Building insulation

Building insulation

Overview

building insulation refers broadly to any object in a building used as insulation for any purpose. While the majority of insulation in buildings is for thermal
Thermal insulation
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...

 purposes, the term also applies to acoustic insulation, fire insulation
Fireproofing
Fireproofing, a passive fire protection measure, refers to the act of making materials or structures more resistant to fire, or to those materials themselves, or the act of applying such materials. Applying a certification listed fireproofing system to certain structures allows these to have a...

, and impact insulation
Cushioning
Package cushioning is used to help protect fragile items during shipment. It is common for a transport package to be dropped, kicked, and impacted: These events may produce potentially damaging shocks. Transportation vibration from conveyors, trucks, railroads, or aircraft can also damage some...

 (e.g. for vibrations caused by industrial applications). Often an insulation material
Building insulation materials
Building insulation materials are thermal insulation used in the construction or retrofit of buildings.The materials are used to reduce heat transfer by conduction, radiation or convection and are employed in varying combinations to achieve the desired outcome .-Categories:Insulation may be...

 will be chosen for its ability to perform several of these functions at once.

Thermal insulation
Thermal insulation
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...

 in buildings is an important factor to achieving thermal comfort
Thermal comfort
Thermal comfort is a term used by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, an international body. It is defined as the state of mind in humans that expresses satisfaction with the surrounding environment...

 for its occupants.
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Encyclopedia

building insulation refers broadly to any object in a building used as insulation for any purpose. While the majority of insulation in buildings is for thermal
Thermal insulation
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...

 purposes, the term also applies to acoustic insulation, fire insulation
Fireproofing
Fireproofing, a passive fire protection measure, refers to the act of making materials or structures more resistant to fire, or to those materials themselves, or the act of applying such materials. Applying a certification listed fireproofing system to certain structures allows these to have a...

, and impact insulation
Cushioning
Package cushioning is used to help protect fragile items during shipment. It is common for a transport package to be dropped, kicked, and impacted: These events may produce potentially damaging shocks. Transportation vibration from conveyors, trucks, railroads, or aircraft can also damage some...

 (e.g. for vibrations caused by industrial applications). Often an insulation material
Building insulation materials
Building insulation materials are thermal insulation used in the construction or retrofit of buildings.The materials are used to reduce heat transfer by conduction, radiation or convection and are employed in varying combinations to achieve the desired outcome .-Categories:Insulation may be...

 will be chosen for its ability to perform several of these functions at once.

Thermal Insulation


Thermal insulation
Thermal insulation
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...

 in buildings is an important factor to achieving thermal comfort
Thermal comfort
Thermal comfort is a term used by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, an international body. It is defined as the state of mind in humans that expresses satisfaction with the surrounding environment...

 for its occupants. Insulation reduces unwanted heat loss or gain and can decrease the energy demands of heating and cooling systems
HVAC
HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...

. It does not necessarily deal with issues of adequate ventilation
Ventilation (architecture)
Ventilating is the process of "changing" or replacing air in any space to provide high indoor air quality...

 and may or may not affect the level of sound insulation. In a narrow sense insulation can just refer to the insulation materials
Building insulation materials
Building insulation materials are thermal insulation used in the construction or retrofit of buildings.The materials are used to reduce heat transfer by conduction, radiation or convection and are employed in varying combinations to achieve the desired outcome .-Categories:Insulation may be...

 employed to slow heat loss, such as: cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....

, glass wool
Glass wool
Glass wool or fiberglass insulation is an insulating material made from fiberglass, arranged into a texture similar to wool. Glass wool is produced in rolls or in slabs, with different thermal and mechanical properties....

, rock wool, polystyrene
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...

, urethane foam
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...

, vermiculite
Vermiculite
Vermiculite is a natural mineral that expands with the application of heat. The expansion process is called exfoliation and it is routinely accomplished in purpose-designed commercial furnaces. Vermiculite is formed by weathering or hydrothermal alteration of biotite or phlogopite...

, perlite, wood fibre, plant fibre (canabis, flax, cotton, cork, etc.), plant straw, animal fibre (sheeps wool), cement, and earth or soil, but it can also involve a range of designs and techniques to address the main modes of heat transfer - conduction, radiation and convection materials.

