Why do people promising themselves the eco-friendly construction
When choosing the materials for the construction of a building, its different characteristics must be evaluated such as whether they are recyclable or not, what is their ecological value and their energy content in order to obtain a work that is healthy and careful of the environment. The home with eco-friendly construction delivers better health to occupants.
These characteristics of the construction materials are considered based on the following:
- Recycled materials are those recovered from the stream of solid waste, separated, processed and reused in the form of raw material to manufacture another product.
- Ecological material: The material is ecological when it does not contribute to the degradation of the local or global environment (destruction of the ozone layer or global warming, acid rain, air, soil and water pollution, the exploitation of resources not renewable) or when it is not harmful to people and animals.
- Energy material: It is one whose manufacture represents energy savings or fossil fuels.
Many of the materials currently used in construction are toxic as they contain elements that are harmful to human health such as cement, PVC (toxic in its manufacture and combustion), chromium, zinc in paints and varnishes, among others. Likewise, these types of materials require high consumption of fossil fuels for their production, which in addition to being increasingly scarce and expensive, increase pollution because they emit large volumes of harmful gases during their combustion. Ecological materials for construction make it possible to create buildings that are healthy and in harmony with the environment.
Faced with these types of materials, there are alternatives that may seem more expensive, but that, in the long run, are more profitable because they provide energy savings and allow the construction of higher quality homes, environment friendly, renewable, healthier and more durable. This refers to those materials that are, on the one hand, those that nature provides and that have been used for thousands of years such as wood, clay, cork or marble.
To these, known as traditional, a series of new materials also conceived for their ecological use have been added, such as thermoclay, bioblock, arlite, sudorite, celenite, heraklith, EPDM rubber, geotextiles based on polypropylene fiber fabrics, afumex cables for electrical installations, biofa paints, etc. We can also find ecological materials made from rubble and industrial solid waste, which replace the growing consumption of scarce raw materials or located in distant places, reducing the increase in costs and being, moreover, cheaper than traditional construction.
In addition to having these types of materials, ecological houses must be built in a sustainable way in all phases, implementing, for example, systems to save water and be self-sufficient with solar and/or wind energy. In this sense, it is of little use to use ecological materials if buildings are poorly oriented and need a large amount of energy to heat up, which is produced daily by emitting enormous amounts of carbon dioxide.
On the other hand, there are also prefabricated modular houses, made with ecological materials and with energy-saving features. These homes do not affect the land and are designed so that at the end of their useful life they can be dismantled and relocated. Their main drawback is the impact of transport from the place of manufacture to the place of implantation.
Sick Building Syndrome or chronic fatigue
In order to be considered an SES (Sick Building Syndrome), at least 20% of the occupants must be affected with symptoms such as colds, nasal and paranasal sinus congestion, aphonia, taste and smell alterations, dryness and irritation of the respiratory tract (nose, throat), of the skin, of the eyes, headache, difficulties in concentration, fatigue, allergies or hypersensitivity of little known origin, and that appear persistently.
Various construction materials and equipment have the ability to “make a building sick”, altering the quality of the indoor air. They generate, in their occupants, a pathology called “chronic fatigue syndrome”, caused by intoxication of certain chemical components.
It is a rare problem in homes, although it can be found in buildings with poor natural ventilation and air conditioning, such as shopping centres and offices.
The main and most frequent chemical pollutants are formaldehyde, toluene, xylene, trichlorethylene, perchlorethylene, nitric oxides, ozone, carbon monoxide and dioxide, dust, alkanes, hexanes and other hydrocarbons.
A combination of these can be found in carpets, floors and furniture based on vinyl (PVC), thermo-acoustic insulators (polystyrene, polypropylene, polyethylene, polyurethane, etc.), paints, veneered wood, ceilings, plastics in general, fabrics synthetics, cleaning supplies, waxes, solvents and oils, furniture glues, copiers, printers and computers, among the multitude of everyday objects.
On the other hand, buildings generate electromagnetic pollution and, without adequate grounding, accumulate electrostatic electricity that causes a series of inconveniences in its occupants.
Another problem that arises is humidity. Any surface that is between 15 to 25 ° C and 65 to 100% RH is the habitat of biological pollutants such as fungi and bacteria.These are concentrated in air conditioning systems, walls and ceilings where there is condensation, upholstery, damp carpets, woods, etc.
Since we cannot do without all these materials, it is necessary to choose the least aggressive ones. Provide good ventilation in homes, commercial and administrative buildings, in order to reduce the chemical load without reducing its energy efficiency, is a way to avoid these building pathologies.
