Colour Rendering Index CRI - Revision history

Designing Buildings at 10:03, 27 July 2021

2021-07-27T10:03:54Z

← Older revision		Revision as of 10:03, 27 July 2021
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	* Colour appearance.		* Colour appearance.
		+	* Colour temperature.
	* Colour in the built environment.		* Colour in the built environment.
	* Commercial lighting.		* Commercial lighting.

Editor at 09:37, 1 July 2021

2021-07-01T09:37:20Z

← Older revision		Revision as of 09:37, 1 July 2021
Line 71:		Line 71:
	* Lighting for circadian rhythms.		* Lighting for circadian rhythms.
	* Lighting of construction sites.		* Lighting of construction sites.
		+	* Light Pollution - Human Health Impacts from LEDs.
	* Luminaire efficacy.		* Luminaire efficacy.
	* The Anatomy of Colour.		* The Anatomy of Colour.

Designing Buildings at 06:50, 1 February 2021

2021-02-01T06:50:44Z

← Older revision		Revision as of 06:50, 1 February 2021
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	* Types of lamp.		* Types of lamp.

−	[[Category:~~Education~~]] [[Category:~~DCN_Education_and_Training~~]] [[Category:~~Design~~]] [[Category:~~Products_/_components~~]] [[Category:~~DCN_Product_Knowledge~~]]	+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Product_Knowledge]] [[Category:DCN_Standard]] [[Category:Education]] [[Category:Design]] [[Category:Products_/_components]]

Designing Buildings at 06:03, 22 May 2020

2020-05-22T06:03:20Z

← Older revision		Revision as of 06:03, 22 May 2020
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	= Introduction =		= Introduction =

−	Colour can only be perceived due to the presence of light. Most light sources produce different ~~light wave~~ combinations.	+	Colour can only be perceived due to the presence of light. Most light sources produce different wavelength combinations.

−	Visual light comprises a wide range of ~~different~~ colours. This can be seen by using a prism to split it into its constituent ~~colours~~. This range of colours is called a ‘spectrum’ and the colours, each with a different wavelength, are always in the same order, from red at one end through orange, yellow, green, blue, indigo to violet at the other end. Red light has longer wavelength~~, green 'medium'~~ and blue shorter.	+	Visual light comprises a wide range of colours. This can be seen by using a prism to split it into its constituent parts. This range of colours is called a ‘spectrum’ and the colours, each with a different wavelength, are always in the same order, from red at one end through orange, yellow, green, blue, indigo to violet at the other end. Red light has a longer wavelength and blue shorter.

−	In reality, there are many, many different colours in the spectral range because it is seamless, as one colour gradually merges into the next. Each wavelength stimulates the cone cells (colour receptors) in the human eye in a different way to produce the sensation of colour. So, when we say that ‘the banana is yellow’, it would be more accurate to say ~~that~~ a sensation of yellow is generated by an area of the retina (at the back of the eye) that corresponds to where light rays from the banana are being received.	+	In reality, there are many, many different colours in the spectral range because it is seamless, as one colour gradually merges into the next. Each wavelength stimulates the cone cells (colour receptors) in the human eye in a different way to produce the sensation of colour. So, when we say that ‘the banana is yellow’, it would be more accurate to say a sensation of yellow is generated by an area of the retina (at the back of the eye) that corresponds to where light rays from the banana are being received.

	= Colour appearance =		= Colour appearance =

−	Colour appearance refers to the visual sensation correlated with the ‘warmth’ or ‘coolness’ of the light emitted by a lamp. There are a wide variety of different types of lamps available. These include filament lamps, discharge lamps (including fluorescent, xenon arc lamps and high intensity discharge or HID lamps), light-emitting diodes (LEDs) and so on. For more information, see ~~types~~ of lamp.	+	Colour appearance refers to the visual sensation correlated with the ‘warmth’ or ‘coolness’ of the light emitted by a lamp. There are a wide variety of different types of lamps available. These include filament lamps, discharge lamps (including fluorescent, xenon arc lamps and high intensity discharge or HID lamps), light-emitting diodes (LEDs) and so on. For more information, see Types of lamp.

