Incorporation of useful daylight in luminous environment of RMG factories by effective use of skylights in context of Dhaka

Abstract

Ready–made garment (RMG) factories in Bangladesh have been heavily criticized over the last few decades for its working conditions especially for the production environment, while more than 78% export earning of Bangladesh come from the RMG sector. Along with other conditions, the quality of luminous environment is affected by poor natural lighting system and high internal heat gains from artificial lighting, creating an intolerably hot and uncomfortable working environment for the workers that are noncompliant with national labour laws and International Labor Organization (ILO) standards. Lighting is critical to productivity as well as to safety and healthy working conditions of workers, since it directly affects visibility, psychological health, and thereby, production. In addition, proper use of daylight can be an effective means to reduce the energy consumption and excessive cooling load caused by artificial lighting. Through literature review and field survey it is found that, most of the Bangladeshi RMG factories do not consider daylighting design strategies during planning and construction of the buildings. Design parameters, such as building height, number of stories and roofing system are very essential to make factories energy efficient through daylighting. A passive skylight system, that is only suitable to specific climatic region, can be a significant building design element to provide an ideal luminous environment for interior production spaces located at top floor, especially in a tropical country, such as Bangladesh. This research tries to find an effective passive skylight configuration for RMG roofing system through computer simulation analysis. Daylight simulation was performed by creating the virtual environment based on the information of an existing RMG building located in Dhaka, Bangladesh, a tropical location, with predominantly overcast skies. Both static and dynamic annual Climate-Based Daylight Modeling (CBDM), methods considering all weather sky luminance model (i.e. DAYSIM), have been used for simulation analysis. Further simulation analysis was done to refine the design parameters, e.g. slope of the skylight, width and spacing, of the most effective skylight configuration. Results indicate that, there is a considerable potential for more useful daylight inclusion into the production space of RMGs by careful selection of skylight configuration and some simple sensible modification of the typical standard roofing system especially for single, or top floor production spaces of multistoried RMG buildings. Field observations, literature review and simulation studies together provide the basis of design guidelines for architects to design sustainable daylit industries. It is expected that the design strategies and recommendations from this research for skylighting will improve the luminous environment of RMG production space of Dhaka by effective inclusion of daylight to increase productivity and save energy for lighting purpose.