1.GENERAL BUILDING REQUIREMENTS, CONTROL AND REGULATION

a) General Building Requirements

According to the Bangladesh National Building Code (BNBC 2020), this project is for a 10-storied residential building situated on a 14,400 square-foot plot. As per the BNBC guidelines, key design considerations such as occupancy classification, building layout, and sustainability measures were evaluated and implemented.

For a residential occupancy building (Occupancy Category A), various essential controls and regulations were applied:

• Site Condition: No building should be constructed on any site with waterlogged conditions or areas with refuse, excreta, or objectionable materials. Sites must be cleared and effectively drained as required by relevant authorities to ensure compliance with BNBC standards.

• Open Space: To facilitate water penetration and minimize surface runoff, at least 50% of the minimum required open space on the plot remains unpaved, with or without vegetation.

• Plinth Level: The building’s plinth is set at a minimum height of 450 mm above the center line level of the adjacent road, adhering to drainage and flood prevention standards.

• Kitchen Requirements: The minimum clear height for the kitchen space is 2.75 meters, with a skid-resistant and watertight floor. Windows provide ventilation with a minimum area of 1 square meter (BNBC 1.14.3).

• Room Size: All habitable rooms in the dwelling unit must have an area not less than 9.5 square meters, with a minimum width of 2.9 meters (BNBC 1.14.2.2). Non-habitable rooms have a minimum area of 5 square meters and a width of 2 meters (BNBC 1.14.2.1).

• Store Room: Any provided store room is at least 1.5 square meters in area, with a width of 1 meter and a clear height of 2.2 meters (BNBC 14.1.9).

• Parking: The minimum clear height of the parking area is 2.03 meters, ensuring adequate space for residential parking needs (BNBC 1.14.10).

• Stairways: Maximum stair flight height between landings is 3660 mm for residential purposes, while clear headroom between flights is set at a minimum of 2.15 meters, allowing a reduced headroom of 2.03 meters for up to three flights (BNBC 1.14.5.3-1.14.5.4).

b) Classification Based on Occupancy

In compliance with BNBC 2020, this building’s occupancy is categorized as Residential (Category A), following specific requirements related to residential structures. This designation informs the building’s overall layout, egress planning, and emergency systems, ensuring that all standards are met to accommodate residential living.

c) Classification of Building Construction Types Based on Fire Resistance

The building's fire resistance features are aligned with BNBC 2020’s construction classification guidelines, specifying materials, compartmentalization, and egress to maximize fire safety. As a residential structure, its design prioritizes fire resistance through appropriate material choices, egress routes, and integrated fire-suppression systems.

d) Energy Efficiency and Sustainability

Energy-efficient practices, such as lighting limitations and renewable energy integration, are essential to the building's design:

• Lighting: For apartment units, the maximum lighting power density is 7 LPD (W/m²), ensuring energy-efficient illumination that aligns with BNBC’s requirements (Table 3.4.5).

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Maximum Allowable Lighting Power Density for Different Occupancies

• Renewable Energy: BNBC 2020 mandates that 30% of the building’s total electric load be sourced from renewable energy, such as solar power, especially for buildings classified under Occupancy Category A (BNBC 4.5.6).

Energy-efficient elevators and escalators are also designed with reduced-speed control and energy-saving shut-down mechanisms. Photocells at escalator landings provide on-demand activation and reduce energy consumption when the equipment is not in use (BNBC 4.5.5).

2) Fire Protection

In alignment with the Bangladesh National Building Code (BNBC 2020), fire protection provisions for the proposed residential building are designed to ensure the safety and orderly egress of occupants. The fire protection strategy integrates both preventative measures and efficient egress systems, ensuring all facilities and equipment meet BNBC standards for fire safety in residential buildings.

a. General Provisions

A comprehensive fire protection system includes alarm, evacuation, and egress solutions to manage fire incidents effectively. The fire alarm system is designed to mitigate panic, which is critical for successful evacuation or controlled relocation of occupants. Key provisions include:

• Sequential Alarm Activation: The fire alarm system is configured to activate alarms in a sequenced manner rather than all at once. This staged approach avoids sudden panic by managing the flow of information and directing evacuation efforts strategically across designated building zones.