	Each type of lamp has an impact on colour appearance. The metric used to characterise the colour appearance of the light emitted by a light lamp is the correlated colour temperature (CCT), expressed in Kelvin (K). Warm white light is produced by lamps with a colour temperature below 3,000 K (reddish hues), whereas 4,000 K and above (bluish) is cool to cold.		Each type of lamp has an impact on colour appearance. The metric used to characterise the colour appearance of the light emitted by a light lamp is the correlated colour temperature (CCT), expressed in Kelvin (K). Warm white light is produced by lamps with a colour temperature below 3,000 K (reddish hues), whereas 4,000 K and above (bluish) is cool to cold.
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	= Colour rendering =		= Colour rendering =

−	BRE notes, '...colour appearance is quite separate from the colour rendering of the lamp, which is the ability of a light source to show surface colours as they should be, usually in comparison with a tungsten or daylight source. Measured on the colour rendering index (CRI) scale. A value of 0 means it is impossible to discern colours at all, and a score of 100 means no colour distortion.’	+	BRE's 'The essential guide to retail lighting' notes, '...colour appearance is quite separate from the colour rendering of the lamp, which is the ability of a light source to show surface colours as they should be, usually in comparison with a tungsten or daylight source. Measured on the colour rendering index (CRI) scale. A value of 0 means it is impossible to discern colours at all, and a score of 100 means no colour distortion.’

	CRI measures the output of lamps (artificial light) compared to natural light (daylight). It also calculates and analyses any colour that is reflected from an object that is illuminated by an artificial source.		CRI measures the output of lamps (artificial light) compared to natural light (daylight). It also calculates and analyses any colour that is reflected from an object that is illuminated by an artificial source.
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	* Types of lamp.		* Types of lamp.

−	[[Category:Education]] [[Category:Design]] [[Category:Products_/_components]]	+	[[Category:Education]] [[Category:DCN_Education_and_Training]] [[Category:Design]] [[Category:Products_/_components]] [[Category:DCN_Product_Knowledge]]

Designing Buildings at 05:56, 22 May 2020

2020-05-22T05:56:58Z

← Older revision		Revision as of 05:56, 22 May 2020
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	Comparing the Colour Rendering Index (CRI) of incandescent and LED lamps.		Comparing the Colour Rendering Index (CRI) of incandescent and LED lamps.

−	~~-----~~
	= Introduction =		= Introduction =

	Colour can only be perceived due to the presence of light. Most light sources produce different light wave combinations.		Colour can only be perceived due to the presence of light. Most light sources produce different light wave combinations.

−	Visual light comprises a wide range of different colours ~~which~~ can be seen by using a prism to split it into its constituent colours. This range of colours is called a ‘spectrum’ and the colours, each with a different wavelength, are always in the same order, from red at one end through orange, yellow, green, blue, indigo to violet at the other end. Red ~~is associated with long waves~~, green ~~with~~ medium~~-length~~ and blue ~~with short waves~~.	+	Visual light comprises a wide range of different colours. This can be seen by using a prism to split it into its constituent colours. This range of colours is called a ‘spectrum’ and the colours, each with a different wavelength, are always in the same order, from red at one end through orange, yellow, green, blue, indigo to violet at the other end. Red light has longer wavelength, green 'medium' and blue shorter.

−	In reality, there are many, many different colours in the spectral range because it is seamless, as one colour gradually merges into the next. Each ~~colour has its own~~ wavelength ~~of light which~~ stimulates the cone cells (colour receptors) in the human eye in a different way to produce the ~~various sensations~~ of colour. So, when we say that ‘the banana is yellow’, it would be more accurate to say that a sensation of yellow is generated by an area of the retina (at the back of the eye) that corresponds to where light rays from the banana are being received.	+	In reality, there are many, many different colours in the spectral range because it is seamless, as one colour gradually merges into the next. Each wavelength stimulates the cone cells (colour receptors) in the human eye in a different way to produce the sensation of colour. So, when we say that ‘the banana is yellow’, it would be more accurate to say that a sensation of yellow is generated by an area of the retina (at the back of the eye) that corresponds to where light rays from the banana are being received.

