Energy and Thermal Comfort Assessment of Insulation Strategies in Moroccan Residential Buildings: A Multi-Zone Simulation Study Based on the Moroccan Thermal Construction Regulation
This study utilizes multi-zone simulations across Morocco's six climatic zones to demonstrate that while extruded polystyrene offers the greatest absolute energy savings due to its thickness efficiency, insulation materials perform similarly when compared at equal thermal resistance, and that wall insulation can paradoxically increase thermal discomfort in hot climates by suppressing the building's natural heat sink, necessitating zone-specific and component-specific selection strategies rather than relying solely on thermal conductivity.
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 fight against climate change, buildings play a surprisingly large role. They consume vast amounts of energy to keep people warm in winter and cool in summer, and that energy use generates significant carbon emissions. The key to fixing this lies in the building's skin: its walls, roof, and windows. When a building is well-insulated, it acts like a thermos, slowing down the flow of heat so that the inside stays comfortable without needing to burn as much fuel or run air conditioners as hard. However, the best way to insulate a building depends entirely on where it is located. A house in a cold, snowy mountain needs to keep heat in, while a house in a hot, sunny desert needs to keep heat out. In Morocco, a country with a diverse landscape ranging from cool Atlantic coasts to scorching inland deserts and high mountain peaks, finding the right balance is a complex puzzle. The country has established a set of construction rules to guide builders, but it has remained unclear whether a single insulation strategy works everywhere or if different climates require different solutions.
To solve this puzzle, a team of researchers set out to test how different insulation materials and thicknesses perform across Morocco's six distinct climate zones. They focused on a typical two-story family home, a standard design found throughout the country, and used powerful computer simulations to see how it would behave over an entire year. The researchers did not just look at one type of material; they tested a wide variety, including common plastic foams, mineral wools made from glass or rock, and natural, plant-based options like hemp and wood fiber. They also looked at a special material that changes state to store heat, known as a phase-change material. The team simulated the house in six different cities, each representing a unique climate: the mild coast of Agadir, the maritime air of Tangier, the inland city of Fez, the cold mountain town of Ifrane, the hot semi-arid city of Marrakech, and the desert heat of Errachidia. By keeping the house's shape, windows, and how people lived inside exactly the same in every simulation, they could isolate the effect of the insulation and the climate.
The simulations revealed a stark reality: the standard, uninsulated version of this Moroccan home fails to meet the country's own energy efficiency rules in every single climate zone. Without added protection, the house loses too much heat in winter and absorbs too much in summer, leading to high energy bills and uncomfortable living conditions. The researchers found that adding insulation to both the walls and the roof together was always the most effective strategy, far outperforming insulating just one or the other. Among the materials tested, a type of plastic foam called extruded polystyrene consistently delivered the biggest drop in energy use. When applied at a thickness of 6 centimeters to both the walls and the roof, this material reduced the home's annual energy demand by nearly 10 percent in the mild coastal city of Agadir and by almost 25 percent in the cold mountain town of Ifrane. This confirms that while insulation works everywhere, its impact is most dramatic in the harshest climates where the difference between the outside and inside temperatures is greatest.
However, the study uncovered a crucial nuance that challenges the idea that "lowest energy use" always equals "best comfort." In the hot, semi-arid climate of Marrakech, the material that saved the most energy was not the one that kept the residents most comfortable. While the plastic foam reduced the energy needed to cool the house, a natural wood fiber insulation actually kept the indoor temperature more stable and reduced the number of uncomfortable hours more effectively. This happens because natural materials often have a heavier, denser structure that absorbs heat slowly and releases it later, acting as a thermal buffer against the intense daytime sun. In contrast, the plastic foam, while excellent at blocking heat flow, does not store heat in the same way. This suggests that in hot climates, choosing insulation based solely on how well it blocks heat might not be the best way to ensure a pleasant living environment; the material's ability to manage heat over time matters just as much.
Despite these improvements, the researchers found that insulation alone could not make the house fully compliant with the national regulations. Even with the best wall and roof insulation, the house still fell short because the windows remained single-pane glass, which lets heat pass through too easily, and the floor on the ground lacked sufficient thermal resistance in some zones. This highlights that a building is a system where every part matters; fixing the walls and roof is a massive step forward, but leaving the windows as they are leaves a significant gap in performance. The study also showed that adding more insulation beyond a certain point, such as going from 6 centimeters to 10 centimeters, yields diminishing returns. The biggest jump in energy savings happens when moving from no insulation to a moderate layer, and adding extra thickness after that brings smaller and smaller benefits.
Ultimately, this research provides a clear, unified guide for building in Morocco. It demonstrates that there is no single "best" insulation for the whole country. While a specific plastic foam offers the highest energy savings across the board, natural materials like wood fiber offer superior comfort in hot, dry regions. The most effective approach is to insulate both the walls and the roof together, choosing a thickness of 6 centimeters for colder or more extreme climates and perhaps 4 centimeters for milder coastal areas. But the study also serves as a reminder that insulation is only part of the solution. To truly meet energy goals and ensure comfort, builders must also upgrade their windows and floors. By understanding these specific needs for each climate, architects and homeowners can make smarter choices that save energy, lower costs, and keep homes comfortable year-round.
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