• Controlled Communication: Instead of announcing "fire" to avoid undue panic, authorized personnel use a passphrase system to coordinate evacuation efforts, as outlined in BNBC 2020. This allows responsible personnel to alert designated areas without overwhelming other zones.

• Zoned Protocols: To support safe evacuation, the building is subdivided into zones for fire alarms and evacuation protocols. This zoned approach includes fight-in-place and delayed egress options, depending on the nature and spread of the fire within the building structure.

b. Precautionary Measures

Precautionary measures involve planning for different types of fire hazards and integrating fire extinguishing options suited to specific needs:

• Gaseous Systems: Where traditional water or foam systems may damage sensitive equipment or materials, a gaseous fire suppression system is implemented. This is essential for rooms or areas with equipment that could be compromised by water.

• Fixed Fire Protection System: A fixed system with an extensive pipe network supplies extinguishing agents throughout the building, covering designated zones either fully or partially. Localized fixed systems are installed in confined spaces to provide automatic discharge of fire-suppressing agents when necessary (BNBC 4.6.2).

• Portable Extinguishers: Portable fire extinguishers are located at strategic points within the building for easy access by occupants in case of a fire emergency. They provide a mobile firefighting solution to tackle initial flames before emergency responders arrive.

c. Means of Egress

Means of egress have been meticulously planned to align with BNBC 2020's stringent safety requirements. These provisions ensure clear, accessible, and unobstructed pathways for occupants to exit the building safely:

• Discernible and Accessible Exits: All exits are clearly visible and easily accessible from within the building, with continuous and unobstructed routes leading to the exit discharge. Exit doors do not pass through hazardous or locked areas, preventing any obstruction or delay during evacuation (BNBC 3.4).

• Number of Exits: The number of exits is calculated based on the occupant load:

  • For up to 50 occupants: Minimum 1 exit

  • For 50 to 500 occupants: Minimum 2 exits

  • For 501 to 1000 occupants: Minimum 3 exits

  • For more than 1000 occupants: Minimum 4 exits

• Capacity of Exits*: For assembly areas, each entry point doubles as an exit, supporting at least half of the occupant load. Additional exits are also provided to ensure the building can be evacuated safely and promptly.*

d. Equipment and In-Built Facilities Standards

The fire protection system incorporates in-built facilities and equipment as per BNBC standards to facilitate quick response during emergencies:

• Alarm and Notification System: The alarm system includes strategically placed devices within each zone to alert occupants and authorized personnel. It is designed to activate in response to fire detection without overwhelming all zones simultaneously.

• Sprinklers and Hydrants: In-built sprinklers and hydrants are located throughout the building, providing immediate fire suppression capabilities. Sprinkler activation is automatic, providing immediate response upon detecting significant temperature changes associated with fire incidents.

e. Specific Requirements for Fire Detection and Extinguishing System

For effective fire detection and suppression, the building’s system adheres to the following BNBC standards:

• Detection System: Smoke and heat detectors are installed in each room and corridor, programmed to automatically activate the alarm system upon detecting fire indicators.

• Extinguishing System Types:

  • Gaseous Fire Suppression: Used in areas where water or foam extinguishing is impractical, the gaseous system minimizes water damage risk.

  • Localized Fixed Systems: Confined spaces within the building are fitted with self-contained extinguishing devices that automatically discharge in case of fire.

  • Portable Fire Extinguishers: Portable extinguishers are stationed across different zones, enabling quick manual intervention if needed (BNBC 4.6.2).

3) Building Services

In alignment with BNBC 2020, the building services for the proposed residential building encompass essential provisions for electrical, mechanical, plumbing, and ventilation needs. These services are designed to maintain comfort, safety, and operational efficiency for residents, ensuring that each system integrates seamlessly into the building structure.

a. Electrical and Electronic Engineering Services for Buildings

The electrical systems are designed to prioritize safety, accessibility, and ease of maintenance:

• Electrical Wiring and Cabling: All electrical installations, alterations, and extensions are implemented in compliance with BNBC 2020, ensuring reasonable safety for both occupants and the property (BNBC 1.3.15). Wiring of over 50 volts is provided with a positive disconnect adjacent to the equipment it serves, enabling easy maintenance and preventing accidental contact with live circuits.

