Thermal conductivity - Revision history

Designing Buildings at 06:41, 26 August 2026

2026-08-26T06:41:27Z

← Older revision		Revision as of 06:41, 26 August 2026
Line 3:		Line 3:
	Thermal conductivity (sometimes referred to as k-value or lambda value (λ)) is a measure of the rate at which temperature differences transmit through a material. The lower the thermal conductivity of a material, the slower the rate at which temperature differences transmit through it, and so the more effective it is as an insulator. Very broadly, the lower the thermal conductivity of a building's fabric, the less energy is required to maintain comfortable conditions inside.		Thermal conductivity (sometimes referred to as k-value or lambda value (λ)) is a measure of the rate at which temperature differences transmit through a material. The lower the thermal conductivity of a material, the slower the rate at which temperature differences transmit through it, and so the more effective it is as an insulator. Very broadly, the lower the thermal conductivity of a building's fabric, the less energy is required to maintain comfortable conditions inside.

−	Thermal conductivity is a fundamental material property independent of thickness. It is measured watts per ~~meter~~ kelvin (W/mK).	+	Thermal conductivity is a fundamental material property independent of thickness. It is measured in watts per metre kelvin (W/mK).

−	The thermal resistance of the layers of ~~the~~ a building's fabric (R measured in in m²K/W) can be calculated from the thickness of each layer / the thermal conductivity of that layer.	+	The thermal resistance of the layers of a building's fabric (R, measured in m²K/W) can be calculated from the thickness of each layer divided by the thermal conductivity of that layer.

−	The U value of an element of a building can be calculated from sum of the thermal resistances (R-values) of the layers that make up the element plus its internal and external surface resistances (Ri and Ro).	+	The U-value of an element of a building can be calculated from the sum of the thermal resistances (R-values) of the layers that make up the element plus its internal and external surface resistances (Ri and Ro).

	U-value = 1 / (ΣR + Ri + Ro)		U-value = 1 / (ΣR + Ri + Ro)

−	U-values (sometimes referred to as heat transfer coefficients or thermal transmittances) are used to measure how effective elements of a ~~buildings~~ fabric are as insulators.	+	U-values (sometimes referred to as heat transfer coefficients or thermal transmittances) are used to measure how effective elements of a building's fabric are as insulators.

−	The standards for the measurement of thermal conductivity are BS EN 12664, BS EN 12667 and BS EN 12939. In the absence of values provided by product manufacturers following thermal conductivity tests, ~~the~~ thermal conductivity data obtained from BS EN ~~12524~~ Building materials and products. Hygrothermal properties.	+	The standards for the measurement of thermal conductivity are BS EN 12664, BS EN 12667 and BS EN 12939. In the absence of values provided by product manufacturers following thermal conductivity tests, tabulated thermal conductivity data can be obtained from BS EN ISO 10456 Building materials and products - Hygrothermal properties - Tabulated design values and procedures for determining declared and design thermal values, which superseded the earlier BS EN 12524.

	= Thermal conductivity of typical building materials =		= Thermal conductivity of typical building materials =

−	Thermal conductivity values of typical building materials shown below.	+	Thermal conductivity values of typical building materials are shown below.

