Energy Efficient Garmentfactories in Bangladesh
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Energy Efficient Garmentfactories in Bangladesh



In 2008 as part of my Masters Research at Architectural Association i did building monitoring of existing garment factories in Dhaka Bangldesh. I identified how helath and wellbeingcan be addressed in ...

In 2008 as part of my Masters Research at Architectural Association i did building monitoring of existing garment factories in Dhaka Bangldesh. I identified how helath and wellbeingcan be addressed in these factories as well as making them energy efficient. This tragic event on 26th april In Bangladesh makes me revisist my work and make a PLEA to ILO and other organizations to work together for a better wokring environment for the factory workers that gives us the bliss of £ tee shirt from Primark.



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Energy Efficient Garmentfactories in Bangladesh Document Transcript

  • 1. PLEA 2008 – 25thConference on Passive and Low Energy Architecture, Dublin, 22ndto 24thOctober 2008Energy Efficient garment factories in BangladeshFarah NazArchitectural Association, Graduate SchoolLondon, United Kingdom.&Gifford LLPLondon, United KingdomEmail: FarahNaz786@gmail.comAbstractGarment factories in Bangladesh have been heavily criticised over the last 30 years for theworking conditions in which employees must labour. High internal gains from artificiallighting and equipment produce an intolerably hot work environment, which exacerbates thealready uncomfortable climatic. This paper identifies the causes of this poor thermalenvironment through a detailed analysis of a garment factory in Dhaka. Two key spaces areselected: the ironing space and the sewing space. Through the evaluation of the buildingfabric, and the reduction of the artificial lighting demand, thermal comfort conditions withinthese spaces is improved relative to a defined comfort zone of the workers. The researchidentifies strategies that can be adopted as a basic design guidelines in the vital workspaces in a garment factory in order to attain a comfortable working environment.Keywords: energy, thermal comfort, garment factory, hot and humid climate.1. Introduction:The context of the research and project issituated in Dhaka, the capital of Bangladesh. Theapparel industry is the economic lifeline of thecountry, employing 10% of the total population.Bangladesh is the twelve largest apparel exporterin the world (fifth largest in EU), with a turnover ofUS$9.52 billion annually. This industry is not atextile oriented business, but more focusedtowards a mass tailoring industry, to support theclothing market of the western investors.Currently there are 8000 factories in the countryand the British Bangladesh Chamber ofCommerce (BBCC) has reported that 1000 morewill be built by the end of 2008. This equates to38 new factories each month.Most of these factories are criticized for their overheated working conditions, causing a healthhazard for the workers. The high density ofpeople, equipment and artificial lighting are thereason for high internal temperatures. Extensivework hours (10-12 hours/day) become mostintensive during summer, when productionincreases to meet the Christmas holidaydeadline. The two main workspaces, sewing andironing, are the most critical. Extensive usage ofartificial lighting in sewing spaces and steamirons in the ironing space is the major cause ofhigh internal temperatures.The cooling solutions for such factories usuallycomprise ceiling and exhaust fans. The potentialfor natural ventilation is minimal with deep floorplans with low ceiling heights. The resulting lackof heat dissipation leads to an oven-like workingenvironment, and is fast becoming a prime healthand safety concern for the industry.2. Design Research Hypothesis:This paper focuses on how thermal comfort maybe achieved within the two critical factory spaces:the sewing and ironing spaces. In the sewingspace, the goal is to reduce artificial lightingdemand through optimized window openings,designed to enhance natural day lighting in thespaces, whilst also reducing the solar gains. Inthe ironing space high internal temperature ismainly due to steam irons. Since these highinternal gains cannot be reduced; building fabricmodulation and convective cooling is investigatedas means to achieving thermal comfort.2.1.Structure of the Research and Paper:This research focuses on two goals:(1) Demand reduction through optimized daylighting design in work spaces.Fig 1: Left: a typical Vertical factory in Dhaka. Right:Interior of a sewing space in a Factory.
