Façade Design in Wet Tropical Climates

In the wet tropics, where climate change presents urgent and unique challenges, designing façades for sustainability and resilience is of utmost importance. The intricate interplay of increased rainfall, humidity, and temperature fluctuations demands immediate and innovative solutions that mitigate carbon emissions and enhance comfort and adaptability. Climate change manifests in the wet tropics through intensified seasonal patterns, leading to extreme weather conditions such as prolonged periods of heavy rainfall that lead to flooding. These shifts impact the built environment and exacerbate existing vulnerabilities, particularly among marginalized communities. 

Since the industrial revolution, global temperatures have risen by 1.5°C. This rise in temperature is primarily attributed to greenhouse gas emissions like CO2, which have escalated due to increased human production and consumption. These emissions trap heat in the atmosphere, contributing to global warming. In Indonesia, the building sector contributes around 5% of the total carbon emission, including embodied emissions from material production and construction processes, whereas façades account for 20% of the total carbon emission. However, hidden behind these direct emissions, buildings in Indonesia contribute more through their indirect contribution from energy consumption. Based on 2021 data, buildings' carbon emissions from operation, including energy consumption for heating, cooling, lighting, and mechanical systems, contribute to 24.9% of Indonesia's carbon emission share and show a trend of rapid increase. These notions underscore that architects and builders have a crucial role in addressing carbon emissions through building design. A measure to cut indirect building emissions through design becomes significant in reducing carbon emissions in Indonesia. By integrating sustainable and resilient design principles into façade design, architects and builders can significantly help mitigate climate change. 

In the tropical landscapes of countries like Indonesia, traditional architectural wisdom manifests as shadings and roof cantilevers to ward off sunlight.

In a wet tropical climate, intense solar radiation typical of tropical regions can increase indoor temperature. Sun radiation creates heat on materials directly exposed to sunlight and produces heat, increasing the energy demand for air conditioning systems. The gained interior temperature is highly influenced by the material's thermal mass. Materials with lower thermal mass allow easier heat penetration, resulting in a higher demand for cooling to maintain thermal comfort. Based on its exposure to direct sunlight, the choice of roof materials will determine the thermal increase within the building. Since ancient times, we have invented methods to prevent excessive heat infiltration into buildings. In the tropical landscapes of countries like Indonesia, traditional architectural wisdom manifests as shadings and roof cantilevers to ward off sunlight. Roof cantilevers remain a staple feature in modern landed housing to mitigate direct sunlight exposure. For example, our house design for Emeralda combines roof cantilevers, external shading devices, and window recesses to limit direct sunlight entering the room. 

The model house of Emeralda shows a playful facade, which helps reduce direct sunlight entering the building.

Taller buildings present unique challenges in managing heat gain due to increased exposure to sunlight, particularly notable in office towers with more expansive floor areas for enhanced efficiency. This broader floor space necessitates wider openings to allow natural light to permeate the building's interior, hence the prevalence of windows in high-rise structures. Focusing on reducing greenhouse gas emissions through improved energy efficiency is central to implementing green building measures nationwide.

The balance is critical for architects and builders to create spaces that are energy-efficient, conducive to human well-being, and visually appealing.

With the current technologies, there are many ways to reduce heat intake in a building. These include the installation of reflective roofing materials to reduce solar heat absorption, the incorporation of high-performance window glazing with low solar heat gain coefficients to minimize heat transfer, and the strategic placement of external shading devices such as louvers or sunshades to deflect direct sunlight. Furthermore, the utilization of thermal insulation within the building envelope helps to limit heat conduction. Investing in green buildings inevitably incurs additional costs during construction compared to regular buildings without green building measures. However, the benefits in terms of operational cost savings can be significant, potentially cutting operational costs by a certain percentage. With good façade design, operational costs for air conditioning can be reduced by a substantial amount, depending on the type of passive cooling approach used. For instance, employing a second skin facade akin to traditional tropical architecture can decrease heat gain, leading to reduced long-term operational costs. This cost-saving aspect of sustainable design should not be overlooked, as it provides a strong incentive for investing in green buildings.

Gran Rubina's unique facade was created from the use of fins and catwalks 

Gran Rubina, designed to achieve a gold certification for green building design, addresses the imperative of reducing air conditioning energy consumption. Without treatments to minimize direct sunlight, cumulative radiation from direct sunlight in Gran Rubina can reach up to 280 kWh/sqm during the daytime. Gran Rubina combines fins and catwalks to mitigate heat gain, creating vertical and horizontal shading like a second skin to prevent direct sunlight from entering the building while allowing natural light into working spaces. A comparison analysis between no shading, catwalk only, and the catwalk + second skin on the three top-most floors reveals that the combination of catwalk and second skin is the most effective in preventing sunlight radiation from entering the building. The catwalk and fin combination reduces up to 56% of cumulative radiation compared to the catwalk only (22%). Placing the fins at a distance created by the catwalk allows for larger openings between the fins while still providing shade. This design choice allows people inside the building to have visual access to the outside.

Comparison of three facade approaches for Gran Rubina

Based on the comparison above, shading and second skin solutions offer effective means to combat heat gain in buildings. However, it is important to recognize that various design approaches exist to address diverse needs. While some situations may warrant the implementation of shading and second-skin solutions, others may prioritize natural lighting and visual connections to the outdoors. We can conclude that by controlling the heat gain from direct sunlight, we can significantly reduce indirect emissions from the cooling system. Moreover, as we delve deeper into understanding facades in tropical climates, we can explore how different design choices can be tailored to meet specific requirements, striking a balance between environmental sustainability, human comfort, and architectural aesthetics. This balance is critical for architects and builders to create spaces that are energy-efficient, conducive to human well-being, and visually appealing. (pdw)