Design of Multi-Storied Green Office Building for RAJUK at Mohakhali, Dhaka
Project Overview and Concept
The Rajdhani Unnayan Kartripakkha (RAJUK) was established in April 30, 1987 with prime intension to develop, improve, extend and manage the city and the peripheral areas through a process of proper development planning and development control. In the new office building of RAHUK, high goals have been set for achieving national recognition for leadership in sustainable and environmentally responsible building design. From the very onset of the project, supreme importance was given on the impact of the building on human performance. Along with creating a world-class sustainable building, the designers constantly attempted to create the healthiest, most effective and comfortable work environment for the employees.
The architects wanted to use the RAJUK Green office building, to showcase their commitment to sustainability and cost-effectiveness. These will also effective for job responsibility of RAJUK, as general public who will visit the building will be highly very impressed with the innovative design and comfortable space. The focus is on creating meaningfully sustainable spaces that engage the public and support the focus on Green building.
The RAJUK complex is characterized by three main buildings on a whole ground floor, arranged in a homogeneous “comb” oriented North / South. This device offers a compact size to the entire project while lowering the solar heat gain on west and east façade and generating breaths between structures, water garden at the center and hanging roof-gardens. It also helps to ensure good readability and legibility, and a strong identity to the RAJUK office at the center position. RAJUK executive offices are joined together at the upper level, creating the visual metaphor of an opening door. Two urban street-front courtyards are created to provide this space a sense of belongingness to the public.
On a symbolic level, the design is an iconic gesture to unite the diverse functions of RAJUK, the unfolding architectonic planes symbolizing the desire to make a better city where diversity flourishes with effective communication between people and Government.
In this project, total built area is 814,383sft including parking space of 170760 sft. Therefore, total 643,623sft spaces are designed for office and other ancillary functions. Of them, 258,347sft is dedicated for RAJUK office and rests are rentable spaces.
The design concept of this RAJUK Project embodies four themes:
Inviting gateway “Door always open”
Connection with the surrounding “People will be connected”
Green open spaces “Land always green”
Sustainability “Sky will be blue”
A. Door Always Open: With a grand gesture of opening up the site from the city, the project is a visual icon projecting the spirit of RAJUK, which is always open and receptive to new ideas and diverse cultures. The Open Door also symbolizes the openness and transparency of governance of RAJUK.
B. People will be Connected: The essence of the design for people is on connectivity, dialogue and communication. On a physical level, the design starts with a macro-view of the urban form adopting a strategy that brings on a seamless connection of urban green nodes. A dialogue has been created between the RAJUK Complex and the flanking green field “Titumir”, signifying the independence as well as the importance of connection with our Mother Nature. The “Green Carpet”, penetrates the heart of this project linking the city with the water feature of waste water treatment and the RAJUK office, which brings the citizens of Dhaka right through the heart of Government with ease and fluidity. As skyline of Dhaka city is shifting upwards day by day in a tremendous rate, soon the whole area will be built-up. So, the aperture within the complex and field will remain for a long time and will keep on inviting people to the public building.
C. Land Always Green: While the RAJUK complex is a civic icon, the gateway gives entry to the natural features and lush landscape. The “Green Carpet” that connects the field through the Door leads to a multitude of people-friendly venues, including a water court for reuse, all for the enjoyment of the public
D. Sky will be Blue: RAJUK demonstrates a passionate commitment to embrace a cleaner future, with emphasis on sustainable design contributing to a concerted effort to bring back the blue sky. Disposition of the blocks allows the prevailing wind to penetrate the inner courts providing ventilation through the double height and void spaces, it also allows solar access to the site, while the buildings allow airflow mixing and recirculation, channeling wind to enhance air ventilation at pedestrian level. Besides, innovative facade design systems are adopted to achieve sustainability for the development.
Design & Innovation
This building will be an excellent example for our city as we move toward net zero design.
Renewable energy: It will be an urban building that minimizes the consumption of natural resources to a high level and generates on-site a significant amount of renewable energy. The building will produce its own power needs from renewable photovoltaic and will require less energy to illuminate the interior through daylight-harvesting and advanced lighting design, compared to typical office buildings. Solar energy and rainwater harvesting, a green roof, and natural ventilation will create a quantitative impact on the building’s overall sustainability.
Perforated outer skin: The exterior of eastern and southern skin, perforated with fields of small holes that will allow light and air to pass through new operable windows hidden beyond is one of the most prolific merge of sustainability with architectural design. This perforated outer skin mitigates solar heat gain while enabling cross-ventilation of the interior. The new perforated skin will create a generously illuminated and well-ventilated interior for the daily users, providing a pleasing view. The office space will be extremely comfortable for the staff who will use the building every day, providing fresh air and light throughout the day.