  • 2. PLEA 2008 – 25thConference on Passive and Low Energy Architecture, Dublin, 22ndto 24thOctober 2008(2) Attaining thermal comfort – through ventilationand building fabric modulation.The paper is structured in two segments: Firstly,to identify comfort criteria, through fieldinvestigation,and reconnaissance survey.Secondly, to apply this information, to design acontext-specific garment factory, with a particularfocus on the sewing and ironing spaces.3. Context:3.1 Climate: Dhaka (20º34 N´ 92º41 E´) is 48meters above sea level, has a hot and humidclimate, with an average mean annualtemperature of 26.5°C. The maximum summertemperature is 37°C and minimum wintertemperature is 6°C, with a diurnal swing between10°C–14°C throughout the year. Groundtemperature can be assumed to be around26.5°C (average annual outdoor air temperature),at depths over 10 meters below grade, which isnot low enough to provide a powerful heat sinkfor cooling. Due to geographic location relativehumidity ranges, between 50-90% throughout theyear. During the summer (June – September)cloud cover averages above 40%. The skyilluminance in an overcast sky in Dhaka is 11,000lux.3.2 Climate Modification (UHI): Dhaka is acongested city with a population density of 1000people and 100 garment factories, per sq.kilometre (approx). Most of the factories arelocated in the industrial area situated in the city,due to close proximity to airports. There issignificant urban warming within these areas as aresult of high congestion of people, traffic, heatgains from air conditioning equipment and a lackof greenery. High levels of solar radiation areabsorbed by the buildings and road surfaces, andcontribute to the microclimatic warming. Thegarment factories are therefore situated in adifficult climate, which is exacerbated by the heatgains from the factories themselves.3.3 Internal Climatic Condition:Reconnaissance Survey: In the early days,most garment factories developed in tin sheds,garages or converted verandas. With space andbuilding cost as limiting factors, and density as akey concern, the architectural language of thistypology became ‘adaptive’ rather than‘definitive’. For the last 30 years a vertical factorybuilding typology emerged, signifying the conceptof multi-storey, open plan floor plates. Thesevertical factories consisted of 5-10 floors with amaximum building height of 20m–26m.A base case factory situated within the city, wasselected for further study. From thereconnaissance survey the following wasidentified :1. Sewing requires a level of lighting between800- 1200 lux, for 10-12 hours a day, which ismet by artificial means. Within these spaces,70% of the internal gains may be attributed toartificial lighting. The ironing space requiresless light 100-300lux, and therefore lessartificial lighting, however the use of steamirons results in internal temperatures as highas 39ºC, resulting in a significant coolingdemand.2. In the chosen garment factory, the ironingspace and the sewing space are adjacent,resulting in heat transfer between these twospaces. Most buildings are made with sandlime brick which is not ideal in terms ofdissipating heat.3. The artificial lighting and lack of naturalventilation is due to the deep floor plan, andsmall windows which are not correctlyorientated. Most windows are not shaded andin many cases are shut to prevent drafts.4. Insufficient ventilation: Most factories haveceiling fans for interior circulation. Fan andexhaust fans are usually used for a 1-2achper hour per person, but in many cases arerandomly placed. As a result they are turnedoff to avoid creating strong breezes in thewrong direction, which may disrupt the work.3.4 Field Investigation: The field investigationwas performed in the urban factory. The goalswere as follows :1) To identify the internal thermal condition of anexisting garment factory through data logging.2) To perform a comfort survey, among thefactory workers, in order to identify the humancomfort adaptability for such a workingenvironment.3.4.1. Methodology:Tiny Tag Temperature loggers were installed inboth the sewing and ironing spaces. Thetemperature was logged during the week ofAugust 7thto 27th2007, when the averageoutdoor temperature was between 25 - 30ºC, RHbetween 70% - 80% with over 20% clear skythroughout the month. A structured questionnairein the local language was issued for datacollection. Spot measurements with hand heldtemperature loggers and anemometers were alsotaken. A random group of 40 workers was alsochosen for an in-depth face to face interview.Their clo value were between 0.5 – 0.75, and thegroup was aged between 20- 35 years.3.4.2. Existing Thermal Condition-LoggedResults:During the recorded occupied hours, the averagemean temperature for the internal spaces rangedbetween 26°C to 34°C. At this time, the averageexternal temperature was 30°C.The ironing space showed the highest internaltemperature, ranging between 27°C to 39°C, witha mean average daily swing between 3-5K.Therise of temperature in the work space was closely
