• Environmentally Sustainable Design
05/06/2024 Vania

Passive Design for Houses in the Tropics

A Case Study by Eco-Mantra

Date Published: June 5th, 2024

Written by: Vania Dian Gunawan, edited by Sean Nino Lotze, Charlene Octavian, Matthew McClintock

Do you often find yourself worn out from the sweltering heat outside, only to come home and find it just as stifling? Or perhaps your air conditioner is perpetually running, struggling to keep up? Imagine a cityscape that’s cooler, with enhanced airflow and reduced heat. The year 2023 has been confirmed as the warmest on record, with a global average temperature of 14.98°C, surpassing the previous record set in 2016 by 0.17°C. This alarming rise is attributed to human activities and El Niño weather patterns. Buildings, where we spend most of our time, are significant energy consumers and emitters, accounting for 30% of global energy usage and 26% of energy-related emissions.

Is there a way to make our homes more comfortable and livable for the future?

Enter passive design—a sustainable approach that emphasizes climate responsiveness and occupant comfort. As we explored in our previous article, passive design leverages natural elements to minimize energy consumption and regulate indoor temperatures. While most effective when integrated during the construction phase, passive design principles can also be retrofitted into existing buildings. Investing in these strategies can lead to substantial benefits: studies show passive design can lower indoor temperatures by 2.2°C, reduce cooling loads by 31%, achieve 29% energy savings, and increase thermal comfort by 23%.

Eco-Mantra demonstrates that urban planning, infrastructure design, and architecture in Indonesia can adopt a different path. By implementing passive design principles in each building, our cities can collectively become cooler.  

Let’s delve deeper into one of our projects, Eco-Mantra house, which exemplifies many key principles of passive design and was built with less than 700$ USD investment per m2.   

Passive Design Case Study: Eco-Mantra House  

Eco-Mantra House showcasing passive design principlesPassive Design Aspects of Eco-Mantra House:

  • Shading Structure:

    Shading is a fundamental technique to prevent direct sunlight from entering the building. In Eco-Mantra house, this is achieved with an extended long roof. This design minimizes solar heat gain and glare, maintaining a cooler ambiance inside the house. 

  • Aerated Brick Wall:

    Aerated blocks are utilized for their lightweight properties and superior thermal and acoustic insulation. These bricks offer significant improvements over conventional cement blocks, providing a better thermal envelope for buildings and reducing air conditioning energy loads. They are also easier and more economical to transport and use, making construction faster and more environmentally friendly. 

  • Stilted Building:

    Embracing the “Rumah Panggung” concept, the house is built on stilts. This design allows cool air to flow beneath the house, reducing overall temperatures. Additionally, it minimizes ground contact, preserving natural topography and local flora. This design choice also facilitates water absorption, reducing flood risk.  

  • Roof Angle and Direction:

    The roof is the most exposed part of the building to direct sunlight. Poor design can trap heat in the attic, raising indoor temperatures. Eco-Mantra house uses an insulated and ventilated roof with materials like Hilon for the upper roof structure and Rockwool for the ceiling. These materials keep the interior cool even in hot weather. Additionally, the house features roof openings to allow hot and humid air to escape, ensuring proper ventilation during the monsoon and dry seasonal winds. 

  • Facade:

    The facade, acting as the building’s outer envelope, plays a crucial role in thermal performance. The house uses high thermal performance materials such as low-emissivity (low-E) glazing for large windows, which effectively reduces heat penetration. Wooden louvers are used as shading devices to shield walls from direct sunlight, minimizing heat absorption and enhancing natural airflow for improved comfort.

  • House Direction:

    The house is designed to face west to prevent prolonged exposure of its long side to direct sunlight. Trees planted around the house provide additional shade, keeping the overall structure cool. The front part of the house receives sunlight from 11 a.m. until sunset, but the shading structures significantly reduce direct solar glare. 

By integrating these passive design elements, this house demonstrates how thoughtful architectural choices can lead to significant improvements in energy efficiency, thermal comfort, and environmental sustainability. 

The Benefits of Passive Design in Houses 

“The maximum temperature in my house is around 27 degrees Celsius. I rarely use an air conditioner in the mornings,” says Nino, the homeowner. Beyond maintaining a comfortable temperature, passive design offers numerous benefits for both occupants and the environment: 

Enhanced Occupant Comfort 

  • Thermal Comfort:

    In tropical climates, air conditioners can lead to uneven cooling and temperature differences between rooms. Passive design, which relies on natural airflow and shading, keeps the entire house at a comfortable temperature, as Nino experiences. 

  • Indoor Air Quality:

    Improved natural airflow and proper ventilation reduce dust, pollution, and allergens. This helps control indoor humidity, preventing mold growth that can harm respiratory health. 

  • Reduced Bills:

    Passive design utilizes natural elements such as thermal mass, natural ventilation, and sunlight to decrease the need for artificial lighting, electronics, and appliances. According to the Energy Research Institute for ASEAN and East Asia, nearly 50% of energy consumption in hot and humid climates goes toward cooling. Passive design minimizes this energy usage by maintaining comfortable indoor temperatures and maximizing natural lighting. Additionally, natural ventilation helps prevent mold, enhancing material durability and reducing maintenance costs. 

Positive Environmental Impact:

Passive design reduces the environmental footprint by lowering energy consumption and greenhouse gas emissions and decreasing reliance on limited resources. 

Rising global temperatures, driven by climate change, pose significant challenges, particularly in urban areas exacerbated by the Urban Heat Island (UHI) effect. With over half of the global population living in cities—projected to reach 60% by 2030—the UHI effect intensifies, leading to higher energy consumption, adverse health effects, and environmental stress. 

Passive design stands as a beacon of hope in these challenges. The eco-mantra house exemplifies how passive design strategies can transition buildings to low-energy consumption while promoting comfortable living conditions and reducing costs. By integrating passive design principles into our buildings, we can pave the way to a more sustainable future and comfortable living spaces. 

If you are interested in implementing ESD on your property, please contact us at team@eco-mantra.com 


A literature review on the improvement strategies of passive design for the roofing system of the modern house in a hot and humid climate region  

Aerated blocks: what are they and what are they used for? 


Copernicus: 2023 is the hottest year on record, with global temperatures close to the 1.5°C limit 

Passive Design Measures 

The Benefits of Passive Houses Explained 

The effects of passive design on indoor thermal comfort and energy savings for residential buildings in hot climates: A systematic review  

The Health Benefits of Living in a Passive House: A Sustainable Approach to Well-Being 

Urban Development 

Urban Heat Island 

What is the city but the people

Why Build a Passive House? Passive House Benefits 

Get In Touch

Let's Work Together

Find out how we can create sustainable destinations and experiences for generations to come.

Keep In Touch

Eco-Mantra Newsletter

Sign up for our newsletter to connect and learn about the built environment, sustainable design and how we value the environment.