Green architecture: Helping buildings breathe without aid

As the world grapples with climate change and the need for sustainable development, the construction industry needs to participate in reducing its environmental impact. And that can be achieved through green construction, sometimes called sustainable or eco-friendly construction, which transforms how buildings are designed, built, and operated.  

Bangladeshi architect Marina Tabassum captured the essence of sustainable design when she remarked that a building "has to be able to breathe without artificial aid". Her Aga Khan award-winning project, the Bait-Ur-Rouf Mosque in Dhaka, exemplifies this philosophy. 

But what does it really mean for a building to be energy-efficient, green, and sustainable?

In designing the mosque, Tabassum avoided windows but ingeniously incorporated openings that allowed for natural ventilation. This design keeps the interior cool without the need for additional cooling systems. The sunlight filtering through these carefully crafted openings not only enhances the spiritual atmosphere but also ensures the privacy of worshippers.

Veteran architect Ehsan Khan praised the project, noting that, despite its simple appearance, the mosque's design is rich in energy-sensitive features. Tabassum used locally-sourced bricks and concrete, blending traditional materials with modern architectural techniques that subtly redefine simplicity.

The concept of green building, introduced in the late 19th century, emphasises the use of environmentally-friendly materials and sustainable practices. Green construction has gained global attention for its effectiveness in water management, waste reduction, energy efficiency, and sustainable development, making it a key element of modern architecture. 

With the main objectives of providing a healthy environment, reducing environmental impact, maximising the use of natural materials and raising employee productivity, green properties involve environmental concerns at every stage of development. 

"Not just with energy efficient materials, green buildings can be developed with diverse engineering solutions, architectural elements, cutting edge technology etc. And this way, not only the building features, but more technical aspects like eclectic mechanical systems can also be made green and sustainable," architect Khan said. 

According to him, traditionally, Bangladeshi homes and structures were always green. If we observe our traditional ancestral homes, they had hay roofs and bamboo walls, and courtyards with water sources nearby, which made the habitat cool without any air conditioning. 

Even in the British period, the structures used to be climate sensitive, with balconies and ventilators. Ventilators made living inside the home comfortable as the warm air would rise up and leave through the ventilators. In today's modern spaces, ventilators are no longer used. 

With locally made bricks, the structures consumed less energy. 

Khan believes we must think about how we can lower our energy consumption, energy waste and overall carbon footprint. The elements that can be reused and repurposed are more energy-sensitive. By using reusable building materials, building construction systems and forms we can make green buildings. These can be incorporated both in planning and also in the interior equipment, fixtures, accessories etc. 

IAB: A model of green building 

The Institute of Architects Bangladesh (IAB) in Dhaka's Agargaon area stands as an excellent example of what a green building should be.

Covering 1,937 square metres on a 3,852 square metre plot (a little over 1.5 bighas), the construction of this building began in 2009 and was completed by 2016. In 2021, it won the prestigious ARCASIA award for its innovative design.

Designed by Ehsan Khan, the building's main structure is made of steel, featuring large columns and branches. The overhanging metal roof is insulated with two layers of material to keep the interior cool. Impressively, the metal structures, including the roof, are designed to be dismantled if needed.

The design integrates three key elements: metal, locally sourced handmade bricks, and a portion of concrete, all seamlessly combined to create a functional and sustainable building. 

Khan explains that the steel structures are reusable, meaning that if the building is ever taken down, these materials can be repurposed for other projects, reducing waste.

To ensure the building is open and breathable, essential for an institutional space with frequent public gatherings, Khan kept the north side more open while shading the south. The hallroom features detachable partitions, allowing for flexible use of space.

The site also includes water features, greenery, and an open courtyard, all contributing to natural ventilation and reducing the need for cooling systems.

In recent decades, as Bangladesh's economy has grown, urban construction has shifted towards modern high-rise buildings with glass and concrete structures. This trend contrasts with the more climate-sensitive, low-rise homes of the past, which often featured brick walls, balconies, and tin or concrete roofs.

However, as Ehsan Khan points out, building codes like the Bangladesh National Building Code (BNBC) can sometimes limit green construction. 

For example, the BNBC includes provisions for earthquake-resistant construction, requiring the use of Reinforced Cement Concrete (RCC), a material that combines concrete with steel reinforcement. While necessary for safety, this material increases the carbon footprint of buildings, highlighting the challenges of balancing green construction with structural resilience. 

"Using RCC makes it a bit tough for us to make an energy sensitive building," he said. 

Because RCC construction uses large amounts of materials like cement, sand, aggregates, and steel, which can lead to waste. The production of concrete can lead to environmental degradation and the heavy weight of concrete increases transportation costs. 

Although architects and engineers are thinking of solutions to this issue. For instance, prefabricated or prefab construction is a greener alternative to RCC construction because it uses fewer materials and less fresh water. Also the components are made in a factory, which minimises waste and allows for the reuse or reprocessing of remaining materials.

Another great option is ferrocement, which uses thinner sections with minimal steel and geometry for structural stability.

The Programme for Energy Efficiency in Buildings (PEEB) and the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) recommend an improved building design in hot climates like Bangladesh that can reduce the massive need for space cooling.

The recommendations include: east-to-west oriented buildings along the main path of the sun that expose only smaller facades to high solar radiation; better air circulation through larger distances between buildings and a green surrounding area; most openings (doors, windows, and vents) should face north or south to reduce sun exposure; the walls of air-conditioned buildings should be airtight and light to mid-weight with thermal insulation — materials such as fibreglass insulation, rammed earth walls, ceramic tiles (floor) and stones can be used. 

For open structures without air conditioning, light walls that have many openings and vents near the floor and ceiling are great, because this creates a pressure difference that causes air circulation and constant ventilation; and light-coloured roofs with a reflective coating, that have thermal insulation, are good, while green roofs are even better.