Worldwide, the construction sector stands as a major energy user, responsible for consuming more than 40% of the total energy supply, with an average annual increase of 1.5% from 2012 to 2040. ¹ In Egypt, due to the rapid growth and higher living standards, residential buildings consume over half of the country’s electricity ¹ as shown in Figure 1.

Each year in the housing sector, energy use increased by 7%, and without finding a solution, the consumption could be more than double by 2030, increasing from 60 to 135 million tons of oil equivalent (MTOE). ² This problem not only strains energy resources but also increases the environmental challenges, making energy efficiency a critical priority.

One of the main approaches to reducing energy consumption in the building sector and to meet with Egypt’s Vision 2030, is through the improvement of insulation materials. Studies show that enhancing insulation in walls, roofs, and windows could decrease CO ₂ emissions by 2190 kilotons per year and save up to 842MW of peak energy demand. ¹ Alongside decreasing energy consumption, this approach safeguards the planet while promoting healthier and more sustainable living conditions for people.

This research explores mycelium as a sustainable and circular insulation material. It first examines its properties and potential as an alternative to conventional insulation. Then, it compares mycelium to commonly used materials in Egypt, such as XPS and Rockwool. Finally, a simulation on Janna Compound analyses four scenarios, evaluating energy consumption, discomfort hours, PMV, and PPD to assess mycelium’s feasibility in building insulation.

The purpose of this research is to increase academics’ and designers’ awareness of the benefits and potential of mycelium insulation. It investigates how well mycelium insulation performs in comparison to two commonly used insulation materials and proposes it to be a sustainable alternative for the construction sector in Egypt.

The literature review will address several important subjects, including the definition of mycelium, and explore its sustainability and circularity as a material. It will also illustrate its thermal conductivity properties, which are essential for evaluating its thermal performance as an insulation material. Following this, the review will provide an overview of two traditional insulation materials that are commonly used in Egypt, XPS, and Rockwool.

The research’s second section examines a case study of a typical floor in a Type A building within Janna Compound, New Cairo. This simulates how insulating materials affect thermal comfort and energy usage, including Predicted Mean Vote (PMV), Predicted Percentage of Dissatisfaction (PPD%), and thermal comfort hours. The primary aim is to assess how well mycelium insulation performs in comparison to commonly used materials like XPS and Rockwool, to evaluate its usefulness. The scenarios evaluated are: •

Baseline model: Wall without insulation.

The investigation’s methodology evaluates mycelium’s efficacy in comparison to two commonly used materials to improve residential buildings’ thermal comfort in Egypt. Design-Builder version 7.3.0.046 & Energy-Plus plugin software were used for this simulation, which will evaluate discomfort hours, PMV-PPD, and energy consumption for a typical floor in a Type A building in Janna Compound, emphasizing how these materials and techniques affect the thermal condition.

The environmentally friendly characteristics of mycelium-based materials and their potential role in shaping the future of sustainable construction. Six principal factors support construction ⁸ as shown in Figure 3.

  -Cost-effectiveness and abundant raw materials   -Biodegradability

  -Rapid manufacturing process          -Flexibility

  -Minimal Energy consumption         -Cardle-to-cradle life cycle

Heat transfer, heat storage capacity, material density, and thermal diffusivity are among the thermal and physical attributes of insulation materials used in the construction sector. These features define a material’s efficiency in terms of heat absorption, transport, and retention. When combined, these characteristics help a structure use less energy and maintain a pleasant interior temperature, which lowers the need for artificial heating or cooling. ⁹

When combining mycelium with agricultural residences, it stands out as a promising alternative to foam insulation materials. This enables the formation of porous composites, such as foams, to be formed. Due to their higher moisture content, the samples show a higher Heat transfer rate. ¹⁰ Thermal conductivity refers to how efficiently a material transfers heat; lower values indicate better insulation performance. Research on Mycelium-based composites suggests that their thermal conductivity ranges between 0.029-0.104 W/mK, making them a good option for insulation. ¹¹

Table 1 shows the characteristics of the mycelium insulation panel made by BIOHM ^® ( https://www.biohm.co.uk/), which is used in the simulation, the panel dimension is 1.2×2.4m, with a thickness of 0.075m. ¹²

Eight factors were taken into consideration while choosing materials from the Egyptian market: fire resistance, simplicity of application, cost, absorption, pressure force, durability, water vapor transmission, and thermal conductivity. ¹³

