Ecological And Sustainable Thermal Insulation

ecological thermal insulation

As I anticipated in the post about the advantages and disadvantages of mineral wool, there are insulators that are more ecological than mineral wool and towards which the future of construction should lean.

The common characteristics of ecological insulators are:

  1. They are healthy. These are non-toxic natural materials that do not contain plastics or any component derived from petroleum or substances or additives that may be harmful to health.
  2. They are durable, recyclable, and biodegradable.
  3. They require minimum energy consumption for their manufacture.
  4. They have a great thermal insulation capacity. In other words, they are poor transmitters of heat or, their thermal conductivity is very low (*).

(*) The Thermal Conductivity Coefficient defined as = W/mK (Watts per meter and degree Kelvin), is the parameter that identifies the capacity of a material as a transmitter of heat, qualifying it as an insulator (very low conductivity) or a conductor (low conductivity). high). In typical insulators, such as air or cork, this coefficient varies between 0.02 and 0.05 W/mK. In contrast, metals such as iron or silver, which are good conductors of heat, have thermal conductivity coefficients between 80 and 400 W/mK

In the United States, there is great ignorance about this type of insulation and, what is worse, about the health and environmental effects of many of the insulations commonly used in construction. For this reason, from this blog we want to start promoting the use of these insulators, among which we can highlight the following:


Cork is a 100% natural material that comes from the bark of cork oaks, and trees that grow in areas with a Mediterranean climate. Its production is sustainable since even during its extraction the generation of waste is low. The cork oak renews its bark every 9-12 years, and this makes it possible to obtain cork without harming the tree.

Its structure in the form of polyhedral cells, which are practically empty inside, gives it waterproof and insulating properties, both thermal (conductivity of 0.041 W/mK) and extraordinary acoustics. These and more characteristics of this material can be found at this link.

As insulation, it is marketed in agglomerate sheets made through pressure and heat without using any type of glue. It can also be found in the form of chips, granules, or crushed to fill cavities and even projected on facades and roofs, floors, and walls. Cork could have the drawback of its limited resistance to fire (dollar class E). However, currently, insulating panels are subjected to a fireproof treatment that considerably increases their fire resistance, making them suitable for sustainable construction.

The tendency to use this material is growing, even being used as facade cladding in the construction of buildings.

Sheep’s Wool

This material has been used for centuries as thermal insulation. Its excellent hygroscopic properties allow it to absorb ambient humidity or release it depending on the ambient temperature, thus acting as a natural temperature regulator in a similar way to how sweat acts on our body: when the outside temperature increases, the fibers heat up and release moisture which, when evaporated, subtracts heat from the environment. That is, it refreshes the environment. On the contrary, in winter the fibers cool down, absorb moisture (it can absorb up to a third of its weight in moisture without losing its insulating capacity), and, in doing so, give off heat.

However, wool as an insulating material must be subjected to cleaning and protection treatments against attack by xylophages, and moths with sodium borate.

It is a 100% ecological and renewable material since it comes from the necessary and regular shearing of the animal during its life. Its thermal conductivity, in a blanket, is very low: about 0.038 W/mK. Like cork sheets, wool sheets can be subjected to fireproof treatments.


This natural fiber, easy to sow and fast-growing, as it does not have nutrients in its stem, does not need to be fumigated or use chemical fertilizers. In addition, the absorption of CO2 during its growth gives it particularly sustainable characteristics.

It has excellent acoustic and thermal insulation properties with a conductivity of only 0.041 W/mK. It is marketed in the form of blankets made with fiber. And, with the woody surplus that remains after separating the fiber, lightweight mortars are made to make walls or bricks.

The Linen

Also of plant origin, this plant is easy to grow and offers good mechanical resistance without additional treatments, which makes it very dimensionally stable.

It has good acoustic and thermal characteristics with a conductivity of 0.047 W/mK. And, in addition, a hygroscopic capacity of up to 15% of its weight without loss of insulating qualities.

However, its use in humid environments is not recommended.


Cellulose-based thermal insulation is made with paper waste (basically newspaper). This paper is ground and treated with borax salts that give it fireproof, insecticide, and antifungal properties. In this way, small-sized fibers are obtained that can be blown into the gaps between walls and ceilings. Another option is to press them to form insulating blankets with which to cover those same holes, thus obtaining a high degree of both thermal and acoustic insulation.

It requires little energy to manufacture and the final product is light, with a Thermal Conductivity coefficient of 0.042 W/mK. It is, therefore, another good alternative for sustainable insulation.

Wood Fiber Boards

Wood fiber boards are manufactured using a wet process, from wood fibers that are 90% leftover from felling in the cleanest forests in Europe and 10% from leftovers from the wood industry. They can be placed on walls, partitions, ceilings, and floors.

The porous structure of its fibers favors vapor diffusion, which gives them good insulating characteristics. But, in addition, they have the particularity that these boards are capable of absorbing sound waves and considerably improving the damping of impact noise. For them to show their optimum insulating capacity, it is advisable to mount them in a dry state.

The Air

We have previously mentioned air as an example of a magnificent thermal insulator since its Thermal Conductivity coefficient is of the order of 0.025 W/mK. That is, lower than any of the previously presented materials. In addition, it is undoubtedly the cheapest of all since its use is free and it is a natural barrier against fire. However, it is also a magnificent transmitter of sound, so its use as an acoustic insulator is null. If our house was located completely isolated in the countryside and the noises of nature (or children playing in the garden) do not bother us, it could be a very economical and efficient thermal insulation option. But acoustically it would be disastrous. Therefore, in the search for comprehensive solutions, any of the above is more appropriate.

When choosing one product or another, it is advisable to contact the distribution companies that will advise you on the ideal ecological insulation depending on the characteristics of your home and where it is located.

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