## 2 The Role of Cellulose Waste in Sustainable Construction
### Cellulose Insulation Products  
Cellulose waste is increasingly being utilized to produce highly effective insulation products, which align with the growing demand for energy-efficient building solutions. Derived from recycled paper [82], agricultural residues [83], and even textile waste [84], cellulose-based insulation materials are treated and processed to create products that can be used in various insulation applications. The natural properties of cellulose fibers, when processed appropriately, result in insulation materials that significantly reduce heat transfer, thereby improving the energy efficiency of buildings [85]. This is especially critical in sustainable construction, where reducing the energy required for heating and cooling is a key objective. In addition to their thermal properties, cellulose insulation products derived from both paper and agricultural waste offer excellent soundproofing capabilities [86]. This makes them ideal for use in a wide range of building types, from residential homes to commercial spaces. Moreover, these materials can be treated with non-toxic fire retardants, making them a safer and more environmentally friendly alternative to conventional insulation products that often rely on harmful chemicals [87]. A study carried out by [PERSON] and [PERSON] [88], set in the context of the UK's climate and landfill crises, explored the potential of cellulose derived from recycled paper as an insulating material to address the country's inadequate recycling rates. In a case study of the retrofit and new-build project in London, their research examined the performance of cellulose insulation compared to other conventional materials. The findings showed that, although cellulose insulation from recycled paper may not offer the highest thermal performance, it meets the requirements for most applications. Furthermore, this type of cellulose insulation emits significantly less carbon dioxide over its life cycle compared to other insulation materials, making it a highly sustainable option. While traditional paper recycling can sometimes result in lower carbon emissions, converting waste paper into cellulose insulation presents a viable alternative that not only improves the recycling rate but provides sufficient insulation for energy-efficient buildings. In exploring the use of agricultural waste for construction insulation, several innovative cases demonstrate both environmental and functional viability. For instance, insulation boards made from pineapple leaves have shown thermal conductivity values between 0.043 and 0.057 W/mK, highlighting their potential as effective and sustainable insulation materials [89]. Similarly, boards crafted from coconut husk and bagasse--by-products of coconut and sugar production--employ no chemical binders and exhibit thermal conductivity values ranging from 0.046 to 0.068 W/mK, underscoring their eco-friendliness [90]. Additionally, innovative boards combining wheat bran and banana peels offer promising properties suitable for building applications, with thermal conductivity ranging between 0.050 and 0.066 W/m\(\cdot\)K, and mechanical properties comparable to those of commercial insulation boards [91]. Agricultural cellulose sources, such as straw and hemp, are also particularly effective in creating insulation products that offer superior thermal performance. For example, hemp-based lightweight concrete exhibits a thermal conductivity of 0.09 W/m\(\cdot\)K, while straw-based concrete shows values as low as 0.078 W/m\(\cdot\)K, making both materials excellent options for thermal insulation in sustainable construction [92]. These examples showcase how agricultural residue can be transformed into valuable, sustainable building materials, contributing to reduced environmental impact and enhanced building performance. Textile waste, which includes discarded garments, industrial scraps, and end-of-life textile products, provides a rich source of cellulose fibers that can be repurposed into high-quality insulation.