The 1986 edition of IS SP Part 32 serves as an extensive guide specifying the functional criteria for lighting and ventilation in industrial structures. It outlines design approaches for both natural and mechanical ventilation, lighting systems including daylight utilization and artificial illumination, and addresses thermal comfort factors to improve safety and efficiency. This standard is vital for professionals engaged in the architectural and engineering planning of industrial facilities within India.
Overview
The 1986 edition of IS SP Part 32 serves as an extensive guide specifying the functional criteria for lighting and ventilation in industrial structures. It outlines design approaches for both natural and mechanical ventilation, lighting systems including daylight utilization and artificial illumination, and addresses thermal comfort factors to improve safety and efficiency. This standard is vital for professionals engaged in the architectural and engineering planning of industrial facilities within India.
Audience
Contents
Structure
This section defines the extent and application of IS SP Part 32, covering the calculation of solar heat loads and thermal transmittance (U-values) for building elements, which supports ventilation and thermal comfort design.
Details the heat balance equation governing human thermal equilibrium, metabolic heat generation rates for various activities, comfort temperature thresholds, and guidelines on controlling wet and dry bulb temperatures for worker safety.
Describes essential formulas such as the room index, coefficient of utilization, and includes tables for initial lamp lumen outputs and luminaire classifications, guiding uniform illumination planning in industrial spaces.
Presents solar altitude data, illumination levels under clear skies, daylight factor requirements, and glazing area recommendations for different roof types to maximize natural lighting effectiveness.
Covers calculation methods for lighting requirements, lamp efficiencies, types of luminaires based on flux distribution, and their suitability for varied industrial environments.
Explains formulas for determining ventilation air quantity based on sensible heat gains and temperature differences, supported by local wind speed data and ventilator performance charts.
Outlines calculation methods and design principles for natural ventilation, including placement of openings, air change rates, and examples of optimal airflow management.
Discusses types of mechanical ventilation systems such as exhaust, positive pressure, and combined methods, including local wind speed influences and ventilator capacities.
Presents solar heat intensity calculations on various surfaces, fuel heat load computation, and recommendations for insulation and shading to regulate interior temperatures.
Describes the use of reflective shields with air gaps to protect workers from radiant heat, along with material specifications and thermal radiation properties.
Details formulas for solar heat calculations relevant to air conditioning loads and maximum solar intensities for walls and roofs, supporting cooling system design.
Explains methods to measure airflow rates using velocity and area measurements, tracer gas techniques, and specifications for opening designs.
Provides formulas for air volume requirements to dilute vapors, capture velocity tables for various emission conditions, and measurement approaches to ensure contaminant control.
Focuses on the importance of colour rendering for specialised tasks, lamp selection criteria based on rendering quality, and brightness contrast ratios for visual comfort.
Discusses roof types such as double-pitched, saw-tooth, and monitor roofs, their ventilation mechanisms, and empirical data on ventilator capacities influenced by temperature and wind.
Frequently Asked
IS SP Part 32 advises a ventilation rate ranging between 30 to 60 cubic meters per hour per square meter of work area to ensure adequate heat dissipation, independent of ceiling height. Natural ventilation is preferred where feasible, with openings amounting to at least 10% of the floor area in narrow buildings (up to 25 meters wide) to facilitate cross-ventilation. Mechanical ventilation should supplement natural methods only when environmental conditions cannot be satisfactorily maintained by natural means alone.
The standard employs a heat balance equation balancing metabolic heat production and work done against heat losses via evaporation, radiation, convection, and body heat storage. It emphasizes maintaining an effective ambient temperature below or equal to 27°C for moderate work, controlling air velocity to assist sweat evaporation without causing excessive convective heat gain, and establishes upper safe limits for dry-bulb and wet-bulb temperatures. When general cooling is not practical, localized cooling methods such as spot cooling or air conditioning are recommended to safeguard worker health.
For general factory illumination, tubular fluorescent lamps are favored due to their shape and diffused light output, offering luminous efficiencies between 50 to 65 lumens per watt. High-pressure mercury vapor lamps suit high-bay industrial spaces requiring intense lighting but have lower color rendering quality. Sodium vapor lamps are used sparingly indoors but are effective outdoors under foggy or cold conditions. Tungsten filament lamps, given their low efficiency and shorter lifespan, are mainly suited for storage or localized lighting. Luminaires range from enclosed types for dusty or oily atmospheres to ventilated open fixtures in high-bay areas, with selection based on flux distribution requirements.
Design for natural ventilation depends on roof form. Double-pitched roofs should incorporate ridge openings with longitudinal baffles to create wind-induced upward airflow, preventing wind suction inside. Saw-tooth roofs require modification of the saw-tooth profile to encourage upward air movement and increased southern wall openings where southerly winds prevail, along with shading devices to block direct sunlight. Monitor roofs utilize louvers or openings in each monitor to enhance stack effect and wind-driven ventilation. Roof designs should leverage wind pressure differences and stack effects to ensure efficient removal of hot or stale air.
The standard suggests measuring air velocity using calibrated instruments like vane-anemometers or pitot tubes across the cross-sectional area of openings or ducts to calculate ventilation rates by multiplying average velocity with free area. For natural ventilation, velocity measurements through vent openings combined with free area calculations give airflow rates. The tracer gas method applies for small spaces, introducing an inert gas and measuring its decay to determine ventilation. Proper procedure includes ensuring windows near fans are closed to avoid cross currents, and when both supply and exhaust systems operate, the higher airflow rate is considered for ventilation evaluation.
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