Code of Practice for Daylighting of Factory Buildings

IS 6060 - Scope: Key Formulas, Tables & Specifications

Scope Summary:

• Applies to daylighting apertures including horizontal/inclined roof lighting.
• Design illumination value: 16,000 Lux (sun + skylight) per IS:2440-1968.
• Use diffusing glass with known transmission factors to reduce glare.
• Illumination on working plane calculated by:
  • Point-to-point method (if area & location known)
  • Lumen method (if required illumination is given)

Important Tables:

Table 3: Transmission Factors of Glazing Materials

Table 4: Maintenance Factors for Glass (Effect of Dust & Cleaning)

Key Formula for Final Illumination:

[ E = E_0 \times T \times M ]

Where:

• (E) = Final illumination on working plane (Lux)
• (E_0) = Incident illumination (16,000 Lux)
• (T) = Transmission factor of glazing
• (M) = Maintenance factor (from Table 4)

Notes:

• Round off values as per IS:2-1960.
• Use diffusing

IS 6060 - Recommended Values of Illumination (Clause 3.1 & Table 1)

Key Points:

• Illumination values are given in lux for various industrial tasks.
• Daylight Factor (DF) = Illumination (lux) ÷ 80.
• Supplementary local lighting is often recommended for detailed tasks.
• Special attention to color quality of light is advised for certain processes.

Sample Recommended Illumination Levels

Formula to Calculate Daylight Factor (DF):

DF = \frac{\text{Illumination (lux)}}{80}

Notes:

• Use optical aids for very fine work (>1500 lux).
• Supplementary lighting required for gauge glasses, instrument panels.
• Illumination values vary widely depending on task precision and safety requirements.

flowchart TD
    A[Industrial Task] --> B{Precision Level}
    B -->|General| C[150-300 lux]
    B -->|Medium| D[300-700 lux]
    B -->|Fine| E[700-1500 lux]
    B -->|Very Fine| F[>1500 lux + Optical aids]
    C --> G[Daylight Factor ~ 2-4%]
    D --> H[Daylight Factor ~ 4-9%]
    E --> I[Daylight Factor ~ 9-19%]
    F --> J[

IS 6060: General Principles - Key Formulas, Tables & Specifications

1. Recommended Illumination Values (Clause 3.1, Table 1)

• Illumination (Lux) and Daylight Factor (DF) are specified for various industrial processes.
• Conversion:
  [ \text{Daylight Factor (DF)} = \frac{\text{Illumination (Lux)}}{80} ]

* Optical aids recommended for very fine tasks.

2. Daylighting Apertures & Transmission Factors (Clause 7.6.2, Table 3)

• Total illumination from sun + skylight: 16,000 Lux (design basis).
• Use diffusing glass to reduce glare and distribute light evenly.
• Transmission factors of glazing materials:

3. Design Notes

• Special attention to colour quality of light in processing areas.
• Supplementary local lighting recommended for precision tasks

IS 6060: Level of Natural Illumination - Key Points

1. Recommended Illumination Levels (Clause 4.1 & Table I)

• The design of openings and glazing should ensure natural illumination meets the values specified in Table I (refer to IS 6060 or IS 3646 Part II for exact values).
• These values depend on the type of work and visual tasks.

2. Combined Lighting (Clause 4.3)

• For work during dusk or low daylight, artificial lighting must supplement natural light so that the reduction in daylight is imperceptible.
• Critical for precision work involving eye strain.

3. Reference Standards

• Terminology: IS 2440-1968
• Illumination & Glare Index: IS 3646 (Part II)-1966

Typical Recommended Illumination Levels (from IS 3646 Part II)

Summary Diagram: Lighting Design Concept

flowchart LR
    A[Natural Daylight] --> B[Work Area]
    C[Artificial Lighting] --> B
    B --> D[Visual Task]
    style B fill:#f9f,stroke:#333,stroke-width:2px
    note right of B
      Combined lighting ensures
      illumination level is maintained
      for precision and comfort.
    end note

Ensure window size, glazing type, and artificial lighting are designed to maintain these illumination levels continuously.

Key Formulas, Tables & Specifications for Fenestration (IS 6060)

1. Daylight Factor (DF) Basics

• Includes sky and reflected light components.
• Assumed clause transmission = 0.85 for glare design sky (Clause 6.1).
• DF = (Indoor illuminance from daylight / Outdoor illuminance under overcast sky) × 100%.

