Dynamic Thermal Modeling and Energy Assessment of a Multi-Zone in F3 Apartment in an Arid Climate of Bechar, Algeria
This paper presents a dynamic multi-zone thermal model of a standard F3 apartment in Bechar, Algeria, developed using MATLAB/Simscape to analyze extreme overheating risks and quantify the significant daily cooling energy demands required to maintain thermal comfort in the region's hyper-arid climate.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
In the hottest corners of the world, the battle for comfort is fought inside the walls of our homes. Buildings are not just static shells; they are living systems that absorb, store, and release heat, reacting to the sun and the people inside them. When the outside air swells with intense heat and the sun beats down with relentless force, the air inside can become dangerously warm, forcing people to rely on air conditioning to survive. However, simply turning on a machine is not enough to understand the problem. To design homes that stay cool without wasting energy, scientists must understand how heat moves through a building over time, how the sun hits different walls at different times of day, and how the daily rhythm of human life adds its own heat to the mix. This requires looking beyond simple snapshots of temperature and instead watching the building breathe and shift as the hours pass.
A team of researchers in Bechar, Algeria, decided to build a digital twin of a standard apartment to watch exactly how these forces play out in one of the most demanding climates on Earth. Bechar sits in a hyper-arid region where summer days are scorching and nights offer only a brief, cool reprieve. The researchers focused on a common three-room apartment layout, known locally as an F3, which represents a large portion of the housing stock in the region. They created a detailed computer simulation that broke the apartment down into six distinct zones: a living room, a kitchen, two bedrooms, an anteroom, and a bathroom. Instead of treating the building as a single box, they modeled the flow of heat through the thick walls, the flat roof, and the single-pane windows, while also accounting for the heat generated by the people living there and the air conditioning units trying to keep them comfortable.
The simulation began by stripping away the air conditioning and the people to see how the building behaved on its own. Without any cooling systems, the apartment quickly became an oven. The researchers found that the building's materials, which included hollow bricks and concrete, absorbed the intense solar energy during the day but could not release it fast enough at night. This caused the internal temperature to climb higher and higher each day until it reached a dangerous peak. The living room and one of the bedrooms, both facing west and south, suffered the most, with temperatures soaring to 46 degrees Celsius. This happened because the setting sun hit these walls directly just as the outside air was already at its hottest, creating a perfect storm of heat that the building's structure could not resist. Even the rooms without direct sun exposure, like the bathroom, warmed up significantly because heat traveled through the internal walls from the hotter rooms next door.
When the researchers added the daily lives of a typical family back into the model, the picture changed in surprising ways. The presence of people added a steady stream of body heat, but more importantly, it shifted the timing of the hottest moments. The simulation showed that the temperature spikes in the bedrooms and living room did not just follow the sun; they followed the family's schedule. As people returned home in the evening, their metabolic heat combined with the heat already stored in the walls, creating sharp, jagged peaks in temperature that mirrored their movements. The living room, where the family gathered in the evening, became the most critical space, reaching temperatures of 47 degrees Celsius when occupied. This demonstrated that a building's thermal performance is not just about its walls and windows, but is deeply tied to when and where people are inside.
To keep the apartment livable, the researchers then switched on the air conditioning in the simulation, setting a strict goal of maintaining a comfortable 25 degrees Celsius. The results were stark. The energy required to fight the extreme heat was massive. The living room alone demanded more cooling power than any other room, consuming nearly 15.6 kilowatt-hours of electricity every single day. Over the course of a month, the entire apartment would use more than 1,600 kilowatt-hours of electricity just to stay cool, a figure that highlights the heavy burden placed on the electrical grid in such climates. The study also tested how much the efficiency of the air conditioning unit mattered. They found that using a more efficient machine could cut the energy bill by nearly 15 percent, while an older, less efficient unit would increase consumption by 20 percent. This proved that the choice of equipment is just as important as the design of the building itself.
The study concluded that the current style of building in this region, with its thin walls and single-pane windows, is simply not built to handle the extreme heat of Bechar without mechanical help. The researchers suggested practical changes that could make a real difference, such as adding shading to the south-facing windows to block the sun before it hits the glass, or upgrading to double-pane windows that trap less heat. They also proposed a strategy of opening windows at night to let the cool air wash over the building's heavy walls, cooling them down before the sun rises again. By understanding the precise way heat moves through a home and how people interact with that heat, scientists can help architects design buildings that are not only cooler but also far more efficient, turning the struggle against the desert heat into a manageable challenge.
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