The effectiveness of insulation is commonly evaluated by its R-value
R-value (insulation)
The R-value is a measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux through it or R = \Delta T/\dot Q_A.The R-value being discussed is the unit thermal resistance...

. However, an R-value does not take into account the quality of construction or local environmental factors for each building. Construction quality issues include inadequate vapor barriers, and problems with draft-proofing. In addition, the properties and density of the insulation material itself is critical. For example, according to Leah Twings, Quality Compliance Manager of Textrafine Insulation, fiberglass insulation materials made from short strands of glass layered over each other is not as durable as insulation made from long entangled strands of glass

Planning


How much insulation a house should have depends on building design, climate, energy costs, budget, and personal preference. Regional climates make for different requirements. Building code
Building code
A building code, or building control, is a set of rules that specify the minimum acceptable level of safety for constructed objects such as buildings and nonbuilding structures. The main purpose of building codes are to protect public health, safety and general welfare as they relate to the...

s specify only the bare minimum; insulating beyond what code requires is often recommended.

The insulation strategy of a building needs to be based on a careful consideration of the mode of energy transfer and the direction and intensity in which it moves. This may alter throughout the day and from season to season. It is important to choose an appropriate design, the correct combination of materials and building techniques to suit the particular situation.

To determine whether you should add insulation, you first need to find out how much insulation you already have in your home and where. A qualified home energy auditor will include an insulation check as a routine part of a whole-house energy audit
Energy audit
An energy audit is an inspection, survey and analysis of energy flows for energy conservation in a building, process or system to reduce the amount of energy input into the system without negatively affecting the output.-Principle:...

.

In the USA


An initial estimate of insulation needs in the United States can be determined by the US Department of Energy's ZIP code
ZIP Code
ZIP codes are a system of postal codes used by the United States Postal Service since 1963. The term ZIP, an acronym for Zone Improvement Plan, is properly written in capital letters and was chosen to suggest that the mail travels more efficiently, and therefore more quickly, when senders use the...

 insulation calculator.

Russia


In Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

 the luxury of cheap gas has led to poorly insulated overheated and inefficient consumers of energy. The Russian Center for Energy Efficiency found that Russian buildings are either over- or under-heated, often consume up to 50 percent more heat and hot water than needed. Fifty-three percent of all carbon dioxide (CO2) emissions in Russia are produced through heating and generating electricity for buildings. However, Green House Gas (GHG) emissions from the Soviet Bloc are still below their 1990 levels.

Cold climates



In cold conditions, the main aim is to reduce heat flow out of the building. The components of the building envelope - windows, doors, roofs, walls, and air infiltration barriers are all important sources of heat loss; in an otherwise well insulated home, windows will then become an important source of heat transfer.. The resistance to conducted heat loss for standard glazing corresponds to an R-value
R-value (insulation)
The R-value is a measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux through it or R = \Delta T/\dot Q_A.The R-value being discussed is the unit thermal resistance...

 of about 0.17W/m2/Ko (compared to 2-4W/m2/Ko for glasswool batts). Losses can be reduced by good weatherisation, bulk insulation, and minimising the amount of non-insulative (particularly non-solar facing) glazing. Indoor thermal radiation can also be a disadvantage with spectrally selective (low-e, low-emissivity
Low-emissivity
Low emissivity - actually low thermal emissivity - is a quality of a surface that radiates, or emits, low levels of radiant thermal energy. All materials absorb, reflect and emit radiant energy...

) glazing. Some insulated glazing
Insulated glazing
Insulated glazing also known as double glazing are double or triple glass window panes separated by an air or other gas filled space to reduce heat transfer across a part of the building envelope....

 systems can double to triple R values.

