**1. Introduction**

The passage of air in and out—and heat along with it—is called infiltration. The significance of infiltration is clear from the fact that the average house has 600 cm2 of vents and flues alone; plus window frames, doors, sills, and corners that need sealing and plugging; fireplaces with unfit dampers; and a front door that is slammed 3000 times a year. Air passes in and out through these openings. Therefore, infiltration is a misleading word—since it only denotes a one-way movement of air into a house. There is need of better word than breathing or respiration or exchange. Focusing entirely on insulation thickness, the best way to define all flow of air in and out through unsealed slits and unplugged holes is by huff and puff of a house. Due to a slit between the sash and the frame or the frame and the house, a 1.25 × 1.25 m<sup>2</sup> double glazed window will easily lose about 70 L of oil in winter, and some studies have suggested that windows account for even more heat

loss than roofs. Double or triple panes are not the only solution. Traditionally, the most effective defense is solid, thermal shutters, put up from the inside that fit the window hole exactly.

This chapter attempts to bring up integrated noise insulation modeling for airflow windows along with their use as a sustainable energy source of electric and thermal energy besides providing daylighting. The airflow window system with photovoltaic modules embedded in solar wall spandrel as illustrated in **Figure 1** has been considered for investigations [1–60]. A triple glazed airflow window combined with a PV solar wall spandrel has many advantages: (i) airflow window provides electric power, hybrid ventilation through heating/cooling, daylighting and reduction in greenhouse gas emissions by energy conservation of fossil fuels; (ii) it provides integrated sound and thermal insulation; (iii) it gives protection from excessive heating from solar radiation by passing and controlling the amount of heat transport; (iv) it gives protection to PV modules from excessive heating, weather deterioration including protection from snow and dust; (v) with frame supporting structures, the system is easily approachable for repair and maintenance jobs; and (vi) it has better esthetic appearance to the occupants and to the viewers from outside in comparison with stand-alone PV module power generating system.

### **1.1 Physical model description**

A full-scale experimental test section comprising an airflow window with a single pane exterior glazing and a double pane interior glazing and a photovoltaic solar wall spandrel was constructed in an outdoor room facility at Concordia University, Montréal, Québec [3–60]. The transportation of heat was achieved through manually operated intake and set of exhaust dampers. The intake and exhaust dampers located on exterior side were fitted with wire mesh screens. The exhaust damper placed on the interior side toward outdoor room is for allowing the pre-conditioned outdoor air directly into the room indoor environment. The air movement in the airflow window system was achieved through: (i) buoyancyinduced hybrid flow and (ii) fan-assisted flow created either in absence or presence of wind-induced flow.

In airflow window integrated with PV module, there are many issues related to its operation. The main objective is to model the integrated thermal and sound

#### **Figure 1.**

*Schematic of an airflow window system with a PV solar wall spandrel section (dimensions provided are in mm).*

**101**

generated.

**2. State-of-the-art**

air is encased, protected and preserved.

tive if there is an excess exhaust air in comparison to supply air.

room is being returned through return grilles, into the exhaust air duct.

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

insulation fields and to maximize the value of total energy generated and therefore increase the combined efficiency of the system. In achieving this objective, the heat transfer model and losses of PV model need to be studied. The heat can be recovered from the heated PV modules in different ways. One of the options is to treat the heated PV module as absorber surface and pass airflow through the surface. The key operation parameters are air mass flow rate, area of the absorber surface (PV, Blind) and its temperature. Air mass flow rate requires optimum air velocity under various conditions to prevent condensation, stagnant zones, flow reversal and other adverse effects that will cause deterioration of the PV panels. This optimization of airflow will maximize the absorbed solar radiation conversion to either thermal or electric power. By placing motorized blind after the integrated PV, will achieve twin objectives, control the amount of daylight transmission and also help in absorbing the excess external heat, which is going inside the room and overheating it. This heat is further taken from blind by mass flow of air, while cooling the PV modules. Depending on the climatic variables the operation of airflow window can be optimized. Damper motion is controlled by both flow and temperature sensors. During the summer, in the daytime, when outside air temperature is in the range of 15–22°C, the exhaust air vent provided will exhaust the heated air from PV modules to outside. But during night, the cooled fresh air can be used inside the room to reduce the cooling load of the building. Another important aspect is to control the amount of daylight transmission by optimizing sizing and distribution of opaque photovoltaic modules for maximizing the value of thermal and electric power

