**2.4 Thermal insulation definition**

The temperatures inside and outside a building are different. Some building materials allow heat to pass rapidly while others do not allow passage of heat smoothly. The term thermal resistance is used to indicate the construction by which

**109**

density.

*Noise Transmission Losses in Integrated Acoustic and Thermo-Fluid Insulation Panels*

transmission of heat from or in the room is retarded. The main aim of thermal insulation is to minimize the transfer of heat between outside and inside of the building. Advantages of thermal insulation: the advantages derived from thermal insulation are as follows: (i) comfort: due to thermal insulation, the room remains cool in summer and warm in winter than outside. Hence, a room provided with thermal insulation gives comfort both in summer and winter. (ii) Fuel saving: due to thermal insulation, transfer of heat from inside to outside of the room is reduced. This results in less quantity of fuel required to maintain the desired temperature in the room. (iii) Condensation: the provision of thermal insulating materials inside a room prevents condensation on interior walls and ceilings. Condensation is the deposition of moisture and it takes place when warm air comes into contact with surfaces having temperature below the dew point. (iv) Water system: the use of thermal insulating materials prevents the freezing of water taps in extreme winter and heat loss in case

General principles: following are the general principles of thermal insulation: (i) the thermal resistance of an insulating material is directly proportional to its thickness. (ii) Provision of an air gap is a very important insulating agent and is very essential. (iii) The thermal resistance of a building depends on its orientation also. The building should be so located that there is maximum transfer of solar energy in winter and there is minimum transfer of solar energy in summer.

Insulating materials: the choice of an insulating material depends on the cost, area to be covered, standard of insulation required and the cost of heating or cooling. The thermal insulating material should be reasonably fire-proof, non-absorbent of moisture, able to resist attack on small insects and not liable to undergo deformation. The usual insulating materials are rockwool, slag wool, fiberboards, flexible blankets, saw dust, wood-shavings, cork board slabs, mineral wool slabs, aluminum foils, products of cement concrete with lightweight aggregates, gypsum board, chip

**Table 2** shows the density, thermal conductivity and thermal resistivity of some of the common building and insulating materials. In general, it may be stated that the materials of low density provide better thermal insulation than those of higher

Doors and windows which are exposed transmit heat to a considerable extent. Following methods may be employed to ensure heat insulation of exposed doors and windows: (i) insulating glass or double glass with air space may be provided for glazed doors and windows. This will reduce heat transmission through doors and windows. (ii) In order to reduce incidence of solar heat, projections in the form of sun breakers, weather-sheds, projections, curtains, venetian blinds, etc. may be

Thermal insulation of exposed roofs may be achieved by treating inside surface

Internal treatment: (i) false ceiling with an air gap may be provided. The ceiling

is made of thermal insulating materials. (ii) Light insulating materials may be pasted by suitable adhesives to the inside surfaces of the exposed roofs.

External treatment: (i) suitable shade may be provided on the exposed roof surfaces. (ii) Shinning and reflecting materials may be fixed on the top of exposed roofs. (iii) For flat roofs, an air space may be created by arranging

*DOI: http://dx.doi.org/10.5772/intechopen.93296*

board, gasket cork sheet, foam plastic, etc.

*2.4.1 Thermal insulation of exposed doors and windows*

provided on the exposed doors and windows.

*2.4.2 Thermal insulation of exposed roofs*

or outside surface.

of hot water system.

#### *Noise Transmission Losses in Integrated Acoustic and Thermo-Fluid Insulation Panels DOI: http://dx.doi.org/10.5772/intechopen.93296*

transmission of heat from or in the room is retarded. The main aim of thermal insulation is to minimize the transfer of heat between outside and inside of the building.

Advantages of thermal insulation: the advantages derived from thermal insulation are as follows: (i) comfort: due to thermal insulation, the room remains cool in summer and warm in winter than outside. Hence, a room provided with thermal insulation gives comfort both in summer and winter. (ii) Fuel saving: due to thermal insulation, transfer of heat from inside to outside of the room is reduced. This results in less quantity of fuel required to maintain the desired temperature in the room. (iii) Condensation: the provision of thermal insulating materials inside a room prevents condensation on interior walls and ceilings. Condensation is the deposition of moisture and it takes place when warm air comes into contact with surfaces having temperature below the dew point. (iv) Water system: the use of thermal insulating materials prevents the freezing of water taps in extreme winter and heat loss in case of hot water system.

