Heat And Sound Insulation

HEAT &

S O U N D

INSULATION

ted by : Vishal , Rajesh , Navdeep ,

H E A T

INSULATION

Heat insulation • Thermal insulation is the method of preventing heat from escaping a container or from entering the container. In other words, • thermal insulation can keep an enclosed area such as a building warm, or it can keep the inside of a container cold. • Heat is transferred by from one material to another by conduction, convection and/or radiation. • Insulators are used to minimize that transfer of heat energy.

Applications of thermal insulation • If you have an object or area that is at a certain temperature, you may want to prevent that material from becoming the same temperature as neighboring materials. This is usually done by employing a thermal insulation barrier. • In any location where there are materials of two drastically different temperatures, you may want to provide an insulating barrier to prevent one from becoming the same temperature as the other. In such situations, the effort is to minimize the transfer of heat from one area to another.

Working principal Insulation is a barrier that minimizes the transfer of heat energy from one material to another by:

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• CONDUCTION • CONVECTION • RADIATION 

Insulation from conduction Conduction occurs when materials--especially solids--are in direct contact with each other. High kinetic energy atoms and molecules bump into their neighbors, increasing the neighbor's energy. This increase in energy can flow through materials and from one material to another. 

Solid to solid

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• To slow down the transfer of heat by conduction from one solid to another, materials that are poor conductors are placed in between the solids. Examples include: • Fiberglass is not a good conductor nor is air. That is why bundles of loosely packed fiberglass strands are often used as insulation between the outer and inner walls of a house. • Heat cannot travel though a vacuum. That is why a thermos bottle has an evacuated lining. Heat cannot be transferred from one layer to the other through the thermos bottle vacuum. 

Insulation from conduction Gas to solid

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• To slow down the heat transfer between air and a solid, a poor conductor of heat is placed in between. • A good example of this is placing a layer of clothing between you and the cold outside air in the winter. If the cold air was in contact with your skin, it would lower the skin's temperature. The clothing slows down that heat loss. Also, the clothing prevents body heat from leaving and being lost to the cold air. 

Liquid to solid

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• Likewise, when you swim in water, cold water can lower your body temperature through conduction. That is why some swimmers wear rubber wet suits to insulate them from the cold water.

Insulation from convection • convection is transfer of heat when a fluid is in motion. Since air and water do not readily conduct heat, they often transfer heat (or cold) through their motion. A fan-driven furnace is an example of this. • Insulation from heat transfer by convection is usually done by either preventing the motion of the fluid or protecting from the convection. Wearing protective clothing on a cold, windy day will inhibit the loss of heat due to convection.

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Insulating material • Several different insulation materials may be used at various locations as part of the house envelope, depending on available space, ease of access and other installation requirements. • Most insulation is used to prevent the conduction of heat. In some cases radiation is a factor. • A good insulator is obviously a poor conductor. • A Less dense materials are better insulators. • The denser the material, the closer its atoms are together. That means the transfer of energy of one atom to the next is more effective. • Gases insulate better than liquids, which in turn insulate better than solids. • poor conductors of electricity are also poor heat conductors. • Wood is a much better insulator than copper. • the material--like wood--does not conduct heat well. 

A ir a s a in s u la tin g m a te r • Still air is not a good conductor of heat and can be a relatively good insulator. However, in large spaces such as wall cavities, heat can still be lost across the air space by convection and radiation. Insulation divides the air space into many small pockets of still air; inhibiting heat transfer by convection. At the same time, the insulation material reduces radiation across the space. 

Blan ket s , i n th e f or m o f b a t t s roll s • Blankets, in the form of batts or rolls, are flexible products made from mineral fibers, including fiberglass or rock wool. • They are available in widths suited to standard spacings of wall studs and attic or floor joists. • Batts can be installed by homeowners or professionals. • They are available with or without vapor-retarder facings. They must be hand-cut and trimmed to fit wherever the joist spacing is non-standard (such as near windows, doors, or corners), or where there are obstructions in the walls (such as wires, electrical outlet boxes, or pipes). Batts with a special flame-resistant facing are available in various widths for basement walls where the insulation will be left exposed.

