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basics:building_physics_-_basics:what_defines_thermal_bridge_free_design [2019/02/13 11:50] – cblagojevicbasics:building_physics_-_basics:what_defines_thermal_bridge_free_design [2022/02/15 19:13] (current) – admin
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-<latex>+$$
 \Large{H_{T} = \sum_{i}A_{i}U_{i}+\sum_{k}l_{k}\varPsi_{k}+\sum_{j}\chi_{j}} \Large{H_{T} = \sum_{i}A_{i}U_{i}+\sum_{k}l_{k}\varPsi_{k}+\sum_{j}\chi_{j}}
-</latex>+$$
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  “Thermal bridge free design” can be defined as follows: the contributions provided by thermal bridging are smaller than or equal to zero:   “Thermal bridge free design” can be defined as follows: the contributions provided by thermal bridging are smaller than or equal to zero: 
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-<latex>+$$
 \Large{\sum\varPsi \cdot l + \sum\chi  \leq 0} \Large{\sum\varPsi \cdot l + \sum\chi  \leq 0}
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 Verification using this definition of thermal bridge free design would imply that all details would have to be calculated in a multi-dimensional way. Therefore, simplified criteria for “thermal bridge free design” should be devised. It was found that for ordinary building geometries, the “thermal bridge free” requirement was almost always adequately met for all linear disturbances only if  Verification using this definition of thermal bridge free design would imply that all details would have to be calculated in a multi-dimensional way. Therefore, simplified criteria for “thermal bridge free design” should be devised. It was found that for ordinary building geometries, the “thermal bridge free” requirement was almost always adequately met for all linear disturbances only if 
 <WRAP centeralign  box round > <WRAP centeralign  box round >
-<latex>+$$
 \Large{\varPsi \leq 0.01 \quad W/(mK)}  \Large{\varPsi \leq 0.01 \quad W/(mK)} 
-</latex>+$$
 \\ \\
 **[TbCrit]** **[TbCrit]**
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 Besides, the remaining contributions are compensated to a certain extent by other connections where there are negative linear thermal transmittances. The //**[TbCrit]**// criterion is adequate for all structures which affect connections, edges, and individual interruptions in ruled surfaces. Recurrent interruptions in ruled surfaces must already be taken into account when giving the regular heat transfer coefficient U<sub>reg</sub> (for example recurring shafts in a wood-stud or panel construction; the connection thermal bridge during the installation of a window is also appropriately included in the regular window U-value, this has already been applied in the PHPP and makes for less work). Besides, the remaining contributions are compensated to a certain extent by other connections where there are negative linear thermal transmittances. The //**[TbCrit]**// criterion is adequate for all structures which affect connections, edges, and individual interruptions in ruled surfaces. Recurrent interruptions in ruled surfaces must already be taken into account when giving the regular heat transfer coefficient U<sub>reg</sub> (for example recurring shafts in a wood-stud or panel construction; the connection thermal bridge during the installation of a window is also appropriately included in the regular window U-value, this has already been applied in the PHPP and makes for less work).
    
-With the simplified criterion, planning and construction become significantly easier: for a particular category of connection details, it only has to be verified once in advance that the //**[TbCrit]**//[] criterion has been met. This can be done, for example, by calculating all the relevant details for building envelopes. Many system manufacturers have already followed this approach and have ensured that their products comply with this criterion. If the planner uses these details, the thermal bridge unit (therm) can simply be omitted during the planning of the Passive House - this saves a lot of work during calculations.+With the simplified criterion, planning and construction become significantly easier: for a particular category of connection details, it only has to be verified once in advance that the //**[TbCrit]**// criterion has been met. This can be done, for example, by calculating all the relevant details for building envelopes. Many system manufacturers have already followed this approach and have ensured that their products comply with this criterion. If the planner uses these details, the thermal bridge unit (therm) can simply be omitted during the planning of the Passive House - this saves a lot of work during calculations.
 On the [[http://www.passivehouse.com/component-database|Passive House Institute website]] there are many examples of construction systems for which all connection details that are normally required have been certified as "thermal bridge free".\\ On the [[http://www.passivehouse.com/component-database|Passive House Institute website]] there are many examples of construction systems for which all connection details that are normally required have been certified as "thermal bridge free".\\
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 [{{:picopen:wbfrei_fusspunkt.png?280|Example showing the thermal bridge free connection of the rising exterior masonry wall to the insulated floor slab (with indication of the reference dimension; as agreed, the exterior reference dimension is always used).The heat transfer coefficients were calculated for this detail depending on the base point block used here (based on [AkkP 16]}}] [{{:picopen:wbfrei_fusspunkt.png?280|Example showing the thermal bridge free connection of the rising exterior masonry wall to the insulated floor slab (with indication of the reference dimension; as agreed, the exterior reference dimension is always used).The heat transfer coefficients were calculated for this detail depending on the base point block used here (based on [AkkP 16]}}]
  
