Mandatory unpaved area Half of this mandatory open space must be non-paved –leaving 20% green for recharging the ground water table
Mandatory unpaved area
Half of this mandatory open space must be non-paved –leaving 20% green for recharging the ground water table. In general, with more open space to play with, some may have them in the front, some more privately at the back or create introverted spaces. Also, the ground area can be further increased by varying floor coverage, having less on the lower floors and saved
area to the higher floors, by cantilevering (Figure 4); provided the set-backs are not violated and one keeps within the permitted FAR and height limits (Ahmed, 2010).
Figure: Setback, Mandatory open space and Mandatory Ground Coverage (MGC) variations
Mandetory road width to get typical Far facilities: 6m for all areas except private housing area where road width should be fixed at 7.62m.
Allocation of community space and children play area:
If the FAR included construction area is over 3000 sqm at residential use, 4% of that area must be allocated as community. 10% plot area must be fixed to allocate as children play area if the plot is 1300 sqm or more.
Maximum ground coverage and FAR based on plot size
To ensure access to natural ventilation and daylight in the building, ground coverage, FAR is fixed on the basis of the plot area. Residential FAR are outlined (as example):
Plot size (in Katha4) FAR Maximum ground coverage (%)
2 and less 3.15 67.5
More than 2 to 3 3.35 65
More than 3 to 5 3.5 62.5
More than 5 to 7 3.75 60
More than 7 to 9 4.0 60
More than 9 to 10 4.25 57.5
More than 10 to 12 4.5 57.5
More than 12 to 14 4.75 55.5
More than 14 to 16 5.0 52.5
More than 16 to 18 5.25 52.5
More than 18 to 20 5.25 50
More than 20 5.5 50
There are other FAR tables according to other building use/ occupancy type.
COMPARISON between 1996 and 2008 ACTS on different Features by Ahmed (2010).
Features Old regulations New regulations Comments on new regulations
Density of built form High – limitless for areas without height limitations Restricted according to FAR restrictions Improves ventilation potential of site’
Allows more consolidated open spaces
Open area/covered area ratio 33% 40% This is referred to as mandatory open space – allows more consolidated open spaces
Paved area/unpaved area Unspecified – hardly any unpaved 50% of mandatory open space Specifying unpaved areas allows rainwater to recharge the ground water table
Prevents rainwater runoff and flooding
Lowers air temperature and thermal comfort ventilation possibilities
FAR Limitless – as high as 10.7 Limited to fixed values for function and site access – 4.25 in example Controls density and improves potential for thermal comfort ventilation
Consolidates open spaces into usable spaces
Building-building distance Based totally on setbacks Variable and high on certain sides – as long as min setbacks are not violated Improves thermal comfort ventilation potential
Creates variation in built form
Allows more consolidated open spaces
Variation in development/ morphology Very low High potential Because FAR and ground coverage is regulated there is tremendous scope for different heights and spreads of buildings, resulting in diverse settlements.
Setback distances from front, back and side of the plots (for upto 33m building height)
• Two buildings in one site must be situated at least 4 meters away from each other if in front or rear, and 2.5 meters away if they are side by side.
• Every dwelling unit in a residential building shall have at least one room, which shall not be less than 9.5 square meters with a minimum width of 2.5 meters. Other habitable rooms in the dwelling unit shall have a minimum area of 5 square meters each, with a minimum width of 2 meters.
• The minimum floor area of kitchen is 4 sqm with a minimum width of 1.5 m.
• The minimum floor area of a bathroom where water closet and bathing facilities are combined shall be 2.8 square meters with a minimum width of 1 meter. For bathrooms without water closet, the minimum area shall be 1.5 square meters with a minimum width of 1 meter. The minimum area of a toilet with water closet only shall be 1.2 square meters with a minimum width of 1 meter. Three fixture bathrooms containing bathing, hand washing and water closet facilities shall have a minimum area of 3 square meters with a minimum width of 1.25 meters.
Benefit of additional FAR 0.05 for every 0.3 m wide road surrender to be 6m wide road.
Benefit of getting concessions for balconies (hanging spaces with railings but no walls/grills on two sides) is existed. Such terms encourage generate ‘indoor-outdoor space’ relationships with and strictly keep provision for rescue the inhabitants in case of any emergency.
Other important features that covers:
• Car parking facility ( parking area)
• Driveway and turning radius for parking.
• Minimum parking areas for buildings.
• Minimum unrestricted stair width
• Floor height
• Internal front space (for light and air)
• Minimum dimension for airwell and lightwell.
