# Mycelium-Based Thermal Insulation for Domestic Cooling Footprint Reduction: A Review
## 5 Conventional Insulation Materials
### Phenol Formaldehyde
#### 5.2.2 Renewable Insulation Materials  
Sustainable insulation materials can reduce buildings' energy consumption and environmental impact by providing thermal and acoustic insulation. They are usually made from natural, recycled, or renewable sources and have low embodied energy and greenhouse gas emissions. Cellulose  
Cellulose insulation is a type of home and commercial insulation made from any cellular plant source, usually recycled paper products such as newspapers, cardboard, office paper, etc. It is blown into the walls or attic of your home using a special machine that fluffs up the cellulose and shoots it through a hose. It can fit in enclosed areas and conform to pipes and ductwork within the space needing insulation [61]. It has low embodied energy and high recycled content, making it an eco-friendly choice for building insulation. Cellulose insulation can be applied as loose fill, sprayed into cavities and spaces, or as boards and mats for walls and roofs. However, cellulose insulation has some limitations, such as its high hygroscopicity, which can absorb moisture readily and cause mold growth, decay, and reduced thermal performance. Cellulose insulation may also settle over time and lose some thickness and effectiveness [62]. Cork  
Cork insulation is a type of insulation made from cork material, which is harvested from the bark of cork oak trees. It is a natural, renewable, and recyclable product with high thermal resistance, sound isolation, fire resistance, and moisture resistance. It can be used for insulating walls, roofs, floors, and ceilings of buildings. It is available in different thicknesses and sizes, usually as boards or rolls. It is also hypoallergenic and toxins-free, making it a healthy choice for indoor environments [63]. Cork insulation has a typical thermal conductivity of 0.036 to 0.38 W/m\(\cdot\)K, corresponding to an R-value of 3.6 per inch. However, cork insulation has some limitations, such as its high cost, low availability, and susceptibility to compression and shrinkage over time. Cork insulation may also not be suitable for very cold or hot climates, as it can handle temperature ranges of \(-\)292 \({}^{\circ}\)F to 248 \({}^{\circ}\)F [64]. Sheep wool insulation is a type of insulation that uses sheared wool from sheep as the base material. It is a natural, renewable, and biodegradable product used on roofs, walls, and floors to regulate temperature, minimize sound, and conserve energy indoors. Sheep wool insulation has some advantages over other types of insulation, such as its ability to manage moisture, improve indoor air quality, and absorb sound. However, sheep wool insulation also has some drawbacks, such as its higher cost, the need for additives to enhance its fire resistance and insect repellence, and its lower availability and ease of installation compared to other types of insulation [65; 66; 67]. Coconut thermal insulation is a type of natural insulation that is made from coconut fibers, which are extracted from the husk of the coconut fruit. Cocnut fibers have a low thermal conductivity of less than 0.04 W/m\(\cdot\)K, which means they can prevent heat transfer and reduce energy consumption. Coconut fibers also have a low density of about 174 kg/m\({}^{3}\), a high heat capacity of 2600 J/kg\(\cdot\)K, and a low water retention of less than 10%, which makes them suitable for thermal insulation in various climates. Coconut fibers can be used as loose-fill insulation in the cores of masonry walls or as mats or boards on concrete slabs' top or inner surfaces. However, coconut thermal insulation has some limitations, such as low compressive strength, high flammability, and possible degradation by microorganisms or insects [68; 69; 70]. Flux wool insulation is a type of natural fiber insulation that is derived from the flax plant. It is a renewable and ecological material that can provide thermal and acoustic insulation for buildings. Flax wool insulation can be used as a replacement for petrochemical-based insulation.