2. Fenestration Area Recommendations

3. Transmission Factors of Glazing Materials (Table 3, Clause 7.6.2)

4. Illumination Design for Roof Lighting (Clause 7.6.2)

• Total illumination (sun +

IS 6060: Design Principles & Aids for North Lights

Key Points from IS 6060:

• Efficiency: Horizontal or low-pitched glazing is more efficient than vertical/steep glazing (Clause 6.5).
• Sunlight Control: Avoid direct sunlight glare on work areas; use Table 2 for sunshine hours on north-facing walls by latitude.
• Sill Height & Bay Width: Common sill heights are 5.0m, 6.5m, and 8.0m; bay widths typically 4m, 7m, and 10m.
• Daylight Factor & Fenestration: Figures 10-13 provide daylight factors (%) at work plane center for 2, 4, 6, and 8 bay factories.

Table 2 (Sunshine Hours on North Walls Example Extract)

(Refer full Table 2 for detailed timings)

Design Aids Summary:

Design Formula for Daylight Factor (Approximate):

[ \text{Daylight Factor} = \frac{\text{Area of glazing} \times \text{Sky Luminance Factor}}{\text{Area of floor} \times \text{Distance Factors}} ]

*(Use Figures

Maintenance Factors for Glazing (IS 6060 - Clause 7.7, Table 4)

Maintenance factor (MF) accounts for reduction in glass light transmission due to dust and maintenance condition. Values depend on glass orientation and environment:

Usage:

• Multiply the initial glass transmission factor by the maintenance factor to get effective transmission.
• For example, clean vertical glazing with 0.85 transmission:
  Effective Transmission = 0.85 × 0.9 = 0.765

Additional Notes:

• Transmission factors for glazing materials (Table 3, Clause 7.6.2) range from 0.55 to 0.85 depending on type.
• For daylight design, use a base transmission coefficient of 0.85 and adjust for maintenance using above factors.
• Horizontal or inclined glazing exposed to direct sunlight requires diffusing glass to reduce glare.

flowchart LR
    A[Initial Glass Transmission] --> B[Apply Maintenance Factor]
    B --> C[Effective Transmission]
    C --> D[Daylighting Calculations]

This ensures realistic daylight availability considering maintenance and environmental conditions.

IS 6060: Transmission Factors of Glazing Materials

Key Tables & Values

Table 3: Transmission Factors of Common Glazing Materials

Table 4: Maintenance Factors (Effect of Dust & Dirt)

Important Notes:

• Design Transmission Coefficient: 0.85 (Clause 7.4.2) is typical for clean glazing.
• Adjust for dust, sashes, bars, and obstructions by applying maintenance factors.
• For roof lighting, use diffusing glass with known transmission factors to avoid glare (Clause 7.6.2).
• Total illumination from sun and skylight can be assumed as 16,000 Lux for design.
• Final illumination can be calculated by point-to-point or lumen method depending on known parameters.

Formula for Effective Transmission Factor (τ_eff):

[ \tau_{\text{eff}} = \tau_{\text{material}} \times \text{Maintenance Factor} ]

flowchart LR
    A[Glazing Material] --> B[Transmission Factor (τ)]
    B --> C[Apply Maintenance Factor]
    C --> D[Effective Transmission Factor (τ_eff)]
    D --> E

IS 6060: Effects of Obstructions on Daylighting - Key Points & Formulas

1. Illumination Values & Design Time

• Total illumination (sun + sky) on horizontal/inclined roof openings: 16,000 Lux (IS:2440-1968).
• Design for solar altitude ~15°; illumination increases by 1.2 to 1.5 times at noon on clear days.

2. Transmission Factors of Glazing Materials (Table 3)

3. Calculation Methods for Interior Illumination

• Point-to-point method: When area and location of openings are known.
• Lumen method: When required illumination is specified.

4. Adjustments for Obstructions

• Reduce transmission for dust, sashes, bars, beams, trusses.
• Account for tall machinery and louvres reducing daylight.

5. General Formula for Available Illumination:

[ E = E_0 \times \tau \times K ]

Where:

• (E) = Illumination on working plane (Lux)
• (E_0) = Total illumination outside (16,000 Lux)
• (\tau) = Transmission factor of glazing
• (K) = Reduction factor for obstructions (0 < K ≤ 1)

Visual Concept: Effect of Obstruction on Daylight Transmission

flowchart LR
    Sunlight[Sunlight & Sky Illumination (16,000 Lux)]
    Glazing[Glazing Transmission (τ)]
    Obstruction[Obstruction Factor (K)]
    Illumination[Ill

IS 6060: Integration of Daylighting and Artificial Lighting

Key Points from Clause 7.6.2 & Related Clauses

• Total illumination from sun and skylight:
  Use 16,000 Lux as the design illumination value for horizontal/inclined roof lighting (IS: 2440-1968).

