There is a wide range of wall materials out there for constructing a home in the tropics. Different materials have various properties and will perform differently. In hot, humid tropical climates, your wall materials need to perform a variety of functions.
Walls provide shelter and security for a home or building. They protect you from the elements and help regulate and achieve a comfortable indoor climate based on your outdoor environment.
To understand the best wall materials for staying cool in hot, humid climates, we should first explore the popular options and how they perform.
Types of Materials and Construction
When considering the typical wall material and construction methods for residential architecture, two main categories come to mind. These are lightweight or framed and heavyweight or mass construction.
Heavyweight or Mass Walls
Heavyweight or mass walls usually consist of solid material. These include concrete, adobe, rammed earth, or masonry units such as concrete blocks, bricks or stone.
They can be covered with a plaster or render or can be left exposed.
Mass walls may or may not be structural or loadbearing.
Lightweight or Framed Walls
Lightweight or framing wall construction typically uses wood or light gauge steel members. The frame is the structural element and transfers the loads from the roof down to the foundation.
Cladding covers the frame and functions as a skin. In addition, exterior claddings include wood, metal, vinyl, or cement board sidings. Drywall or plasterboard is a popular panelling for inside, where it can avoid contact with moisture.
In addition, these types of wall systems can be engineered to resist hurricane-force winds. Also, using metal frames and non-wood or plasterboard claddings and panels will avoid issues with termites and mould.
Thermal Properties
One of the primary factors determining how well a wall performs at making a home cool is its thermal properties.
The thermal property of a material is its response to the application of heat on it. In addition, thermal mass is the capability of a material to absorb and store heat.
Framed walls perform very differently than mass walls when it comes to thermal mass.
High Thermal Mass
Mass or heavyweight materials such as concrete, stone and brick have a high thermal mass. These materials can collect and store large amounts of heat energy. The orientation where the walls and openings face will determine the amount of exposure to the sun.
Therefore, when the sun is shining on these thermal massing materials, they absorb the heat from the sun. After the sun sets, thermal mass walls remain warm.
I live in a concrete block wall house. At night I can feel the heat radiating from the exterior walls. This heat is especially apparent for the west-facing wall, which has no sun shading.
Hence, this heat slowly releases into our homes during the night.
In tropical climates that are hot and humid, this is not ideal. The difference in temperature between day and night is usually not significant. Night-time in such environments can still be reasonably warm, and hence, it is ideal to avoid materials that will make your home warmer.
I think this is especially important because of our lifestyles. During the day, most of us are away from our homes at work or school. However, at night, the entire family returns home. Furthermore, it is the time when more lights, computers, gaming consoles, cable boxes and big-screen televisions are on. These are the primary sources of entertainment in our current lifestyles.
All these appliances, along with our bodies, produce heat. It also happens that we tend to keep our windows and doors closed at night because of security reasons. This heat can build up in our home that has little or no potential for natural ventilation overnight.
In temperate climates or even hot, dry climates, where the night-time temperature can be much lower than the daytime temperature, thermal mass walls are ideal.
However, where thermal comfort is a concern, mass or heavyweight walls exposed to direct sunlight are not ideal for hot, humid climates. Hence, when using mass walls in this type of climate, it would be best to have them shaded from direct sunlight.
Low Thermal Mass
Lightweight wall construction tends to have a low thermal mass. Hence, framed walls tend to have a low capacity for storing heat energy.
Walls that consist of wood or metal framing with cladding do not store a lot of heat. They heat up quickly with little exposure to a heat source. However, they cool rapidly once the heat source, such as the sun, is no longer there.
You may be wondering if, since these materials heat up quickly, wouldn’t that mean they will make inside your home hot during the day. Unfortunately, the answer is yes. An unshaded, uninsulated lightweight wall would transfer heat inside. Not ideal if you are at home during the day.
High thermal mass materials have low thermal conductivity. Hence, though materials like concrete store heat and releases it slowly, they also transfer that heat slower from outside to inside. Low thermal mass materials are the opposite. Framed walls transfer heat quickly.
Therefore, it is good to add insulation to these walls to reduce the heat transfer during the day.
What Are The Best Wall Materials For Staying Cool In Tropical Climate?
Lightweight or framed construction using timber or metal framing is ideal for hot, humid tropical climates.
Mass or heavyweight walls are better in temperate climates or climates where the temperature significantly differs between the day and night-time. Due to their thermal massing properties, they are ideal for warming up your home at night.
However, based on the properties of lightweight walls, they are better at maintaining cooler temperatures at night. These properties make framed walls ideal for tropical buildings.
Our lifestyles, where we are not home during the day and at home during the night, also dictates this. We should do all that we can to ensure our homes are as cool as possible at night when we are using our appliances or trying to sleep.
I know how miserable it can be living in a house that is not cool during the night. Trying to sleep in the sweltering heat is challenging, especially during the hotter months of the year.
How To Make Heavyweight or Mass Walls Cool?
However, both lightweight and heavyweight wall systems and materials are prevalent. Both tropical and temperate climates use them.
Therefore, like me, the house you currently live in may be built using concrete, blocks or bricks.
Heavyweight walls have benefits in tropical climates as well. They are not susceptible to mould or termites. In addition, they typically have higher resistance to hurricane-force winds as well as fires.
I think you can find ways to make this wall system work for you.
As much as possible, try to shade the walls from direct sunlight. You could add vertical screens or trees to shade east and west-facing walls. Adding canopies or roof overhangs over covered outdoor areas is also effective. These shading strategies protect the north and south-facing walls.
Providing means for natural ventilation all through the day and night without compromising security is also an excellent idea. This strategy will ensure the heat radiating from mass walls can escape as quickly as possible.
Proper Shading and passive ventilation strategies are excellent ideas for any tropical home. Whether or not their walls use mass or framed construction materials.
They are several strategies for designing a home suited for the tropics. Choosing the best wall materials is one element along with site orientation, roof design and several others.
Though having the best wall materials for a cool tropical home would be ideal, they are still other ways to ensure your home is thermally comfortable.
Feature image by klimkin from Pixabay
Related topics in this series:
Find out all the major principles of designing a house in the tropics.
Or explore more of the other topics in this series.
Site Orientation: The orientation of your home on its site dictates how well it responds to passive design principles.
Shading Strategies: Reducing the solar heat gain in your home can create a better thermally comfortable home.
Passive Ventilation: Natural or passive ventilation is one of the primary concerns of a tropical home.
Wall Materials and Construction: In hot, humid climates, your wall materials need to perform various functions.
Roof Design: Choosing the right roof in hot tropical climates is essential to minimize heat gain.
Exterior Spaces: Making outdoor spaces and nature part of tropical homes is ideal.
Water and Energy Efficiency: With climate change, renewable energy and water resource management are crucial.