Les solutions chanvre pour le bâtiment / Building solutions with hemp

Technical vocuabulary
Please find below definitions of specific terms used in our website :

Life-cycle assessment

Life-cycle assessment (LCA, also known as life-cycle analysis, ecobalance, and cradle-to-grave analysis) is a technique to assess environmental impacts associated with all the stages of a product’s life from-cradle-to-grave (i.e., from raw material extraction through materials processing, manufacture, distribution, use, repair and maintenance, and disposal or recycling). LCAs can help avoid a narrow outlook on environmental concerns by:
Compiling an inventory of relevant energy and material inputs and environmental releases;
Evaluating the potential impacts associated with identified inputs and releases;
Interpreting the results to help make a more informed decision.


Acoustic absorption (α w)

Acoustic absorption refers to a material, structure or object absorbing sound energy when sound waves collide with it, as opposed to reflecting the energy. Part of the absorbed energy is transformed into heat and part is transmitted. The energy transformed into heat is said to have been ‘lost’. This figure is from 0 to 1. Close to 1, it is more efficient.


Sound reduction (Rw )

The effectiveness, measured in decibels, that a building assembly exhibits at lessening the intensity of sound. A measure of the sound-insulation value of a partition; the amount, in decibels, by which the intensity of sound is reduced in transmission through the partition.


Wooden cladding

Wooden slats wich covers a front house. The cladding can be horizontal or vertical, bout it is more often horizontal, with 3 types of implementation : recovering, overlapping, and dimpling (by a tongue and groove connection).


shingles

(or “tavaillons”) Small strips of wood used for cladding or roof. With a thickness of 0,5 cm approximately, they are arranged as slate tiles that covers roofs to let the water running and are fixed using steel nails or screws.


whitewash reinforced with hydrated lime

Paint with diluted lime used for inside and outside wall coatings.


Thermal capacity

Heat capacity, or thermal capacity, is the measurable physical quantity of heat energy required to change the temperature of an object or body by a given amount. The SI unit of heat capacity is joule per kelvin, J/K and the dimensional form is M1L2T−2Θ−1.


Specific thermal capacity

Heat capacity is an extensive property of matter, meaning it is proportional to the size of the system. When expressing the same phenomenon as an intensive property, the heat capacity is divided by the amount of substance, mass, or volume, so that the quantity is independent of the size or extent of the sample. The molar heat capacity is the heat capacity per mole of a pure substance and the specific heat capacity, often simply called specific heat, is the heat capacity per unit mass of a material. Occasionally, in engineering contexts, the volumetric heat capacity is used.


Specific heat

specific heat, is the heat capacity per unit mass of a material. Occasionally, in engineering contexts, the volumetric heat capacity is used. Unité : J/kg.°C


hemp set in a wood frame

Pouring of Mix of wood of hemp and a lime bounder between forms (modern technology). A wooden framework is needed to hold the structure.


lime

Lime is obtained by calcination of (controlled heating-time and temperature) limestone at temperatures above 900oC.to 1300oC. This highly reactive Calcined Lime are essential to many industrial processes.


Chaux aérienne

non-hydraulic limes need air to carbonatate and set. A non-hydraulic lime is produced from high purity calcium lime stones. It is used for finishes.


Lime NHL

European abréviation of natural hydraulic lime (“Natural Hydraulic Lime”).


“Chènevis”

Oilseeds of hemp.


“Chènevotte” or hemp wood, or hurd

Cellulose in the central part on the hemp stem wich is mechanychely separated from fibers mechanically.These aggregates are used for hemp mortars.


Thermal conductivity ( λ )

thermal conductivity (often denoted k, λ, or κ) is the property of a material to conduct heat. It is evaluated primarily in terms of Fourier’s Law for heat conduction.
Heat transfer occurs at a higher rate across materials of high thermal conductivity than across materials of low thermal conductivity. Correspondingly materials of high thermal conductivity are widely used in heat sink applications and materials of low thermal conductivity are used as thermal insulation. Thermal conductivity of materials is temperature dependent. The reciprocal of thermal conductivity is called thermal resistivity. Insulation products have λ close to: 0,06 W/mK.