	= Colour appearance =		= Colour appearance =

−	Colour appearance refers to the visual sensation correlated with the ‘warmth’ or ‘coolness’ of the light emitted by a lamp. There are a wide variety of different types of lamps available. These include filament lamps ~~(including incandescent or halogen, although the use of most halogen lamps and some incandescent - aside from the low voltage type - was banned across Europe in 2018)~~, discharge lamps (including fluorescent, xenon arc lamps and high intensity discharge or HID lamps) ~~and~~ light-emitting diodes or LEDs (For more information see~~: LED lights)~~.	+	Colour appearance refers to the visual sensation correlated with the ‘warmth’ or ‘coolness’ of the light emitted by a lamp. There are a wide variety of different types of lamps available. These include filament lamps, discharge lamps (including fluorescent, xenon arc lamps and high intensity discharge or HID lamps), light-emitting diodes (LEDs) and so on. For more information, see types of lamp.

−	~~For more information, see types~~ of lamp.	+	Each type of lamp has an impact on colour appearance. The metric used to characterise the colour appearance of the light emitted by a light lamp is the correlated colour temperature (CCT), expressed in Kelvin (K). Warm white light is produced by lamps with a colour temperature below 3,000 K (reddish hues), whereas 4,000 K and above (bluish) is cool to cold.

−	Each type of lamp has an impact on colour appearance. According to BRE’s The essential guide to retail lighting, colour appearance refers to the ‘…visual sensation correlated with the ‘warmth’ or ‘coolness’ of the light emitted by a lamp. The metric used to characterise the colour appearance of the light emitted by a light source is the correlated colour temperature (CCT), expressed in Kelvin (K). Warm white light is produced by lamps having a colour temperature below 3,000 K (reddish hues), whereas 4,000 K and above (bluish) is cool and cold white light.’	+	In some instances, the colour of light can trigger certain behaviours. For instance, in outdoor applications, artificial light with bluish tones may have a disruptive impact on wildlife and plants that depend on warmer tones to maintain their circadian rhythm.
−		+
−	In some instances, the colour of light can trigger certain behaviours. For instance, in outdoor applications, artificial light with bluish tones may have a disruptive impact on wildlife and plants that depend on warmer ~~lighting~~ tones to maintain their circadian rhythm.	+

	= Colour rendering =		= Colour rendering =

−	BRE notes, ~~“The~~ colour appearance is quite separate from the colour rendering of the lamp, which is the ability of a light source to show surface colours as they should be, usually in comparison with a tungsten or daylight source. Measured on the colour rendering index (CRI) scale. A value of 0 means it is impossible to discern colours at all, and a score of 100 means no colour distortion.’	+	BRE notes, '...colour appearance is quite separate from the colour rendering of the lamp, which is the ability of a light source to show surface colours as they should be, usually in comparison with a tungsten or daylight source. Measured on the colour rendering index (CRI) scale. A value of 0 means it is impossible to discern colours at all, and a score of 100 means no colour distortion.’
−		+
−	CRI is a general term used to label the colour rendering characteristics of many commercial lighting products. However, the proper term is CIE Ra value, which is the international standard colour rendering index as determined by the International Commission on Illumination (or Commission internationale de l'éclairage, CIE).	+

	CRI measures the output of lamps (artificial light) compared to natural light (daylight). It also calculates and analyses any colour that is reflected from an object that is illuminated by an artificial source.		CRI measures the output of lamps (artificial light) compared to natural light (daylight). It also calculates and analyses any colour that is reflected from an object that is illuminated by an artificial source.
−
−	~~Under some lamps, the reproduced colour will be fairly accurate, but other types of lamps will not generate the same results. The accuracy of the colour is its CRI rating.~~

	= CRI rating scale =		= CRI rating scale =
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	\|}		\|}

−	A lamp’s spectrum ~~is what~~ determines its CRI. A low CRI can make it difficult to distinguish colour, so lamps that fall in this range are not ideal for installations where this characteristic is a priority. An incandescent lamp has a continuous spectrum, which means it should have a high CRI and will deliver a clear visual experience with little distortion.	+	A lamp’s spectrum determines its CRI. A low CRI can make it difficult to distinguish colour, so lamps that fall in this range are not ideal for installations where this characteristic is a priority. An incandescent lamp has a continuous spectrum, which means it should have a high CRI and will deliver a clear visual experience with little distortion.
−		+
−	A CRI score or rating is the number that measures how light output influences the perception or appearance of colour. For most indoor lighting applications a CRI value of at least 80 is recommended, according to BRE.	+

−	The preferred CRI rating will relate to the mood or experience that is required in the area being lit. If the accuracy of colour is vital, a higher CRI rating should be selected. ~~It is also preferred in settings where~~ lighting ~~should appear natural and realistic~~.	+	The preferred CRI rating will relate to the mood or experience that is required in the area being lit. If the accuracy of colour is vital, a higher CRI rating should be selected. For most indoor lighting applications a CRI value of at least 80 is recommended, according to BRE.

