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Incorporating Eco-Friendly Materials in Construction

Green building requires the use of sustainable materials. How to choose them based on energy performance, recyclability, and durability

Currently in Europe, buildings are responsible for about 40% of final energy consumption, of which 25% is attributable to residential buildings and 15% to the tertiary sector. This value exceeds the percentages assigned to industry (28%) and transportation (32%).

The construction sector accounts for about 30% of greenhouse gas emissions in the atmosphere.

Another critical aspect associated with the construction sector concerns land consumption, with the artificial surface in Europe currently representing 4% of the total, but from 2000 to 2006, it recorded a loss of about 600 thousand hectares of agricultural land, resulting in a 3.4% increase in built-up areas.

An important aspect of green building is undoubtedly the selection of building materials. Let’s discover what sustainable materials are and why it is important to choose them.

Towards environmental, economic, and social sustainability

Cemented and urban surfaces are increasing, while at the same time, there is a decrease in agricultural land, with a 0.2% reduction in arable land and permanent crops and a 0.3% decrease in grazing land.

It is essential to try to contain these issues with the rational use of land. In which direction should we go, then? Certainly towards reducing energy consumption and harmful emissions, through targeted territorial and urban planning policies; towards the adoption of high-energy efficiency technologies, the use of low-impact materials, and the use of renewable sources. These interventions are aimed at environmental, economic, and social sustainability. This transformation does not only concern new constructions but represents above all a challenge in the recovery of existing building heritage, which we will address later.

These are the key themes of sustainable construction, green building, and bioconstruction.

Eco-friendly architecture: how to choose materials?

The choice of materials for the construction world represents the heart of the implementation phase of a work. We are witnessing a return to the past in terms of the type of materials used for constructions, but with two advantages: technological development and modernity. Using natural materials means making a responsible choice both for human well-being and for the environment.

Sustainable architecture is increasingly moving towards construction systems to be combined with natural materials (bioconstruction systems). Wood, for example, is a material that has seen exponential development even in locations with milder climates. But how can we evaluate the impact of materials on the environment? Certainly by analyzing them throughout their entire life cycle, from extraction to recycling. Among the aspects to consider, we cannot fail to mention:

  • the energy saving that must dominate the production process, in order to minimize CO2 emissions into the air;
  • the toxicity of the material during the operating phase;
  • the durability and recyclability;
  • the pollution due to material transport.

For evaluating the energy performance of buildings for any intended use, it is essential to use a Dynamic energy analysis and simulation software that allows taking into account sustainable materials in the building model and high-efficiency generators and renewable energy systems in the plant part.

Evaluation of energy performance of buildings with TerMus

Evaluation of energy performance of buildings with TerMus PLUS

Eco-friendly building materials

Building materials represent 50% of the material extracted from the earth’s crust for the activities we carry out every day. Global primary energy consumption and greenhouse gas emissions account for 40%. This is why it is crucial to carefully choose the materials to be used for environmental sustainability. As mentioned earlier, it is necessary to consider the life cycle of the material and conduct a thorough evaluation to consider the environmental, economic, and social impacts of a material.

A material is considered sustainable when it meets at least the following characteristics:

  • lower energy consumption compared to traditional buildings throughout the life cycle;
  • lower water consumption compared to traditional buildings;
  • lower environmental impact throughout the entire life cycle;
  • higher quality and indoor comfort;
  • greater durability compared to a traditional building;
  • absence of toxic substances;
  • recyclability.

But what are the most common sustainable building materials? We can include various types of bricks, blocks of lightweight concrete with expanded clay and expanded clay, natural stones, and raw earth in the list. Let’s analyze them in detail.

Brick

In Ancient Rome, the term “brick” referred to the brick used in the opus latericium: the construction technique of the wall facing. Over the years, the term has acquired a more general meaning that encompasses a wide range of products including solid and perforated bricks, pots, tiles, volterranas, copings, Marseille tiles, etc., used in the construction of vertical structures (load-bearing walls, infill walls, etc.) and horizontal structures (slabs, roofs, etc.).

Bricks are the result of a mixture of clay, sand, and water, which, after mixing, is shaped by extrusion or molding. The subsequent drying and firing in tunnel kilns at a temperature of 1200°C give rise to the finished product. To improve the insulating properties of the material, various components such as polystyrene balls, sawdust, paper processing residues, or other waste materials are added to the raw mix. These, after firing, are removed, generating small air pores. This reduces the density of the brick and increases its thermal-acoustic properties.

These are products made with natural raw materials, whose production process does not generate waste but allows the recovery of waste from other processes. It is important to note, however, that the firing process requires a considerable amount of thermal energy, usually produced by fossil fuels with a significant environmental impact.