	{\|		{\|
Line 53:		Line 53:
	\| 1.4		\| 1.4
	\|-		\|-
−	\| ~~fibreglass~~ quilt	+	\| Fibreglass quilt
	\| 0.033		\| 0.033
	\|-		\|-
−	\| ~~glass~~	+	\| Glass
	\| 1.05		\| 1.05
	\|-		\|-
−	\| ~~glass~~ foam aggregate (dry)	+	\| Glass foam aggregate (dry)
	\| 0.08		\| 0.08
	\|-		\|-
−	\| ~~hemp~~ slabs	+	\| Hemp slabs
	\| 0.40		\| 0.40
	\|-		\|-
−	\| ~~hempcrete~~	+	\| Hempcrete
	\| 0.25		\| 0.25
	\|-		\|-
−	\| ~~mineral~~ wool	+	\| Mineral wool
	\| 0.038		\| 0.038
	\|-		\|-
−	\| ~~mortar~~	+	\| Mortar
	\| 0.80		\| 0.80
	\|-		\|-
−	\| ~~phenolic~~ foam (PIR)	+	\| Phenolic foam (PIR)
	\| 0.020		\| 0.020
	\|-		\|-
−	\| ~~plaster~~ (gypsum)	+	\| Plaster (gypsum)
	\| 0.46		\| 0.46
	\|-		\|-
−	\| ~~plasterboard~~ (gypsum)	+	\| Plasterboard (gypsum)
	\| 0.16		\| 0.16
	\|-		\|-
−	\| ~~polystyrene~~ foam	+	\| Polystyrene foam
	\| 0.032		\| 0.032
	\|-		\|-
−	\| ~~polyurethane~~ foam (PUR)	+	\| Polyurethane foam (PUR)
	\| 0.025		\| 0.025
	\|-		\|-
−	\| ~~render~~ (sand/cement)	+	\| Render (sand/cement)
	\| 0.50		\| 0.50
	\|-		\|-
−	\| ~~screed~~ (cement/sand)	+	\| Screed (cement/sand)
	\| 0.41		\| 0.41
	\|-		\|-
−	\| ~~steel~~	+	\| Steel
	\| 16 - 80		\| 16 - 80
	\|-		\|-
−	\| ~~stone~~ (limestone)	+	\| Stone (limestone)
	\| 1.30		\| 1.30
	\|-		\|-
−	\| ~~stone~~ (sandstone)	+	\| Stone (sandstone)
	\| 1.50		\| 1.50
	\|-		\|-
−	\| ~~stone~~ (granite)	+	\| Stone (granite)
	\| 1.7 - 4.0		\| 1.7 - 4.0
	\|-		\|-
−	\| ~~stone~~ chippings	+	\| Stone chippings
	\| 0.96		\| 0.96
	\|-		\|-
−	\| ~~straw~~ bale	+	\| Straw bale
	\| 0.09		\| 0.09
	\|-		\|-
−	\| ~~timber~~ (softwood)	+	\| Timber (softwood)
	\| 0.14		\| 0.14
	\|-		\|-
−	\| ~~timber~~ (hardwood - commonly used)	+	\| Timber (hardwood - commonly used)
	\| 0.14 - 0.17		\| 0.14 - 0.17
	\|-		\|-
−	\| ~~woodfibre~~ board	+	\| Woodfibre board
	\| 0.11		\| 0.11
	\|}		\|}

−	= Related articles on Designing Buildings ~~Wiki~~ =	+	= Related articles on Designing Buildings =

	* Conventions for calculating linear thermal transmittance and temperature factors.		* Conventions for calculating linear thermal transmittance and temperature factors.
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	* Thermal admittance.		* Thermal admittance.
	* Thermal mass.		* Thermal mass.
−	* U ~~Value~~.	+	* U-value.
	* U-value conventions in practice: Worked examples using BR 443.		* U-value conventions in practice: Worked examples using BR 443.

	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Standard]] [[Category:Theory]] [[Category:Standards_/_measurements]]		[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Standard]] [[Category:Theory]] [[Category:Standards_/_measurements]]

Designing Buildings: Reverted edits by Saggyhaggis (talk) to last revision by Daniel Wells

2023-07-07T11:30:46Z

Reverted edits by Saggyhaggis (talk) to last revision by Daniel Wells

← Older revision		Revision as of 11:30, 7 July 2023
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	{\|		{\|
−	\| Material	+	\|width="50%"\| Material
−	\| W/mK	+	\|width="50%"\| W/mK
	\|-		\|-
	\| Blockwork (light)		\| Blockwork (light)
Line 75:		Line 75:
	\|-		\|-
	\| phenolic foam (PIR)		\| phenolic foam (PIR)
−	\| 0.~~022~~	+	\| 0.020
	\|-		\|-
	\| plaster (gypsum)		\| plaster (gypsum)
Line 81:		Line 81:
	\|-		\|-
	\| plasterboard (gypsum)		\| plasterboard (gypsum)
−	\| 0.21	+	\| 0.16
	\|-		\|-
	\| polystyrene foam		\| polystyrene foam
Line 114:		Line 114:
	\|-		\|-
	\| timber (softwood)		\| timber (softwood)
−	\| 0.13	+	\| 0.14
	\|-		\|-
	\| timber (hardwood - commonly used)		\| timber (hardwood - commonly used)