Blown-in loose-fill • Blown-in loose-fill insulation includes cellulose, fiberglass, or rock wool in the form of loose fibers or fiber pellets that are blown using pneumatic equipment, usually by professional installers. • This form of insulation can be used in wall cavities. • It is also appropriate for unfinished attic floors, for irregularly shaped areas, and for filling in around In the open wall cavities of a obstructions.

new house, cellulose and fiberglass fibers can also be sprayed after mixing the fibers with an adhesive or foam to make them resistant to settling.

Foam insulation • Foam insulation can be applied by a professional using special equipment to meter, mix, and spray the foam into place. • Polyisocyanurate and polyurethane foam insulation can be produced in two forms: open-cell and closed-cell. In general, open-celled foam allows water vapor to move through the material more easily than closed-cell foam. 

Rigid insulatio • Rigid insulation is made from fibrous materials or plastic foams and is produced in board-like forms and molded pipe coverings. • These provide full coverage with few heat loss paths and are often able to provide a greater R-value where space is limited. • Such boards may be faced with a reflective foil that reduces heat flow when next to an air space. • Rigid insulation is often used for foundations and as an insulative wall sheathing.

Reflective insulation • Reflective insulation systems are fabricated from aluminum foils with a variety of backings such as kraft paper, plastic film, polyethylene bubbles, or cardboard. • The resistance to heat flow depends on the heat flow direction, and this type of insulation is most effective in reducing downward heat flow. • Reflective systems are typically located between roof . rafters, floor joists, or wall studs

R-value

R-Value

• The R-value of a material is its resistance to heat flow and is an indication of its ability to insulate. It is used as a standard way of telling how good a material will insulate.The higher the R-value, the better the insulation.

Definition

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• The R-value is the reciprocal of the amount of heat energy per area of material per degree difference between the outside and inside. Its units of measurement for R-value are: • (square feet x hour x degree F)/BTU in the English system and • (square meters x degrees C)/watts in the metric system • Table • Insulation for the home has R-values usually in the range of R-10 up to R-30. 

R-value of different material Material

R-value

Hardwood siding (1 in. thick)

0.91

Wood shingles (lapped)

0.87

Brick (4 in. thick)

4.00

Concrete block (filled cores)

1.93

Fiberglass batting (3.5 in. thick)

10.90

Fiberglass batting (6 in. thick)

18.80

Fiberglass board (1 in. thick)

4.35

Cellulose fiber (1 in. thick)

3.70

Flat glass (0.125 in thick)

0.89

Insulating glass (0.25 in space)

1.54

Air space (3.5 in. thick)

1.01

Free stagnant air layer

0.17

Drywall (0.5 in. thick)

0.45

Sheathing (0.5 in. thick)

1.32

I N S U L

A T I O N

SOUND

Sound Insulation • The use of building materials and construction assemblies designed to reduce the transmission of air-born structure-born sound from one room to another or from the exterior to the interior of a building . • the function of sound insulation is the prevention of transmission of sound .

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The role of noise in sound insulation NOISE AND ITS TYPES:

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• Noise is defined as unwanted sound and may be due to frequency of sound or intensity of sound or both. • Noise from their origin point of view is of the following two types.  

OUTDOOR NOISES

• These noise have source of origin outside the room or buildings such as road traffic, railways , airplanes ,lifts , loud speakers ,moving machinery in the neighborhood or in adjacent buildings.  

INDOOR NOISES

• These noise have their source of origin inside the room or building, such as conservation of the occupants ,cisterns, in water closets , working of typewriters, playing of radios, gramophones. 

TRANSMISSION OF sound The role of noise in sound insulation • Any noise whether of outdoor or indoor origin is transmitted through the walls ,frames , ceilings or floors or an enclosure or through air. • The noise is transmitted in the following three ways .

• Through air . • By the vibration of structure members. • Through the structure members. 