  • 3. PLEA 2008 – 25thConference on Passive and Low Energy Architecture, Dublin, 22ndto 24thOctober 2008Fig 2:Logged Interior logged temperature ofSewing and Ironing Space of the Base Caserelated to the external temperatures, with a timelag of 1-2 hours and reflected the effect of naturalventilation during some days.The internal temperature increased everymorning due to the presence of a natural gasboiler which is used for the steam irons but notfor any heating. This natural gas powered boileris located between two sewing spaces in a closedroom. During lunchtime between 12pm and 1pm,all the artificial lights were turned off, leading toan internal ambient temperature drop between 2-4°C.3.4.3 Discussion: Comfort votes vs loggedtemperature:When the logged internal temperatures werebetween 28º and 34º C, with a wind speed above0.50 m/sec, 55% of the surveyed people saidthey were in acceptable conditions. As the windspeed decreased their acceptability of highertemperatures decreased as well. When thetemperatures reached between 35º – 37ºC, andthe wind velocity was less than 0.50 m/sec, 75%people reported unacceptable conditions. Thisdata corresponded with research by Giovani(1980), Shabbir (1995), where it is stated that inhot climates people are more adaptable to highertemperatures. So it can be deduced that theworkers had an acceptability of highertemperatures and increased wind speed made adifference in their comfort perception. They alsoused different adaptive measures to habituatethemselves to their work environment includingopening windows, sitting under fans, drinkingwater / potassium based snacks and listening tomusic. Based on the data collected a designresearch hypothesis was formed to propose adesign solution for the garment factory.3.4.4. Thermal Comfort:Calculation of PMV and PPD values suggeststhat comfort conditions (as identified by ISO 7730and the ASHRAE standard 55 -92) can beachieved when the air and mean radianttemperature is, within the range of 19º - 30º C,when the other variables are suitably adjusted toreflect common human adaptive behaviour(Yannas 2007). Similarly calculating monthlyneutral temperature for Dhaka, using Auliciems’empirical equation (Tn=17.6+0.31*) for thefactory occupied hours, (8-18 hrs) shows that thecomfort temperature ranges between 20º to 30ºC. (Auliciems and Szokolay 1997).This reflectsthat the comfort zones can be extended by +/-2K, which gives an adaptive comfort rangebetween 20-30° C over the annual cycle. There isno fundamental difference observed between theresults obtained using the Auliciems’ empiricalequation or the PMV/PPD calculation.3.4.5. Environmental Performance Criteria:Thermal Requirement:The hypothetical design temperature based onAuliciems’ empirical theory was identified,adaptive comfort range was hypothesized asbeing between 24°C and 30°C for summer andbetween 11°C and 20°C for winter. However, thefield work comfort survey indicated that thecomfort temperatures for summer can beredefined and extended to 34º C.Areas with a reduced amount of occupied timeand density, like circulation spaces, storage andpackaging, can have a higher or lowertemperatures. Sewing and ironing spaces shouldmaintain a comfort temperature, between 20º to32º C, with upper limits of 34º C if needed.4. Design Proposal:After identifying the comfort criteria for the workspaces, the next part of this paper focuses onhow to apply the information to design a contextspecific garment factory.4.1. Site: The location of the site is a hypotheticalurban site, situated in Dhaka city, close to theairport, in a future industrial site designated bythe government. The height limitation is 21meters, with an H/W ratio of 2. Total building footprint, will be 600m², comprising in total a 3000 m²floor space, within 5 floors. The focus of thedesign is to maximise floor space whilst at thesame time maximise the opportunities for passivedesign strategies appropriate to that climate.Building massing studies were performed toidentify the optimal shape for daylighting,minimisation of solar radiation and self shadingovershadowing of a 21 meter building block.4.2. Spatial Requirement: The spatialrequirements of a factory are primarily activitybased and secondarily time sensitive. TheFig 3: Comparative Analysis of logged temperatureswith the comfort votes.
