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Wärmeübergangswiderstand

English translation: surface resistance

12:41 Jul 30, 2023
German to English translations [PRO]
Tech/Engineering - Construction / Civil Engineering / UK English
German term or phrase: Wärmeübergangswiderstand
Der Wärmedurchgangswiderstand errechnet sich aus der Summe des Wärmedurchlasswiderstandes des Bauteils sowie aus dem Wärmeübergangswiderstand der Bauteiloberfläche, welcher sowohl auf der Innenseite als auch der Außenseite berücksichtigt werden muss.

This text is about heating and cooling systems and the way they work.

Thermal or heat resistance seems to be the umbrella term, but I am not sure how to distinguish between Wärmedurchgangswiderstand Wärmedurchlasswiderstand Wärmeübergangswiderstand

thermal/heat conductivity resistance?
thermal/heat flow resistance
thermal/heat transfer resistance

Thanks
Wendy Lewin
United Kingdom
Local time: 17:49
English translation:surface resistance
Explanation:
Compare the relevant standards:

https://www.beuth.de/de/norm/din-en-iso-6946/255315365 (Inhaltsverzeichnis), where it says

Berechnung des Wärmedurchgangskoeffizienten und des Wärmedurchlasswiderstandes
Ausgabedaten
Zeitintervalle für die Berechnung
Eingabedaten
Grundlagen des vereinfachten Berechnungsverfahrens
Wärmedurchgangskoeffizient
Nach dem detaillierten Berechnungsverfahren
Nach dem vereinfachten Berechnungsverfahren
Wärmedurchlasswiderstand
Gesamt-Wärmedurchlasswiderstand
Wärmedurchlasswiderstand homogener Komponenten
Wärmedurchlasswiderstand homogener Schichten
Gesamt-Wärmedurchlasswiderstand einer Bauteilkomponente aus homogenen Schichten
Gesamt-Wärmedurchlasswiderstand einer Bauteilkomponente aus homogenen und inhomogenen Schichten
Anwendbarkeit
Gesamt-Wärmedurchlasswiderstand einer Komponente
Oberer Grenzwert des Gesamt-Wärmedurchlasswiderstandes
Unterer Grenzwert des Gesamt-Wärmedurchlasswiderstandes
Fehlerabschätzung
Wärmeübergangswiderstände
Wärmedurchlasswiderstand von Luftschichten
Anwendbarkeit
Ruhende Luftschicht
Schwach belüftete Luftschicht
Stark belüftete Luftschicht
Wärmedurchlasswiderstand unbeheizter Räume
Allgemeines
Dachräume
Sonstige Räume

and

https://infostore.saiglobal.com/preview/is/en/2017/i.s.eniso... (see table of contents on page 11 of the PDF, which is almost identical to the slightly more detailed German version)
6 Calculation of thermal transmittance and thermal resistance
6.1 Output data
6.2 Calculation time intervals
6.3 Input data
6.4 Principles of the simplified calculation procedure
6.5 Thermal transmittance
6.5.1 By detailed calculation method
6.5.2 By simplified calculation method
6.6 Thermal resistance
6.7 Total thermal resistance
6.7.1 Thermal resistance of homogeneous components
6.7.2 Total thermal resistance of a building component consisting of homogeneous and inhomogeneous layers
6.8 Surface resistances
6.9 Thermal resistance of air layers
6.9.1 Applicability
6.9.2 Unventilated air layer
6.9.3 Slightly ventilated air layer
6.9.4 Well-ventilated air layer
6.10 Thermal resistance of unheated spaces
6.10.1 General
6.10.2 Roof spaces
6.10.3 Other spaces

Hence, we can make the following distinction:

Wärmedurchgangswiderstand = Wärmedurchgangskoeffizient = thermal transmittance
Wärmedurchlasswiderstand = Thermal resistance
Wärmeübergangswiderstand = Surface resistance


--------------------------------------------------
Note added at 1 hr (2023-07-30 14:24:04 GMT)
--------------------------------------------------

Note that there is also a British edition of this ISO standard - see https://www.thenbs.com/PublicationIndex/documents/details?Pu...
Selected response from:

Steffen Walter
Germany
Local time: 18:49
Grading comment
thanks
4 KudoZ points were awarded for this answer



