Materials
Natural insulation for an eco-friendly home
From time to time on the blog, we share more specific construction-related topics, as it is important to understand the difference between an ecological, natural house and one that is not. This includes the implications this has on our health, the indoor air quality of our home, and the environment.
Natural insulation refers to a group of products that undergo minimal transformation from extraction or manufacture until they arrive at the construction site. For example, wood fiber or cork insulation has practically not been treated with anything other than steam or pressure to shape it and facilitate its installation on-site.
The natural properties of breathability, moisture absorption, and absolute safety for health of a natural insulating material such as cork remain intact, and we benefit from them throughout our lives.
In contrast, if we look at sprayed polyurethane, for example, we start with a somewhat controversial material from an ecological standpoint—petroleum—which is transformed through complex chemical processes dangerous to the environment. Once installed on-site, it does not allow walls to breathe, as it is a waterproof plastic that generates condensation and is dangerous in the event of a fire.
Let us then examine the advantages of using natural insulation and which materials we should use. The reality is that many insulation materials are disguised as ecological and natural when they are not, such as rock wool, which I will discuss later—a material that generates many environmental and health problems.
Why build an eco-friendly home with natural insulation?
An eco-friendly home is a construction that respects the environment, built with natural materials, and makes the most of the natural resources of the sun and the earth to achieve comfort for its inhabitants.
It is a house with very low consumption both in its daily use and in its construction. For this reason, we use natural insulation for an eco-friendly home, as little energy is needed to manufacture them and they are natural materials that require a simple transformation process.
Likewise, just like the insulation, the rest of the construction materials for our home will also be natural and environmentally friendly.
Characteristics of thermal insulation
The use of thermal insulation spread in Spain just over half a century ago. Although it is now a basic requirement for all buildings and homes, it was not installed at the beginning of the 20th century. Gradually, it began to gain market share, but even today, less insulation thickness is installed than should be.
Among the characteristics of thermal insulation, we find lambda, which is the coefficient of thermal conductivity. That is, the lower the value for a material, the less heat it can conduct from one side of the wall to the other, and therefore, the greater its insulating capacity.
Most insulation materials have a conductivity of around 0.040 W/mK. It is important to always look at the three digits after the decimal point, as some companies only write 0.04 to make the value appear lower.
Insulation, like other construction elements, can also be hygroscopic, meaning it has the capacity to absorb moisture from the environment. Thanks to this, insulation can absorb excess water vapor when the air is too humid and release it when the air is too dry. This capacity ensures that humidity is regulated naturally, in addition to promoting our well-being.
We must also check the reaction to fire. Insulation and all materials are classified by the European Euroclasses law, which works similarly to the energy rating of household appliances. Each material is assigned a letter from A to F; insulation with the letter A consists of products that contribute little or nothing to the spread of fire, while those rated F have no characteristics that protect them against fire.
Insulation materials to avoid
Before looking at the complete list of natural insulation for an eco-friendly home, let us look at certain insulation materials that should be avoided due to their characteristics.
– Rock wool: although it is of mineral and natural origin, its manufacture involves melting rocks at high temperatures, resulting in high energy consumption during the manufacturing process. Furthermore, synthetic additives and binders dangerous to health, such as formaldehyde, are added during its transformation. Formaldehyde is classified as a carcinogen by the EU and can reach the indoor environment of our home. This makes rock wool a product with a high ecological footprint that is not recommended.
– Glass wool: the environmental problem with glass fiber or glass wool is that it releases small fibers during its manufacture and installation. These fibers can reach our lungs and are associated with skin irritation and lung problems for the workers who install them.
– Extruded polystyrene: this is an insulation that, in addition to requiring a large amount of energy for its manufacture, comes from petroleum derivatives. These are insulation materials that are not very ecological in their extraction and transformation processes; furthermore, once installed on-site, they become poorly breathable insulators that generate condensation and moisture inside our home.
– Polyurethane foam: its origin is 100% petrochemical, it has a high chemical load, and its manufacture is very energy-intensive. Besides having a large ecological footprint, the chemical components it contains are very unhealthy during its transformation process and, like most petroleum-derived insulation, it does not breathe properly.
Natural insulation for an eco-friendly home
That said, let us look at working with natural insulation for an eco-friendly home with the aim of achieving a healthy and natural dwelling. These insulation materials are gaining more and more importance in construction thanks to their advantages and increasingly competitive prices.
– They are recyclable and renewable, as well as biodegradable.
– They are produced with low energy consumption, so their ecological footprint is very low.