  • 4. PLEA 2008 – 25thConference on Passive and Low Energy Architecture, Dublin, 22ndto 24thOctober 2008Fig 4: Workflow of a Vertical factory.thermal conditions will vary according to thefunction of a space, the density of people and theoccupancy hours. In a garment factory, therequired activity spaces are: sewing, ironing,packaging, storage, administration and cafeteria,day care and medical room. The work flow of afactory is usually from the top to the bottomfloors. Fabric is stored at the top and then the rawgoods work their way through the different stagesand different floors, emerging from the groundfloor where packaging area is situated, ready tobe shipped out. These spatial requirements arebased on the document ‘Improving WorkingConditions and Productivity in garment Industry –An Action Manual’ by Juan Carlos Hiba, certifiedby ILO as a guide for setting up the basic layoutfor most garment factories.4.3. Building Design Strategies: In embarkingon a design solution, following passive strategieswere identified as key design considerations:Architectural:• The floor plates and height of a vertical factorycan be varied depending on the lighting levelsrequired, occupancy and activity requirements.Based on the internal heat gain, space layout canbe adjusted. Massing studies informed the idealposition for windows, to minimise solar gain butmaximise day lighting.• A vertical factory workflow from top floor tobottom floor is as follows: Storage, (level 5),preparation/cutting (level-4), sewing (level-3),ironing (level 2), quality check (level1), shippingand packaging(level-0).• Sewing / ironing spaces separated.• Linear floor plates (10m) with windows,depending on the lighting level required.• Roof (level 5) is a double roof, at elevation 19mfrom ground with storage between the doubleroof, protected from rain by a permeable façade.• Sewing spaces are arranged in an L shapedlinear block, situated at elevation 12m andelevation 9.5m from ground level, with a split floorplan and internal opening to induce air flow.• Roof garden is situated at elevation 9m,separating the sewing space from the ironing,creating a social space.• Ironing space is situated at 2.5m elevationlevel, overshadowed by other building and withindirect window openings to avoid direct sun.Solar Control:• Solar shading is needed and reduction of solargains on interior spaces, to reduce overheating.• Permeable openings that provide security andprivacy as well as adequate day lighting is thekey design goal.Comfort Cooling:• Thermal Mass for the structure to keep thestructure cooler.• Controlled natural Ventilation with high and lowlevel windows. Ceiling fan to maintain a constantair flow and extractor fan to exhaust hot air duringstagnant conditions.• Glazing can be sized and placed based on theactivity and the hours of operation of differentfactory spaces. It is not essential for all thewindows to have glazing. If glazing is to be usedLow E or Solar Glass equivalent can be utilized.• Radiative Cooling has potential along with nightcooling.• Evaporative Cooling has limited potential dueto high humidity and in many cases the humidityreduces the needle longevity.• Adaptive measures for thermal comfort cangive the users a control over their environment.4.4 Day lighting Study- Sewing:The day lighting study was performed withEcotect V 5.1. The illumination level in Dhaka,with a CIE overcast sky is 11,000 lux. Frequencyof occurrence of diffuse illumination shows over4500 hours, more than 1500lux, during theoccupied hours (8-18hrs). The illuminance valueused for the study is 11,500 lux, whichcorresponds to 75% of the working hours (8-18hrs).Sewing space has a lighting requirementbetween 800-1200lux and ironing between 100-300lux. From the day lighting study followingconclusion was reached:• Sewing space orientated north south requires aW/F ratio of 14%, for East west orientation12.6% and ironing space needs 5.5% to meetthe daylight requirements.• Floor depth 10 m, height can vary between 3.5to 5 meters.• The double roof provides shading 78% of theyear to most of the windows. Table 2 shows theshading data from the windows.• North south facing sewing block requires highand low level horizontal windows with anoverhang of 1.5 meter deep. In comparison withTable2: Shading Analysis of the Openings.Buildingheight(m)Season South North AnnualAverageShading%0-5m All Season All orientation 78.95-15m Summer(Mar-Aug)30-46.5%Winter 67-75%15-21m Summer 10-30% 30-45%Table1: Spatial Organization of a Vertical factory.Area name SpaceRatioMetRateExistingTempSuggestedDesignTempHours/DayOccupiedSewing(s)S = X 1-1.5 26-35 º C 20-32 º C 12Ironing S: I= X:2X2- 2.5 26-40 º C 20-32 º C 12