• Grounding and Receptacles: For equipment requiring more than 50 volts, a 230-volt AC grounding-type receptacle is installed within 8 meters for service access. Low-voltage wiring of 50 volts or less is routed to prevent physical damage (BNBC 2.9.1.8).

b. Air-Conditioning, Heating, and Ventilation

The air conditioning, heating, and ventilation systems are installed with operational efficiency and convenience in mind:

• Plant Room Location: The air conditioning plant room is located close to the main electrical panel to minimize cable length and facilitate power distribution. If the plant room is located in the basement, service ramps or hatches are provided for equipment movement to ensure easy maintenance and replacement.

• Drainage and Water Supply: Dedicated drain channels or pipes with slope are installed to remove wastewater effectively. Additionally, a fresh water connection is provided in the plant room, supporting equipment that requires water supply.

c. Building Acoustics

Building acoustics are essential for maintaining comfort and privacy within residential spaces:

• Soundproofing: Acoustic treatment is applied to reduce noise transmission between units, especially around high-traffic areas like stairwells, elevators, and common areas. Soundproofing measures in walls and floors help reduce noise from mechanical systems and maintain a quiet residential environment.

• Noise Isolation for Equipment: Equipment like HVAC units is installed with vibration-dampening mounts to limit noise transfer. Air ducts and mechanical systems are also equipped with silencers to ensure minimal disturbance to residents.

d. Lifts, Escalators, and Moving Walks

Vertical transportation systems are installed to ensure safe and efficient access between floors:

• Lift Design: Elevators are designed per BNBC guidelines for energy efficiency and operational safety. Reduced-speed control settings conserve energy during periods of inactivity, while escalators are equipped with photocell activation at landing areas, enabling on-demand use.

• Accessibility: The lifts are compliant with accessibility standards, providing sufficient space for mobility aids and supporting the safe movement of all building occupants.

e. Water Supply

Water supply provisions meet the daily needs of residents, with systems designed to ensure reliability and safety:

• Occupant-Based Design: Water supply requirements are calculated based on the estimated number of occupants per unit, with an average family size of five. This approach ensures sufficient supply for domestic needs, including drinking, cooking, and sanitation (BNBC 5.6.3).

• Pressure and Distribution: Pumps and storage tanks are installed to maintain consistent water pressure across all floors. The layout is designed to avoid disruption and ensure equitable distribution.

f. Sanitary Drainage

The drainage system is planned to manage wastewater and sewage efficiently, prioritizing hygiene and environmental safety:

• Building Drain and Ventilation: A ventilating pipe is installed as close as possible to the building drain, situated at a distance from where it connects to the sewer to prevent gas buildup and ensure effective flow (BNBC 6.4.1).

• Fixture Requirements: Each residential unit has at least one water closet, a kitchen sink, and a bathroom with either a shower or tub to meet sanitation standards. Additional fixtures like separate bathing and toilet areas help maintain personal hygiene and sanitation (BNBC 6.6.1).

g. Rainwater Management

Rainwater management is integrated into the building’s plumbing design to handle stormwater and reduce water runoff:

• Drainage Systems: Roof drains and downspouts are installed to direct rainwater away from the building foundation. These systems are connected to the drainage network to prevent flooding, erosion, and other water-related issues.

• Rainwater Harvesting: Where feasible, rainwater harvesting systems are installed to capture and store rainwater for non-potable uses, contributing to water conservation efforts.

h. Fuel Gas Supply

Fuel gas services are designed with strict safety protocols to prevent hazards and ensure operational efficiency:

• Qualified Installation: Gas piping and appliance installations are conducted by qualified professionals to prevent leaks and other risks. Maintenance and repair work are also restricted to certified personnel, ensuring the system’s integrity (BNBC 8.2.5.1).

• Corrosion Prevention: Piping is installed with protective measures to prevent contact with walls, reducing corrosion risk. Epoxy sealants or polyethylene conduits are used where pipes cross walls, ensuring durability and compliance with BNBC 2020 standards (BNBC 8.2.5.4).