Hot climates


In hot conditions, the greatest source of heat energy is solar radiation. This can enter buildings directly through windows or it can heat the building shell to a higher temperature than the ambient, increasing the heat transfer through the building envelope. The Solar Heat Gain Co-efficient (SGHC) (a measure of solar heat transmittance) of standard single glazing can be around 78-85%.. Solar gain can be reduced by adequate shading from the sun, light coloured roofing, spectrally selective (heat-reflective) paints and coatings and various types of insulation
Building insulation materials
Building insulation materials are thermal insulation used in the construction or retrofit of buildings.The materials are used to reduce heat transfer by conduction, radiation or convection and are employed in varying combinations to achieve the desired outcome .-Categories:Insulation may be...

 for the rest of the envelope. Specially coated glazing
Insulated glazing
Insulated glazing also known as double glazing are double or triple glass window panes separated by an air or other gas filled space to reduce heat transfer across a part of the building envelope....

 can reduce SHGC to around 10%. Radiant barrier
Radiant barrier
Radiant barriers or reflective barriers inhibit heat transfer by thermal radiation. Thermal energy may also be transferred via conduction or convection, however, and radiant barriers do not necessarily protect against heat transfer via conduction or convection....

s are highly
effective for attic spaces in hot climates . In this application, they are much more effective in hot climates than cold climates. For downward heat flow, convection is weak and radiation dominates heat transfer across an air space. Radiant barriers must face an adequate air-gap to be effective.

If refrigerative air-conditioning is employed in a hot, humid climate, then it is particularly important to seal the building envelope. Dehumidification of humid air infiltration can waste significant energy. On the other hand, some building designs are based on effective cross-ventilation instead of refrigerative air-conditioning to provide convective cooling from prevailing breezes.

Orientation - Passive Solar Design


Optimal placement of building elements (e.g. windows, doors, heaters) can play a significant role in insulation by considering the impact of solar radiation
Radiant energy
Radiant energy is the energy of electromagnetic waves. The quantity of radiant energy may be calculated by integrating radiant flux with respect to time and, like all forms of energy, its SI unit is the joule. The term is used particularly when radiation is emitted by a source into the...

 on the building and the prevailing breezes. (See Passive Solar Design
Passive solar building design
In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer...

) Reflective laminates can help reduce passive solar heat in pole barns, garages and metal buildings.

Building envelope


The thermal envelope
Building envelope
The building envelope is the physical separator between the interior and the exterior environments of a building. Another emerging term is "Building Enclosure". It serves as the outer shell to help maintain the indoor environment and facilitate its climate control...

 defines the conditioned or living space in a house. The attic or basement may or may not be included in this area. Reducing airflow from inside to outside can help to reduce convective heat transfer significantly .

Ensuring low convective heat transfer also requires attention to building construction (weatherization
Weatherization
Weatherization or weatherproofing is the practice of protecting a building and its interior from the elements, particularly from sunlight, precipitation, and wind, and of modifying a building to reduce energy consumption and optimize energy efficiency.Weatherization is distinct from building...

) and the correct installation of insulative materials.

The less natural airflow into a building, the more mechanical ventilation
Mechanical ventilation
In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...

 will be required to support human comfort. High humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...

 can be a significant issue associated with lack of airflow, causing condensation
Condensation
Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....

, rotting construction materials, and encouraging microbial growth such as mould and bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

. Moisture can also drastically reduce the effectiveness of insulation by creating a thermal bridge (see below). Air exchange
Heat exchange
Heat exchange may refer to:*Heat transfer, an area of engineering concerned with the transfer of thermal energy *Heat exchanger, a device built for heat transfer from one medium to another...

 systems can be actively or passively incorporated to address these problems.

Thermal bridge


Thermal bridges are points in the building envelope that allow heat conduction to occur. Since heat flows through the path of least resistance, thermal bridges can contribute to poor energy performance. A thermal bridge
Thermal bridge
A thermal bridge, also called a cold bridge, is a fundamental of heat transfer where a penetration of the insulation layer by a highly conductive or noninsulating material takes place in the separation between the interior and exterior environments of a building assembly .Thermal...

 is created when materials create a continuous path across a temperature difference, in which the heat flow is not interrupted by thermal insulation. Common building materials that are poor insulators include glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...

 and metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

.

