart, W.; Feist, W.: Raumluftströmungen im Passivhaus: Messung und Simulation HLH 03-2002, Seite 61\\ | ||
+ | (**Indoor air flows in the Passive House: measurement and simulation HLH 03-2002**, page 61; | ||
+ | Abbreviated online version in German: [[http:// | ||
+ | \\ | ||
+ | **[Lipp 2004]** Lipp, B. und Moser, M.: Heizsysteme und Behaglichkeit: | ||
+ | (**Heating systems and comfort: is comfort physiologically measureable? | ||
+ | \\ | ||
+ | **[Hermelink 2004]** Hermelink, Andreas: Werden Wünsche wahr? Temperaturen in Passivhäusern für Mieter; in: AkkP Protokollband Nr. 25, Darmstadt, 2004\\ | ||
+ | (**Can dreams come true?: Temperatures in Passive Houses for tenants**, in Protocol Volume No. 25, Darmstadt, 2004; Abbreviated online version in German: [[http:// | ||