Saggyhaggis at 10:51, 7 July 2023

2023-07-07T10:51:15Z

← Older revision		Revision as of 10:51, 7 July 2023
Line 20:		Line 20:

	{\|		{\|
−	~~\|width="50%"~~\| Material	+	\| Material
−	~~\|width="50%"~~\| W/mK	+	\| W/mK
	\|-		\|-
	\| Blockwork (light)		\| Blockwork (light)
Line 75:		Line 75:
	\|-		\|-
	\| phenolic foam (PIR)		\| phenolic foam (PIR)
−	\| 0.~~020~~	+	\| 0.022
	\|-		\|-
	\| plaster (gypsum)		\| plaster (gypsum)
Line 81:		Line 81:
	\|-		\|-
	\| plasterboard (gypsum)		\| plasterboard (gypsum)
−	\| 0.16	+	\| 0.21
	\|-		\|-
	\| polystyrene foam		\| polystyrene foam
Line 114:		Line 114:
	\|-		\|-
	\| timber (softwood)		\| timber (softwood)
−	\| 0.14	+	\| 0.13
	\|-		\|-
	\| timber (hardwood - commonly used)		\| timber (hardwood - commonly used)

Daniel Wells at 16:38, 9 November 2022

2022-11-09T16:38:19Z

← Older revision		Revision as of 16:38, 9 November 2022
Line 20:		Line 20:

	{\|		{\|
−	\| Material	+	\|width="50%"\| Material
−	\| W/mK	+	\|width="50%"\| W/mK
	\|-		\|-
	\| Blockwork (light)		\| Blockwork (light)
Line 43:		Line 43:
	\| Concrete (aerated)		\| Concrete (aerated)
	\| 0.16		\| 0.16
		+	\|-
		+	\| Concrete (cellular 400 kg/m3)
		+	\| 0.1
		+	\|-
		+	\| Concrete (cellular 1200 kg/m3)
		+	\| 0.4
	\|-		\|-
	\| Concrete (dense)		\| Concrete (dense)

Designing Buildings at 08:41, 25 September 2020

2020-09-25T08:41:44Z

← Older revision		Revision as of 08:41, 25 September 2020
Line 131:		Line 131:
	* U-value conventions in practice: Worked examples using BR 443.		* U-value conventions in practice: Worked examples using BR 443.

−	[[Category:~~Theory~~]] [[Category:~~Standards_/_measurements~~]] [[Category:DCN_Standard]]	+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Standard]] [[Category:Theory]] [[Category:Standards_/_measurements]]

Designing Buildings at 07:07, 1 December 2019

2019-12-01T07:07:57Z

← Older revision		Revision as of 07:07, 1 December 2019
Line 105:		Line 105:
	\|-		\|-
	\| straw bale		\| straw bale
−	\| 0.~~055 - 0.065~~	+	\| 0.09
	\|-		\|-
	\| timber (softwood)		\| timber (softwood)
Line 131:		Line 131:
	* U-value conventions in practice: Worked examples using BR 443.		* U-value conventions in practice: Worked examples using BR 443.