A building design may have limited capacity for insulation in some areas of the structure. A common construction design is based on stud walls, in which thermal bridges are common in wood or steel studs and joist
Joist
A joist, in architecture and engineering, is one of the horizontal supporting members that run from wall to wall, wall to beam, or beam to beam to support a ceiling, roof, or floor. It may be made of wood, steel, or concrete. Typically, a beam is bigger than, and is thus distinguished from, a joist...

s, which are typically fastened
Fastener
A fastener is a hardware device that mechanically joins or affixes two or more objects together.Fasteners can also be used to close a container such as a bag, a box, or an envelope; or they may involve keeping together the sides of an opening of flexible material, attaching a lid to a container,...

 with metal. Notable areas that most commonly lack sufficient insulation are the corners of buildings, and areas where insulation has been removed or displaced to make room for system infrastructure, such as electrical boxes (outlets and light switches), plumbing, fire alarm equipment, etc.

Thermal bridges can also be created by uncoordinated construction, for example by closing off parts of external walls before they are fully insulated.
The existence of inaccessible voids within the wall cavity which are devoid of insulation can be a source of thermal bridging.

Some forms of insulation transfer heat more readily when wet, and can therefore also form a thermal bridge in this state.

The heat conduction can be minimized by any of the following: reducing the cross sectional area of the bridges, increasing the bridge length, or decreasing the number of thermal bridges.

One method of reducing thermal bridge effects is the installation of an insulation board (eg. foam board EPS XPS, wood fibre board, etc) over the exterior outside wall. Another method is using insulated lumber framing for a thermal break inside the wall.

Materials


see Thermal insulation
Thermal insulation
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...

 This topic is all about Thermal and Bulk Insulation

There are essentially two types of building insulation - Bulk Insulation and Reflective Insulation. Most buildings use a combination of both types to make up a total building insulation system. The type of insulation used is matched to create maximum resistance to each of the three forms of building heat transfer - Conduction, Convection, and Radiation.

Conductive and convective insulators ('Bulk insulation')


Bulk insulators block conductive heat transfer and convective flow either into or out of a building. The denser a material is, the better it will conduct heat. Because air has such low density, air is a very poor conductor and therefore makes a good insulator. Insulation to resist conductive heat transfer uses air spaces between fibers, inside foam or plastic bubbles and in building cavities like the attic. This is beneficial in an actively cooled or heated building, but can be a liability in a passively cooled building; adequate provisions for cooling by ventilation or radiation are needed.

Radiant heat barriers



Radiant barriers work in conjunction with an air space to reduce radiant heat transfer across the air space. Radiant or reflective insulation reflects heat instead of either absorbing it or letting it pass through. Radiant barriers are often seen used in reducing downward heat flow, because upward heat flow tends to be dominated by convection. This means that for attics, ceilings, and roofs, they are most effective in hot climates.
They also have a role in reducing heat losses in cool climates. However, much greater insulation can be achieved through the addition of bulk insulators (see above).

Some radiant barriers are spectrally selective and will preferentially reduce the flow of infra-red radiation in comparison to other wavelengths. For instance low-emissivity
Low-emissivity
Low emissivity - actually low thermal emissivity - is a quality of a surface that radiates, or emits, low levels of radiant thermal energy. All materials absorb, reflect and emit radiant energy...

 (low-e) windows will transmit light and short-wave infra-red energy into a building but reflect back the long-wave infra-red radiation generated by interior furnishings. Similarly, special heat-reflective paints are able to reflect more heat than visible light, or vice-versa.

Thermal emissivity values probably best reflect the effectiveness of radiant barriers. Some manufacturers quote an 'equivalent' R-value for these products but these figures can be difficult to interpret, or even misleading, since R-value testing measures total heat loss in a laboratory setting and does not control the type of heat loss responsible for the net result (radiation, conduction, convection).

A film of dirt or moisture can alter the emissivity and hence the performance of radiant barriers.

Installation of insulation


Insulating buildings during construction is much easier than retrofitting, as generally the insulation is hidden, and parts of the building need to be deconstructed to reach them.

See also


  • Thermal insulation
    Thermal insulation
    Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...

  • R-value (insulation)
    R-value (insulation)
    The R-value is a measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux through it or R = \Delta T/\dot Q_A.The R-value being discussed is the unit thermal resistance...