Summary of answers provided
4 +3surface resistance
Steffen Walter
4 +2heat transfer resistance
Kartik Isaac
5coefficient of thermal insulation (thermal insulance)
Johannes Gleim
Summary of reference entries provided
How to distinguish between R-values
Björn Vrooman

Discussion entries: 11





  

Answers


16 mins   confidence: Answerer confidence 4/5Answerer confidence 4/5 peer agreement (net): +2
heat transfer resistance


Explanation:
Hope this helps :)

https://www.htflux.com/de/documentation/randbedingungen/waer...

https://www.htflux.com/en/documentation/boundary-conditions/...

Kartik Isaac
Switzerland
Specializes in field
Native speaker of: Native in EnglishEnglish
PRO pts in category: 32

Peer comments on this answer (and responses from the answerer)
neutral  Andrew Bramhall: Yes, in effect Wendy answered her own question;
1 hr
agree  TechLawDC: The other 2 answers offered are false.
3 hrs
agree  Adrian MM.: also, thermal contact resistance https://iate.europa.eu/search/result/1690788713683/1
18 hrs
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1 hr   confidence: Answerer confidence 4/5Answerer confidence 4/5 peer agreement (net): +3
surface resistance


Explanation:
Compare the relevant standards:

https://www.beuth.de/de/norm/din-en-iso-6946/255315365 (Inhaltsverzeichnis), where it says

Berechnung des Wärmedurchgangskoeffizienten und des Wärmedurchlasswiderstandes
Ausgabedaten
Zeitintervalle für die Berechnung
Eingabedaten
Grundlagen des vereinfachten Berechnungsverfahrens
Wärmedurchgangskoeffizient
Nach dem detaillierten Berechnungsverfahren
Nach dem vereinfachten Berechnungsverfahren
Wärmedurchlasswiderstand
Gesamt-Wärmedurchlasswiderstand
Wärmedurchlasswiderstand homogener Komponenten
Wärmedurchlasswiderstand homogener Schichten
Gesamt-Wärmedurchlasswiderstand einer Bauteilkomponente aus homogenen Schichten
Gesamt-Wärmedurchlasswiderstand einer Bauteilkomponente aus homogenen und inhomogenen Schichten
Anwendbarkeit
Gesamt-Wärmedurchlasswiderstand einer Komponente
Oberer Grenzwert des Gesamt-Wärmedurchlasswiderstandes
Unterer Grenzwert des Gesamt-Wärmedurchlasswiderstandes
Fehlerabschätzung
Wärmeübergangswiderstände
Wärmedurchlasswiderstand von Luftschichten
Anwendbarkeit
Ruhende Luftschicht
Schwach belüftete Luftschicht
Stark belüftete Luftschicht
Wärmedurchlasswiderstand unbeheizter Räume
Allgemeines
Dachräume
Sonstige Räume

and

https://infostore.saiglobal.com/preview/is/en/2017/i.s.eniso... (see table of contents on page 11 of the PDF, which is almost identical to the slightly more detailed German version)
6 Calculation of thermal transmittance and thermal resistance
6.1 Output data
6.2 Calculation time intervals
6.3 Input data
6.4 Principles of the simplified calculation procedure
6.5 Thermal transmittance
6.5.1 By detailed calculation method
6.5.2 By simplified calculation method
6.6 Thermal resistance
6.7 Total thermal resistance
6.7.1 Thermal resistance of homogeneous components
6.7.2 Total thermal resistance of a building component consisting of homogeneous and inhomogeneous layers
6.8 Surface resistances
6.9 Thermal resistance of air layers
6.9.1 Applicability
6.9.2 Unventilated air layer
6.9.3 Slightly ventilated air layer
6.9.4 Well-ventilated air layer
6.10 Thermal resistance of unheated spaces
6.10.1 General
6.10.2 Roof spaces
6.10.3 Other spaces

Hence, we can make the following distinction:

Wärmedurchgangswiderstand = Wärmedurchgangskoeffizient = thermal transmittance
Wärmedurchlasswiderstand = Thermal resistance
Wärmeübergangswiderstand = Surface resistance


--------------------------------------------------
Note added at 1 hr (2023-07-30 14:24:04 GMT)
--------------------------------------------------

Note that there is also a British edition of this ISO standard - see https://www.thenbs.com/PublicationIndex/documents/details?Pu...