THC checking

A Dedicated organisation checks 30% of hemp field in France. They collect the 30 highest centimeters of the plant within 50 different types of plants. Samples shall be analysed by recognised laboratories .


Thermal phase shift

The phase shift is the interval between the appearance of the highest temperature on the external surface of a component until the highest temperature is reached on the inside. It depends on the heat storage capacity of the building material. A high characteristic value > 12 hours is important for the summertime thermal insulation, a rapid breakthrough of the high temperatures being thus prevented..


Thermal diffusivity

In heat transfer analysis, thermal diffusivity (usually denoted α but a, κ, and D are also used) is the thermal conductivity divided by density and specific heat capacity at constant pressure.It measures the ability of a material to conduct thermal energy relative to its ability to store thermal energy. It has the SI unit of m²/s. or Unity : m²/h


D.T.U

Unified technical files. “DTU are all specifications for works, reference materials for building activities.” (source CSTB)


Eco-building or green building

Green building (also known as green construction or sustainable building) refers to a structure and using process that is environmentally responsible and resource-efficient throughout a building’s life-cycle: from siting to design, construction, operation, maintenance, renovation, and demolition. This requires close cooperation of the design team, the architects, the engineers, and the client at all project stages.The Green Building practice expands and complements the classical building design concerns of economy, utility, durability, and comfort.


impact noises insulation ( Δ Lw)

Sound generated by impact and carried through a structure; typically, footsteps, the slamming of a door.(in Decibels).contre les bruits d’impact) Il est exprimé en décibels (dB).The higher is Δ Lw the stronger is the insulation performance.The degree of effective reduction of impact noise transmission accomplished by the structures and materials designed and used specifically for that purpose


Grey energy

Grey energy is the energy hidden in a product, i.e. the amount of energy required to extract that product from nature, or to cultivate, manufacture, package and transport it. Objects can conceal very different levels of grey energy: for example an apple that is grown locally or one that is shipped from from New Zealand to Europe. (in kWh).


“Entraxe”

distance between the centres of two objects at any given time during measuring.


water vapour diffusion resistance facto µ

The water vapour diffusion resistance factor µ is obtained by dividing the water vapour diffusion coefficient in air, by the moisture permeability of a porous material. The values will be related to the different driving mechanisms that are used to consider the water vapour transmission through the porous material, which may be either humidity by volume or partial pressure of water vapour. The values measured will also be dependent upon temperature. The water vapour resistance factor, commonly called µ-factor, is therefore a dimensionless number describing how many times better a material or product is at resisting the passage of water vapour, compared with an equivalent thickness of air.Thus high µ-factor = high resistance to water vapour transmission.
The most common µ for building material are put in writing in “DIN 4108-4”.


Fiber

peripheral wall portion of hemp stem, it represents from 25 to 33% of plant weight.


Log houses

Log houses are made by hand, from carefully selected resinous trees and they are especially spectacular, due to their rustic appearance and to the massiveness of their structure..


“Hérisson”

(ou “hérissonnage”) a bed of clean crushed stone under a concrète slab. Stop capillary rise from footings to foundation wall.


HEP

high energy performance buildings is a rank for building that is energy-efficient, healthy, and comfortable for its occupants.


HQE

The Haute Qualité Environnementale or HQE (High Quality Environmental standard) is a standard for green building in France, based on the principles of sustainable development first set out at the 1992 Earth Summit. The standard is controlled by the Paris based Association pour la Haute Qualité Environnementale (ASSOHQE).The standard specifies criteria for the following:
Managing the impacts on the outdoor environment,Harmonious relationship between buildings and their immediate environment,Integrated choice of construction methods and materials,The avoidance of nuisance by the construction site.,Minimizing energy use,Minimizing water use,Minimizing waste in operations,Minimizing building maintenance and repair,Creating a pleasant indoor environment,Hydrothermal control measures,Acoustic control measures,Visual attractiveness,Measures to control smells,Hygiene and cleanliness of the indoor spaces, Air quality controls
Water quality controls.


hydrophobicity

hydrophobicity (from the Attic Greek hydro, meaning water, and phobos, meaning fear) is the physical property of a molecule (known as a hydrophobe) that is repelled from a mass of water.


