FACTORY CONDITIONS BANGLADESH
40.00 38.00 36.00 34.00 32.00 30.00 28.00 26.00 24.00 22.00 20.00
Temp – external
Temp – internal sewing
Temp – internal Cutting
Figure 1: Temperaure fluctuation – August 7 to Aug 14, 2007
unacceptable conditions. Naz says this data corresponds with empirical studies that show people are more adaptable to higher temperatures in hot climates.2 For sewing and ironing spaces, Naz identified the comfort temperature to be
between 20°C and 32°C, with upper limits of 34°C. To try to come up with a possible solution to overheating, Naz looked at the structure and thermal mass of a Dhaka factory.
Fabric focus Typically, factories in Bangladesh are built using sandlime brick. When tested, this produced higher internal temperatures than materials with a heavier thermal mass, such as concrete or TermoDeck hollow core – a concrete slab with built-in pipes for running water or air. ‘It’s important to get the passive strategies
right from the very beginning,’ says Naz. Lighting was another huge contributor to
the factory’s high internal temperatures and was its biggest source of energy consumption. But compared with grey London’s 5,000 lux, the illumination level of natural light in Bangladesh is 15,000 lux, which provides an ample light source. ‘If factories are not particularly deep-plan, why can’t we use natural daylight?’ says Naz.
‘When I experimented with that, I found that 50% of natural daylight could be used.’ This would also reduce load-shedding [the shutdown of electric power when demand
52 CIBSE Journal March 2014
Naz’s proposed vertical factory design
becomes greater than supply] and ease the burden on Bangladesh’s busy grid, says Naz. The close proximity of buildings in Bangladesh creates a lot of shade. ‘There’s no concept of solar glass in Bangladesh, but the buildings are very close to each other – so overshadowing actually works positively.’ Mechanical ventilation with heat recovery
was ruled out from the start, says Naz. ‘It’s very expensive, and the concept and the systems aren’t there. I can’t use a western-world solution in a country like Bangladesh. “The way to cool the space is to run air through it, either by natural means or by different passive measures, or to use the fabric
There are 400-year-old palaces in Dhaka that don’t have a mechanical ventilation system, but they have thick walls, so the thermal mass is creating the comfort temperature
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Temperaure degree celcius
07/08/2007 Min 07/08/2007 Max 07/08/2007 Average 08/08/2007 Min 08/08/2007 Max 08/08/2007 Average 09/08/2007 Min 09/08/2007 Max 09/08/2007 Average 10/08/2007 Min 10/08/2007 Max 10/08/2007 Average 11/08/2007 Min 11/08/2007 Max 11/08/2007 Average 12/08/2007 Min 12/08/2007 Max 12/08/2007 Average 13/08/2007 Min 13/08/2007 Max 13/08/2007 Average 14/08/2007 Min 14/08/2007 Max 14/08/2007 Average
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