Steffen Walter
Germany
Local time: 18:49
Specializes in field
Native speaker of: Native in GermanGerman
PRO pts in category: 825
Grading comment
thanks

Peer comments on this answer (and responses from the answerer)
neutral  Andrew Bramhall: Some of the text smacks of MT; " INhomogenous" ?? in English? No- " non-homogenous". And that's just one example.
1 hr
  -> No, "inhomogeneous" is a perfectly established native English term. See, for instance, https://research-repository.st-andrews.ac.uk/handle/10023/51... / Also, there is no translation involved because ISO standards are first published in English.
agree  Kim Metzger: surface resistance https://www.htflux.com/en/documentation/boundary-conditions/...
3 hrs
agree  Bernd Runge: Ja, wenn man dem bei Beuth erschienenen Fachwörterbuch vertrauen kann, ist es (thermal) surface resistance. Viele Grüße
16 hrs
  -> Viele Grüße zurück!
agree  Björn Vrooman: By rights, I should give you my agree considering you posted the BSI standard, which includes thermal resistance (the alternative to "resistance to heat flow"). I maintain that it'd be better to call them R-values but don't want to clog up the page./True!
17 hrs
  -> Fair enough re. your discussion entry, but in the context of the three terms used one after another in Wendy's context, "(thermal) surface resistance" wouldn't go amiss.
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3 hrs   confidence: Answerer confidence 5/5
coefficient of thermal insulation (thermal insulance)


Explanation:
Wärmeübergang (DIN 1341) / heat transmission
Endlicher Wärmeübergang an der Oberfläche / finite heat transfer
Wärmeübergangskoeffizient / surface coefficient of heat transfer
Wärmewiderstand / (reziproker Wert der Wärmedurchgangszahl) / thermal resistance | thermal resistivity
(Dictionary of Exact Science and Technology)

DIN 1341:1986-10
Wärmeübertragung; Begriffe, Kenngrößen
Englischer Titel
Heat transfer; concepts, dimensionless parameters
https://www.beuth.de/de/norm/din-1341/1312687

BS EN ISO 9251:1996
Thermal insulation. Heat transfer. Conditions and properties of materials. Vocabulary
https://knowledge.bsigroup.com/products/thermal-insulation-h...

Der Wärmeübergangswiderstand Rs (früher: 1/α) ist ein thermodynamischer Kennwert bei einem Wärmeübergang und bezeichnet den Widerstand (engl. resistance), den die Grenzschicht bzw. Oberfläche (engl.: surface) vom umgebenden Medium (im Allgemeinen ein Fluid) zum Bauteil dem Wärmestrom entgegensetzt.
Der Wärmeübergangswiderstand ist definiert als Kehrwert des Wärmeübergangskoeffizienten:
https://de.wikipedia.org/wiki/Wärmeübergangswiderstand

In thermodynamics, the heat transfer coefficient or film coefficient, or film effectiveness, is the proportionality constant between the heat flux and the thermodynamic driving force for the flow of heat (i.e., the temperature difference, ΔT ).
:
The heat transfer coefficient is the reciprocal of thermal insulance. This is used for building materials (R-value) and for clothing insulation.
https://en.wikipedia.org/wiki/Heat_transfer_coefficient

2.9 surface coefficient of heat transfer: Density of heat flow rate at a surface in the steady state divided by the temperature difference between that surface and the surroundings:
1) In ISO 31/4, "thermal resistance" is called "thermal insulance" or "coefficient of thermal insulation", with the Symbol M.
https://www.iso.org/obp/ui#iso:std:iso:7345:ed-2:v1:en

Heat transfer coefficient = U-value (formerly k-value): central unit of measurement when determining the heat loss of a building component. It indicates the amount of heat that passes through 1 m² per unit of time at a temperature difference of 1 Kelvin between the adjacent room and outside air. The smaller the U-value, the greater the thermal insulation. The unit of measurement is W/(m²K).
The heat transfer coefficient, also called the U-value, describes the insulation properties of a building component. The lower the coefficient, the better the thermal insulation.
https://www.enersign.com/en/glossar/waermedurchgangskoeffizi...

