• Environmentally Sustainable Design
15/12/2023 eco-mantra

Let Passive Design Cool Your House

Discover the different strategies for implementing passive design

Date Published: December 15th, 2023

Written by: Annisa Sabran, edited by Irvan Tadaru, Mubashir Moqeem

Building Better through Passive Design

If you live in a tropical or subtropical region, you know how hot and humid it can get during the summer months. You might be tempted to crank up the air conditioner or fan to keep yourself cool and comfortable. However, this can lead to high energy consumption and carbon emissions, which are harmful to the environment and your wallet. According to the International Energy Agency (IEA), cooling devices account for 20% of global building energy consumption. Eco Mantra’s projects show that cooling and ventilation systems can consume anywhere from 35% to 60% of total electricity usage. 

But did you know that there is a smarter and greener way to design your house that can reduce your energy consumption and carbon emissions, while maintaining a pleasant indoor environment? This is why Environmentally Sustainable Design (ESD), especially, passive design principle is essential for a comfortable and environmentally sustainable house.   

What is passive design?  

Passive design is a design approach that uses natural elements and processes to regulate the indoor environment of a building, without relying on mechanical devices. The aim of passive design is to reduce energy consumption and carbon footprint by harnessing the local climate to achieve thermal comfort for the occupants. Passive design is a key component of environmentally sustainable design (ESD), which strives to create buildings that are resilient, efficient, and healthy. Passive design optimization is the first step towards achieving a net-zero carbon building.

5 Principles Of Passive Design  

Passive design is a set of principles that can be used to create energy-efficient buildings. There are five principles of passive design:  

  • Orientation 

The way that the house is oriented has a big impact on the amount of light that it will be able to receive. In passive design, you want to make sure that the light is coming from the south in the northern hemisphere and from the north in the southern hemisphere. This allows the winter sun to warm the property. The exact orientation will depend on the type of area that you are living in.  

  • Thermal Mass  

Thermal mass refers to the type of building materials that are used and how dense they are. Materials such as concrete, brick, stone, and tile have high thermal mass. They absorb heat during the day and release it at night when temperatures drop. This helps regulate indoor temperatures.  

  • Insulation  

Insulation is designed to create a barrier between inside the property and the outside temperature. For example, during the winter months, it might be cold outside, but inside the house, you’ll be toasty and warm. The insulation can also help you control the way that heat dissipates during the summer months.  

  • Windows  

Windows play an important role in passive design. They allow natural light into your home and can help regulate temperature by letting in or keeping out heat. Windows should be placed at the right positions along the wind direction to push cool air into the house.  

  • Shading  

Shading is another important element of passive design. It helps keep your home cool in summer by blocking out direct sunlight. Appropriate shading strategies exploit the sun’s energy in the heating season and minimize overheating during the cooling season. There are many ways to shade your home, including using trees, awnings, or shutters.  

Strategies for Implementing of A Passive Design  

Passive design strategies aim to create comfortable and energy-efficient indoor environments while minimizing the use of mechanical systems and reducing the building’s environmental impact. There are different types of passive design strategies depending on the climate, site conditions, and materials of the building. Some of the key passive design strategies are:  

1. Shading Strategy  

Shading is a passive design strategy that aims to reduce the amount of solar heat gain and glare in a building by blocking or filtering the direct sunlight. Shading can improve the thermal comfort and energy efficiency of a building by lowering the cooling load and reducing the need for artificial lighting. Shading can also enhance the aesthetic and architectural quality of a building by creating interesting patterns and shapes. The addition of shading should not significantly reduce the daylight received by the room unless the light causes glare.  

Diagram illustrating a shading strategy to reduce solar heat gain in a building

Figure 1 : Shading strategy


2. Opening for natural ventilation strategy  

This involves creating openings in the building envelope, such as windows, doors, vents, or skylights, to allow fresh air to flow through the building. Openings should be placed strategically to create crossflow or stack-driven ventilation. Crossflow ventilation is more effective than one-sided ventilation to provide flow along the room, reducing risk of air trapped inside the room. Stack-driven natural ventilation is driven by the difference in pressure and temperature inside the room/building, requiring two openings with different heights.   

Diagram showing cross ventilation, highlighting airflow through windows to cool a building

Figure 2 : Cross ventilation

Diagram depicting stack ventilation, showcasing air movement driven by temperature and pressure differences

Figure 3 : Stack ventilation

3. Airtight construction  

Proper air-tight building can minimize heat transfer through infiltration which can reduce cooled air from inside to release. This involves sealing gaps and cracks in the building envelope to prevent unwanted air infiltration or leakage. Airtight construction can improve thermal performance and comfort by reducing heat loss or gain through the envelope. Airtight construction should be complemented by adequate ventilation and insulation. 