  • 5. PLEA 2008 – 25thConference on Passive and Low Energy Architecture, Dublin, 22ndto 24thOctober 2008Table 4: Six materials variants.MATERIALCONFIGURATION SURFACE MATERIAL U= VALUEOption 01ROOF SAND LIME BRICK 1.072WALL SAND LIME BRICK 1.072FLOOR SAND LIME BRICK 1.072Option 02ROOF SAND LIME BRICK 1.072WALL CONCRETE PLASTER 2.038FLOOR THERMADECK HOLLOW CORE 1.036Option 03WALL THERMADECK HOLLOW CORE 1.036ROOF THERMADECK HOLLOW CORE 1.036FLOOR THERMADECK HOLLOW CORE 1.036Option 04ROOF SAND LIME BRICK 1.072WALL CONCRETE PLASTER 2.038FLOOR SAND LIME BRICK 1.072Option 05ROOF DOUBLE ROOF – CONCRETE PLASTER 1.072WALL THERMADECK HOLLOW CORE 1.036FLOOR THERMADECK HOLLOW CORE 1.036Option 06ROOF DOUBLE ROOF – CONCRETE PLASTER 1.072WALL THERMADECK HOLLOW CORE 1.036FLOOR THERMADECK HOLLOW CORE 1.036Fig 5. ProposedVertical factorydesign.ribbon window, tall vertical windows providebetter light penetration as part of their openingis located higher up and the variation from frontto back of the room is much less compared to aribbed horizontal windows (Baker,Steemers2002). East-west blocks works better withvertical openings.• The day lighting results are reported in thefollowing Table 3. From the study it was seenthat the lighting levels in the sewing space hadan average DF 5, and 52% of the work hoursthroughout the year the lights switches can beturned off.In the same way in the ironing space,the average DF was 2.2, and 55% of the workhours the switches can be turned off. This 50%reduction of artificial lighting usage will minimizethe internal heat gain of the work spaces.Thermal Analysis:Building surfaces especially the roof, wall andfloor are critical in terms of minimising heat flowfrom outside. The three main factors that affectthe heat transfer through the building surfacesare thermal transmittance, thermal resistance andthermal time constant. A parametric analysis wasundertaken in order to identify the most suitablematerial and construction method capable ofstabilizing the internal resultant temperaturewithin the defined comfort range, without addingadditional cost or high technology. Traditionally amaterial with low U value is used, providing highthermal resistance and providing constanttemperature during the day time. For this buildingtypology higher internal temperatures areproblematic, and heat dissipation through thematerial is therefore critical. As a result, amaterial with a higher U value and heattransmissivity is desired.Ventilation: Bangladesh factory Law 1965suggests a ventilation of 10m³/person and theILO factory regulations suggests 8-12l/sec/person. According the BSI, standards theminimum ventilation required for factories is 0.75ach, which does not specify the type of factory. Ina garment factory there is people, equipment andlight which constitutes majority of the high internalgain. Keeping the ventilation rate as a constantparameter 0.75 ach, construction material andmethods were targeted as a way to achievecomfort temperature.4.5 Parameter Setting- Material andConstruction variants:Three materials were chosen for the study:1) Sandlime Brick (traditional constructionmaterial), 2) Concrete Plaster (most conventionalmaterial) and 3) Hollow core concrete slabs.These three construction materials were formedin six different construction methods by varyingthe position of the materials in three surfaces: theroof, wall and the floor. The impact of changingthe construction materials in different surfacewere observed and the resultant temperature ofall the six combinations were compared, toidentify which construction combination wouldkeep the internal temperatures within the comfortrange 20 - 32º C (Ach: 0.75, Spatial Density: 8m²/person)4.6 Result : Sewing Space & Ironing Space:The result indicates the following:The lowest internal resultant temperature isobserved between 29 ºC to 30 ºC for bothOption 4 and Option 6, where hollow core isTable3: Results of the different optionsActivitySpaceDFAvg>850lux>1200luxArtificialLightsoffSewingSpace4 2250hrs1600hrs 52% oftheworkinghours>100lux>300luxIroningSpace2.2 2000hrs 4000hrs 55% oftheworking