Hiervon abweichend ist in den Normen DIN 4108 Teil 1,DIN 4701 Teil 1,DIN 52 611 Teil 1
und Teil 2, DIN 52 612 Teil 1 und Teil 3 der Quotient Temperaturdifferenz durch Wärmestromdichte, je nach zugrundegelegter Temperaturdifferenz, als „Wärmedurchlaßwiderstand" (auch Wärmeleitwiderstand, Wärmedämmwert), „Wärmeübergangswiderstand" und „Wärmedurchgangswiderstand" bezeichnet. Eine solche Größe ist in ISO 31/4 -1978 ebenfalls enthalten, sie wird englisch "thermal insulance, coefficient of thermal insulation ", französisch „coefficient d'lsolation thermique" genannt
https://api.pageplace.de/preview/DT0400.9783410281443_A40629...

The results of research studies presented in the paper involving the changes of "thermal conductivity λ coefficient of thermal insulation" cylindrical products made of closed-cell polyurethane foam (PUR) blown with n-pentane, constitute a significant database of information that can be useful both for manufacturers of these products and for designers of thermal insulation used mainly in industrial installations, but also in construction engineering.
https://www.sciencedirect.com/science/article/abs/pii/S23527...

With an increase in the average density of samples to 120 kg/m3, the vapor permeability coefficient of thermal insulation slabs made of flax fibers is 12% higher than that of samples made of flax noils.
https://www.e3s-conferences.org/articles/e3sconf/pdf/2020/72...

Global coefficient of thermal insulation is a performance criteria of the energy consumption required in the operation of buildings, used to calculate the amount of heat needed to heat a cubic meter of volume building during a year.
http://www.bipcons.ce.tuiasi.ro/Archive/471.pdf

--------------------------------------------------
Note added at 7 Stunden (2023-07-30 19:49:02 GMT)
--------------------------------------------------

Thermal Resistance
The R-value (thermal insulance factor) measures the thermal resistance of a material. This can also be expressed as the temperature difference that will cause one unit of heat to pass through one unit of area over a period of time. The thermal insulance factor R has the units [m²K/W]
https://www.owa.de/wp-content/uploads/2022/05/Constellation_...

When dealing with building structures, thermal resistance or R-value means what is
also described as thermal insulance. …
Typical SI units of thermal resistance (R value) = λ/L, are K²*m²/W.
https://tcmaxis.com/wp-content/uploads/2019/11/ISOVER-Ultima...

Interior convective thermal insulance
Thermal insulance of external wall, internal side
Thermal insulance of TABS, room side | construction data DIN 6496 (2018) and construction data assumption
http://www.ibpsa.org/proceedings/BS2019/BS2019_210443.pdf

English | thermal insulance| inverse of the heat transfer coefficient | coefficient of thermal insulance
German | Wärmeübergangswiderstand | Kehrwert des Wärmeübergangskoeffizienten | Wärmedämmungskoeffizient
https://www.wikidata.org/wiki/Q2596212

5-11 thermal insulance, coefficient of thermal insulance | M | m² K/W | In building technology, this quantity is often called thermal resistance, with the symbol R.
https://www.iso.org/obp/ui/#iso:std:iso:80000:-5:ed-2:v1:en

You will recognize that this values have slight different expression, but always the same unit.

Johannes Gleim
Local time: 18:49
Works in field
Native speaker of: German
PRO pts in category: 322
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Reference comments


7 days
Reference: How to distinguish between R-values

Reference information:
I feel like no one (including me) has answered your actual question yet so I’m going to try and do that as part of this reference entry. You said: "Thermal or heat resistance seems to be the umbrella term, but I am not sure how to distinguish between..."

First off, they’re all just different kinds of resistances (or R-values).

(a) Wärmedurchgangswiderstand

That’s the opposite of Wärmedurchgangskoeffizient, better known as the U-value in the construction industry.

The symbol used to denote this kind of resistance is Rt (or Rtot), as it’s the total thermal resistance of some part of a structure. It tells you how great the overall resistance to heat flow is at that point.