Traditionally, insulation is dead air space, or a dead gas space, sometimes combined with a reflective surface. Air has a low inherent conductivity. If it is dead or motionless there is no convection and when there is a reflective surface, radiation is cut to a minimum. Dead air space can be found in materials like fiberglass blanket, loose-fill and foam. They embody thousands of tiny pockets where dead

Outdoor duct system consists of combination of fans, duct construction elements, heat exchangers and air filters. The location of fan in outdoor duct is decided by the direction of flow and desired pressure relations. A supply fan is used to pump air into a space and exhaust fan is used to draw air out of a space. The pressure relations for the two cases are different. There is a buildup pressure in case of supply air and reduction of pressure in case of exhaust air. The space pressure is determined based on the relative quantity of air handled by supply and exhaust air. The space pressure will be positive if there is an excess supply air in comparison to exhaust air and nega-

The total energy provided by the fans to the air passing through a given system is fixed, assuming the same capacities and end pressures for a supply fan, an exhaust fan or both are used. A motor-driven fan is used to circulate filtered heated air from outdoor duct through supply duct to outdoor test-room. As the hot air is delivered through the ducts and into the room through the supply outlet, cooler air from the

The choice of fan is dependent on creating a sufficient pressure is achieved to overcome the total losses based on the flow through the duct with longest run. Fan performance must meet and match system requirements. The only possible operating characteristic points are those where the system curve intersects the fan curve. These are the points where the pressure developed by the fan exactly matches the system

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

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

insulation fields and to maximize the value of total energy generated and therefore increase the combined efficiency of the system. In achieving this objective, the heat transfer model and losses of PV model need to be studied. The heat can be recovered from the heated PV modules in different ways. One of the options is to treat the heated PV module as absorber surface and pass airflow through the surface. The key operation parameters are air mass flow rate, area of the absorber surface (PV, Blind) and its temperature. Air mass flow rate requires optimum air velocity under various conditions to prevent condensation, stagnant zones, flow reversal and other adverse effects that will cause deterioration of the PV panels. This optimization of airflow will maximize the absorbed solar radiation conversion to either thermal or electric power. By placing motorized blind after the integrated PV, will achieve twin objectives, control the amount of daylight transmission and also help in absorbing the excess external heat, which is going inside the room and overheating it. This heat is further taken from blind by mass flow of air, while cooling the PV modules. Depending on the climatic variables the operation of airflow window can be optimized. Damper motion is controlled by both flow and temperature sensors. During the summer, in the daytime, when outside air temperature is in the range of 15–22°C, the exhaust air vent provided will exhaust the heated air from PV modules to outside. But during night, the cooled fresh air can be used inside the room to reduce the cooling load of the building. Another important aspect is to control the amount of daylight transmission by optimizing sizing and distribution of opaque photovoltaic modules for maximizing the value of thermal and electric power generated.

### **2. State-of-the-art**

*Noise and Environment*

window hole exactly.

stand-alone PV module power generating system.

**1.1 Physical model description**

of wind-induced flow.

loss than roofs. Double or triple panes are not the only solution. Traditionally, the most effective defense is solid, thermal shutters, put up from the inside that fit the

A full-scale experimental test section comprising an airflow window with a single pane exterior glazing and a double pane interior glazing and a photovoltaic solar wall spandrel was constructed in an outdoor room facility at Concordia University, Montréal, Québec [3–60]. The transportation of heat was achieved through manually operated intake and set of exhaust dampers. The intake and exhaust dampers located on exterior side were fitted with wire mesh screens. The exhaust damper placed on the interior side toward outdoor room is for allowing the pre-conditioned outdoor air directly into the room indoor environment. The air movement in the airflow window system was achieved through: (i) buoyancyinduced hybrid flow and (ii) fan-assisted flow created either in absence or presence

