2. Building Code
A building code is a set of rules that specify the minimum standards for Design and construction objects such as buildings and non-building structures (Banerjee, 2015). The building code becomes law of a particular jurisdiction when formally enacted by the appropriate governmental or private authority and are generally intended to be applied by architects, engineers, constructors and regulators but are also used for various purposes by safety inspectors, environmental scientists, real estate developers, subcontractors, manufacturers of building products and materials, insurance companies, facility managers, tenants and others.
The code addresses all aspects of the construction including structural integrity, fire resistance, safe exits, lighting, electrical energy conservation, plumbing sanitary facilities, ventilation, seismic design and correct use of materials (http://www.cusec.org/, 2018). Generally, A Building code is a combination of the following elements:
• structural code,
• fire code,
• Enclosure, interior environment and material code
• Plumbing code
• Mechanical code
• Electrical & gas code
• Energy code
• General safety code,
• special regulations (like accessibility code for accessibility to the physically handicapped, use and maintenance code of the building, etc.)
The purpose of building codes is to establish minimum standards for design, construction, quality of materials, use and occupancy, location and maintenance of buildings to protect public health, safety and general welfare. If properly administered building codes can:
• Reduce death, property damage, disruption to employment in institutions and businesses and need for aid following a disaster
• Contribute to the durability of buildings and help maintain quality of life and property values
• Ensure the protection of consumers especially homebuyers from purchasing substandard or dangerous housing
• Offer a predictable playing field for designers, builders and suppliers
• Allow economies of scale in the production of building materials and construction of buildings (Theckethil, 2006).
Though codes may be adopted at the state or local levels, they are administered locally.The enforcement process begins with construction permit application, followed by plan review, permit issuance, inspections and certificate of occupancy issuance.
Types of Building Codes
Building codes may be broadly classified into two types:
• prescriptive and
• performance-based building codes.
In general, building codes are prescriptive in nature provided with the details of what must be done and how to do it. They require certain materials to be used and describe how to build them in detail. In contrast to this, the performance-based building codes specify goal to achieved and therefore are very broad, flexible and versatile that allows solution of the problem without prescriptive requirements and requires completed work to satisfy within specified standards (Benge, 1999). Some codes combine both the prescriptive and performance elements. To make resilient city, there is a certain requirement of explore and integration of more exclusive performance-based building codes, institutional framework to ensure democratic and participatory code-making process and above all, conscious efforts at the policy level to bridge the gap between technical expertise and experiential knowledge (Theckethil, 2006).
In this research work dealing with Floor area ratio (FAR), FAR is imposed as performance-based building code according to meet the challenge of the megacity within the general guideline of prescriptive codes named “DHAKA IMARAT NIRMAN BIDHIMALA ‘2008”.
Building regulation for resilience
It is evident that, in most of disaster-prone cities are associated with failures in urban land management, Insufficient legislative foundation and Inadequate building codes, weakness in building code administration and institutional capacity, Costly and inefficient building code implementation procedures (Moullier & Krimgold,2015). Implementation of building regulation and supporting active compliance work as a catalyst to leverage the total investment of building and infrastructure toward greater safety and security. As they provide checks and balances for orderly development, in developed country dedicated resilience supportive building standards and certification system as well as building codes are indispensable.
3. Floor Area Ratio
floor area ratio is an urban planning & design tool also known floorspace index, floor lot ratio, plot ratio. It is widely imposed in developed cities to mitigate negative population externalities (e.g. congestion or disperse) as density regulations. Central areas of cities are characterized by high population density, that must be provided convenient access to various urban amenities and services including employment, shopping, healthcare, and entertainment.
In the urban context, these negative externalities are classifiable into three types (Kono & Morisugi, 2010) according to their origin:
• population externality, such as Low or high density.
• building height externality, such as insufficient sunlight exposure & ventilation; and
• others, such as racial tension and landscape deterioration.
As density regulations, a city generally imposes floor area ratio (FAR) regulation where FAR is an index whose value indicates the limit of construction building floors.
There are many influencing Inter-related aspects involved such as adequacy of water supply, sewerage system, solid waste disposal, road capacity, land availability, harmony with surrounding developments and other facilities, amenities and services in urban design. FAR guides urban design conception and intervention where urban form can be controlled and optimized practically through the index.
FAR regulation is intended to control population density optimizing population externalities, lot size zoning (only setback guided) can control only the plot size, not the building size.
