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IS 7942:1976 is the Indian Standard (BIS) for daylighting of educational buildings. This code of practice provides guidelines for the effective use of natural light in educational buildings. It specifies recommended daylight factors for various spaces like classrooms, libraries, and labs to ensure visual comfort and reduce energy consumption. The code also outlines methods for calculating daylight levels and gives design recommendations for windows and shading.
Code of practice for daylighting of educational buildings
Overview
Status
Current
Usage level
Specialized
Domain
Architectural — Functional Requirements in Buildings
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
Practical Notes
! While this standard is still listed as active (reaffirmed 2002), its principles are more comprehensively covered in the latest National Building Code (NBC) of India, Part 8, Section 1 - Lighting and Ventilation.
! Modern daylighting analysis is predominantly done using simulation software (e.g., DiaLUX, Radiance) which provides more accurate results than the manual methods (like BRS protractors) detailed in the appendix.
! Achieving the minimum daylight factor is not the only goal; controlling glare through appropriate shading devices and window placement is equally critical for visual comfort.
BS EN 17037:2018BSI / CEN - British Standards Institution, UK / European Committee for Standardization
HighCurrent
Daylight in buildings
Provides a comprehensive framework for daylighting in all buildings, including educational ones, but uses more advanced metrics.
BS 8206-2:2008BSI - British Standards Institution, UK
HighWithdrawn
Lighting for buildings. Code of practice for daylighting
A direct counterpart in methodology, heavily reliant on the Daylight Factor (DF) metric, similar to IS 7942.
ANSI/IES LP-2-18IES - Illuminating Engineering Society, USA
MediumCurrent
Lighting Practice: Lighting for Educational Facilities
Specifically targets educational buildings but integrates daylighting within a broader context of total (electric and natural) lighting design.
CIBSE LG5:2018CIBSE - Chartered Institution of Building Services Engineers, UK
HighCurrent
Lighting for Education
A highly influential design guide focused exclusively on lighting for educational facilities, providing detailed daylighting recommendations.
Key Differences
≠IS 7942 exclusively uses the static Daylight Factor (DF) metric, based on a standard overcast sky. Modern standards like BS EN 17037 use dynamic, climate-based metrics such as Daylight Autonomy (DA) and Useful Daylight Illuminance (UDI).
≠The Indian standard provides only basic qualitative advice on glare control. International standards (e.g., BS EN 17037) mandate quantitative analysis using metrics like Daylight Glare Probability (DGP).
≠IS 7942 is a single, non-climate-specific code for all of India. Modern international approaches often require the use of local climate files (e.g., TMY weather data) for simulation to create climate-responsive designs.
≠Modern standards like BS EN 17037 and CIBSE LG5 explicitly require evaluation of 'View Out', assessing the quality of the view through windows, a factor not considered in IS 7942.
Key Similarities
≈All standards, including IS 7942, are founded on the primary goal of providing sufficient natural light to perform visual tasks and enhance occupant comfort and well-being in learning environments.
≈The concept of a 'working plane' (a horizontal plane at desk height where light is measured) is a fundamental principle shared by IS 7942 and all its international counterparts.
≈There is a common emphasis on architectural design elements, such as placing windows high on the wall (close to the ceiling) to maximize daylight penetration depth into the room.
≈Both the Indian code and international standards recognize the importance of room surface reflectances in maximizing interior light distribution and recommend using light-colored finishes.
Parameter Comparison
Parameter
IS Value
International
Source
Primary Daylighting Metric
Daylight Factor (DF)
Target illuminance levels (e.g., 300 lux) for a percentage of time
BS EN 17037:2018
Minimum Daylight Factor for Classrooms
2% (referred to as daylight penetration)
2% (Average DF was a common recommendation)
BS 8206-2:2008
Working Plane Height
0.85 m above floor
0.75 m for secondary schools, 0.6 m for primary schools
CIBSE LG5:2018
Target Illuminance Level (Classrooms)
~100 lux (implied by 2% DF under 5000 lux sky)
300 - 500 lux on desks
ANSI/IES LP-2-18
Glare Assessment Method
Qualitative advice (orientation, shading)
Quantitative Daylight Glare Probability (DGP)
BS EN 17037:2018
Sky Condition for Calculation
Standard CIE Overcast Sky
Uses annual, climate-specific weather data files for simulation
BS EN 17037:2018
Consideration of View
Not specified as a performance metric
Mandatory requirement with three levels of quality: 'High', 'Medium', 'Minimum'
BS EN 17037:2018
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
Minimum Daylight Factor for Classrooms2.0%
Minimum Daylight Factor for Libraries (Reading Tables)3.0%
Minimum Daylight Factor for Laboratories (General)3.0%
Minimum Daylight Factor for Art Rooms4.0%
Minimum Daylight Factor for Corridors and Stairs1.0%
What is the minimum recommended daylight factor for a school classroom?+
2.0 percent, as specified in Table 1.
What is a Daylight Factor (DF)?+
It is the ratio of the daylight illumination at a point on a given plane inside a room to the simultaneous illumination on a horizontal plane from an unobstructed sky, expressed as a percentage (Clause 3.4).
Which spaces require the highest daylight factor in an educational building?+
Art rooms require the highest minimum daylight factor of 4.0% (Table 1).
Does this code cover artificial lighting?+
It briefly touches upon supplementary artificial lighting but is primarily focused on daylighting. For detailed electrical and artificial lighting design, other codes like IS 3646 and the NBC should be referred.