−	[[Category:Theory]] [[Category:Standards_/_measurements]]	+	[[Category:Theory]] [[Category:Standards_/_measurements]] [[Category:DCN_Standard]]

94.197.120.250 at 03:21, 1 December 2019

2019-12-01T03:21:14Z

← Older revision		Revision as of 03:21, 1 December 2019
Line 1:		Line 1:
	= Introduction =		= Introduction =

−	~~cccdcdcdc~~	+	Thermal conductivity (sometimes referred to as k-value or lambda value (λ)) is a measure of the rate at which temperature differences transmit through a material. The lower the thermal conductivity of a material, the slower the rate at which temperature differences transmit through it, and so the more effective it is as an insulator. Very broadly, the lower the thermal conductivity of a building's fabric, the less energy is required to maintain comfortable conditions inside.
		+
		+	Thermal conductivity is a fundamental material property independent of thickness. It is measured watts per meter kelvin (W/mK).
		+
		+	The thermal resistance of the layers of the a building's fabric (R measured in in m²K/W) can be calculated from the thickness of each layer / the thermal conductivity of that layer.
		+
		+	The U value of an element of a building can be calculated from sum of the thermal resistances (R-values) of the layers that make up the element plus its internal and external surface resistances (Ri and Ro).
		+
		+	U-value = 1 / (ΣR + Ri + Ro)
		+
		+	U-values (sometimes referred to as heat transfer coefficients or thermal transmittances) are used to measure how effective elements of a buildings fabric are as insulators.
		+
		+	The standards for the measurement of thermal conductivity are BS EN 12664, BS EN 12667 and BS EN 12939. In the absence of values provided by product manufacturers following thermal conductivity tests, the thermal conductivity data obtained from BS EN 12524 Building materials and products. Hygrothermal properties.
		+
		+	= Thermal conductivity of typical building materials =
		+
		+	Thermal conductivity values of typical building materials shown below.
		+
		+	{\|
		+	\| Material
		+	\| W/mK
		+	\|-
		+	\| Blockwork (light)
		+	\| 0.38
		+	\|-
		+	\| Blockwork (medium)
		+	\| 0.51
		+	\|-
		+	\| Blockwork (dense)
		+	\| 1.63
		+	\|-
		+	\| Brick (exposed)
		+	\| 0.84
		+	\|-
		+	\| Brick (protected)
		+	\| 0.62
		+	\|-
		+	\| Chipboard
		+	\| 0.15
		+	\|-
		+	\| Concrete (aerated)
		+	\| 0.16
		+	\|-
		+	\| Concrete (dense)
		+	\| 1.4
		+	\|-
		+	\| fibreglass quilt
		+	\| 0.033
		+	\|-
		+	\| glass
		+	\| 1.05
		+	\|-
		+	\| glass foam aggregate (dry)
		+	\| 0.08
		+	\|-
		+	\| hemp slabs
		+	\| 0.40
		+	\|-
		+	\| hempcrete
		+	\| 0.25
		+	\|-
		+	\| mineral wool
		+	\| 0.038
		+	\|-
		+	\| mortar
		+	\| 0.80
		+	\|-
		+	\| phenolic foam (PIR)
		+	\| 0.020
		+	\|-
		+	\| plaster (gypsum)
		+	\| 0.46
		+	\|-
		+	\| plasterboard (gypsum)
		+	\| 0.16
		+	\|-
		+	\| polystyrene foam
		+	\| 0.032
		+	\|-
		+	\| polyurethane foam (PUR)
		+	\| 0.025
		+	\|-
		+	\| render (sand/cement)
		+	\| 0.50
		+	\|-
		+	\| screed (cement/sand)
		+	\| 0.41
		+	\|-
		+	\| steel
		+	\| 16 - 80
		+	\|-
		+	\| stone (limestone)
		+	\| 1.30
		+	\|-
		+	\| stone (sandstone)
		+	\| 1.50
		+	\|-
		+	\| stone (granite)
		+	\| 1.7 - 4.0
		+	\|-
		+	\| stone chippings
		+	\| 0.96
		+	\|-
		+	\| straw bale
		+	\| 0.055 - 0.065
		+	\|-
		+	\| timber (softwood)
		+	\| 0.14
		+	\|-
		+	\| timber (hardwood - commonly used)
		+	\| 0.14 - 0.17
		+	\|-
		+	\| woodfibre board
		+	\| 0.11
		+	\|}
		+
		+	= Related articles on Designing Buildings Wiki =
		+
		+	* Conventions for calculating linear thermal transmittance and temperature factors.
		+	* g-value.
		+	* Heat transfer.
		+	* Insulation.
		+	* k-value.
		+	* Limiting fabric parameters.
		+	* R-value.
		+	* Thermal admittance.
		+	* Thermal mass.
		+	* U Value.
		+	* U-value conventions in practice: Worked examples using BR 443.

