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.

IS 7942

: 1976

Code of practice for daylighting of educational buildings

CurrentSpecializedCode of PracticeBIMArchitectural · Functional Requirements in Buildings

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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

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%

Assumed Sky Luminance for Overcast Sky5000 lux

Key Formulas

Daylight Factor (DF) = (Ei / Eo) x 100

Total DF = Sky Component (SC) + Externally Reflected Component (ERC) + Internally Reflected Component (IRC)

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.