Air-borne sound transmission • Sound transmitted when a surface is set into vibration by the alternating air pressure of incident sound waves. • Air borne noises or sound is one which is generated in the air and is transmitted the air directly to the human ear . • This type of sound travels from one part of the building to anther or from outside of the building to inside , through the openings such a door ,window , ventilators , keyholes etc.  

Structure-borne sound transmission • Sound transmitted through the solid media of building’s structure as a result of a direct physical contact of impact. As by vibrating equipment or footstep. • Structure borne noises or sounds are those that originate and progress in the buildings structure. • These sounds or noises may be caused due to structural vibrations due to any activity at around above or below the structure. • The most common sources of this type of sound are foot steps , hammering ,drilling ,operating machinery etc.

Transmission loss • A measure of a performance of a building material or construction assembly in preventing the transmission of airborne sound, equal to the reduction in sound intensity as it passes through the material or assembly when tested at all one -third octave band center frequencies from 125 to 4000 Hz. expressed in decibels

Working principal • The first and foremost way of insulating against air borne noise is to isolate it at source . • The residential building should be properly located in a quiet area away from the noisy surroundings the building should be properly oriented. • The different units of a building should be properly planned. • The provision of furnishing material and living of walls and ceilings by means of air filled materials like felts ,strawboards ,glass wool quilts, coyotes, acoustic etc help to reduce the noise to a great extent . 

Working principal • The transmission of noise by vibration can be prevented by making the walls, floors, partisan very rigid and massive or heavy. • The control of impact sound to some extent is possible by either providing resilient material like carpet ,linoleum ,cock under layers etc. • Structure borne noise or sounds can be prevent by introducing discontinuities in the path of vibrating waves and by sound absorbing materials 

Constructional measures sound insulation • The levels of desired sound insulation for different types of building and between the individual rooms or apartment of a building can be achieved by the following constructional measures of noise control and sound insulation.

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Wall & partitions • These wall construction should act as vertical barriers in the transmission of air borne sound or noise . • To achieve this objective the following methods of wall construction can be adopted depending upon the extent of sound insulation required . • Rigid and massive homogeneous partition • The sound insulation of a partition increases with the increase in its thickness . • But the increase in insulation value of a solid wall construction is slow in proportion to the increase in its thickness. • Hence it is not economical to increase the thickness o a solid wall beyond a certain limit. 

Partition of porous material • The sound insulation increase about 10% higher than the non-porous variety of the same weight due to the absorptive property of the material but partition of flexible porous material, such as felt mineral wool, quilt etc offer very low sound insulation as compared to rigid materials. •

Hollow and composite partition • It is established that a cavity wall or double wall construction is better for sound insulation than a solid wall construction . • A composite partition of cavity wall type construction by filling the cavity or leaving the aie space with some resilient material is best for increasing insulation value or sound proofing rooms . This consist of two leaves of • wall made of light material ,such as metal lath and plaster foreboards,plaster boards ,plywood etc fixed on studs with an air space in between the air space of about 10 to 12 is kept between the leaves of wall and staggered wooden studs are provided as supports.

DOUBLE LEAFED CAVITY WALL,EACH LEAF10CM THICK BRICK MASONARY

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CELOLUX OR ACOUSTEX INSULATING BOARD

INSULATE IN GAP OR GLASS QUILT

CARPET OR LINOLEUM FLOOR FINISH

COKE BREEZE CONCRETE FLOORING

SAND

RCC FLOOR

FOUNDATION WALL

Floor & ceiling • These floors and ceiling are required to act as horizontal barriers in the transmission o both air borne and impact sounds or noises . • In most of cases where the ceilings and floors construction is of solid type like r.c.c floors they offer adequate insulation against air borne sounds because of rigid and heavy construction but offer poor insulation for structure borne or impact sounds . • This objective can be met by the following constructional measures. • Use of resilient surface material on floors • In this method over the massive and rigid construction of floors slabs ,a surface layer of resilient materials such as linoleum insulation boards ,cork, asphalt mastic and carpet etc are employed. 