Composition of materials
To choose environmentally friendly materials it is important to know their intrinsic characteristics and those of their manufacture:
- Wood: Cultivation woods should be used. To avoid their rapid decomposition, they require chemical treatment. The less aggressive ones are made on the basis of boron, zinc, diclofuanide and permethrin, although the latter is somewhat irritating. Due to their toxicity, treatments with arsenic, chromium, dieldrin, creosote, lindane and pentachlorophenol are not recommended (the latter has already been banned in our country).
- Glass: Although it is a material with a high energy content and polluting in its production, it is totally recyclable. Given that it has a low thermal resistance compared to opaque closings, it is necessary to multiply the layers with air chambers or to design double glazed facades, or double carpentry, which not only improve their thermal behavior but also the acoustic one. The hermetic double glazing DVH (R = 0.35 m2 ° C / W) is the best option. You must have adequate sun protection for each orientation. With double glazing, it is important that at least one of its faces is low emissivity, and that the glass sheets are of different thickness to maximize their thermoacoustic behavior.
- Concrete: It has a low energy content and is chemically not very aggressive. The greatest environmental impact is caused by the extraction of aggregates and that is why it is convenient to incorporate part of recycled concrete into the concrete made.
- Masonry: Construction solutions with a higher environmental level comply with the following decreasing order:
- The mud and adobe- These are two compounds of soil with an additive such as straw, to stabilize it, or small stones, to achieve a more resistant result. They differ in the way of construction and it is recommended that both are stabilized with lime or cement.
- Hollow or solid bricks based on clay.
- Lightened ceramic blocks.
- Lightweight aerated concrete blocks.
- Metals: The various metals used in construction, from their extraction to their commissioning, have a high polluting effect, depending on each metal and the technology used in their production. The main problem of contamination appears when metals must be protected to avoid corrosion, particularly in the case of steel. Their biggest advantage is that they are almost totally recyclable. Even blast furnace slag is used to make special cement.
- Steel: The more durable it is made (galvanized, stainless) the more energy it consumes.
- Aluminium: It is the one with the highest energy content, but of very high durability. Primary aluminium is not used in our country; the marketed contains up to 30% recycled material.
- Other metals: Lead and zinc are almost depleted. Copper is noble but has a very high energy content.
- Thermal insulators: The international standard considers any material that has a thermal conductivity below 0.30 W / mK as thermal insulator This includes:
- Glass wool (0.033 to 0.045 W / mK)
- Mineral wool (0.038 a 0.042 W/m.K)
- Perlite (0.088 a 0.018 W/m.K)
- EPS expanded polystyrene (0.032 to 0.041 W / mK)
- Polyurethane or PUR (0.022 a 0.027 W/m.K)
- Vermiculite (0.07 a 0.34 W/m.K)
Normal expanded polyethylene, aerated concrete and others are not considered.
Energy and construction
Construction materials, at the time of their commissioning, have an energy content due to the processes of raw material extraction, manufacturing, transformation, transport, commissioning, maintenance and disposal. This is a subject in development, called the “life cycle” of materials. The data in the table are average values from various sources without specifying the technology of the manufacturing processes. It is necessary to clarify that the reliability of the data depends on the possibility of accessing the values of energy consumed in obtaining a kilo of construction material.
On the other hand, there are variations in all the fields of application (local, provincial, national or international). These values may change over time, as an energy labelling system is implemented that indicates the relative environmental impact of each construction material. This is a process already started in several countries.
When building an ecological home, one should take into account replacing traditional cement with natural ones, and in the carpentry elements, aluminium with wood or similar, reduce the use of steel and connect to the ground so that electricity is discharged, use raw materials as less elaborate as possible. We should resort to the use of locally sourced materials whenever possible. In this way, it will be possible to reduce costs and achieve greater integration of construction with its surroundings, following the recycling-reuse criteria to design and construct buildings in a way that contributes to sustainable development.
|Energy Content of Materials||Primary energy content W / kg.|
|Commercial aluminium (30% recycled)||44.444|
|Synthetic paints and varnishes (enamels, solvent-based)||27.778|
|Expanded polystyrene (EPS)||27.778|
|Primary polypropylene (PP)||22.222|
|Polyurethane (PUR) with HCFC-type blowing agent||19.444|
|Commercial steel (20% recycled)||9.722|
|Baked clay Toilets||7.639|
|Classic paint (water-based)||5.556|
|Wood, chipboard with formaldehyde||3.889|
|Fired clay, vitrified ceramic materials||2.778|
|Fiber cement (made of synthetic fibers or wood)||2.500|
|Baked clay, bricks and tiles||1.250|
|Temperate climate wood||833|
|Hollow brick masonry||822|
|Solid brick masonry||794|
|Mortar M-160a (1: 3) (cement / sand)||508|
|Mortar M-20b (1: 2: 10) (cement / lime / sand)||342|
|Concrete H-150 (300-620-1240 Kg / m3) (cement / sand / gravel)||275|