How to choose thermal insulation for the house

There are many different materials for insulating your home. Some of them, such as polystyrene or glass wool, we have known for years. Others, such as jute, wool, hemp, cork, are new, natural materials that we are hearing more and more about lately. Globally, things are changing and in addition to the actual insulating characteristics of the material, new criteria are emerging. It is becoming important how the material is produced, whether it is made from renewable or waste materials, what the carbon dioxide balance is or whether the material is recyclable. However, thermal insulation must meet certain conditions to be considered effective. Let's see which parameters are important in insulation and how to choose the best natural thermal insulation.

Why houses need to be insulated

Thermal insulation of houses is necessary to minimize heat loss in winter and prevent heat from entering in summer. This means, in addition to increased comfort, reducing the energy costs needed to heat or cool your home.

Insulation can be done while the house is being built. Passive houses built to cut energy costs down to 90% just in. But there are also special materials used in house construction that reduce heat loss. For example Thermibloc from France has developed a building material made from mineralized wood chips in which thermal insulating materials can be embedded. This material is in the form of blocks, similar to BCA. So the house will have its walls ready insulated as soon as it is built.

Also in the range of building materials that also have an insulating purpose are thermal insulating plasters. Their manufacturers claim that when they are used, walls are better insulated. But there are those who believe they are not very effective and much more expensive than traditional insulation methods (e.g. mineral wool).

All types of houses, whether concrete, brick or BCA, need thermal insulation. Wooden houses also need insulation, although wood is a good insulator. Round log houses or rectangular need insulation at structural joints between elements. Timber frame or prefabricated wall houses need insulation at the roof, between the rafters, in the attic, between the layers forming the walls.

Parameters according to which thermal insulation is chosen

Thermal insulation materials, natural or not, are chosen according to their performance, which is determined by several parameters:

• thermal conductivity - determines how easily heat passes through the material. The lower it is, the better the material insulates. It is also called lambda value (λ) and is expressed in W/mK;
• thermal resistance - is the parameter that relates the conductivity to the thickness of the insulating material. The resistance value is the ratio between the thickness of the material and its thermal conductivity. Thermal resistance is therefore inversely proportional to conductivity and the higher the thermal resistance, the better the insulation material. Unit of measurement: Km²/W;
• Thermal diffusivity - is the ability of a material to conduct heat relative to that of storing it (e.g. metals conduct heat quickly, wood slowly). For insulators this parameter should have a low value. Unit of measurement: m²/s
• density - a material with high density has a high total weight which means it has low thermal diffusivity; kg/m³
• vapor permeability - measures the ability of a material to allow water vapor to pass through it. Thermal insulation must be vapor permeable. Timber-framed houses have an even greater need for insulation materials to allow moisture transfer. Otherwise, mold and mildew will develop, and the next step is wood rot, which affects the strength structure.

A newer but increasingly recognized criterion is the carbon dioxide balance. It is also referred to as bound carbon. It is not a criterion related to insulation performance but to the gases that lead to global warming. It is a ratio that shows how much carbon dioxide was released into the atmosphere during the production of the insulation material compared to that absorbed by the raw materials from which it was made. From this point of view, insulation made from renewable plants has a positive balance sheet.

Natural thermal insulation

The most popular natural materials for home insulation are wood fiberboard, wood fibers, sheep's wool, hemp, jute, cork, recycled cellulose. There are others - seaweed, straw, corn cobs - but they are used occasionally. But the others have reached the stage of industrially manufactured insulation products and are easy to use.

Wood fiber boards and independent fibers

Insulation is the use of waste from the wood industry. The fibres are obtained by a chemical process that partially removes lignin, the substance that stiffens wood. The result is a kind of wood wool that can be used as individual fibers or pressed into boards.

Wood fibers are used to insulate hard-to-reach places and need special installations and specialists to install them. The plates are mainly used for external insulation because they are stiffer and can be easily fitted. This stiffness also means that they are combined with other natural materials in the form of a mattress (hemp, wool) to stiffen them and make them easier to fit.