– They are healthy. Natural insulation for an eco-friendly home is non-toxic and does not contain substances that could be harmful to our health.
– They allow our house to breathe while being airtight. Excessive and non-breathable insulation can lead to condensation in some parts of the house.
– They have great durability. Unlike conventional insulation, natural materials last for many years without losing their properties.
Cork
Cork is arguably the most widespread thermal insulation for an eco-friendly home. It is obtained from the outer bark of the cork oak, and it is not necessary to fell the tree to obtain it. This makes it a renewable natural resource, although it must be used in moderation as it is harvested every 10 years.
It was one of the first ecological insulation materials to appear. It has a transmittance of 0.045 W/mK and is used primarily in areas prone to moisture, such as under tiles and floors, in foundations, and in basements, since unlike other natural insulation like wood fiber or cellulose, cork does not degrade with water.
Hemp
Hemp is obtained by separating the fibers of a plant that are used for both making blankets and insulation. Its cultivation is very simple as it is a hardy plant that requires almost no pesticides or fertilizers and does not need irrigation.
Some builders find hemp panels expensive and difficult to cut; however, hemp is gaining a presence in the market not only as an insulation material but also as a construction system for walls combined with lime or earth.
By using hemp, breathable insulation is achieved, which is an advantage for the indoor environment of our home. Its transmittance is 0.041 W/mK, so it still provides good performance.
Flax
The characteristics of flax are very similar to those of hemp; it also comes from an easily cultivated plant and produces natural, breathable insulation.
It has a transmittance of 0.040 W/mK and, like hemp, it is a plant material that is not attacked by rodents or insects, as they do not find it appealing. Furthermore, flax offers good mechanical resistance without additional treatments, meaning the sheets are stable on their own.
Wood fibers
This insulation is obtained from wood chips to which natural binders are added. It can be obtained from a recycling process of wood waste or small branches.
Wood fibers have a slightly higher energy expenditure in their manufacturing process and transport, but they are also easy and convenient to work with. Their transmittance is 0.050 W/mK, and they are also a good acoustic insulator thanks to their high density.
Cellulose
Cellulose has been used since the 1930s in the United States and in some Nordic countries. Today in Spain, it is one of the most widely used due to its good quality-price ratio.
It is a conglomerate of recycled paper waste. Although certain substances are required to treat cellulose against moisture, it is a lightweight insulation that requires little energy for its manufacture. It has an average transmittance of 0.042 W/mK, but its manufacturing method can vary its characteristics depending on the density and technique used.
Wool
So far we have seen insulation of plant origin, but in this case, we are evaluating an insulation that has an animal origin.
Wool is a very economical insulating material if a local supplier is available; it has a transmittance of 0.040 W/mK and is one of the few that increases its insulating capacity when it becomes damp.
It should be noted that wool requires the application of an insecticide to prevent attacks by moths or other insects, and therefore we are no longer dealing with a toxin-free natural insulation.
Perlite
Perlite is another natural insulation for an eco-friendly home. It is a mineral that, although it requires slightly more energy than other materials, remains completely natural and without toxic additives.
With a transmittance of 0.050 W/mK, perlite is increasingly common in conventional construction. It is also composed of very porous and lightweight fibers that are also used as fireproof insulating material.
Cotton
Cotton is a natural insulation of plant origin that comes from an easily cultivated plant with a low environmental impact. It has a transmittance of 0.040 W/mK, and the fiber it is composed of has great strength and is easy to braid. It is marketed in blankets, boards, or even in bulk and is manufactured in different densities, thicknesses, and insulating capacities. It is also used as acoustic insulation. Cotton is a very healthy material as it does not require the use of any toxic components during its manufacture for proper maintenance.
As we can see, building with natural insulation for an eco-friendly home is important if we want to be respectful of the environment and ourselves, as quality of life also improves with toxin-free materials that do not emit harmful substances into the indoor environment of our home. This is especially important when we have people from so-called risk groups, such as children, pregnant women, people with immunological conditions or respiratory diseases like asthma, people with MCS, and of course, the elderly.
But it is not just risk groups; healthy people who live continuously in a home where the indoor environment is loaded with harmful substances are constantly forcing their defenses to work, which gradually diminishes their health. We are talking about building houses for a lifetime; we want them to be healthy sanctuaries where one can live a full life.
This is one of the objectives we have at our studio: that all families can enjoy a healthy life in a home that becomes their daily toxin-free sanctuary, with a pleasant indoor environment and where, of course, the energy cost does not become a second mortgage paid in the form of energy bills every month. As always, do not hesitate to consult us with any questions that may arise.