Insulation (important factor in Ecological Construction)
Insulation (important factor in Ecological Construction)
Nomads in the beginning, villagers - growers then bourgeois apartment owners more then until the beginning of this century, people followed the following strategy to overcome the cold, in homes that they made:
Only heats a room with a stove or a fireplace. There they spent most of their time and when it came time to sleep, those who could fit not to sleep near the hearth heat, used and adjoining unheated rooms, which were covered with heavy leather or wool quilts.
Farmers had a complementary strategy. Incorporated, usually at the northern floor plan of the house, a shed or a barn and thus create a buffer area in contact with the main housing area, which helped to achieve better thermal comfort conditions. The walls of these buildings were not adequate thickness (much larger current), so the rate of lag was much better than today.
In a stone wall of 60 and 80 million. The heat or cold, respectively, "entered" into roughly two or three times a year, compared with a current of 10 or 20 cm. Brick wall with light insulation!
Regular treatment of heat was about equivalent and epitynchaneto and using DIY (wind chimneys, Calafate, awnings, canopies, pergolas etc.)
But all were upset, first after the 2nd World War, which led millions of people to flock in large urban centers (for security reasons) and seek shelter in a multi-story (and often well-built buildings!) and then, immediately after the oil crisis of 1973, that put for the first time in light-hearted humanity, dilemmas about saving energy and the depletion of resources of land.
At the 1974 show, and then the first thermal regulations in European countries (France, Germany) in order through proper insulation of buildings energy efficient. In Greece, the debate starts in 1979 (a lag of five years, so good on!) And on 04.07.1979 (Government Gazette 362) necessary thermal insulation of all new buildings. Gradually, in the mid-80s, Europe discovers, (massive !!) and another component in addition to the insulation, which is the Sustainable Architecture.
This teaches us not only thermally insulated homes, but also to properly oriented relative to the sun (winter and summer) and with the prevailing winds. Finally in the late 80s, Europe, putting and another last component, which is none other than ecological building, who simply tells us that: "what is the point to save energy when the materials (insulating Fr. .g.) used is carcinogenic for residents users of a building.
How the heat loss of a house created
A closed space heated radiates heat to the colder environment around him. Simultaneously, the heat escapes from the casing defects. These losses must be treated in various ways insulation. Beware that by blocking cracks and reducing unintentional air infiltration should not prevent the necessary ventilation of the house. For the health of users, it is necessary to renew the air inside a house.
A proper thermal insulation requires approximately 2-5% of the original building construction cost can save up to 50% of the heating operation costs.
Advantages and disadvantages of different insulation techniques
The walls can be insulated with four main techniques:
A) From the inside part thereof.
In this case the insulating material is placed on the side of the interior and is protected by a solid structural material that operates as the coating.This method of insulation has the following results:
- It has limited construction time
- It is a cheaper solution than the external insulation
- No particular protection of insulation from external influences.
- It has simple construction
- Heated very quickly the site
- The structure can be made independently of the outside weather conditions.
The thermal insulation of the walls from the inside has the following drawbacks:
- Limited internal space
- The space is cooled very quickly. Gather dust the heat capacity of the outer wall.
- It solved the problem of thermal bridges.
- The structural elements at risk of contraction and expansion due to temperature changes. Danger of cracking and rainwater inflow.
- There is little problem in arranging the electrical installation.
B) From the outside the place
In this case the insulation is placed on the outside of the wall. With this construction the following advantages appear:
- The area retains heat after stopping the heating by the heat capacity of the walls.
- Especially in the southern areas of the buildings kept the heat from the solar heat gain is stored because the heavy interior walls.
- Not prevent the smooth operation of the interior during the construction of the internal insulation.
- It reduced usable living space.
- The outer surfaces of the walls protected by the contractions and expansions.
- Ensure coverage of thermal bridges especially on concrete slabs on the beams and columns.
The disadvantages of this technique are:
- The construction of the outer insulation is more expensive than in the thermal insulation of the inner side wall.
- It is not very easy to application of external insulation where the walls have many architectural projections.
- There inapplicability of external insulation in buildings with strong external morphological interesting facets.