Thermal inertia

Thermal inertia is a term commonly used by scientists and engineers modelling heat transfers and is a bulk material property related to thermal conductivity and volumetric heat capacity. For example, this material has a high thermal inertia, or thermal inertia plays an important role in this system, which means that dynamic effects are prevalent in a model, so that a steady-state calculation will yield inaccurate results. The thermal inertia of a material is defined as the square root of the product of the material’s bulk thermal conductivity and volumetric heat capacity, where the latter is the product of density and specific heat capacity.


Intrants

in Agricultural Economics, nutritive elements coming from outside.


Acoustic insulation

Soundproofing is any means of reducing the sound pressure with respect to a specified sound source and receptor. There are several basic approaches to reducing sound: increasing the distance between source and receiver, using noise barriers to reflect or absorb the energy of the sound waves, using damping structures such as sound baffles, or using active antinoise sound generators.


Thermal insulation

Thermal insulation is the reduction of heat transfer (the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with specially engineered methods or processes, as well as with suitable object shapes and materials.


Accoustic attenuation

Acoustic attenuation is a measure of the energy loss of sound propagation in media. Most media have viscosity, and are therefore not ideal media. When sound propagates in such media, there is always thermal consumption of energy caused by viscosity. For inhomogeneous media, besides media viscosity, acoustic scattering is another main reason for removal of acoustic energy. Acoustic attenuation in a lossy medium plays important role in many scientific researches and engineering fields, such as medical ultrasonography, vibration and noise reduction.(In Db). The current rule is 53 dB between two new buildings.


CE markin

The concept of CE marking for all construction products and steel products is introduced by the Construction Products Directive (CPD). The CPD is a European Directive that ensures the free movement of all construction products within the European Union. (source CSTB)


M.O.B

Abreviation of a wooden framework home. A global wooden framework, with floor support beams with insulating material between them (hemp wool, hemp mortar and lime or hemp bricks…). This framework is associated with a cladding and coating outside.


rainscreen or raincap

A rainscreen is the exterior weather-facing surface of an exterior wall detail that stands off from the moisture-resistant surface of the main exterior wall. The rainscreen is the first interruption between conditions that exist on the outside of a walled building and conditions that are required on the inside of a walled building.A veneer that does not stand off from the moisture-resistant surface of the structural backup wall to create a cavity is not a true rainscreen. However, a masonry veneer can be a rainscreen.
In a rainscreen the air gap allows the circulation of air across the air (or weather) barrier. (These may or not also serve as a vapour barrier, which can be installed on the interior or exterior side of the insulation depending on the climate). This helps helps direct water away from the main exterior wall which in many climates is insulated. Keeping the insulation dry helps prevent problems such as mold formation and water leakage. The vapour-permeable air/weather barrier prevents water molecules from entering the insulated cavity but allows the passage of vapour, thus reducing the trapping of moisture within the main wall assembly.


energy efficiency of a building

Green buildings often include measures to reduce energy consumption – both the embodied energy required to extract, process, transport and install building materials and operating energy to provide services such as heating and power for equipment.


Moisture vapor transmission rate

Moisture vapor transmission rate (MVTR), also water vapor transmission rate (WVTR), is a measure of the passage of water vapor through a substance.
There are many industries where moisture control is critical. Moisture sensitive foods and pharmaceuticals are put in packaging with controlled MVTR to achieve the required quality, safety, and shelf life. In clothing, MVTR as a measure of breathability has contributed to greater comfort for wearers of clothing for outdoor activity. The building materials industry also manages the moisture barrier properties in architectural components to ensure the correct moisture levels in the internal spaces of buildings.Unity : g/m2.h.mm/Hg


Breathability

Breathability is the ability of a fabric to allow moisture vapor to be transmitted through the materi.