In airflow window integrated with PV module, there are many issues related to its operation. The main objective is to model the integrated thermal and sound

*Schematic of an airflow window system with a PV solar wall spandrel section (dimensions provided are* 

This chapter attempts to bring up integrated noise insulation modeling for airflow windows along with their use as a sustainable energy source of electric and thermal energy besides providing daylighting. The airflow window system with photovoltaic modules embedded in solar wall spandrel as illustrated in **Figure 1** has been considered for investigations [1–60]. A triple glazed airflow window combined with a PV solar wall spandrel has many advantages: (i) airflow window provides electric power, hybrid ventilation through heating/cooling, daylighting and reduction in greenhouse gas emissions by energy conservation of fossil fuels; (ii) it provides integrated sound and thermal insulation; (iii) it gives protection from excessive heating from solar radiation by passing and controlling the amount of heat transport; (iv) it gives protection to PV modules from excessive heating, weather deterioration including protection from snow and dust; (v) with frame supporting structures, the system is easily approachable for repair and maintenance jobs; and (vi) it has better esthetic appearance to the occupants and to the viewers from outside in comparison with

**100**

**Figure 1.**

*in mm).*

Traditionally, insulation is dead air space, or a dead gas space, sometimes combined with a reflective surface. Air has a low inherent conductivity. If it is dead or motionless there is no convection and when there is a reflective surface, radiation is cut to a minimum. Dead air space can be found in materials like fiberglass blanket, loose-fill and foam. They embody thousands of tiny pockets where dead air is encased, protected and preserved.

Outdoor duct system consists of combination of fans, duct construction elements, heat exchangers and air filters. The location of fan in outdoor duct is decided by the direction of flow and desired pressure relations. A supply fan is used to pump air into a space and exhaust fan is used to draw air out of a space. The pressure relations for the two cases are different. There is a buildup pressure in case of supply air and reduction of pressure in case of exhaust air. The space pressure is determined based on the relative quantity of air handled by supply and exhaust air. The space pressure will be positive if there is an excess supply air in comparison to exhaust air and negative if there is an excess exhaust air in comparison to supply air.

The total energy provided by the fans to the air passing through a given system is fixed, assuming the same capacities and end pressures for a supply fan, an exhaust fan or both are used. A motor-driven fan is used to circulate filtered heated air from outdoor duct through supply duct to outdoor test-room. As the hot air is delivered through the ducts and into the room through the supply outlet, cooler air from the room is being returned through return grilles, into the exhaust air duct.

The choice of fan is dependent on creating a sufficient pressure is achieved to overcome the total losses based on the flow through the duct with longest run. Fan performance must meet and match system requirements. The only possible operating characteristic points are those where the system curve intersects the fan curve. These are the points where the pressure developed by the fan exactly matches the system

resistance, and the flow in the duct system equals the fan capacity. The overall system resistance is calculated by summing the pressure losses for the individual components along any one flow path.

Air passing through the outdoor duct system is either heated or cooled. It results in decreased or increased density, respectively, and with assumption of constant mass flow rate, its total volume rate will be increased or decreased accordingly. The developed resistance in the duct is calculated based on actual gas density, volume, and velocity through it. The total system resistance is calculated by summation of these resistances along the flow path.

The difference in power requirements at various locations can be calculated. For the case of constant system resistance, the pressure required for the fan (P2 − P1) will be constant regardless of the location. The volume of air flow (Q ) will vary with the location. The fan location with least power requirements is that place where density of air will be highest assuming constant efficiency.

Exterior duct insulation can be attached with adhesive, with supplemental preattached pins and clips, with wiring or bands. Liners can be attached with adhesive and supplemental pins/clips. Rectangular ducts and fittings are fabricated by grooving, folding, and taping with metal accessories such as turning vanes, splitters, and dampers incorporated into the system. If rectangular ducts exceed the pre-determined dimensions for particular static pressure, the ductwork must be reinforced. Insulation can significantly reduce operating costs that depend upon unit cost of heating and cooling energy, extent of duct exposed to outside conditions. In addition, duct insulation maintains the supply air temperature unaltered thereby, maintaining the conditioned space within acceptable temperature range. Vapor retarders are required on exterior insulation of ducts that are used for alternate heating and cooling.