For more information, see the following links:
https://de.wikipedia.org/wiki/Wärmedurchgangskoeffizient
https://en.wikipedia.org/wiki/Thermal_transmittance

See also:
"The Total Resistance (Rt) is then the sum of all R-Values combined. Once you have the Rt value, the U-Value can be calculated using the following formula:

U = 1 divided by Rt"
https://www.insulationexpress.co.uk/blog/understanding-u-val...

(b) Wärmedurchlasswiderstand

That’s the basic R-value, or "der Widerstand, den ein homogenes Bauteil oder bei mehrschichtigen Bauteilen eine homogene Bauteilschicht dem Wärmestrom bei einer Temperaturdifferenz von 1 Kelvin auf einer Fläche von 1 m² zwischen seinen Oberflächen entgegensetzt."
https://de.wikipedia.org/wiki/Wärmedurchlasswiderstand

As the English Wiki says:
"The R-value is the building industry term for thermal resistance 'per unit area.' It is sometimes denoted RSI-value if the SI units are used. An R-value can be given for a material (e.g. for polyethylene foam), or for an assembly of materials (e.g. a wall or a window)."
https://en.wikipedia.org/wiki/R-value_(insulation)

That's one of the issues, I guess. "Thermal resistance" is used for both the total value and individual component values, which may seem confusing.

(c) Wärmeübergangswiderstand

Now, we get to the term you asked about. According to Wiki, it’s a "thermodynamischer Kennwert bei einem Wärmeübergang und bezeichnet den Widerstand (engl. resistance), den die Grenzschicht bzw. Oberfläche (engl.: surface) vom umgebenden Medium (im Allgemeinen ein Fluid) zum Bauteil dem Wärmestrom entgegensetzt."
https://de.wikipedia.org/wiki/Wärmeübergangswiderstand

There are two ways to specify surface resistance, one of them being Rsi—on the inside of a wall, for example—and the other Rse—as in the external surface resistance on the outside of the building.

I think the following explanation in German helps demonstrate how all these R-values relate to each other:
"Zu unterscheiden sind die drei Begriffe Wärmedurchgangswiderstand (RT), Wärmedurchlasswiderstand (R) und Wärmeübergangswiderstand (RS).

Wärmedurchgangswiderstand = Wärmedurchlasswiderstände + Wärmeübergangswiderstände

Aus der Summe aller Wärmedurchlasswiderstände (für jede einzelne Materialschicht eines Bauteils) und der beiden Wärmeübergangswiderstände (in der DIN EN ISO 6946 festgelegte Werte der Innen- und Außenkanten) ergibt sich der Wärmedurchgangswiderstand."
https://www.baunetzwissen.de/daemmstoffe/fachwissen/glossar-...

Similar explanation in English:
"R-values can be calculated by dividing the thickness of a material (in metres) by its thermal conductivity (k-value or lambda value (λ) in W/mK). R-values are therefore expressed in m2K/W (or ft2·°F·hr/Btu in the USA). The overall R-value of a multi-layered element can be calculated by adding the R-values of its component materials."
https://www.designingbuildings.co.uk/wiki/R-value

In conclusion, as already hinted at above, (a) is the sum of (b) and (c). See, for example, p. 8 (entitled "Graphical representation of surface resistance layers") at http://tea.ie/wp-content/uploads/2011/09/Module-3.2-Resistan...

Or see chapter 4.1 ("Surface resistance") at https://www.bregroup.com/wp-content/uploads/2019/10/BR443-Oc...

Or just take a look at the table on the following page:
https://www.greenspec.co.uk/building-design/u-value-introduc...

The table included with the last link shows that to arrive at a certain U-value, you first need to determine the Rt value of a wall piece, for example. You do this by adding up the internal surface resistance Rsi, the external surface resistance Rse, and the R-values of all wall materials.

See also the formula used for calculating the total resistance Rt on this page (same website as posted by Chris in the d-box):
https://www.firstinarchitecture.co.uk/a-quick-and-easy-guide...

It's basically the same formula here (albeit the other way around, as you are again trying to calculate the U-value):
https://www.lonsdalemetal.co.uk/blog/what-is-u-value/

Björn Vrooman
Works in field
Native speaker of: Native in GermanGerman
PRO pts in category: 16
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