     - includes a list of insulations with R-values
  • Installing building insulation
  • Thermal mass
    Thermal mass
    Thermal mass is a concept in building design which describes how the mass of the building provides "inertia" against temperature fluctuations, sometimes known as the thermal flywheel effect...

  • Eco-friendly Insulation
    Eco-friendly Insulation
    Eco-friendly insulation is a term used for insulating material or methods used as an alternative to regular insulating material derived from petroleum.-Examples of eco-friendly insulation:...



Materials
  • Building insulation materials
    Building insulation materials
    Building insulation materials are thermal insulation used in the construction or retrofit of buildings.The materials are used to reduce heat transfer by conduction, radiation or convection and are employed in varying combinations to achieve the desired outcome .-Categories:Insulation may be...

  • Window insulation film
    Window insulation film
    Window insulation film is a plastic film which can be applied to glass windows to reduce heat transfer. There are two types in common use designed to reduce heat flow via radiation and convection respectively.- Solar control film :...

  • Wool insulation
    Wool insulation
    Wool insulation is made solely from sheep wool fibres that are either mechanically held together or bonded using up to 12% polyester adhesive to form insulating batts, rolls and ropes. Batts are commonly used in timber-frame buildings, rolls for lofts and ropes are primarily used between the logs...

  • Mineral wool
    Mineral wool
    Mineral wool, mineral fibers or man-made mineral fibers are fibers made from natural or synthetic minerals or metal oxides. The latter term is generally used to refer solely to synthetic materials including fiberglass, ceramic fibers and stone wool...

  • Packing (firestopping)
    Packing (firestopping)
    Packing is the process and/or the materials used in filling both service penetrations and building joints with backer materials as approved components within a firestop.-Purpose:...

  • Greensulate
    Greensulate
    Greensulate is a renewable and biodegradable material that can be used for thermal insulation, fire insulation and also as a substitute for styrofoam and other plastics used in packaging and other applications....



Design
  • Cool roof
    Cool roof
    Cool roofs are the roofs that can deliver high solar reflectance and high thermal emittance...

  • Green roof
    Green roof
    A green 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...

  • Passive house
    Passive house
    The term passive house refers to the rigorous, voluntary, Passivhaus standard for energy efficiency in a building, reducing its ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling. A similar standard, MINERGIE-P, is used in...

  • Zero energy building
    Zero energy building
    A zero-energy building, also known as a zero net energy building, Net-Zero Energy Building , or Net Zero Building, is a popular term to describe a building with zero net energy consumption and zero carbon emissions annually. Zero energy buildings can be independent from the energy grid supply...

  • Superinsulation
    Superinsulation
    Superinsulation is an approach to building design, construction, and retrofitting that dramatically reduces heat loss by using much higher levels of insulation and airtightness than normal...

  • Low-energy building
  • Passive solar design
  • Passive solar building design
    Passive solar building design
    In passive solar building design, windows, walls, and floors are made to collect, store, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer...



Construction
  • Building construction
  • Building Envelope
    Building envelope
    The building envelope is the physical separator between the interior and the exterior environments of a building. Another emerging term is "Building Enclosure". It serves as the outer shell to help maintain the indoor environment and facilitate its climate control...

  • Building performance
    Building performance
    Building performance or home performance is a comprehensive whole-house approach to identifying and fixing comfort and energy efficiency problems in a home....

  • Deep energy retrofit
    Deep energy retrofit
    A deep energy retrofit is a building retrofit approach that uses to improve the economics of efficiency and achieve much larger energy savings than conventional energy retrofits. Deep energy retrofits can be applied to both residential and non-residential buildings...

  • Weatherization
    Weatherization
    Weatherization or weatherproofing is the practice of protecting a building and its interior from the elements, particularly from sunlight, precipitation, and wind, and of modifying a building to reduce energy consumption and optimize energy efficiency.Weatherization is distinct from building...



Other
  • Condensation
    Condensation
    Condensation is the change of the physical state of matter from gaseous phase into liquid phase, and is the reverse of vaporization. When the transition happens from the gaseous phase into the solid phase directly, the change is called deposition....

  • HVAC
    HVAC
    HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...

  • ventilation
    Ventilation (architecture)
    Ventilating is the process of "changing" or replacing air in any space to provide high indoor air quality...