Handbook on Functional Requirements of Industrial Buildings (Lighting and Ventilation)

Scope of IS SP Part 32: Solar Heat and Thermal Transmittance

This part covers estimation of solar heat loads and thermal transmittance (U-values) for building surfaces to aid in ventilation and thermal comfort design.

Key Tables & Formulas

1. Solar Heat Transmission Factors (S) — Table 21

Note: Adjust S for color: medium ×0.8, light ×0.6.

2. Maximum Solar Intensity (kW/m²) — Tables 19 & 20

• Walls (Table 19): Varies with latitude & orientation (e.g., South-facing wall at 30° latitude: 0.73 kW/m²)
• Roofs (Table 20): Flat roof ~0.8 to 1.03 kW/m² depending on latitude

3. Thermal Transmittance (U-values) — Table 22

| Construction Type | U-Value (

Key Formulas and Specifications from IS SP Part 32 on Physiological Needs and Comfort

1. Heat Balance Equation (Clause 10.1.3)

[ \boxed{ M - W = E \pm R \pm C \pm S } ]

• M = Metabolic heat generation (rate)
• W = Work done (rate)
• E = Evaporative heat loss (rate)
• R = Radiative heat loss/gain (rate)
• C = Convective heat loss/gain (rate)
• S = Heat storage in the body (rate)

The body maintains thermal equilibrium at 37°C by balancing these terms. Evaporation is critical in hot/humid environments.

2. Metabolic Heat Generation by Activity (Clause 1.1, Table A-1.1)

3. Comfort Temperature Limits (Clause 11.3)

• Effective ambient temperature in summer: ≤ 27°C for moderate work.
• No perceptible sweating should occur under comfort conditions.

4. Control of Heat - Wet Bulb vs Dry Bulb Limits (Clause 11.6, Table 12)

Note: Efficiency decreases with higher dry-bulb temperatures even if wet-bulb is controlled. Refrigeration recommended beyond these limits.

Summary Diagram: Heat Exchange Processes

flowchart LR
    M(Metabolic Heat) -->|Generates| Body[Human Body]
    Body -->|Work Done| W

Lighting Requirements & Design Principles (IS SP Part 32, Clause 6.5)

Key Formulas

• Room Index (RI):

[ RI = \frac{\text{Width} \times \text{Length}}{\text{Mounting height above working plane} \times (\text{Width} + \text{Length})} ]

• Coefficient of Utilization (CU):
  Ratio of luminous flux reaching the working plane to the total flux emitted by lamps, depends on luminaire type, room index, and surface reflectances.

Important Tables

Table 7: Initial Lumen Output of Lamps

Table 8: Luminaire Classification by Flux Distribution

Design Principles

• Use Lumen Method for uniform illumination:
  Calculate total luminous flux needed based on area and required illuminance.

• Place luminaires close to walls for work areas near walls.

• Select luminaire type based on desired flux distribution and room reflectance.

flowchart TD
    A[Determine Room Dimensions] --> B[Calculate Room Index (RI)]
    B --> C[Select Luminaire Type (Table 8)]
    C --> D[Find Co

Key Formulas, Tables & Specs for Daylighting & Skylight Design (IS SP Part 32)

1. Solar Altitudes (Clause 5.1, Table 2)

Solar altitude varies by latitude, day, and time, critical for daylight design:

2. Horizontal Illumination from Clear Sky (Fig. 1)

• Illumination (excluding direct sunlight) ranges 0-1000 lux depending on solar altitude.
• Use this to estimate skylight contribution.

3. Daylight Factor (Clause 5.2.3)

• Defined as ratio of indoor illuminance to outdoor illuminance under overcast sky.
• Required daylight factors for factory interiors are given in Table 1 (not provided here).
• Glazing area to floor area ratio depends on fenestration position.
• Use daylight protractors (CBRI method) for sky component estimation.

4. Fenestration Design (Clause 5.3.1.5)

• Double-pitch or horizontal roof glazing:
  • Direct sunlight incidence expected.
  • Total illumination (sun + skylight) ~ 10,000 lux.
  • Use diffusing glass or translucent materials to avoid glare.
  • Typical glazing area:
    • Monitor roof vertical glazing: 30% of floor area.
    • Monitor roof with 60° slope glazing: 16% of floor area.

