Heat insulator

In Thermal, a thermal Isolant is a material having weak a thermal Conductivité.
Il makes it possible to ensure good a Thermo isolation by avoiding the escapes of heat (cooling) or the entry of heat (“guard with the expenses”). A very powerful thermo isolation results in the absence of bridge thermics and the use of a thick insulator (up to 40 cm in the cold countries). The thermo isolation is one of investment of the most profitable energy saving, in particular in the new building. Houses positive in energy are thus built, which do not require any more a boiler and produce more electricity that they do not consume any.

Principal heat insulators

The principal heat insulators used for the insulation of the walls and supports are, by order ascending of thermal conductivity:

the foam of Polyurethane: excel insulator, expensive, it is less stable in time than its competitors,
the Glass wool: good market, stable, irritating for the skin during the installation, it is proposed in panels or rollers,
the Rockwool: similar to glass wool but less unpleasant to pose, it does not melt in contact with the flame.
foams of Polymeric:

expanded Polystyrene: it has the advantages of polymers and the air ; light, rigid, fragile, easy with découper , it must be protected from the rodents, does not require vapor barrier. Exist in incompressible plates for the insulation of the floating flagstones.
extruded polystyrene (Styrodur)

the Depron 6 mm (also exists in plates of 3mm).
the fiber of Wood - less good insulator than the precedents but cheaper and more ecological, used in bulk and faggot between two partitions.
the Wool of Sheep
the Straw
the Hemp, concrete of hemp, the Brick of hemp
Wadding of cellulose
Polymeric S: plastic, rubber…
the Air imprisoned: in wire of a clothing, not woven fibers, feathers or hairs of an animal, a double glazing…
the vacuum between two walls: dewar (principle of the bottle Thermos flask).

For the applications at high temperatures, one uses in general insulators Céramique S.

One finds in the trade various products (not always new) presented like having thermal resistances much higher than insulators listed above. Their effectiveness or durablility is generally not proven, for a very high price often.

Insulation, and inertia…

The insulation of a building must be under consideration via

its coefficient of insulation ,
its thermal dephasing ; i.e. capacity of component materials the envelope of the dwelling to slow down the changes of temperature (thermal, useful Inertia for example to store solar calories the day and to redistribute them slowly the night).

Cette inertia is in connection with the mass of materials.
Elle exists even for glass wool, which with high density will have an inertia larger than with low density. What could be more logical in theory but let us think there during the construction or of the restoration of a dwelling (except habitat Bioclimatique which strongly develops thermal inertia). As regards the walls, inertia in general poses less problem (especially in the case of an insulation by the external one) that in the case of the insulation of the roofs. For the roofs, as the cover slows down only little the transfer of heat, the inertia of insulating materials is consequently much more important. There financially exist simple and accessible alternatives which are in particular based on insufflated cellulose (must be placed by a professional to avoid any cold bridge) which allows dephasings of ten hour, sufficiently to ensure a very good thermal comfort in summer, contrary to rock or glass wool low density which does not avoid an overheating of the roofs in summer…

Thermo isolation for the building

For the building, here some equivalences:

Seek and prospective

Research is very active in the field of architecture Bioclimatique, HQE and of écomatériaux (bricks monomurs. insulating concretes using of natural and renewable materials, materials with strong thermal inertia, insulation by outside.), although profiting only from little of public subsidies.
Côté industrial one succeeded in producing solid insulating slabs and of big size (walls and industrial roofs of hangards) but difficult to recycle and whose insulators can pose problem for the environment or of toxicity in the event of fire.
On seeks by scoffers with to reduce the thickness of insulators by means of strategies or new technological materials.
On seeks for example to imitate the insulating capacities of furs or plumages of animals, or to reduce the air or gas insulating by imprisoning it better in a material nanoporeux and insulating, so as to trap the air or a gas even less conducting, in cavities smaller than that allowing one its freedom of movement (openings between pores lower than 70 nanometers if it sagit of air). These materials are sometimes fragile or sensible to moisture (microcapillarity). One tests powders of Silice. The Aérogel S form exceptional insulators, but still too fragile.

In particular nanostructurés insulators and preserving a air space are being studied, others are filled up rare gases thermically more neutral than the air. An intermediate solution consists in trapping a gas with low pressure in nanoporeux materials. But these materials are still recent products or laboratories, do not profit yet from a sufficient experience feedback to guarantee their durability. Their écobilans also requires to be thorough and compared with those of other more traditional insulators.

The industrial insulator manufacturers also seek to make their materials less harmful for the environment. Thus CFC formerly used (HFC, HFA) in certain insulating foams (polyurethans) could be replaced by pentane little by little, even of CO2, like krypton and argon started to replace the air of the double glazings, whose coefficient of insulation can be still reinforced by replacing them by triple or quadruple glazings, whose glasses can not be completely parallel (better soundproofing). Rigid glazings and panels where the air is replaced by vacuum or quasi-vacuum are tested, but one is unaware of still their capacity to maintain this vacuum with the long-term.

Research also progressed in the insulation of the great colds and as regards substitutes to asbestos against the very high temperatures, with for example of the walls of (Vermiculite drowned in a binder, mineral fibers, of which mono or multi-layer fabrics insulating, using silica fiber felt aiguilleté in sandwich between layers of silica fabric), protecting effectively against from the temperatures of more than 1000°C.

See too

thermal Conductivity
energy Efficiency
Minergie
Écomatériaux, HQE (environmental high-quality)

External bonds

''' VitrageVir ''' - the site of the Glazing with Reinforced Insulation

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