In a standard / moderate situation, lot size zoning can be the first-best policy, whereas FAR regulation is not the first-best but a second-best policy. Lot size zoning directly controls population density by regulating each lot size, and can therefore be a first-best policy against negative population externalities. FAR regulation is expected to change dynamically and concomitantly with population growth in changing urban area where rapid industrialization creating extreme pressure upon land and transport (Kono & Morisugi, 2010).
Every city has a limited resource and capacity. Any use beyond that point put it undue stress. The higher population density at an optimum level enables governments to deliver easier and more economic essential infrastructure and services in urban areas. Urban planners fixed population density and FAR to maintain sustainable urbanization process. Industrial, residential, commercial agricultural and non-agricultural spaces have differing safe load factors, so they typically have differing FARs. To reduce population density, a small FAR have to be imposed, yet again allowing maximum FAR will expand population density. With this regulation, it is more difficult to design than a first-best policy of only setback & height bindings.
FAR is a measure of how much square footage can be built on a given piece of land. By definition, FAR is the ratio of the total floor area of a building to the area of the plot on which it is located.
FLOOR AREA RATIO (FAR) = total floor area of a building / Plot area
A FAR of 3.0 means that the developer is allowed to build an equivalent of three times area of the site. For example, the FAR of 3 on a 1,000 square-feet land means 3,000-square-foot building area which can be:
• A single -story building of 3000 sft (100% ground coverage) or
• A two-story building of 1500 sft (50% ground coverage) or
• A three-story building of 1000 sft (33% ground coverage)or
• A four-story building of 750 sft (25% ground coverage)or
• A five-story building of 600 sft (20% ground coverage)or
• A six-story building of 500 sft (16.66% ground coverage).
So, on the same plot, there can be different per floor areas and different height of building having the same FAR value. Again, in FAR based building regulation codes, there are specific maximum ground coverage (MGC) area fixed upon adjacent road width and plot size.
Thus, FAR do control the amount of building floor area, and often don’t really state how much of the site will be covered by a building. FAR is likely to vary because population dynamics, growth patterns and construction type vary and because the nature of the land or space where a building is placed varies. Industrial, residential, commercial agricultural and non-agricultural spaces have different safe load factors, so they typically have differing FARs. In the end, governments put regulations and restrictions that determine FAR into effect. Towns and cities should be well designed, compact and connected, support a range of diverse uses within a sustainable environment which is well integrated with public transport and adaptable to change. FAR act as one of the crucial tools developing and providing necessary techniques to inform the balance, sequence and implementation of decisions to achieve the desired results (Steemers, 2003).
According to urban researchers and planners, to encourage more walking and vibrant, sociable urbanism, there should at least 1.5 FAR. Anything less than about 1.0 locks a community into sprawl, unwalkable and extreme auto dependence that feel as “no-man’s-land”. People feel more comfortable in the quaint, enclosed spaces of 2.0 FAR. Walkable urbanism and healthy transit require FARs to be at least 1.5 to 3.0. In Europe, those livable cities have FARs around 3.0. Study shows, every 20 percent increase in floor space in commercial centers developed as non-office uses are associated with a 4.5 percent increase in ride sharing and transit use (https://domz60.wordpress.com, 2018).
Urban development policies are responsible for land use, the size of blocks and plot subdivision, the structure and hierarchy of the road networks and street patterns, and the spatial distribution of social services and environmental amenities. Floor area ratio is stated One of the main policy tools for urban planning is the control of over the building footprint area in world bank’s report (Planning Energy Efficient and Livable Cities).
a. Purpose and use
Sustainability of cities has favored the implementation and conservation of greenery by low impact development in the urban context. The benefits of open spaces with plants are not just environmental but recreational, aesthetic and emotional.
• FAR is viable Indicator to use as a bench mark in passive energy design for the Built Environment and as a policy implementation guideline and strategy (Dawodu ; Cheshmehzangi, 2017).
• Facilitates the optimal use of land considering the existing energy cost, scarcity of arable land and backlog of environmental pollution.
• Not only the population but also building density and energy management can be regulated through FAR.
• impact on natural lighting, solar gains and ventilation of designing a building.
• FAR, energy production and consumption; wider surface areas and higher buildings allow for more indirect solar radiation which is linked to higher gains. However, if the buildings are too short this would affect radiation coverage and also productivity of solar energy technologies such as solar facades. Ultimately, it is up to the developer working with existing laws on height to find which design best suites a specific development at specific location.
• As city contains different width of roads that differentiates FAR index and building height. buildings of different height mean different population capacity, economic benefits and traffic pressure brought about by the buildings due to their difference in inner space.
• Concern on ‘level of service’
• In developed countries, FAR has proven a strong determinant of economic, social, and environmental co-benefits of energy efficient and livable urban forms.