Summary Table for Glazing Area Ratios

Key Formulas & Tables for Artificial Lighting Systems (IS SP Part 32)

1. Room Index (K) Calculation

Used to determine utilization factor based on room geometry and luminaire type (direct, semi-direct, diffuse):

[ \boxed{ K = \frac{\text{Width} \times \text{Length}}{\text{Mounting height above working plane} \times (\text{Width} + \text{Length})} } ]

2. Initial Lumen Output of Lamps (After 100 Burning Hours)

3. Luminaire Classification by Flux Distribution

4. Lamp Types: Efficiency & Life

Ventilation Fundamentals per IS SP Part 32

1. Key Formula for Ventilation Quantity (Clause 13.1):

[ \text{Quantity of air (m}^3/\text{min)} = \frac{0.0496 \times \text{Sensible heat gain (Watts)}}{\text{Temperature rise (°C)}} ]

• Sensible heat includes heat from sun, equipment, occupants, etc.
• Temperature rise = Indoor temperature - Outdoor temperature.

2. Practical Guidance (Clause 13.3):

• Use the larger of air quantity calculated from sensible heat or latent heat.
• Usually, sensible heat governs ventilation needs.
• Applies to both natural and mechanical ventilation.

3. Mechanical Ventilation Wind Speeds (Clause 14.4.1.1):

(Refer to full table for other locations.)

4. Exhaust Capacity of Robertson Ventilators (Clause 14.3.1.1):

Summary:

• Calculate ventilation air quantity mainly from sensible heat load.
• Adjust for latent heat if significant.
• Use local wind speed data for natural/mechanical ventilation design.
• Robertson ventilators' capacity varies with temperature difference and wind speed.

Natural Ventilation Techniques (IS SP Part 32)

Key Formula for Ventilation Quantity (Clause 13.1):

[ \text{Quantity of air (m}^3/\text{min)} = \frac{0.0496 \times \text{Sensible Heat Gain (W)}}{\text{Temperature Rise (°C)}} ]

• Sensible Heat Gain: Heat from sun, machinery, occupants, etc.
• Temperature Rise: Indoor temp. above outdoor temp.

Important Specifications:

• Use the larger of sensible or latent heat-based ventilation rates (Clause 13.3).
• Typical temperature rise assumed for calculation: 5°C (example in Clause 14.4.3.1).
• Air changes per hour (ACH) can be calculated as:

[ ACH = \frac{\text{Ventilation rate (m}^3/\text{min)} \times 60}{\text{Building volume (m}^3)} ]

Example Summary (Clause 14.4.3.1):

Wind Speed Data (Clause 14.4.1.1):

Ventilation Design Tips:

• Locate inlet openings on the windward side and outlets on the leeward side.
• Use monitors or ventilated roofs for hot air exhaust.
• Consider radiation shields with ventilated air gaps to reduce heat gain (see Fig. 17 in code).

flowchart LR
    OutsideAir -->|Inlet Openings| Building[Building Interior]
    Building -->|Hot Air Exhaust| Outlet[Outlet Openings (Monitor)]
    Building -->|Heat Sources|

Mechanical Ventilation Methods (IS SP Part 32)

Types of Mechanical Ventilation (Clause 15.2)

• Exhaust Ventilation: Air is removed by fans; fresh air enters through openings.
• Positive Ventilation: Air is supplied by fans/blowers; can include cooling (evaporative or AC).
• Combination: Both exhaust and positive ventilation used.

Key Data: Wind Speeds for Mechanical Ventilation (Clause 14.4.1.1, Table 15)

(Use local wind speed data to size ventilation equipment)

Exhaust Capacity of 60 cm Robertson Ventilators (Clause 14.3.1.1, Table 14)

Heat Load & Thermal Control per IS SP Part 32

Key Formulas:

• Solar Heat Intensity on Horizontal Surface:

  [ I_h = I_d \sin a + I_f ]

• Solar Heat Intensity on Vertical Surface:

  [ I_v = I_d \cos a \cos B + 0.5 I_r + 0.1 I_h ]

Where:

• (I_d) = Direct solar radiation intensity
• (I_f) = Diffuse radiation intensity
• (I_r) = Reflected radiation intensity
• (a) = Altitude angle of the sun
• (B) = Angle between surface normal and sun direction

Maximum Solar Heat Intensities (at Sea Level):

Refer to Table 19 & 20 for detailed values by orientation and latitude.