- Scaffolding required for the construction work in high-rise buildings.
- You need special protection of materials of various layers for protection from external weather influences.
C) Insulation using special bricks.
In this case the wall is built with special insulating bricks with their construction, their shape, size, etc. Should ensure the thermal permeability coefficient K values imposed by thermal regulation. If required to increase the coefficient insulating added in some cases are inherently embedded in the heat insulating brick. This construction presents many advantages but should be ensured by proper construction of coatings proper tightness as not to moisten the mass of insulating bricks.
D) Thermal insulation in the core between two walls.
Is insulation installation method used much in our country. Usually the insulating material is placed between two rotors walls and this is probably the main drawback of the method. ie ensure the insulation, but it is certainly sufficient to ensure the static strength of the system and particularly the strength required by the seismic regulation. The construction of this type of insulation can be improved even if generated in the worst case thermal bridges of the construction of the cement rings.
Properties of insulating materials
The thermal conductivity coefficient is not a fixed size, but a linear function which increases with temperature. Usually, characterized by an average value. The thermal conductivity is adversely affected by moisture, which is easily explained if we consider that the thermal conductivity of water is 0,57 W / mk, i.e. much greater than that of the stationary, dry air. The values of thermal conductivity coefficients provided by various companies usually apply with a tolerance of 5 to 10% depending on the type of material. This increase takes into account measurement errors and unevenness of most insulating. In practice, construction, thermal insulation materials absorb moisture than using vapor barrier. Also due to their properties and method of manufacturing the more insulating materials deteriorate due to mechanical interdependencies and temperature changes. Thus altering the original balance of solid and gaseous components. Despite the research done in this area, the aging mechanisms of thermal insulation materials remain big unknown. What is certain is that the thermal conductivity coefficient always increasing and never decreases.
The resistance factor to water vapor diffusion (m):
As already mentioned thermal insulation materials must be and remain dry. This is most easily achieved larger resistance exhibits a material in water vapor permeation and defined by the dimensionless coefficient of resistance to water vapor diffusion s. This rate is relative dimensionless and gives whether greater the resistance to vapor diffusion a layer of the material relative to the a thickness of air layer. So the smaller is the coefficient, the more sensitive is a material moisture.
The mechanical strength required for a structure determines the insulation system to be used. Thus, materials with high mechanical strength can be used as self-supporting, but a lower resistance may be placed in a carrier matrix and other very small as fillers. The compressive strength is a key size on heat insulation of floors. It should be noted that in many cases it is useful and knowledge of intermediary deformation until rupture of some charges, which do not damage the material, but they can create excessive strain on alleged evidence or investments. In many cases they need information about the strength of the material in bending or tensile. This is especially needed in internal thermal insulation of floors with large openings or self-supporting structures are strained by the weather.
The dimensional stability:
In thermal insulation board made by thermal processes can change the nominal dimensions in the cooling step and the situation deteriorate due to aging. This can be avoided by artificial aging during the production phase in order to stabilize dimensions. Large temperature changes result in an appreciable linear shrinkage in all solid insulation materials. Finally some insulating materials have large expansion coefficients, which must take account of the manufacturer when fitting. Still need to be checked and the tolerances may have the dimensions to control their behavior.
Resistance to fire:
The behavior of thermal insulation materials in the fire may have an immediate economic impact. Overall, despite the increased costs, increasingly used thermal insulating materials which do not ignite or at least difficult to ignite or moderate. Generally the best behavior to fire foam glass, fibrous materials, perlite etc.
The specific gravity:
The specific gravity is further useful property because even in the same class of materials can a lighter material have poorer thermal insulation properties than heavier because it is larger and denser cells.
The ecological insulating materials
First ecological considered those thermal insulation materials, covering the following:
a) They do not require much energy to produce them.
b) they are recyclable
c) Do not pollute the environment during their production.
d) contain toxic / carcinogenic pollutants dangerous to human health and do not emit such pollutants during their implementation and to their destruction.