• Distance of electric lines
• Floor requirement per head
• Width of exit per head
• Maximum no. of people and maximum distance of movement for exit
• Fire exit stair width
• Buildings with single exit
5. Emergence of FAR implementation in Dhaka
The new building construction rule 2008 encourages a high-density urban development through a relaxed building height and plot coverage rules and regulations. Building height, distance between buildings and street widths are important design features which need to be considered at the design stage of urban outdoor spaces. The impact of the rule is being reflected in the recent high-rise characters in city’s residential and commercial areas (Sharmin et al.,2012). The following burning issues have necessitated to introduce floor area ratio (FAR) as an enhancement of the traditional methods of urban development legislation.
• As the growth has been indiscriminate and haphazard, incredible pressures (described at chapter two) are threatening Dhaka. Only setback guided layout with little scope for lighting & ventilation was inadequate and required a unique and significant mandatory feature to guide sustainable infrastructure development in Dhaka.
• Land price of Dhaka almost knows no bounds. Hence, the city is losing critical land uses like rivers, lakes and other vital key water bodies (wetlands), crucial for flood water retention and run-off to monumentally skewed demand for land by the neo-rich, black money traders, foreign remitters, public and private sectors professionals – resulting in high appetite to specular land value (Ahmed et al. 2018). As a result, the city is becoming less livable with degraded environment and more prone to natural & manmade risks and vulnerability.
• Land owner want full utilization of land to maximise returns from the land as rent or see. Therefore, it is often seen that minimum setback requirements of the regulations indicate the actual land left over and landowner tends to build up in setback areas.
• The growth of Dhaka has been random. Dhaka city deserves high density and innovative urban form that could embrace greeneries as a mandatory provision. (Ahmed, 2018). In order to manage the ever-increasing pressures, the city has no other way but to expand vertically. FAR eliminates mandatory height limitations of buildings, increased open spaces allowing design flexibility.
• Dhaka also needs to find innovative ways to greening (roof-top gardening) and water consumption (rainwater harvesting) and move away from groundwater consumption as the groundwater table is depleting faster (Araos et al. 2016).
• Stated by DESA, the demand for power in Dhaka city has increased by around 10% a year. As the supply is not adequate to meet the demand in the city, so either we have to adopt it or think alternative path way to solve the power crisis (Rahman & Siddiquee, 2012). In a study it was found that Lowering site coverage with an increased building height improves outdoor ventilation. FAR maintained well design have possibility to reduce the cooling load of the residential flats by 64% and hence reduce the total energy use by 26% by natural ventilation and direct sunlight (Sharmin et al. 2012). Building codes need to be developed to dependence on conventional energy & to promote and influence energy efficiency in buildings (Ahmed, 2018).
• The process of designing energy efficient buildings is not a ‘one-man’s show’. It is just not the architect responsible for designing energy efficient buildings ; to change design practice. Architects, developers, interior designers and the clients are closely intertwined actors. The architect, with increased knowledge and awareness can be initiator of designing energy efficient buildings and the change in design practice and can encourage others. A mandatory code can influence this innovative approach of buildings design on the way to achieve energy efficiency with a strong base.
• Deterioration of urban microclimate due to unplanned construction of built forms is a major concern in Dhaka. Regarding the context where climate change is a crucial issue, a proper arrangement of urban are with comfortable outdoor spaces can positively contribute to mitigate the harmful impacts of urban climate as well as urban heat island.
• Urban experts believe that Floor Area Ratio of RAJUK, NWBPPA (Natural Water Body Protection and Preservation Act) along other supporting acts are adequate for prevention of hazards in Dhaka (Chowdhury, 2017).
• Decisions made on density profile also have significant impact on health, urban environment, productivity of cities, and on human development as a whole (Acioly ; Davidson,1996). FAR creates scopes to recover, recreate ; provide ‘Urban spaces’ for mitigating ; to combat the urban crisis.
• Dhaka if extremely affected by flood and water logging. Building urban resilience to floods is essentially a process of adaptation—instead of fighting the waterbody / authorities; by allowing rain water inside the plot, water runoff delay by vegetation to recharge ground water, wider road with improved drainage facility can help to be resilient.
Thus, Floor Area ratio (FAR) was imposed as in Dhaka Imarat Nirman Bidhimala ‘2008 with very realization for the need of innovative approaches to create innovative sustainable “urban form” that can:
? Balance between rapid urbanization & densification.
? Develop strong socio-economic characteristics.
? Low impact development.
? Environment responsive.
? Minimize costs and productive Investments
? Support to reconstruct sustainable and healthy environment.
? DM implications: Adopt, mitigate and combat urban crisis (shock & stresses).
? Recharge ground water level.
? Achieve Energy efficiency.
? Adopt Changing climate and mitigate urban heat island effect.