Light Reflectance Value
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In architecture, Light Reflectance Value (LRV), is a measure of the percentage of visible and usable light that is reflected from a surface when illuminated by a light source. The measurement is most commonly used by design professionals like architectural color consultants, architects, environmental graphic designers and interior designers.
LRVs are frequently reported on paint chips or paint samples. The values are used by lighting designers to calculate the number and type of light fixtures needed to provide a certain amount of light for interior spaces.
Designers of buildings need to comply with the Building Regulations applicable to the structure under consideration. Since 2004 guidance has existed on access to and use of buildings. The guidance is particularly concerned with provisions to assist the disabled, including those who are visually impaired. The guidance highlights the need for certain surfaces and features to contrast visually with their surroundings. Areas of particular interest are:
- wall to ceiling and wall to floor junctions;
- exposed edges of sloping floors;
- seating and its surroundings;
- leading edges of doors, door opening furniture and door surfaces;
- sanitary fittings and grab bars.
This is relevant to a wide range of non-residential buildings, e.g. hospitals, schools, hotels, theatres, etc.
Codes of practice
The current guidance in the Regulations and in the relevant Codes of Practice, BS 8300:2009 is that adequate visual contrast is provided if the Light Reflectance Values (LRV) of the contrasting areas differ by at least 30 points. The current British Standard for the measurement of LRV is BS8493:2008+A1:2010.
Manufacturers are advised, for example, by the Guild of Architectural Ironmongery to publish LRV values for their products. Designers are beginning to demand them.
On signage with words or pictograms The Americans with Disabilities Act Accessibility Guidelines (ADAAG) recommends a 70% light reflectance value but this is not a strict requirement. There are a number of color combinations in the 60-70% range that work well, which is why 70% is not a requirement.
Color contrast is determined by the calculations [(B1 - B2) / B1] x 100
B1 = light reflectance value (LRV) of lighter area, B2 = light reflectance value (LRV) of darker area, (ADA Accessibility Guidelines)
- Jeffries, John. "The use of Light Reflectance Values (LVRs) in achieving visual contrast". BRE CIAT RIBA Technical Taskforce. Retrieved 1 May 2013.
- Bradshaw, Vaugh, P.E. Building Control Systems. New York: John Wiley & Sons, Inc. Second Edition, 1993.
- LRV - What is it? How is it used?
- ADA Accessibility Guidelines for Buildings and Facilities (ADAAG)
- Measurement: http://www.ceram.com/industries/construction/building-products/light-reflectance-value-testing
Media related to Light Reflectance Value at Wikimedia Commons