-[{{:picopen:psi_waermebruecke_fusspunkt_aussenwand.png?400|Dependence of the linear thermal transmittance (Ψ-value) on the thermal conductivity λ of the base point block. If this is smaller than 0.25 W/(mK), then Ψ ≤ 0.01 W/(mK) and consequently the detail will be thermal bridge free. This criterion is indicated by a horizontal blue line. However, one can also see that substantial thermal bridge losses can result with "normal blocks" (λ >0.8 W/(mK)) (taken from **[AkkP 16]**).}}]+[{{:picopen:psi_waermebruecke_fusspunkt_aussenwand.png?400|Dependence of the linear thermal transmittance (Ψ-value) on the thermal conductivity λ of the base point block. If this is smaller than 0.25 W/(mK), then Ψ ≤ 0.01 W/(mK) and consequently the detail will be thermal bridge free. This criterion is indicated by a horizontal blue line. However, one can also see that substantial thermal bridge losses can result with "normal blocks" (λ >0.8 W/(mK)) (taken from [[basics:building_physics_-_basics:what_defines_thermal_bridge_free_design?#Literature|[AkkP 16] ]])}}]
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     * Solid constructions with solid bricks,     * Solid constructions with solid bricks,
 +
     * Solid constructions with low-conductivity blocks (e.g. porous concrete blocks),     * Solid constructions with low-conductivity blocks (e.g. porous concrete blocks),
 +
     * Timber constructions (solid wood beams as well as lightweight beams),     * Timber constructions (solid wood beams as well as lightweight beams),
 +
     * Constructions using formwork elements,     * Constructions using formwork elements,
 +
     * Constructions using prefabricated lightweight concrete elements.     * Constructions using prefabricated lightweight concrete elements.
  
-Details for solid constructions, timber constructions and formwork constructions can be found in the Protocol Volume [[basics:building_physics_-_basics:Thermal bridges#Literature|[AkkP 16] ]]. Timber construction details can be found in the Timber Construction Handbook+Details for solid constructions, timber constructions and formwork constructions can be found in the Protocol Volume [[basics:building_physics_-_basics:what_defines_thermal_bridge_free_design#Literature|[AkkP 16] ]]. Timber construction details can be found in the Timber Construction Handbook
  [[basics:building_physics_-_basics:what_defines_thermal_bridge_free_design?#Literature|[Kaufmann 2002] ]].  [[basics:building_physics_-_basics:what_defines_thermal_bridge_free_design?#Literature|[Kaufmann 2002] ]].
  
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 \\ \\
  [{{:picopen:thermo_ext_wall_passive_house_en.png?400|The thermographic image of the base point of the external wall in\\ a Passive House building from the inside shows that there are no\\ cold spots any more. Thermal separation by means of the\\ porous concrete block has proved successful. \\ (Image: PHI, in the Passive House in Darmstadt Kranichstein.}}]  [{{:picopen:thermo_ext_wall_passive_house_en.png?400|The thermographic image of the base point of the external wall in\\ a Passive House building from the inside shows that there are no\\ cold spots any more. Thermal separation by means of the\\ porous concrete block has proved successful. \\ (Image: PHI, in the Passive House in Darmstadt Kranichstein.}}]
-\\+
 <WRAP centeralign 90% > <WRAP centeralign 90% >
  [{{:picopen:ohne_trennung_kalte_fussleiste.png?400|This is what it looks like if there is no thermal separation: a cold\\ strip (blue) appears alongside the skirting board. Moisture damage \\ often occurs as  a result of this. This can be prevented with \\thermal bridge free design – with practically “zero” extra costs\\ for new buildings. (Picture: Klaus Michael, Director of the\\ Low Energy Institute in Detmold and Head of the Working\\ Group at the Passive House Conference on a regular basis).}}]  [{{:picopen:ohne_trennung_kalte_fussleiste.png?400|This is what it looks like if there is no thermal separation: a cold\\ strip (blue) appears alongside the skirting board. Moisture damage \\ often occurs as  a result of this. This can be prevented with \\thermal bridge free design – with practically “zero” extra costs\\ for new buildings. (Picture: Klaus Michael, Director of the\\ Low Energy Institute in Detmold and Head of the Working\\ Group at the Passive House Conference on a regular basis).}}]
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 ===== References ===== ===== References =====
  
-**[AkkP 16]** Wärmebrückenfreies Konstruieren ; Protokollband Nr. 16 des Arbeitskreises kostengünstige Passivhäuser, 1. Auflage, Passivhaus Institut, Darmstadt 1999 ({{:picopen:faxb.pdf|Link to list of PHI publications}})+**[AkkP 16]** Wärmebrückenfreies Konstruieren ; Protokollband Nr. 16 des Arbeitskreises kostengünstige Passivhäuser, 1. Auflage, Passivhaus Institut, Darmstadt 1999 [[https://shop.passivehouse.com/en/products/16-warmebruckenfreies-konstruieren-34/|Link to PHI publications]]
  
 **[Kaufmann 2002]** Das Passivhaus – Energie-Effizientes-Bauen, holzbau handbuch **[Kaufmann 2002]** Das Passivhaus – Energie-Effizientes-Bauen, holzbau handbuch
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 [[basics:building_physics_-_basics:heat_transfer| Overview]] of Passipedia articles on the topic of "Heat transfer" [[basics:building_physics_-_basics:heat_transfer| Overview]] of Passipedia articles on the topic of "Heat transfer"
  
 +[[basics:building_physics_-_basics:thermal_bridges:start]]
  
-  * [[basics:building_physics_-_basics:thermal_bridges:start]]+[[basics:building_physics_-_basics:thermal_bridges:thermal_bridges_catalogue]]
  
  
basics/building_physics_-_basics/what_defines_thermal_bridge_free_design.1550055046.txt.gz · Last modified: 2019/02/13 11:50 by cblagojevic