	[[Category:Theory]] [[Category:Standards_/_measurements]]		[[Category:Theory]] [[Category:Standards_/_measurements]]

94.197.120.250: Replaced content with "= Introduction = cccdcdcdc Category:Theory Category:Standards_/_measurements "

2019-12-01T03:20:57Z

Replaced content with "= Introduction = cccdcdcdc Category:Theory Category:Standards_/_measurements "

← Older revision		Revision as of 03:20, 1 December 2019
Line 1:		Line 1:
	= Introduction =		= Introduction =

−	Thermal conductivity (sometimes referred to as k-value or lambda value (λ)) is a measure of the rate at which temperature differences transmit through a material. The lower the thermal conductivity of a material, the slower the rate at which temperature differences transmit through it, and so the more effective it is as an insulator. Very broadly, the lower the thermal conductivity of a building's fabric, the less energy is required to maintain comfortable conditions inside.	+	cccdcdcdc
−		+
−	~~Thermal conductivity is a fundamental material property independent of thickness. It is measured watts per meter kelvin (W/mK).~~	+
−		+
−	~~The thermal resistance of the layers of the a building's fabric (R measured in in m²K/W) can be calculated from the thickness of each layer / the thermal conductivity of that layer.~~	+
−		+
−	The U value of an element of a building can be calculated from sum of the thermal resistances (R-values) of the layers that make up the element plus its internal and external surface resistances (Ri and Ro).	+
−		+
−	~~U-value = 1 / (ΣR + Ri + Ro)~~	+
−		+
−	~~U-values (sometimes referred to as heat transfer coefficients or thermal transmittances) are used to measure how effective elements of a buildings fabric are as insulators.~~	+
−		+
−	The standards for the measurement of thermal conductivity are BS EN 12664, BS EN 12667 and BS EN 12939. In the absence of values provided by product manufacturers following thermal conductivity tests, the thermal conductivity data obtained from BS EN 12524 Building materials and products. Hygrothermal properties.	+
−		+
−	~~= Thermal conductivity of typical building materials =~~	+
−		+
−	~~Thermal conductivity values of typical building materials shown below.~~	+
−		+
−	{\|	+
−	~~\| Material~~	+
−	~~\| W/mK~~	+
−	\|-	+
−	~~\| Blockwork (light)~~	+
−	~~\| 0.38~~	+
−	\|-	+
−	~~\| Blockwork (medium)~~	+
−	~~\| 0.51~~	+
−	\|-	+
−	~~\| Blockwork (dense)~~	+
−	~~\| 1.63~~	+
−	\|-	+
−	~~\| Brick (exposed)~~	+
−	~~\| 0.84~~	+
−	\|-	+
−	~~\| Brick (protected)~~	+
−	~~\| 0.62~~	+
−	\|-	+
−	~~\| Chipboard~~	+
−	~~\| 0.15~~	+
−	\|-	+
−	~~\| Concrete (aerated)~~	+
−	~~\| 0.16~~	+
−	\|-	+
−	~~\| Concrete (dense)~~	+
−	~~\| 1.4~~	+
−	\|-	+
−	~~\| fibreglass quilt~~	+
−	~~\| 0.033~~	+
−	\|-	+
−	~~\| glass~~	+
−	~~\| 1.05~~	+
−	\|-	+
−	~~\| glass foam aggregate (dry)~~	+
−	~~\| 0.08~~	+
−	\|-	+
−	~~\| hemp slabs~~	+
−	~~\| 0.40~~	+
−	\|-	+
−	~~\| hempcrete~~	+
−	~~\| 0.25~~	+
−	\|-	+
−	~~\| mineral wool~~	+
−	~~\| 0.038~~	+
−	\|-	+
−	~~\| mortar~~	+
−	~~\| 0.80~~	+
−	\|-	+
−	~~\| phenolic foam (PIR)~~	+
−	~~\| 0.020~~	+
−	\|-	+
−	~~\| plaster (gypsum)~~	+
−	~~\| 0.46~~	+
−	\|-	+
−	~~\| plasterboard (gypsum)~~	+
−	~~\| 0.16~~	+
−	\|-	+
−	~~\| polystyrene foam~~	+
−	~~\| 0.032~~	+
−	\|-	+
−	~~\| polyurethane foam (PUR)~~	+
−	~~\| 0.025~~	+
−	\|-	+
−	~~\| render (sand/cement)~~	+
−	~~\| 0.50~~	+
−	\|-	+
−	~~\| screed (cement/sand)~~	+
−	~~\| 0.41~~	+
−	\|-	+
−	~~\| steel~~	+
−	~~\| 16 - 80~~	+
−	\|-	+
−	~~\| stone (limestone)~~	+
−	~~\| 1.30~~	+
−	\|-	+
−	~~\| stone (sandstone)~~	+
−	~~\| 1.50~~	+
−	\|-	+
−	~~\| stone (granite)~~	+
−	~~\| 1.7 - 4.0~~	+
−	\|-	+
−	~~\| stone chippings~~	+
−	~~\| 0.96~~	+
−	\|-	+
−	~~\| straw bale~~	+
−	~~\| 0.055 - 0.065~~	+
−	\|-	+
−	~~\| timber (softwood)~~	+
−	~~\| 0.14~~	+
−	\|-	+
−	~~\| timber (hardwood - commonly used)~~	+
−	~~\| 0.14 - 0.17~~	+
−	\|-	+
−	~~\| woodfibre board~~	+
−	~~\| 0.11~~	+
−	\|}	+
−		+
−	~~= Related articles on Designing Buildings Wiki =~~	+
−		+
−	* Conventions for calculating linear thermal transmittance and temperature factors.	+
−	* g-value.	+
−	* Heat transfer.	+
−	* Insulation.	+
−	* k-value.	+
−	* Limiting fabric parameters.	+
−	* R-value.	+
−	* Thermal admittance.	+
−	* Thermal mass.	+
−	* U Value.	+
−	* U-value conventions in practice: Worked examples using BR 443.	+