−	~~Highly rated CRI~~ lamps ~~are frequently used indoor such~~ as ~~neonatal wards~~, ~~museums~~, ~~textile mills, paint manufacturing facilities or even photography or film studios~~.	+	LED lamps typically fail to register a CRI higher than 90. However, they have emerged as a popular replacement, especially in Europe, for incandescent and halogen lamps (which are disappearing from the marketplace).

−	~~LED lamps typically fail to register a~~ CRI ~~higher than 90~~. However, ~~they have emerged as a popular replacement~~, ~~especially in Europe, for incandescent and halogen lamps (~~which ~~are disappearing from~~ the ~~marketplace). This has prompted the development of another form of~~ colour rendering ~~measurement to replace CRI~~.	+	CRI is a general term used to label the colour rendering characteristics of many commercial lighting products. However, the correct international term is the CIE Ra value, which is the international standard colour rendering index as determined by the International Commission on Illumination (or Commission internationale de l'éclairage, CIE).

	= Related articles on Designing Buildings Wiki =		= Related articles on Designing Buildings Wiki =

Editor at 18:15, 21 May 2020

2020-05-21T18:15:09Z

← Older revision		Revision as of 18:15, 21 May 2020
Line 81:		Line 81:
	* Lighting of construction sites.		* Lighting of construction sites.
	* Luminaire efficacy.		* Luminaire efficacy.
−	* Rights to light.
	* The Anatomy of Colour.		* The Anatomy of Colour.
	* Types of lamp.		* Types of lamp.

	[[Category:Education]] [[Category:Design]] [[Category:Products_/_components]]		[[Category:Education]] [[Category:Design]] [[Category:Products_/_components]]

Editor at 18:12, 21 May 2020

2020-05-21T18:12:27Z

← Older revision		Revision as of 18:12, 21 May 2020
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	* LED lights.		* LED lights.
	* Lighting.		* Lighting.
−	* Lighting ~~energy numeric indicator LENI~~.	+	* Lighting for circadian rhythms.
	* Lighting of construction sites.		* Lighting of construction sites.
	* Luminaire efficacy.		* Luminaire efficacy.

Editor at 18:09, 21 May 2020

2020-05-21T18:09:53Z

← Older revision		Revision as of 18:09, 21 May 2020
Line 77:		Line 77:
	* Lamp efficacy.		* Lamp efficacy.
	* LED lights.		* LED lights.
−	* Light pollution.
	* Lighting.		* Lighting.
	* Lighting energy numeric indicator LENI.		* Lighting energy numeric indicator LENI.

Editor at 18:07, 21 May 2020

2020-05-21T18:07:11Z

← Older revision		Revision as of 18:07, 21 May 2020
Line 65:		Line 65:
	* Colour appearance.		* Colour appearance.
	* Colour in the built environment.		* Colour in the built environment.
		+	* Commercial lighting.
	* Daylight benefits in healthcare buildings.		* Daylight benefits in healthcare buildings.
	* Daylight factor.		* Daylight factor.

Editor at 18:05, 21 May 2020

2020-05-21T18:05:02Z

← Older revision		Revision as of 18:05, 21 May 2020
Line 63:		Line 63:
	= Related articles on Designing Buildings Wiki =		= Related articles on Designing Buildings Wiki =

		+	* Colour appearance.
	* Colour in the built environment.		* Colour in the built environment.
	* Daylight benefits in healthcare buildings.		* Daylight benefits in healthcare buildings.
Line 82:		Line 83:
	* Rights to light.		* Rights to light.
	* The Anatomy of Colour.		* The Anatomy of Colour.
		+	* Types of lamp.

	[[Category:Education]] [[Category:Design]] [[Category:Products_/_components]]		[[Category:Education]] [[Category:Design]] [[Category:Products_/_components]]