To determine how mycelium would function, the simulation compares its thermal performance with two conventional materials that are utilized in Egypt. •

XPS (extruded polystyrene) insulation material is manufactured by using an extrusion process, where expansion gases and retardant are added to melted polystyrene. It has a flexible size and shape according to the use; Due to its non-permeable structure, it has low water absorption. However, its production can be harmful to the environment as it relies on Hydrofluorocarbon (HFC) and CO ₂ gases. ¹⁴

An Egyptian company specializing in building insulation materials, Rockal Al Alamia ( https://www.rockalinsulation.com/), for Insulation, provided the data shown in Table 2. Since the simulation and the materials are based in Egypt, the selection of this data source is consistent with the study’s setting and provides relevance to regional environmental conditions and construction methods.

This research examines the bioclimatic conditions in Egypt utilizing Climate Consultant v.6.0 to create a psychrometric chart based on weather data. This chart aids in identifying effective design strategies aimed at improving indoor thermal comfort, as illustrated in Figure 4, which showcases climate-responsive design methods.

Figure 4 reveals that only 18.5% annually falls within Egypt’s thermal comfort range. Several climate-responsive design strategies were evaluated to improve thermal comfort: •

Internal heat gains could increase comfortable hours by 32.6%, particularly in winter.

Nevertheless, the results are based on general climate data recommendations. To identify the most effective solutions, further investigation of the building’s design parameters will be required.

New Cairo, which is located between latitudes 30.03°N and longitudes 31.47°E, has a mainly hot desert climate. Climatic data indicates that summer temperatures typically reach between 35–45°C in August, highlighting the need for effective cooling systems during the hot months. In contrast, winter temperatures are lower, ranging from 15–20°C, which may reduce heating requirements. ¹⁷

The examined building model is a type A building, part of a residential project created by the Egyptian Government to accommodate the growing need for homes. It’s a six-story building, each containing four residential apartments, each around 130 square meters. Each flat typically houses at least two residents, and the simulation was conducted on a typical floor of the building ¹⁸ as shown in Figure 5.

The typical floor plan has four similar apartments, each covering 130 sqm. Each apartment includes a kitchen, living room, two bathrooms, and three bedrooms ¹⁸ as shown in Figure 5.

Janna Compound is a residential gated compound developed by the Egyptian Government to accommodate the growing need for homes across multiple cities across Egypt, including El-Sheikh Zayed, Al-Minya, New Cairo, and Mansura. The project consistently utilizes the same design models (Types A and B), regardless of local climate variations or material costs. ¹⁹ The Type A building in New Cairo, Egypt, was selected for simulation to compare Mycelium insulation with traditional materials, as many residential projects in the area lack appropriate insulation, making this comparison crucial for enhancing energy efficiency and thermal comfort. As shown in Figure 6, solar exposure on the selected building provided by the sun path diagram is a key factor in thermal performance assesment.

Design Builder 7.0.2.006 with an Energy Plus 9.4 plugin is the energy simulation software used in this case study. It works by modeling the building’s environmental conditions on an annual and monthly basis, including humidity, lighting, thermal balance, and energy consumption.

Activity

The activity of each space is specified accurately as well as the number of users, occupancy density, and metabolic rate as shown in Table 3.

Construction

Accurate simulation requires detailed building information, encompassing the materials used for external walls, slabs, and roofs. The U-value and insulation properties play a critical role in energy consumption, as they affect thermal exchange. Table 4 outlines the layers of building envelope materials utilized in the Design-Builder program.

Openings

Energy consumption is greatly affected by thermal gain and loss via windows, particularly in hot regions where solar thermal energy plays a significant role. For accurate simulation, detailed information on window glazing and shading systems is essential, as shown in Table 5.

HVAC

HVAC was employed to calculate total energy consumption during the hot months to assess how mycelium insulation would reduce energy usage. However, for the calculation of PMV, PPD, and discomfort hours, the HVAC was turned off. The HVAC configurations utilized in the program are presented in Table 6 below.

The simulation was conducted from the beginning of January to the end of December, evaluating four different cases of different insulation materials, as summarized in Table 7. However, when calculating PMV, PPD, and energy consumption, the simulation focused primarily on the hot months, from June 1 to August 31. •

Base Case: Brick wall without any insulating layers.