Bricks also offer the possibility of being recycled after use: they can be used as a base for road construction after being crushed. During the production process, the waste from one cycle is reused in the next cycle, contributing to sustainable resource management.

Lightweight concrete blocks with expanded clay

Lightweight concrete blocks with expanded clay are obtained by mixing expanded clay granules with the traditional mix used for the production of blocks for load-bearing walls, infill walls, partition walls, and pavements. Expanded clay is obtained by grinding and firing raw clay. During the heating process, the granules, subjected to increasing temperatures, expand thanks to the development of carbon dioxide and water. Subsequently, passing through a fluid bed of air currents induces the cooling of the granules and the hardening of their outer layer, while the inner core remains porous. This characteristic gives the material high lightness and, at the same time, good mechanical resistance.

Loose expanded clay granules have good thermal inertia and compression resistance. Being of mineral origin, they boast incombustibility, refractoriness, chemical inertia, temporal stability, immutability, and resistance to moisture. The presence of these granules gives the concrete blocks remarkable insulating properties both thermal and acoustic, as well as considerable lightness that facilitates installation, leading to economic advantages. The vapor permeability of such blocks prevents the formation of condensation and mold inside walls, ensuring the breathability of the building.

The fireproof properties combined with the controlled geometry of the expanded clay blocks allow minimizing the use of mortar in the joints and, if necessary, reducing the thickness of the plaster.

Natural stone

Natural stone was partly replaced in the 20th century by materials such as steel, reinforced concrete, and glass. However, with the focus on low-impact building components, stone has regained relevance both in renovations and new constructions. From a bioecological point of view, stone is suitable, but it is essential to consider requirements such as bioecological properties (permeability and thermal conductivity), volumetric weight, compactness and porosity, durability, resistance, and aesthetic appearance.

Stones, classified based on volumetric weight and processing, include tuff, granite, travertine, marble, diorite, syenite, porphyry, and basalt. The choice of stone should also consider compatibility with mortars to ensure structural coherence. Stone processing can be rough, tanned, cut, or in the form of slabs.

Raw earth

Raw earth is obtained by drying a mixture of clay, plant fibers such as hemp and straw, and inert materials of various sizes such as sand and gravel. This natural building material, known since ancient times, is easily workable, environmentally friendly, and completely recyclable. Thanks to the flexibility in the composition of the mixture, it can be used for load-bearing walls, roofs, floors, and finishes. The remarkable thermal inertia of raw earth offers effective thermal insulation, suitable even for extreme climates. Furthermore, clay acts as a “sponge,” absorbing and releasing moisture in a controlled manner, maintaining a comfortable relative humidity rate in indoor environments.

There are 3 main techniques for the implementation of raw earth, depending on the proportions in the mixture. The rammed earth technique, used with a low percentage of clay, involves inserting the earth into formwork of the desired dimensions, compacting and beating each successive layer. With a high percentage of clay and sand, the raw brick technique is adopted, inserting the earth and straw into wooden molds inverted for drying, avoiding excessive shrinkage with drying under sand heaps. Finally, with a high presence of silt, the cob technique is used, spreading the mixture on wooden frames anchored to the building structure.

Thanks to a building design software, you can carry out your 2D/3D architectural design of new constructions and renovations by choosing eco-friendly materials.

Designing eco-sustainable buildings with Edificius

Designing eco-sustainable buildings with Edificius

Eco-friendly building materials: insulation materials

An important feature in terms of eco-sustainability is certainly the insulating capacity of a material. Thermal insulation, often linked to acoustic insulation, is a fundamental aspect of building design, as it affects energy consumption and heat loss through the external envelope. The use of materials with high thermal insulation performance helps reduce the energy needs of buildings, reducing CO2 emissions and lowering operating costs.

Despite the insulating effectiveness of “artificial” materials of petroleum origin (such as expanded or extruded polystyrene, polyurethane, etc.), their production involves risks of environmental pollution, potential toxic emissions in case of fire, and challenges in recycling. Therefore, the choice of insulation should favor materials of plant or animal origin, such as wood fiber, cork, cellulose, sheep wool, cotton or linen fibers. This selection aims to ensure high insulation performance while minimizing negative environmental impacts.

Wood fiber

Wood fiber panels are widely used as natural insulation components. The production process involves grinding red fir or pine woods, followed by drying at high temperatures (350°C) and pressing. The addition of alum promotes the release of the wood’s natural resins, giving the panel a marked hydrophobicity, further enhanced by treatments with wax or latex. This method uses natural raw materials such as sawmill residues and weak woods, making the panel fully recyclable. The residues from the panels can be reused for the production of other insulators or composted.