Insulation product performance

During winter, conductivité of the insulation product (lambda λ) is the most important criteria. If the conductivity is weak, the insulation product is efficient. The thermal résistance R depends on the wall tickness . During summer, it is important to keep theat oustide of the building. That’s why, you have to choose a material with a high thermal capacity to let the heat outside the house as longest as possible. (cf. thermal phase shift)


Dew point

The dew point is the temperature below which the water vapor in air at constant barometric pressure condenses into liquid water at the same rate at which it evaporates. The condensed water is called dew when it forms on a solid surface.
The dew point is a water-to-air saturation temperature. The dew point is associated with relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. Relative humidity of 100% indicates the dew point is equal to the current temperature and that the air is maximally saturated with water. When the moisture content remains constant and temperature increases, relative humidity decreases.


Post&Beam

A Post&Beam structure for building is for those who enjoy a large amount of living space but would like it all on one floor.The construction general principle is based on a post-beam framework, with the walls acting as a filling element, what leaves great freedom to the carpentry design and to the indoor separating elements. Comprising of vertical posts supporting horizontal beams; another term for this is ‘trabeated’.


Thermal resistance (R)

Thermal resistance is a heat property and a measurement of a temperature difference by which an object or material resists a heat flow (heat per time unit or thermal resistance). Thermal resistance is the reciprocal of thermal conductance.
Thermal resistance R has the units (m2K)/W..


“Rondin”

Cutting trees with the highest value and leaving those with lower value, often diseased or malformed trees, is referred to as high grading. It is sometimes called selective logging, and confused with selection cutting, the practice of managing stands by harvesting a proportion of trees.hr][/hr]

“Rouissage”

Phenomenon allowing to remove gummy substance (pectine) from textile fibers.


RT

For 30 years, thermal insulation is regulated within a global rule (RT), wich is aim to reduce the french dependence on imported energy.(with a decrease of energy consumption. After the current RT 2005 , RT2010 is ongoing.


Thermal break

Insulation around a bridge is of little help in preventing heat loss or gain due to thermal bridging; the bridging has to be eliminated, rebuilt with a reduced cross-section or with materials that have better insulating properties, or with a section of material with low thermal conductivity installed between metal components to retard the passage of heat through a wall or window assembly, called a thermal break.


SCOP

A SCOP, A cooperative (“coop”) or co-operative (“co-op”) is an autonomous association of persons who voluntarily cooperate for their mutual, social, economic, and cultural benefit.Cooperatives include non-profit community organizations and businesses that are owned and managed by the people who use its services (a consumer cooperative) or by the people who work there (a worker cooperative) or by the people who live there (a housing cooperative), hybrids such as worker cooperatives that are also consumer cooperatives or credit unions, multi-stakeholder cooperatives such as those that bring together civil society and local actors to deliver community needs, and second and third tier cooperatives whose members are other cooperatives.For more informations : http://www.scop.coop


THC

TétraHydroCannabinol, is the principal psychoactive constituent (or cannabinoid) of the cannabis plant.


Green roof

A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainage and irrigation systems. Container gardens on roofs, where plants are maintained in pots, are not generally considered to be true green roofs, although this is debated. Rooftop ponds are another form of green roofs which are used to treat greywater.
Green roofs serve several purposes for a building, such as absorbing rainwater, providing insulation, creating a habitat for wildlife, and helping to lower urban air temperatures and mitigate the heat island effect. There are two types of green roofs: intensive roofs, which are thicker and can support a wider variety of plants but are heavier and require more maintenance, and extensive roofs, which are covered in a light layer of vegetation and are lighter than an intensive green roof..


authorised primary processor

For the purposes, ‘authorised primary processor’ shall mean a natural or legal person or a group of natural or legal persons, irrespective of its legal status under national law, or that of its members, that has been authorised by the competent authority of the member state in territory of wich its facilities for producing hemp fibers are located. The agreement should be based on an audit programme adopted by the committee wich consider that the “authorised primary processor” have skills in order to guarantee the traceability of the hemp. Its counterpart funds is 90 euros per each tone of pure hemp fiber. (From “Sylvestre Bertucelli, 2006, Réglementation de la culture du chanvre dans “Le chanvre industriel : production et utilisations”, éditions France Agricole).