News Thermal insulation. From sheep’s wool to aluminium A well-insulated home, as we saw in previous entries, is one of the biggest concerns of users. Not only because of the savings in heating bills but, above all, because of the superior comfort of a well-insulated home. A house with minimum leaks, and in this we surely agree, offers a better standard of habitability and a more pleasant and stable temperature throughout the year than one that does not. This is why we need to know well the materials that will help us to improve the thermal insulation of our homes. In this post we will review the most common and used thermal insulators in the market, which include from mineral wool to synthetic materials and ecological insulators. If this is a topic that interests you, you have come to the right place. Let’s go there. The importance of insulation Thermal insulation is one of the keys to improving the energy efficiency of a building. And, as we saw in our entry about energy efficiency, it refers to the minimum amount of energy that can be consumed to carry out a process. This means that our homes will be more efficient if we have to make less effort to heat or cool them, and this is where thermal insulation comes into play, whose main benefit is to help reduce the need for energy. In addition, with a good insulator the risk of dampness, leaks, proliferation of harmful microorganisms inside the home, condensation, etc. is reduced. In this way, thermal insulation also protects the health and condition of the building. Insulation material properties There are different factors when assessing the quality of an insulating material. They are related to the behaviour that it presents before different eventualities, such as heat conduction or the energy needed to heat it. These properties help us to choose the thermal insulator that best suits the peculiarities of each installation. The values presented by the materials are directly related to their internal structure and their relationship with the air/gas that flows inside them. Thermal conductivity It measures the heat conduction capacity, i.e. the transfer of energy in the form of heat by conduction between two bodies. Among the most common materials, the usual conductivity is between 0.03 and 0.05 W/mK Thermal transmittance Thermal transmittance refers to the measurement of heat flowing per unit of time and surface area. This means that this value reflects the ability of a material to transmit heat. The international unit of measurement is W/m²K. A low value will mean better performance from an insulator. Thermal resistance Thermal resistance is the opposition of a material to a flow of temperature that affects it. With regard to thermal insulators, thermal resistance is the sum of the surface and thermal resistance of the layers that make up the insulator. It is expressed in W/(Km). Specific heat It describes the amount of energy required to increase the temperature of a material in a given unit. The higher the specific heat, the better the material’s performance as a thermal insulator against the outside temperature. Thermal insulation types As we will see below, there are different types of thermal insulators on the market, ranging from mineral wools to plastic or ecological insulators, among others. Each one behaves differently as an insulator and, as mentioned above, it will depend on the circumstances of the home whether one or the other is more efficient. Mineral wool Mineral wools are insulating materials made up of a series of interwoven fibres of mineral origin (silica for glass wool and mainly basalt for rock wool). Their excellent acoustic and thermal properties have made mineral wools one of the most popular products in insulation. The interwoven fibres form a kind of felt that can be adapted, by cutting it out, to different installations. It is also highly fire-resistant and offers a certain resistance to water without losing any of its properties. Rock wool With low thermal conductivity and permeability to water vapour, rock wool is one of the most widely used thermal insulators. Its applications cover not only the building sector, both in new construction and in renovation, but also industry. One of the advantages of this product is its useful life, which can reach 50 years without deteriorating, and its high content of recycled material, since the waste produced during the production process is reinserted into the melting furnace, so the resulting waste is minimal. Glass wool Glass wool is made by mixing silica (sand), additives and recycled glass. The fibres resulting from the manufacturing process are bound by a solution and then heated to 200º to give the material strength and stability. As with rock wool, it is widely used as a thermal and acoustic insulator. However, it has a better environmental balance than rock wool. That is, the effects in terms of CO2 emissions of the material over its lifetime. Expanded polystyrene (EPS) Expanded polystyrene is a plastic material derived from polystyrene and can be found in many applications. As a thermal insulator, it is usually used in false ceilings, floors or walls, among others. Extruded polystyrene (XPS) Extruded polystyrene is presented as rigid foam sheets. It is highly water resistant and demonstrates high durability. It is commonly used for facades, but also for floors or vertical enclosures, and is popular in various industrial applications. Polyurethane foam (PUR) Polyurethane foam is a synthetic material derived from a mixture of isocyanate and polyol. It has a high insulating capacity and low thermal conductivity. It is often used to waterproof and eliminate thermal bridges. It can be found on facades, roofs, ceilings, etc., and its application must be carried out on site and after studying the thickness required for construction. Ecological insulators Currently, in addition to the synthetic solutions we have seen, ecological insulating materials are also beginning to make more inroads, as their impact on the environment is lower and they offer interesting properties as thermal insulators. Generally, they are durable and their thermal conductivity is low, in addition to the advantage that they are biodegradable and energy efficient in their manufacture. Cork Cork is found on the market for insulation in the form of tiles, sheets or rolls. It is a very light material and is used indiscriminately as a thermal or acoustic insulator. Debe ser aplicado sobre una superficie previamente alisada y es altamente resistente a la acción del agua y las altas temperaturas gracias a sus características aislantes e impermeables. Hemp fiber It is an insulator of plant origin that is characterised by its good thermal and acoustic performance. It is usually used in floors and ceilings with a wooden structure. Despite its vegetable origin, it is not edible for insects or rodents. It can be found in the form of a flexible blanket or in flakes. Flax fiber As an insulator, linen fibre is a lightweight and newly developed material. Its fibres are interconnected, as in the case of hemp fibre, with polyester. It is usually presented in the form of flax or in slabs. Its best characteristics are its resistance to fire and its long life, as well as its impermeability to water vapour, which prevents the appearance of humidity and mould. Wood The porous structure of its fibres favours the diffusion of vapour, which gives them good insulating characteristics. But they also have the particularity that these boards are capable of absorbing sound waves and considerably improving the damping of impact noise. In order for them to show their optimum insulating capacity, they should be installed in a dry state. Sheep’s wool Sheep’s wool is one of the oldest ecological thermal insulators, having been used for centuries. Its use is increasing because it is a natural thermoregulator, in addition to its durability and ease of installation. The most attractive feature of sheep’s wool is its hygroscopic nature, which allows it to release moisture to cool the environment on hot days and absorb it on cold days to warm up. Unfortunately, its cost is high and it should not be in contact with water. Cellulose Surprising as it may seem, cellulose, as a thermal insulator, is produced by shredding newsprint. When it has been processed and turned into strips, it is mixed with boron salts to give it insulating properties, as well as protecting against insects and fungi. As a thermal insulator, contrary to what it may seem, it is highly breathable and offers great resistance to fire. Another advantage is its durability, which can extend over several decades. Reflective insulation Reflective-type thermal insulation has been on the insulation market for over 30 years. Their standardisation for installation in buildings has accelerated in recent years. This type of insulation consists of one or more inner layers of foam or fibres with two outer layers of low-e aluminium, which reflect heat instead of absorbing it. To improve their performance they should be placed between two chambers The transmission of heat to the outside during the summer and to the inside during the winter is done by conduction and convection, reflecting up to 95% of the heat received. At this point we will conclude this introduction on thermal insulation. Energy efficiency is something that concerns us all more and more, so we will pay special attention to it in the next posts. If you are interested in more information about insulating and efficient materials, stay tuned because over the next few weeks we will be publishing more related articles.