Providing a floating floor construction • The principal underlying the construction of a floating floor is its insulation from any other part of structure. • To achieve this an additional floating floor is made to rest or float over the existing floor by means of a resilient like glass wool ,material wool ,quilt, hair felt ,cork ,rubber etc, so that impact sounds and consequent vibration are not transmitted to the room below it also improves insulation against air borne sounds. • Floating floor construction can be adopted for both concrete as well as wooden floor and is described below.

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Concrete floor • In case of concrete floor ,the resilient layer on which the floating floor is intended to rest, is turned up at all edges which about the wall partition or other parts of structure the various types of floating floor construction for concrete floor are explained below. •

concrete floor with floating concrete screed

• This consist of a layer of concrete screed (1:11/2:3) not less than 5 cm in thickness and resting on a resilient layer of mineral wood quilt laid over the structural floor slab and turned up against the surrounding walls ar all the edges. • The quilt is covered with a waterproof paper to prevent wet concrete running through it. •

concrete floor with floating wood raft • This consist of floor boarding nailed to wooden bitterns (5cm x 5cm size) to form a raft which is laid over 2 cm thick resilient quilt and in turn is made to rest over the structural concrete floor slab. •

Suspended ceiling • In this type the uses of suspended ceiling provides insulation against air borne sound and soft floor finish of resilient covering such as carpets,corks or linoleum etc. thick ,provide • If sufficiently insulation against structure borne or impact sound . •

Soft floor • In this type 5 cm thick light weight concrete screed gives a certain amount of insulation against air borne sound but in addition the uses of resilient floor gives a high insulation against both air borne and impact sound . • The uses of dense topping has two fold functions • It provides a suitable base for the floor finish. • It provides an impervious air tight layers ,sealing the top of the light weight screed. 

Wooden floors • In case of floors constructed of wooden joists, the problem of sound insulation becomes more difficult particularly in the presence of heavy mechanical impact sound . • This problem in case of timber floors is taken care of either by making the wall thicker below the floor or making the floor itself heavy and stiff enough to reduce the vibration of the walls . • Two different types of wooden joist floating floor which gives adequate insulation are given below .

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Supporting walls are 10 cm thick or less • A ceiling of expanded metal and 3 coated plaster loaded directly with plugging of 5 cm of dry sand and properly constructed is considered to be satisfactory. • The flowing floor consists of floor boarded nailed to the battens to from a raft which rests on a resilient quilt draped or arranged over the wooden joists . the whole raft should be insulated from the surrounding wall either by turning up the resilient quilt at the edges or by leaving a gap round the edges to be covered by skirting. • The plugging in the air space is uses to deaden the sound effect.

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Supporting wall are 20 cm or more • The ceiling consist of plaster boards and plaster finish are directly loaded with plugging of slag wool or mineral wool other detail are same as type 1.

• TYPE III USE OF SUSPEVDED CEILING WITH AIR SPACE • In this construction ,a false independent ceiling is connected below the solid or wooden floor by means of metal hanger , acoustic clips etc with an air space in between . • The construction offer good insulation against both the air borne as well as the structure borne sound and especially suitable in case of wood joist floor . 

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Window & door • In case of window ,sound insulation of single window is improved by making them as air tight as possible by filling the air space at the edges of such panels with sound absorbing material . • In case of door ,the transmission loss or sound reduction increase with the increase in weight ,the sound insulation can further be improved by packing the sound absorbing material in the space between the jamb and frame .

conclusion • The increase in transmission loss or sound reduction of a solid massive construction is slow in proportion to the increase in its thickness. • If the material is uses is of porous and flexible nature ,like hair felt ,its sound insulation is proportional to its thickness . • In double wall or cavity wall construction an air space is generally better than a filling material ,since it may be detrimental to sound insulation ,if it bridge the separated surfaces. 

conclusion • A cavity wall with two leaves having thickness of 10 cm each has 80% increase in insulation value as compared to a single brick solid wall of 20 cm thickness, without any increase in weight bit with little increase in cost. • and solid glass panel have better insulation property as compared to larger and thicker flexible glass panel. • Double glazing of glass window improves insulation to a considerable degree. • Sealed double windows or triple window of plate glass with an air space in between can be successfully used where sound proofing is desired. 

Any question