The open office layout: It will afford views to all of the interior spaces. The overall atmosphere will be positive regardless of the work being done because of the abundant light, fresh air, and views the design provides.
On-site black water treatment: It will be reused and meet the non-potable water needs. The waste water is treated by septic tank, Anaerobic Baffled reactor, anaerobic filter, planter gravel filter (with ‘Kolaboti’ plant and polishing pond. Then this treated water can be reused for irrigation.
A clear visual relationship is established with the neighboring playground, and extends the pedestrian experience to activate this urban space. The building lobbies are open to the public, and allow for public interaction, bringing the space into the public realm. Having the amenities and culture at work to encourage biking by providing bicycle parking at the ground level means giving back in a positive way to our community and environment.
Land Use & Site Ecology
This office is designed to respond appropriately to the urban context by opening up to the public at street level to create a gathering space and urban living room. The generous pedestrian invites people to heavily landscaped urban forest. The rainwater is harvested and re-used to the toilet fixtures of various levels. At the ground level courtyards and green roofs, native plant species like Nim, Ashshoth, Nagalingom (local names) etc will be used throughout the site resulting a sustainable landscape, and will decrease the urban heat-island effect and reconnect the city dweller to nature.
“Energy strategies reduce consumption and carbon emissions by 40% over a typical office tower,” described NBBJ. “In addition, the slight rotation of the towers and their offset heights capture the site’s prevailing winds, ventilating the atria while minimizing exposure to direct sun. To control glare and heat-gain, the curtain wall incorporates a modular shading system that varies according to the degree of sun exposure.” The main concern is the living quality of the users and the efficiency of the construction by minimizing direct sunlight and heat intake. The west side is block with the cores on the three towers. The east side is blocked with the perforated skin of the RAJUK office and by core for the other two buildings.
A building that works efficiently and in a sustainable manner is one that has a carefully thought-out space from the inside, not that just looks good from the outside: the façade is an external translation of the internal efficiency not just an aesthetic frame. The north and south facade was carefully composed to be in harmony with the microclimate and surrounding structures, while responding passively to the local climate. The north facade is of clear glass, the south façade has horizontal louvers was specifically shaped to respond to the local sun path. The East façade of the middle building exhibits the RAJUK executive office zone and East facade features a more contemporary design to mirror the city.
Light & Air
The lighting design for the building includes high performance, energy efficient fixtures located to accentuate architectural design and provide appropriate light levels for the use of each space. Extensive thought is given to each area of the building interior, as well as the exterior, in terms of appropriate fixtures and amount of light to provide a natural, comfortable and the most efficient workplace. The perforated eastern and southern facades will shade the building from direct light while allowing views to the neighborhood. Throughout the regularly occupied offices, the spaces will be day lit with direct views to the outside, allowing occupants to experience the changes of the day. The occupants are aware of the passage of time by the light that enters through these skylights of the hanging exhibition spaces. Both in the exhibition space and the upper office spaces, daylight sensors automatically adjust the output of the main light fixtures to take full advantage of available sunlight. On most days, the lights within the space will not be needed during daylight hours. Simulation of Daylight Analysis shows that connecting mass central points illumination level are around 1000-1100lux, which is sufficient for office task work. Therefore, there is no need of artificial lighting from 9:30am to 4.30 pm.
Wind simulation data shows better result in upper level because most of the surrounding buildings are low or mid rise. Above 60m, wind speed is high enough for naturally ventilated floors while the main road showing low wind speed for its surrounding high-rise commercial belt. Designed building gets the positive micro-climate effect from its surrounding large open field.
This building will consume less water than similarly sized buildings as rainwater is harvested on the rooftop and used throughout the low-pressure toilet fixtures of the project. These new systems will begin a dialogue for a potential paradigm shift in the way we think about using water. It is one of the first urban buildings in Dhaka with on-site waste water treatment .Water demand will be reduced through highly efficient fixtures throughout the project. Planters inside and outside the building filter the building’s wastewater through a process similar to that employed naturally in a wetland. Pervious surfaces, including landscaping, pervious pavers and drivable grass pavers, account for maximizing the non-building site area.
Energy Flows & Materials
The generous daylight and passive cooling of the building will result in less than expected energy use. Day lighting strategies including open office spaces and exposed concrete designed with a high Solar Reflectance Index, help to reduce lighting loads. Manually controlled operable windows increase user comfort. Durable and low-emitting materials will be used throughout the project. Recycling, composting and creating less waste will be important issues while building construction. The top soil will be restored after the project completion.
The design team has considered, all these above mentions sustainable issues to propose the iconic Green Office building of RAJUK in Dhaka.