Heat from Fuel:

[ \text{Heat Load (kW)} = \text{Calorific Value (kJ/kg)} \times \text{Fuel Consumption (kg/s)} ]

Adjust for:

• Incomplete combustion losses
• Flue heat losses
• Heat absorbed by stock/materials

Thermal Control Recommendations:

• Use 2.5 cm air space with insulating boards and GI sheets for roof insulation.
• Apply shading devices like thatch roofs, Mangalore tiles, or venetian blinds to reduce solar gain.
• Consider reflective or heat-absorbing glass types for windows.
• Account for local atmospheric conditions (humidity, altitude) when estimating solar heat loads.

flowchart LR
    A[Sun's Radiation] -->|Direct + Diffuse + Reflected| B[Building Surface]
    B --> C{Surface Type}
    C -->|Vertical Wall| D[Use Table 19

Radiation Shielding in Industrial Settings (IS SP Part 32 - Clause 12.1.5)

Key Concept:
Radiant heat from hot surfaces (furnaces, molten metal) is best controlled by reflective shields placed between the heat source and workers.

Important Specifications:

• Shield Material: Highly reflective sheets like polished aluminium or tin.
• Shield Placement:
  • Not in direct contact with hot surface to avoid secondary radiation.
  • Provide an air gap (~2.5 cm or more) for air circulation to carry away heat upward.
• Air Space: Minimum 2.5 cm air space recommended between hot surface and shield.

Reflectivity & Emissivity Table (Thermal Radiation)

High reflectivity = low emissivity → better shielding

Design Formula for Radiant Heat Control:

[ Q = \sigma \cdot \epsilon \cdot A \cdot (T_s^4 - T_a^4) ]

• (Q) = heat transfer by radiation (W)
• (\sigma) = Stefan-Boltzmann constant (5.67 \times 10^{-8} , W/m^2K^4)
• (\epsilon) = emissivity of shield surface
• (A) = area of shield (m²)
• (T_s), (T_a) = absolute temperatures of source and ambient (K)

Shielding Setup (Conceptual Diagram)

graph LR
  HotSurface[Hot Surface (Furnace)] -->|Radiant Heat| ReflectiveShield[Reflective Shield]
  ReflectiveShield -->|Reflected Heat| HotSurface
  ReflectiveShield -->|Transmitted Heat| Worker[Worker Area]
  subgraph AirGap
    AirSpace[Air

Key Formulas & Tables for Air-Conditioning & Cooling Systems (IS SP Part 32)

1. Solar Heat Intensity Calculation

• Direct solar heat intensity on horizontal surface:

  [ I_h = I_d \sin a + I_f ]

• Total solar heat on vertical surface facing direction B° from sun:

  [ I_v = I_d \cos a \cos B + 0.5 I_r + 0.1 I_h ]

Where:

• (I_d) = Direct solar radiation intensity
• (I_f) = Diffuse radiation intensity
• (I_r) = Reflected radiation intensity
• (a) = Altitude angle of the sun
• (B) = Angle of wall from sun direction

2. Maximum Solar Intensity on Vertical Walls (Table 19)

3. Maximum Solar Intensity on Roofs (Table 20)

Measurement and Evaluation of Ventilation (IS SP Part 32)

Key Formulas:

• Ventilation Rate (Q):
  [ Q = A \times V ] Where:

  • ( Q ) = Airflow rate (m³/s)
  • ( A ) = Effective (free) area of opening (m²)
  • ( V ) = Average velocity of airflow (m/s) measured by vane-anemometer or pitot tube.

• Tracer Gas Method:
  Used for small rooms by measuring decay/change in inert gas concentration to calculate airflow rate.

Measurement Procedure:

• Traverse the cross-sectional area of openings/ducts to get average velocity.
• Measure free area of openings accurately.
• Multiply average velocity by free area for ventilation rate.