	[[Category:Theory]] [[Category:Standards_/_measurements]]		[[Category:Theory]] [[Category:Standards_/_measurements]]

81.107.194.76 at 14:09, 23 April 2019

2019-04-23T14:09:05Z

← Older revision		Revision as of 14:09, 23 April 2019
Line 20:		Line 20:

	{\|		{\|
−	~~\|width="50%"~~\| Material	+	\| Material
−	~~\|width="50%"~~\| W/mK	+	\| W/mK
	\|-		\|-
	\| Blockwork (light)		\| Blockwork (light)
Line 105:		Line 105:
	\|-		\|-
	\| straw bale		\| straw bale
−	\| 0.09	+	\| 0.055 - 0.065
	\|-		\|-
	\| timber (softwood)		\| timber (softwood)

Designing Buildings: Reverted edits by 195.167.5.3 (talk) to last revision by Designing Buildings

2019-04-15T06:38:00Z

Reverted edits by 195.167.5.3 (talk) to last revision by Designing Buildings

← Older revision		Revision as of 06:38, 15 April 2019
Line 20:		Line 20:

	{\|		{\|
−	\| Material	+	\|width="50%"\| Material
−	\| W/mK	+	\|width="50%"\| W/mK
	\|-		\|-
	\| Blockwork (light)		\| Blockwork (light)
Line 105:		Line 105:
	\|-		\|-
	\| straw bale		\| straw bale
−	\| 0.~~05-0.07~~	+	\| 0.09
	\|-		\|-
	\| timber (softwood)		\| timber (softwood)