The concrete and asphalt in cities absorb and radiate heat, making urban areas warmer than their rural surroundings. This phenomenon is called the Urban Heat Island Effect (UHI).
Various factors contribute to this, but the biggest one is albedo, or how much of the sun’s radiation it reflects. Using light-colored construction materials like bamboo can help mitigate the UHI.
Concrete
Concrete is a building material that is used throughout the world to build roads, bridges, dams, and buildings. It is a composite material consisting of a filler and a binder. The binder is made of cement, and the filler is made from coarse or fine aggregates. Aggregates are typically made of sand or crushed stone, but recycled aggregates such as air-cooled blast furnace slag and bottom ash are becoming more popular.
Concrete’s thermal characteristics are determined by its density, specific heat, and thermal conductivity. Block type materials like brick and aerated concrete have high densities, while pervious concrete has lower densities. Moreover, pervious concrete has a higher thermal conductivity and can dissipate heat more quickly than other materials.
The permeability of concrete is controlled by its water to cement ratio (porosity). A low water to cement ratio results in higher strength but less workability. However, a high water to cement ratio results in lower strength but good workability.
The use of non-combustible materials for floors, ceilings, and roofs can help reduce the urban heat island effect by reducing energy demand. These types of materials can also contribute to a more sustainable environment by avoiding the release of carbon dioxide into the atmosphere. In addition, the embodied energy of these materials is lower than that of traditional building materials such as cement and bricks.
Bricks
With the world becoming more and more urbanized, there is a need to look for better ways of dealing with the heat island effect. This problem is caused by a number of factors, including high population density and fewer green areas. These factors can cause the urban temperature to be higher than that of the surrounding rural area. The heat island effect is dangerous for humans and can cause heat-related illnesses and death.
One of the biggest problems is the use of construction materials that have a low albedo. These materials reflect a small amount of sunlight and absorb more heat than they should. They also restrict natural wind flow, which can cool buildings and the surrounding environment. These problems can lead to a significant increase in cooling energy consumption and power outages.
Several long-term solutions have been proposed to reduce the impact of urban heat islands. One of these is the use of reflective building materials, such as glass. Another is to use building materials that have a lower thermal mass, which can help to reduce the impact of the UHI effect.
Another way to reduce the UHI effect is to replace brick walls with insulated sandwich walls. These walls have a high surface-to-volume ratio, which reduces their temperature rise compared to brick and aerated concrete walls. The insulating material in the sandwich wall also allows the inner and outer surfaces of the wall to release heat quickly, which can significantly reduce the UHI effect.
Metals
Metals are opaque, lustrous elements that conduct heat and electricity. Their malleability allows them to be stretched into thin sheets that make cars, airplanes, train tracks and cargo containers, as well as delicate surgical tools and jewelry. Their ductility allows them to be drawn into long wires that carry power from generating stations across the country and to your homes.
The high temperatures in cities compared to their surroundings are called the urban heat island effect (UHI). It is caused by various factors such as the construction materials used and the lack of vegetation. Moreover, the thermal behaviour of building walls also plays an important role in this phenomenon.
Paving and building materials in urban areas tend to have a lower albedo than natural environments, which means that they reflect less sunlight and absorb more of the sun’s energy. This reflects on surface temperatures and also in the air temperature, creating the UHI.
The UHI is exacerbated when buildings are built close together with little space for vegetation, and when the roofs are covered in impermeable materials such as concrete or asphalt. This creates an environment that traps heat and prevents it from dispersing at night. The impact of the UHI is felt most severely in historically disadvantaged neighborhoods where residents often lack access to air conditioning and may be at higher risk from health issues caused by extreme heat.
Glass
Glass is an inorganic material that is often transparent or translucent, hard and brittle. It has many practical, technological and decorative uses, including window panes, tableware and optical lenses. Glass has been used by humans since ancient times, and archaeological finds include 2,000-year-old glass beads and arrowheads. Modern glass is produced by melting raw materials such as sand, soda ash and limestone in a furnace at high temperatures. It is then cooled and shaped into its final form, using blowing, pressing or moulding techniques.
Glass can be made to have a variety of properties, such as strength and colour, by altering its atomic structure. This flexibility makes it a good choice for renewable energy systems, such as wind turbines, and it is also used to produce solar panels. Cars, trains and planes also use glass because it is strong but lightweight, allowing the vehicles to fly through the air at high speeds.
Urban areas that are dominated by asphalt and concrete absorb more heat than surrounding rural landscapes, which can lead to higher night-time temperatures and increased energy costs. This effect is known as the urban heat island effect, and it occurs during both the day and the night, in small or large cities and during all seasons. To mitigate the effects, city planners should consider using alternative construction materials.