Insulating parameters: thermal conductivity - 0.38; strength - 2.5; density - 160 for boards and 50 for fibers. It is vapor permeable, so suitable for wooden houses.

Sheep wool

I've often wondered why Romanian shepherds throw wool away instead of finding a way to recover it, and insulation seemed to me to be one of the best ways of recovering it. As I studied wool insulation more, I understood that wool goes through many operations and transformations before it gets there, which consumes labor and energy.

The wool is collected, cleaned, washed and then pulled into mats of thin strands. All this must be done without the use of dangerous chemicals (aggressive detergents). To be made into insulation it is mixed in a ratio of 5-10% with recycled polyester adhesive and boric acid salts (in a ratio of 2-3%) for protection against pests. Wool insulation is available in rolls of various thicknesses.

The thermal conductivity is o.038; thermal resistance: 2.63; density: 23 and is vapor permeable.

Hemp

Hemp is an industrial plant long used as a fiber for natural fabrics. That used for fabrics is different from hemp used as a drug.

Hemp grows fast, reaching 4 m tall in 3-4 months. The leaves are large and shade the soil, so herbicides are no longer needed to protect crops. The hemp fiber obtained is therefore free of dangerous chemical compounds. As with wool, up to 10% of recycled polyester adhesives are added to hemp insulation. For fire protection 5% sodium salts are added.

Found as rollers or mattresses of different thicknesses. Conductivity: 0.039-0.040; resistance: 2.5; density: 25-38; vapor permeability

Jute

Jute is an annual plant grown mainly for the fibers obtained from its stem. They are used to make twine, rope, carpet yarn and sacking. Jute insulation is a recent development. It's made from recycled jute bags used to transport cocoa beans, and the idea came from chocolate maker Ritter. It has a beautiful story behind its creation here. Tests have shown that is the best summer insulatorcompared to all existing products on the market.

Jute fibers are used to make insulation in the form of mattresses that are easy to install, do not cause irritation and do not rot. The thermal conductivity is 0.038; resistance: 2.63 at a mattress thickness of 100 mm and density 34-40. It is vapor permeable.

Pluta

Pluta is actually the bark of an oak tree that grows in the Mediterranean area of western Europe and northern Africa. The bark is harvested when the trees are 20-25 years old and regenerates so that after 9 years it can be harvested again. Such oaks live for around 200 years.

The main producer of cork products is Portugal. The thick bark is used to produce natural cork stoppers of the highest quality, while the thin bark is made into pellets. These pellets are used to make cork sheets.

And from the plates you get stoppers. Only 25-301-30% of the surface area of a plate is used for the stoppers, the rest is losses. From these losses came the idea of an insulation material. The scraps are cut into thin strips and pressed. During pressing, suberin, a natural binder, is released, which binds the strips together to form slabs of different thicknesses.

Cork insulation has very good insulation properties, both thermal and sound insulation and vapor permeability. Conductivity 0,36-0,38 and density 110-120. Unfortunately I couldn't find any information about thermal resistance.

Recycled cellulose insulation

It's basically recycled newsprint. The newspaper is chopped very finely and mixed with sodium salts, which make it fire-resistant, and non-hazardous organic substances (such as boric acid salts) for resistance to mold and insect attack. Insulation is similar to individual wood fibers, which is why it is applied using special equipment that distributes it evenly in the tight spaces being insulated.

Thermal conductivity is between 0.38 and 0.40, thermal resistance is 2.63 and density 27-65. It has vapor permeability.

As you can see there are lots of natural materials for insulating your home. And I haven't told you all of them, but especially those you can find in the country. For example. Naturalpaint you can find 4 of the materials shown. It is hard to say which is the best insulation for your home because the factors on which the choice depends are many and varied. It's best, when deciding to insulate, to discuss the pros and cons of each type at length with the supplier and let them know what you expect from the insulation of your home. This is the only way to make sure you won't be disappointed.