Energy-efficient building design focuses on managing exterior thermophysical properties, such as the U-value (thermal transmittance), which is key for assessing thermal efficiency and energy savings. Figure 7 shows that the base case without insulation has the highest U-value at 1.71 W/m ²K, while Mycelium insulation has the lowest at 0.323 W/m ²K. XPS and Rock Wool have U-values of 0.34 W/m ²K and 0.61 W/m ²K, respectively, indicating varying levels of thermal performance. Therefore, Mycelium demonstrates the best U-value compared to other traditional materials.

The simulation, based on ASHRAE 55–2004 standards, evaluates discomfort hours due to inadequate cooling, heating, and humidity levels without HVAC systems. As shown in Figure 8, the base case with a conventional wall recorded 1986 discomfort hours annually. Mycelium insulation reduced this to 1481.71 hours, while XPS reduced it to 1485.04 hours, and Rock Wool to 1616.88 hours. The results show that Mycelium performs similarly to XPS, indicating that it can compete with traditional materials in terms of thermal comfort.

The percentage of discomfort hours per year for the four scenarios is as follows: the base case recorded 22.6% discomfort, while Mycelium showed 16.9%, XPS recorded 16.95%, and Rock Wool had 18.4% discomfort. These results demonstrate that Mycelium not only performs better than Rock Wool but also shows a similar percentage of discomfort hours to XPS, making Mycelium an equally effective choice for improving thermal comfort and energy efficiency. As shown in Figure 9.

From June 1 to September 30, specific thermal comfort strategies are applied to enhance comfort during the summer and minimize air conditioning use. The evaluation focuses on Predicted Mean Vote (PMV) and Percentage of People Dissatisfied (PPD%), using a PMV scale from -3 (cool) to +3 (hot). By concentrating on the hot months, as shown in Figure 10, this approach allows for precise adjustments to environmental systems, ensuring optimal thermal comfort and energy efficiency during peak cooling periods.

Table 8 illustrates the variations in the outcomes relative to the baseline case across all four scenarios, emphasizing the PPD% values during the warmest months.

As shown in Table 9, the comparison of the four scenarios in the case study offers key insights for improving thermal comfort. In the base case, without insulation, the Predicted Mean Vote (PMV) is 1.46, with a Percentage of People Dissatisfied (PPD) of 53.26%. Adding Mycelium insulation in Alternative-1 improves the PMV to 1.37 and reduces the PPD to 50.48%. Alternative-2, which uses XPS insulation, shows similar results, with a PMV of 1.37 and a PPD of 50.46%. Alternative-3, featuring Rock Wool insulation, slightly improves comfort further, achieving a PMV of 1.35 and a PPD of 49.76%. As shown in Figures 11 and 12.

Mycelium, with its impressive performance values, not only matches traditional insulation materials in terms of thermal efficiency but also provides added advantages. As a sustainable and biodegradable material, Mycelium is an eco-friendly choice, making it a highly suitable option for thermal insulation.

The simulation of annual energy consumption reveals that electricity usage varies throughout the year, with a notable increase during the summer months. In contrast, consumption is relatively low during the cooler months, as heating and cooling needs are reduced. However, from May to August, energy consumption peaks due to the heightened cooling demands driven by intense solar radiation. As shown in Figure 13, this simulation underscores the significant effect of seasonal changes on overall energy performance.

Regarding energy consumption, it is observed that the base case wall material led to higher energy usage during the warmer months. Particularly from May to August, due to increased solar radiation. The simulation findings indicate that the total electricity consumption for the base case during these hot months was 10,203.75 kWh. In comparison, XPS insulation resulted in 8,601.1 kWh, Mycelium insulation consumed 8,587.42 kWh, and Rock Wool insulation had a consumption of 8,838.77 kWh. As shown in Figure 14.

The energy consumption reductions are 15.7% for XPS, 15.8% for Mycelium, and 13.3% for Rock Wool. As shown in Figure 15. These results show that Mycelium performs similarly to XPS in terms of energy savings and makes a notable contribution to improving energy efficiency. According to these results, CO ₂ emission was also reduced, Mycelium reduced 979.5 kg of CO ₂, while XPS reduced 971.2 kg and Rock wool reduced 827.18 kg of CO ₂.

To calculate the percentage of energy reduction, the energy consumption of the base case scenario (without intervention) is compared to the improved scenario (with intervention). The formula used is: Percentage of Energy Reduction = ( Base case Energy Consumption − Improved Energy Consumption Base case Energy Consumption ) × 100