straw or clay for example... There are many experts around the world

Concrete based on vegetable fibers

Expanded insulation cork boards, but unfortunately the availability of raw materials is limited.

Hemp has been a building material for many centuries which have both excellent insulation and strength characteristics Many products can be made from hemp including building materials, Insulation, brick-blocks, cupboards, carpets, linen etc. are but a few of these.

Steel Fibers!

Insulation Cork Board (ICB), Natural Wool, Hemp, Wood Fiber. There are some MsC thesis comparing all the alternatives but unfortunately these are in Portuguese.

For Cork:

Application overviews:

• doi: 10.3390/ma8020625
• doi: 10.1179/174328008X353529

Life-cycle assessment:

• doi: 10/gcsk7d

Research in application in construction:

• Sousa, Jose, From Digital to Material: Rethinking Cork in Architecture through the use of CAD/CAM Technologies (2010)
• Varela et al, The cork vault pavilion: A Design Research through Practice (2014)
• Brandão et al, Cork Re-Wall: Computational Methods of Automatic Generation and Digital Fabrication of Cork Partition Walls for Building Renovation (2015)
• Lakreb et al, Mechanical strength properties of innovative sandwich panels with expanded cork agglomerates (2015)
• Zheliazkova et al, ACOUSTIC CHARACTERISATION OF A NOVEL WOOD-CORK COMPOSITE MATERIAL FOR ARCHITECTURAL APPLICATIONS (2020)

Insulated Concrete Foam blocks, ICF for short. Structurally as tough as they come, and adaptable to any environment, competitive in cost with other materials, and excellent thermal mass and insulative properties.

I think wood fiber and plant fiber are eco-friendly and economical and is the best solution of insulating the building.

expanded perlite to give excellent insulation results used as aggregates and substituted for portland cement.

sand brick

There is a house in El Sheik Zayed City - Giza - Egypt that is entirely made of recycled materials including old concrete. The owner's name is Taimur El Hadidi.

You can check the following link:

https://linesmag.com/el-hadidi-builds-his-house-with-recycled-materials-in-egypt/

Miguel Brito, Ing. Civil; se requiere el artículo para un trabajo de investigación de Tesis

Phase change materials (PCMs) used for the storage of thermal energy as sensible and latent heat are an important class of modern materials which substantially contribute to the reduction in indoor temperature of the zone and the reduction in cooling load and as a result saving in electricity consumption.

I consider wood treated with modern technologies, for example, heat - treated wood, to be the most environmentally friendly both in terms of the production cycle and in terms of the application cycle (https://www.researchgate.net/publication/344317184_EkosistemaDerevoZizni_ASI). In terms of an effective thermal insulator with a positive "green" effect on the environment, we can consider the ash of coal-fired power plants, which largely consists of hollow spheres, and can significantly increase the thermal insulation characteristics of concrete and stucadur mixtures (https://www.researchgate.net/publication/341298099_Zelenye_tehnologii_stroitelstva_infrastruktury_v_Arktike)

Hemp derivatives or strawbale/ similar fibres are amazing for sustainable insulated material and easy to cultivate and source.

1) One of the very interesting if you want to consider a Building element is concerned is - Insulated Prestressed Precast HollowCore Concrete Wall Panels which is the highly effective Building material for Our Covering of Warehouse & malls. ( Ex Made By Spancrete of USA)

2) Lightweight Aggregate made up of Flyash is another very interesting material which can be used for making Concrete - this is an environment friendly & lightweight using the waste of Thermal Power plant & thus is high on sustainability.

По собственному опыту могу сказать, что когда речь идет о декоративных штукатурных смесях, предлагается растительная и древесная щепа (в зависимости от толщины от 0,063 до 0,63 мм), перлит магматических пород составляет 0,6% ... 2% (до смесителя). Сделан вывод о возможности полной замены добавочного, физико-механического, технико-экономического, экологически чистого, 100% прочного строительного материала, будь то вяжущее - портландцемент, гипс,

A very eco - friendly material (especially for industrial floors) is magnesia fibrolite - wood chips or straw bonded with magnesia cement, because magnesia cement is used to make millstones, among other things: https://www.researchgate.net/publication/342212592_Experience_with_the_use_of_magnesia_binder_in_construction_and_manufacturing_of_building_materials

Used expanded polystyrene (EPS). Here is a paper I published on the same.

Also, you can check this fiber cement board made up of recycled fibers: https://doi.org/10.1016/j.conbuildmat.2020.122179

The materials of hemp, peat and flax are eco-friendly and have a low thermal conductivity (between 0.03 W/mK to 0.06 W/mK). They could potentially replace mineral wool or polystyrene.

Please have a look at the following good papers:

Article Investigation of thermal conductivity of natural fibres proc...

Article THERMAL CONDUCTIVITY INVESTIGATION OF COMPOSITE FROM HEMP AN...

Special kind of ceramics might also be suitable for insulation purposes, as you can read here:

Article Fabrication of a Porous Ceramic Material Suitable for Cost-e...