General principles: following are the general principles of thermal insulation: (i) the thermal resistance of an insulating material is directly proportional to its thickness. (ii) Provision of an air gap is a very important insulating agent and is very essential. (iii) The thermal resistance of a building depends on its orientation also. The building should be so located that there is maximum transfer of solar energy in winter and there is minimum transfer of solar energy in summer.

Insulating materials: the choice of an insulating material depends on the cost, area to be covered, standard of insulation required and the cost of heating or cooling. The thermal insulating material should be reasonably fire-proof, non-absorbent of moisture, able to resist attack on small insects and not liable to undergo deformation. The usual insulating materials are rockwool, slag wool, fiberboards, flexible blankets, saw dust, wood-shavings, cork board slabs, mineral wool slabs, aluminum foils, products of cement concrete with lightweight aggregates, gypsum board, chip board, gasket cork sheet, foam plastic, etc.

**Table 2** shows the density, thermal conductivity and thermal resistivity of some of the common building and insulating materials. In general, it may be stated that the materials of low density provide better thermal insulation than those of higher density.

#### *2.4.1 Thermal insulation of exposed doors and windows*

Doors and windows which are exposed transmit heat to a considerable extent. Following methods may be employed to ensure heat insulation of exposed doors and windows: (i) insulating glass or double glass with air space may be provided for glazed doors and windows. This will reduce heat transmission through doors and windows. (ii) In order to reduce incidence of solar heat, projections in the form of sun breakers, weather-sheds, projections, curtains, venetian blinds, etc. may be provided on the exposed doors and windows.

#### *2.4.2 Thermal insulation of exposed roofs*

Thermal insulation of exposed roofs may be achieved by treating inside surface or outside surface.

Internal treatment: (i) false ceiling with an air gap may be provided. The ceiling is made of thermal insulating materials. (ii) Light insulating materials may be pasted by suitable adhesives to the inside surfaces of the exposed roofs.

External treatment: (i) suitable shade may be provided on the exposed roof surfaces. (ii) Shinning and reflecting materials may be fixed on the top of exposed roofs. (iii) For flat roofs, an air space may be created by arranging

*Noise and Environment*

sound absorbing material.

structure-bore sound.

metal spring.

**2.4 Thermal insulation definition**

are employed for this purpose.

f. Box-type construction: this type of construction gives exceptionally low value of air-borne transmission and hence, it is adopted at places such as broadcasting studios where low air-borne sound transmission is most essential. A

g.Design of doors and windows: for good insulation, it is necessary to design carefully the doors and windows of the room. The sound travels through very thin cracks between the door and wall. The space between the jamb and frame may be packed with sound absorbing material. In case of a door, the transmission loss increases with the increase in weight. In case of a window, the transmission loss increases with increase in thickness of glass. Excellent sound insulation is obtained by constructing glazed windows with double or triple panes of glass. The air space at the edges of such panes is filled with

h.Planning of rooms: if rooms within residential buildings are suitably arranged, good sound insulation is achieved. It is also economical than

3.When noise is structure-borne: the sounds which originate and progress on the building structure are known as structure-borne sounds or impact sounds. The structure-borne noise is powerful, propagates over long distances and persists for a very short duration. Following methods of sound insulation may

a.Treatment of floors and ceilings: the floors and ceilings may be treated for floating floors and suspended ceilings which help in considerably reducing

b.Discontinuous construction: this method is similar to box-type construction. The walls of the rooms are constructed on floating floors and the ceilings of the rooms are suspended from the structural floors. The use of structural ties with the main walls is avoided as far as possible or special resilient isolators

c.Insulation of machinery: mechanical equipment such as refrigerators, lifts, and fans create vibrations in the structure and hence, if they are isolated properly, structure-borne sound is reduced to a considerable extent. The main principle of insulation of machinery is to rest the mechanical equipment on a flexible support which may be of rubber, cork, felt or

d.Town planning: vibrations from external sources such as railways, metros, cars, traffic, and factories create structure-borne sound. The most effective method for reducing such type of structure-borne sound is to have a rational town planning. The city is divided into suitable zones and residential zone is

placed away from railways, workshops, factories and main streets.