Some thermal insulation materials can also serve purpose of sound control [1]. Acoustic efficiency depends upon physical structure of the material. Materials with open, porous surfaces have sound absorption capability [2]. Those with high density and resilient character can be used for absorption of vibrations. Insulation for sound conditioning includes flexible and semi-rigid, formed-in-place fibrous materials and rigid fibrous insulation. Thermal insulation materials improve their sound insulation when installed with discontinuous construction. A wall of staggered stud construction that uses resilient clips or channels on one side of the stud or resilient boards of special manufacture to prevent acoustic coupling mechanically between the surfaces, reduces sound transmission. Sound absorption by thermal insulation blanket in a cavity wall reduces sound transmission.

The energy conversion and noise characterization in an exterior double wall is important, for example, in modeling PV solar wall and transpired unglazed structures [1–60]. The energy conversion in a double of cavity wall is a function of solar irradiation, air gap width, mass flow rate and pressure, wall and air temperatures. A generalized two dimensional thermal analysis of an outdoor duct is presented by placement of surface and air nodes into two adjacent stacks of control volumes representing outer and inner walls of duct. A matrix solution procedure is adopted by constituting conjugate heat exchange of conduction, convection, radiation and ventilation heat transport.

The requisite amount of ventilation air in a building in a given climate depends on heating/cooling load. The HVAC load on building varies with the condition of outdoor ventilation air that may require additional heating, cooling and humidification or dehumidification. In temperate climates, outdoor air is more economical to use than recycled return air. The analysis of double or cavity wall for ventilation purposes using airflow window with PV solar wall structures is investigated. The investigation of energy conversion, ventilation and integrated insulation

**103**

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

wave approaching an open window must completely pass through it.

tically good. The important characteristics of absorbent materials are:

waves are converted into other form of energy by friction.

the material, its density and frequency of sound.

Sound absorbent materials: most of the common building materials absorb sound to a small extent and hence, for better acoustical requirement, some other materials are to be incorporated on the surfaces of the room. Such materials are known as absorbent materials and they help a great deal in making the room acous-

1.An ideal absorbent material should be economical in construction and maintenance, waterproof, fire-proof, sufficiently strong and good in appearance.

2.Noise level of the room provided with absorbent materials is considerably

3.In the hall treated with absorbent materials, speech can be heard clearly, and

4.All the absorbent materials are found to be soft and porous. They work on the principle that sound waves penetrate into the pores, and in this process, sound

5.The absorbing capacity of the absorbent materials depends on the thickness of

6.The sound properties of the absorbent materials are considerably changed by their modes of fixing. Suspended absorbers in the form of inverted cones may

7.There is no royal road for making a particular room acoustically good. It mainly depends on the ideas of the technical staff either engineer or architect. Each case is to be studied separately and after proper thinking, suitable absorbent

8.Great care should be exercised while prescribing the covering for an absorbent material so as to improve its appearance. Improper covering destroys the absor-

be provided in the ceiling to make the hall acoustically sound good.

system is based on complete information for the given design conditions and

When a sound wave strikes a surface, part of its energy is absorbed by friction, part of its energy is transmitted, and the remaining part of its energy is reflected. But as reverberation directly depends on the loss of energy of sound wave due to friction, it is of greater importance. This property of a surface by which sound energy is converted into other form of energy is known as absorption and absorption coefficient of a surface indicates the degree to which this surface affects the absorption of sound. It is thus the ratio of energy absorbed by the area to the energy striking the area. The value of coefficient of absorption will depend on the frequency of sound. **Table 1** gives the value of coefficients of absorption for some common surfaces. These values correspond to the normal frequency of 500 cycles per second. It may be noted that coefficient of absorption for an open window is taken as unity. This is very easy to understand as sound

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

limitations of operation results.

**2.1 Absorption of sound**

reduced.

music can be fully enjoyed.

materials may be specified.

bent properties of the material.

system is based on complete information for the given design conditions and limitations of operation results.