  • 6. PLEA 2008 – 25thConference on Passive and Low Energy Architecture, Dublin, 22ndto 24thOctober 2008Fig 6: Frequency of occurrences of the internaltemperatures of the material variants.Table5: Results of Six variants.Variants Sewing(Summercomforttemp)Ironing(Summercomforttemp)Notes:Option 1 30 ºC to 34ºC29 ºC to 36ºCconventionalmaterialOption 4 29 ºC to 30ºC29 ºC to31ºCHollow core on3 surfacesOption 6 29 ºC to 30ºC30 ºC to 32ºCHollow core on2 surfacesOption 2 30 ºC to 33ºC31 ºC to32.5 ºCconventionalmaterialOption 3 30 ºC to 32ºC31 ºC to 32ºCconventionalmaterialplaced on all three surfaces and two surfaces(with a double roof) respectively. Likewise in theironing space resultant temperatures within 29 ºCto 31ºC, a 6ºC lower than the conventionalconstruction option 01 and 4ºC lower than theexternal temperature. - sandlime brick on threesurfaces (the conventional construction method),has the highest internal resultant temperature,ranging between 30 ºC to 34 ºC, is 4ºC higherthan external.4.7 Comparative Analysis:In the sewing space, the hollow core slabsmaintains a stable temperature between 25º-30ºC for more than 3000 hours, and performs10% better than sand lime brick. Lime brick wasalso found to achieve temperatures between 32º-34ºC for 1400 hours, compared to hollow corewhich achieved 240 hours, (83% better than theconventional material). This proves that hollowcore plays a significant role in maintaining a lowertemperature in comparison with the traditionalconstruction material in such high internal gainspaces.The same pattern is observed in the ironingspace, where the temperature is between 25º-30ºC, the hollow core construction has afrequency of occurrence of 3079 hours, which is24% better compared to sand lime brick. In theupper limit with temperatures above 30ºC, hollowcore performs 20% less hours of occurrencesthan sand lime brick. Above 34ºC the hollow corehas 0 hours of frequency of occurrences. Forboth sewing and ironing space, hollow core worksefficiently bring the temperature within thecomfort zone.5. Conclusion:The focus of this dissertation was to reducedemand in sewing spaces and secondly to attaincomfort temperatures through passive means.The analysis proves that natural daylight can beutilized by using optimized window design in highlighting demand spaces like sewing. 50% of theworking hours the artificial lights can be turnedoff, which will reduce the lighting demand, thusthe internal gains within the space. Introducinghigh and low level windows will increase crossventilation. Conventional construction materialslike sand lime brick or concrete on all thesurfaces or even with a double ventilated floor,does not really contribute to lower internaltemperature for either the sewing or ironingspaces. The ironing spaces in particular, withconsiderable internal heat gains benefit fromcareful selection of the fabric construction, withhollow deck proving especially effective.Overshadowing will occur and is desirable; with aconcrete double roof the internal temperaturewithin the ironing space can be lowered close tothe comfort range (and still 4ºC lower than theconventional construction types. Finally having alinear floor plan with higher ceiling height, shadedwindows, separation between high internal gainspaces, in addition to the creation of voidsbetween the vertical floor plates, thermal comfortmay be significantly improved.Additional experimentation of the thermal and daylighting should be carried out in-depth which canform a guideline for industrial building typology inthe context of Dhaka.6. Acknowledgements1. Dr. Simmos Yannas, Werner Graiser, KlauseBode and Raul Moura, Ruchi Chowdhury2. Giles Bruce 3. Dr. M.A. Alam7. References1. Auliciems A and S Szokolay (1997) ThermalComfort, PLEA Note 2, Passive and LowEnergy Architecture International.2. Majumder, Pratima Paul and Begum Anwara,Engendering Garment Industry : TheBangladesh Context, The University PressLimited, January 2006 Dhaka Bangladesh.3.CIBSE (1989 Lighting Guide: The industrialEnvironment, Chartered Institute of BuildingServices Engineers, London.4. Chartered Institution of Building ServicesEngineers (1986), CIBSE Guide A, CIBSELondon.5. EDSL (2006), TAS v9.0.9 software.Environmental Design solutions Ltd.6. Ecotect Version5.5, Square One Ltd.
  • 7. PLEA 2008 – 25thConference on Passive and Low Energy Architecture, Dublin, 22ndto 24thOctober 2008