The temperatures inside and outside a building are different. Some building materials allow heat to pass rapidly while others do not allow passage of heat smoothly. The term thermal resistance is used to indicate the construction by which

structural measures required for good sound insulation.

be adopted for the reduction of structure-borne noise:

box-like structure is construction on the structural floor.

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#### **Table 2.**

*Density, thermal conductivity and thermal resistivity of some common building and insulating materials.*

cement sheets or corrugated galvanized iron sheets on bricks. (iv) Flat roofs may be kept cool by water which may either be stored or sprayed at regular intervals. The surface temperature of the roof is reduced by this method. (v) Thermal insulation of flat roof may also be provided by putting a layer of about 25 mm thickness of coconut pith cement concrete. For this purpose, coconut pith and cement are mixed in dry state and then the mix is transferred to concrete mixer. Water in required quantity is added so as to obtain concrete of workable consistency. It is then conveyed and laid in suitable thickness on the roof. Wet coconut pith may also be used with due care and hard mixing may be adopted for small quantity of work. To avoid loss of water from concrete surface, it is covered by an impermeable layer and then it is allowed to dry in air for a period of 20 days to 1 month. Any cracks which are seen during drying period are filled up by the pith concrete. When the pith concrete layer has fully dried, water-proofing treatment may be given in the usual manner.

### *2.4.3 Thermal insulation of exposed walls*

Following methods may be adopted for thermal insulation of exposed walls: (i) suitable thickness of wall may be provided. (ii) Hollow wall or cavity wall construction may be adopted. (iii) For partitions, an air space may be created by fixing hard boards on battens. (iv) The inside and outside surfaces of exposed wall

**111**

**Figure 2.**

*Grid size in the duct: distribution of nodes and control volumes.*

*Noise Transmission Losses in Integrated Acoustic and Thermo-Fluid Insulation Panels*

exposed side of the wall will grant substantial thermal insulation.

may be provided with thermal insulating materials in such a way that the value of overall thermal transmittance is brought within desired limit. (v) If it is structurally suitable, the exposed wall may be constructed of thermal insulating materials. (vi) It is found that the application of light-colored whitewash or distemper on the

The assumptions used in the development of the model for a building integrated photovoltaic airflow window (BIPV-AW) system as depicted in **Figure 1** are: (i) fully developed heat transfer has been assumed for mixed convection heat transfer assuming a parallel plate wide channel at low air velocities ~0.5 m/s; (ii) temperature variation only along y-axis with lumped temperature distribution along x and z-axes; (iii) applicability of first law of thermodynamics at the surface; (iv) clear sky is applicable; (v) quasi steady state heat transfer analysis has been performed assuming a vertical channel; (vi) uniform average air velocity distribution; (vii) temperature variation only in y-direction (vertical), being taken as lumped in other directions (x-axis and z-axis); (viii) air properties are evaluated at film temperature of 300 K; (ix) negligible heat transfer from side walls/insulation panel and room air zone; (x) conduction (diffusion) equation for performing energy balance on air nodes is not taken into consideration; (xi) negligible thermal storage capacity of duct wall; (xii) no infiltration or air leakage sources from the test section; and (xiii) ambient air and room air temperatures are specified.

The system is discretized into network of two adjacent stacks of control volumes common to surface and air nodes (see **Figure 2**). The energy balances are performed on both surface and air nodes with aid of constitutive relations for noise fields due to solar intensity, sound intensity, airflow power intensity, electric power intensity and heat power intensity. The energy conversion and noise characterization is important, for example, in modeling airflow window and PV solar wall building structures. The resultant noise field due to composite wave elements (of heat, fluid, electricity, sound and sun) is a function of solar irradiation, sound intensity, air gap width, mass flow rate and pressure, wall and air temperatures of the double wall building structure. The integrated noise insulation due to thermal and sound

*DOI: http://dx.doi.org/10.5772/intechopen.93296*

**3. Model assumptions and development**

may be provided with thermal insulating materials in such a way that the value of overall thermal transmittance is brought within desired limit. (v) If it is structurally suitable, the exposed wall may be constructed of thermal insulating materials. (vi) It is found that the application of light-colored whitewash or distemper on the exposed side of the wall will grant substantial thermal insulation.