• Transmission factors of glazing materials (Table 3):

• Calculation methods:

  • Point-to-point method: When area & location of openings are known.
  • Lumen method: When required illumination is given.

• Daylight Factor (DF):
  Percentage of outdoor illuminance reaching the working plane. Use tables/figures (7.4.3, Figs 10-13) for factory bays with varying sill heights (5m, 6.5m, 8m) and bay widths (4m, 7m, 10m).

• Design considerations:

  • Use diffusing glass to avoid glare.
  • Adjust design illumination by factor 1.2 to 1.5 for solar altitude >15°.
  • Fenestration area typically expressed as % of floor area (e.g., 17% for continuous horizontal roof lights).

Simplified Formula for Illuminance on Working Plane (E):

[ E = E_{outdoor} \times \tau \times DF ]

Where:

• (E_{outdoor} = 16,000 , \text{Lux}) (design illumination)
• (\tau) = Transmission factor of glazing
• (DF) = Daylight Factor (from tables/figures

IS 6060: Key Formulas & Tables for Daylight Illumination

1. Design Sky Illumination (Clause 7.4.3)

• Design sky corresponds to solar altitude 15°.
• Actual daylight illumination at noon on clear days =
  [ \text{Illumination} = (1.2 \text{ to } 1.5) \times \text{Value from Fig. 10-13} ]
• Increase due to total illumination on roof + sky luminance.

2. Work Plane Illumination (Fig. 10-13)

• Illumination depends on:
  • Bay Width: 4 m, 7 m, 10 m
  • Sill Height: 5.0 m, 6.5 m, 8.0 m
  • Percent Daylight Factor and Percent Fenestration
• Use respective figures (10 to 13) for 2, 4, 6, 8-bay north light factories to find illumination at work plane center.

3. Horizontal/Inclined Roof Lighting (Clause 7.6.2)

• Total illumination (sun + sky) ≈ 16,000 Lux.
• Use diffusing glass with known transmission factors.
• Calculation methods:
  • Point-to-point method: when area & location of openings known.
  • Lumen method: when required illumination is given.

4. Transmission Factors of Glazing Materials (Table 3)

5. **General Design

IS 6060 - Health and Ergonomic Considerations: Key Illumination Specifications

The code emphasizes proper illumination levels in industrial buildings to ensure health, safety, and ergonomic efficiency. Recommended illumination values (lux) and daylight factors (DF) for various industrial processes are tabulated below:

Notes:

• Daylight Factor (DF) = Illumination (Lux) ÷ 80 (approximate conversion).
• Special attention to colour quality of light is essential for processing areas.
• Supplementary local lighting recommended for precision tasks.
• Optical aids should be used where necessary.

Summary Formula for Daylight Factor (DF):

[ \text{DF} = \frac{\text{Illumination (Lux)}}{80} ]

flowchart TD
    A[Industrial Process] --> B[Recommended Illumination (Lux)]
    B --> C[Daylight Factor (DF) = Lux/80]
    C --> D[Ergonomic Lighting Design]
    D --> E[Improved Health & Productivity]

This ensures ergonomic lighting suitable for various factory tasks, minimizing eye strain

IS 6060: Key Tables and Formulas for Illumination (Appendices)

1. Recommended Illumination Levels (Table 1)

• Illumination values (Lux) for various industrial tasks.
• Daylight Factor (DF) = Illumination (Lux) ÷ 80.

*Note: Optical aids recommended for very fine work.

2. Maintenance Factors for Glass (Table 4)

3. General Formula for Daylight Factor

[ \text{Daylight Factor (DF)} = \frac{\text{Illumination (Lux)}}{80} ]

Summary:

• Use Table 1 for selecting illumination levels per industrial activity.
• Adjust for maintenance using Table 4 for glass transmission.
• Calculate daylight factor by dividing lux value by 80.
• Supplementary local lighting is recommended for precision tasks and instrument panels.
• Pay attention to color quality of light for all processing areas.

flowchart TD
    A[Industrial Task] -->|Refer Table