Wood fiber panels have remarkable thermal insulation properties, with a thermal conductivity coefficient of about 0.04 W/mK, and acoustic insulation due to the interweaving of fibers that hinder the propagation of sound waves. The open structure of the slabs allows the passage of water vapor, promotes the breathability of roofs or walls, and contributes to the natural regulation of humidity in environments. Additionally, the aesthetic quality of the panels allows for the creation of pleasant environments, offering visual and tactile well-being sensations due to the natural origin of the material.

Cork

Cork panels are obtained by compressing chips of the less valuable bark of a specific oak tree (Quercus Suber L.), known as male cork. These components, also made from natural raw materials, are biodegradable and free of toxic substances. It is important to note that the bark regeneration cycle of the tree takes about 9 years. The cellular structure of cork, with about 30-40 million air cavities per cm3, gives the material high elasticity, mechanical resistance, and excellent thermal insulation properties (with a thermal conductivity coefficient of about 0.038 W/mK) and acoustics. Cork is also waterproof, fireproof, and resistant to attacks by insects, rodents, woodworms, and bacteria.

The panels, sold in 50×100 cm formats with thicknesses ranging from 1 to 6 cm, are used for thermal and acoustic insulation of vertical structures such as external walls and partitions, as well as horizontal elements such as floors, attics, and roofs. Cork is rot-proof, a characteristic that allows it to be placed directly under the tile or brick layer without the need for a waterproof membrane.

Cellulose fiber

Cellulose insulation is produced by grinding newspaper sheets, followed by treating the resulting flakes with boron salts for fireproofing and pest control. The production process has a low environmental impact, but the resulting material is not landfill disposable due to the aforementioned salts, requiring incineration.

Cellulose fiber, with a thermal conductivity coefficient of about 0.037 W/mK, proves to be a valid thermal insulator thanks to the tiny cavities in the flakes that hinder heat transmission. Characterized by high hygroscopicity, it can absorb about 30% of the moisture present in an environment, releasing it slowly to ensure habitable comfort.

Installation is carried out by blowing the flakes into the cavities or by spraying them on the previously wetted walls. In addition to flakes, pressed cellulose panels are commercially available suitable as coverings for existing walls during renovation work.

Eco-friendly design materials: finishing materials

Finishing materials represent the layer that covers buildings. It is important to choose them with the utmost care to avoid nullifying all the work done during the construction of the building. Therefore, two elements must be evaluated: painting and plaster.

Natural plaster

Plaster is applied to the walls to give homogeneity to the surface and serves as protection against climatic events and/or mechanical factors. Breathability is certainly the most important characteristic to consider: generally, plasters based on natural hydraulic lime with dehumidifying properties are preferred, as well as breathable. It is important to remember that lime is the best natural insulator, a material used since ancient times. Furthermore, lime plaster is very breathable: it promotes an exchange with the outside and prevents condensation on the walls.

Another case of natural plaster is raw clay, always a natural material, easy to extract, and 100% recyclable. It is becoming increasingly popular for its aesthetic and functional properties, ranging from porous to smooth with a variety of colors. Clay plaster can be applied to various supports, providing thermal and acoustic insulation and is biocompatible, hypoallergenic, and hygroscopic. It plays a significant role in Passivhaus, contributing to maintaining stable temperature and humidity, improving the habitable comfort.

Natural paints

Natural paints, also known as natural varnishes, are made exclusively with biological ingredients, mainly based on resin extracted from conifers such as larches and pines. These materials offer numerous advantages, including high breathability, anti-allergic and anti-mold properties, absence of toxic substances, durability over time, no dust attraction, a pleasant scent derived from natural pigments, can be applied even with closed windows, offer quality aesthetics, are easy to work with, require simple maintenance. These natural paints are ideal for bioconstruction projects, both for interiors and exteriors, and can be used in new constructions or in the renovation of existing buildings, including those located in historic centers. Their healthy, safe, and high-performance nature contributes to general well-being and high habitable comfort.

Environmental Sustainability: Between Innovation and Benefits

In conclusion, the increasingly widespread adoption of eco-friendly materials in construction represents a fundamental step towards creating living environments that combine environmental sustainability, energy efficiency, and occupant well-being. The careful selection of materials such as certified wood, clay, wood fiber, and other eco-friendly solutions not only reduces the environmental impact of construction but also helps create healthier spaces conducive to well-being.

These materials not only meet rigorous environmental standards but also offer intrinsic beneficial properties, such as excellent thermal regulation, the ability to absorb excess moisture, and resistance to pathogens like mold and bacteria. Beyond environmental considerations, the use of these solutions translates into significant long-term energy savings, thus contributing to the economic sustainability of buildings.

In a context where environmental awareness is increasingly central, the construction industry is embracing these practices to meet current and future needs.

Edificius
Edificius