Illustration of window air gap, emphasizing airtight construction to minimize heat transfer

Figure 4 : Window air gap

4. Thermal Zoning in HVAC System  

A thermal zone is an area or group of areas in a building that share similar temperature requirements and use the same heating and cooling settings. It is the fundamental unit for modelling the building’s thermal properties and can consist of one or more spaces.  Thermal zoning is achieved by dividing the building into different zones based on their thermal requirements and preferences. Each zone can have its own heating or cooling system with independent controls. Thermal zoning can improve efficiency and comfort by providing customized temperature settings for each zone.   

Diagram of a house with different types of roomsFigure 5 : Diagram of a house with different types of rooms

Diagram of a house with different thermal zoning in an HVAC system

Figure 6 : Typical thermal zoning diagram

5. High performance material selection  

This involves choosing materials that have low environmental impact and high thermal performance for the building envelope. Materials such as roofs, walls, glazing, insulation, or finishes should be selected based on their properties such as reflectivity, emissivity, conductivity, or resistance. High performance materials can reduce heat transfer through the envelope and improve indoor comfort.

Drawing of a building with highlighted door and windows for high performance material selection

Figure 7 : A drawing of a building with a door and windows

What are the benefits of passive design?  

Passive design has many benefits for both the environment and the occupants of a building. Some of these benefits are:  

  • Energy Efficiency: By using natural sources for heating, cooling, ventilation, and lighting, passive design can significantly reduce a building’s energy consumption. This can lead to lower energy bills and a reduced carbon footprint.  
  • Health and Well-Being: Passive design can improve health and well-being by promoting natural ventilation, reducing indoor air pollution, and providing access to natural light. Natural ventilation can improve respiratory health by removing pollutants and allergens from the air. Natural light can enhance mood and productivity by regulating circadian rhythms and boosting serotonin levels.  
  • Durability and Longevity: Passive design often relies on durable materials and simple systems that require minimal maintenance, which can increase the building’s longevity and reduce the need for frequent repairs or replacements.  
  • Aesthetic Appeal: Passive design can enhance the aesthetic appeal of a building by creating a harmonious relationship between the building and its surroundings. Passive design can also incorporate local materials, culture, and traditions, creating a unique and authentic identity for the building.  
  • Environmental Stewardship: Passive design can demonstrate environmental stewardship by reducing the environmental impact of a building throughout its life cycle. Passive design can also contribute to the conservation of natural resources, such as water, land, and biodiversity, by minimizing waste generation, water consumption, and land degradation.  

Eco Mantra’s projects highlighting passive design  

Eco Mantra’s passive design principle respects the local environmental conditions while preserving the beauty of the building design. Eco Mantra are proud to take part in The Loop Project by Alexis Dornier as the ESD and MEP consultant, a project located in Keliki, Bali. Through passive design, it takes advantage of nature’s existing condition to improve the user’s indoor comfort while reducing energy consumption. Shading structure, reflective building surface material, natural ventilation, daylighting, and high thermal performance building materials are considered to improve comfort and reduce energy consumption.  

Photo of Eco Mantra's project, The Loop, demonstrating passive design principles

Passive design is the first step towards achieving the goal of low-energy buildings. It is in line with the principles of environmentally sustainable design, which aim to create resilient buildings that not only operate efficiently, but also enhance indoor comfort and the well-being of building occupants.  

Passive design is a smart and sustainable way to design your house in the tropics. It can help you save energy, money, and the environment, while enjoying a comfortable and healthy indoor environment. If you are interested in learning more about passive design or implementing it in your house, you can contact us at team@eco-mantra.com. We are a company based in Bali, Indonesia, with a passion for sustainable development and environmental engineering. We can help you design and build your dream house using passive design principles and techniques.  


Eco Mantra is a company based in Bali, Indonesia, with a passion for sustainable development and environmental engineering. Our mission is to rethink the way we design and build our environments in order to harmonize them with nature. We offer a wide range of services for companies and leaders at any stage of the sustainability journey, from consulting and auditing to design and engineering.  

If you are interested in implementing ESD in your project, please contact us at team@eco-mantra.com. We will be happy to assist you with our expertise and experience. Together, we can create a greener future for ourselves and our planet. 


References :

The Future of Cooling

Steps to Net Zero: Step 1 – Passive Design Optimisation

Diagram of a house with different types of rooms



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