Specifications for Openings (Clause 2.5):

Note: For low velocity ( V_x < 0.75 , m/s ), reduce normal ( K ) values by ~20% at ( V_x = 0.25 , m/s ).

Wind Speed Data for Mechanical Ventilation (km/h):

(Refer Clause 14.4.1.1 for full table)

Summary Diagram:

flowchart LR
    A[Measure Velocity (V)] --> B[Measure Free Area (A)]
    B --> C[Calculate Ventilation Rate Q = A × V]
    C --> D{Is Q adequate?}
    D -- Yes --> E[Ventilation OK]
    D -- No --> F[Consider Mechanical Ventilation]
``

IS SP Part 32: Ventilation for Contaminant Control (Clauses 18.3, 19.1.2, 19.2.2)

Key Formulas

• Air required for vapor dilution (m³/kg evaporation):

[ \text{Air required} = \frac{\text{Molecular weight of liquid} \times \text{TLV}}{K} ]

• Detailed formula:

[ \text{Air required} = \frac{403 \times \text{sp. gr. of liquid} \times 10^6 \times K}{31 \times \text{Molecular weight} \times \text{TLV}} ]

Where:

• K = coefficient (3 to 10, depending on solvent and conditions)
• TLV = Threshold Limit Value (ppm or mg/m³)

Capture Velocities (Table 18, Clause 19.1.2)

Measurement Methods (Clause 18.3)

• Natural ventilation rate: Measured by vane-anemometer velocity × free area of openings.
• Tracer gas technique: Used in small rooms to find ventilation rate by monitoring inert gas concentration decay.

Notes

• Ensure exhaust fans are sized to overcome duct resistance and air cleaning devices.
• Ventilation must reduce contaminant concentration below TLV.

flowchart LR
    A[Contaminant Source] --> B[Capture Velocity Zone]
    B --> C[Exhaust Opening]
    C --> D[Exhaust Fan]
    D --> E[Air Cleaning Device]
    E --> F[Discharge to

IS SP Part 32: Colour and Colour Rendering in Lighting

Key Points from Clause 3.1.5:

• Colour Rendering: Ability of a light source to reveal the colours of objects faithfully compared to natural light.
• Critical for tasks like cotton grading, paint matching, and inspections.
• Lamps are selected based on colour rendering rather than luminous efficiency for such tasks.
• Some light sources (e.g., mercury vapour lamps) are used to enhance contrast by colour distortion.

Important Formulas & Tables:

1. Room Index (for lighting design)

[ \text{Room Index} = \frac{\text{Width} \times \text{Length}}{\text{Mounting height above working plane} \times (\text{Width} + \text{Length})} ]

2. Initial Lumen Output of Lamps (Table 7 excerpt)

3. Luminaire Classification (Table 8)

Brightness Contrast Ratios (Clause 3.1.3)

• Task : Immediate background = 3:1
• Task : General surroundings = 10:1
• Luminaire (or sky) : Adjacent surface = 20:1
• Anywhere in environment = 40:1

flowchart LR
    A[Light Source] --> B[Colour Rendering]
    B --> C{Task Type}
    C -->|Critical Colour Judgement| D[High CRI Lamps]
    C -->|Contrast Enhancement| E[Colour Distorting Lamps]
    D --> F[Specialised Lighting

Design of Roofs and Ventilation Openings (IS SP Part 32)

1. Roof Types & Ventilation Principles

• Double-pitched roof (Clause 14.3.1.1):

  • Ridge openings on both sides cause no wind suction inside.
  • Longitudinal baffles create wind jump → upward air movement.
  • Suitable for high-bay buildings, warehouses.
  • Robertson ventilators (Fig. 20) use circular wind bands for upward airflow.

• Saw-toothed (north-light) roof (Clause 14.3.1.2):

  • Complex airflow; wind direction affects ventilation.
  • Modify saw-teeth shape to create upward draughts.
  • Increase southern wall openings if southerly winds dominate.
  • Use overhangs/louvers to block direct sun rays.

2. Empirical Ventilation Capacity (Robertson Ventilators)

• Ventilation volume depends on:
  • Temperature difference (ΔT, °C)
  • Height of ventilator above intake (h, m)
  • Wind velocity (V, km/h)