Thermal insulation materials can be found in the Greek market
1) Extruded polystyrene
- from non-renewable energy source (hydrocarbons)
- Gray energy (energy of the output) 450 KWh / m3, to 850 KWh / m3
- Contamination: Leakage of toxic volatile gases in the environment, such as CFCs (chlorofluorocarbons) and pentane (deplete the ozone layer and enhance the greenhouse.
- Health effects: Escape styrene in the atmosphere (neurotoxic substance implicated in carcinogenesis). In case of fire, produce toxic brominated gases, because of the substances contained in fire retardation. Develop strong electrostatic fields. No possibility of transpiration of the building.
- from non-renewable energy source.
- Gray energy: 1.000 KWh / m3 up to 1.200 KWh / m3
- The HCFC which replaced the CFC also implicated in the destruction of the ozone layer
- Health effects: The isocyanates derived from a complex manufacturing process based on chlorine, release into the environment (interior and exterior of the building) amines, substances particularly dangerous for people. If no fire produced cyano, terrible substance toxic.
- No possibility of transpiration of the building.
3) Glass wool / rock wool
- Non-renewable (except glass) but come from abundant materials in nature (sand, basalt, etc.).
- Gray energy: 150 KWh / m3 to 250 KWh / m3.
- Primary infection: Only production units (because of the CO2 carbon dioxide) and during transport.
- Health effects: The I.A.R.C. (International Center for Cancer Research) under the World Health Organization classifies the potentially carcinogenic materials !! that affect humans through the respiratory tract. Unlike asbestos fibers, the fibers of these materials are not segregated in their length, but any break in the mass under I.A.R.C. their hazard lies in their dimensions (length greater than 5 micron and a diameter less than 3 micron.
In Germany banned their use in public buildings and smaller works are allowed only when completely sealed !!
The I.A.R.C. also points to the risk of respiratory infections, laryngitis, pharyngitis, etc. in countries where these materials are applied.
Moreover, the binders used and are based on formalin urea, releasing large amounts of toxic formaldehyde.
- Non-renewable source, but with high availability in nature.
- Gray power: 230 KWh / m3
- Partial recycling.
- Health effects: Perlite (volcanic origin), does not release toxic substances during use.
- But be careful in its usage in complex structures with silicones and polyurethane !!
- Also in case of fire does not release toxic gases.
- General proposed as a good heat insulator.
5) Eraklit (Heraklith)
- Acceptable material
- Renewable in this wood wool, less for the magnesite.
- Gray energy: Requires less (but still adequate) energy production, less however, other materials.
- Important that Greece is a country of magnesium producer !!
- Easily recyclable.
- Health Effects: All materials which belongs the Eraklit present no problems for the health of residents of a building. They burned difficult fire and do not release toxic substances. Show little, but conductivity in electric fields due to the cement (which is why I insist on proper earthing of concrete reinforcement).
In Europe there are 3 Materials: the Heraklith, the Fibralith, and the Eco-lith. In Greece we have unfortunately only the first
5) The expanded cork
- Renewable source.
- Gray energy: Low energy consumption for the production of 80 up 90 KWh / m3
- Recyclable, 100%.
- Health effects: Absolutely friendly and healthy. But be careful because some manufacturers use during placement, synthetic glues containing formaldehyde !! Therefore always seek certificates in accordance with the relevant European Union regulations.
- Unfortunately far more expensive than other materials. (Always, I wondered, why Greece does not promote a policy of planting fellodendron, which belong to Portugal today of quertus - Oaks family. Produces 70% of EU needs ...)
Having worked several years in France and having design buildings and in Switzerland and Northern Italy, always wondering why in Greece can not find these exquisite and ecological thermal insulating materials, which can be easily found in all other European countries :
2) Roller coconut fibers
3) Insulating roll of cotton residues (ISO COTTON formula)
4) Matting (sheets and strip), and finally
5) Expanded (granular) Clay
All five above materials, cost little, are 100% recyclable, and 100% environmentally friendly and human. Also, Greece has and flax and cotton and clay. but it does not yet have the appropriate market and even worse the opinion makers Greek engineers ignore, even tragic dimension of ecology in the materials used in their construction ...
Our partner K. Tsipiras Civil Engineering