IRJET-Experimental Thermal Analysis of Composite Roof and Its Effects on Overall Thermal Resistant in Building Envelope

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A design and analysis of three types of composite roof has been evaluated. The adoptive temperature in the range of 22ºC to 32ºC in moderate zone is achieved. It is important, that a designer should be able to calculate the temperatures and heat transfer rate for any combination of materials exposed to any climatic conditions. The new innovative and modified composite roof helps make building envelope cool in summer and warm in winters and saves energy in respective seasons. The composite materials, innovated are concrete (M20), Expanded Polystyrene (thermocol) foam insulation plus ferroconcrete; concrete plus Polyethylene foam insulation plus ferroconcrete and concrete, Polyurethane foam insulation plus ferroconcrete material. This composite material is sandwiched between water proofing compound layer and are further analyzed for techno-economical feasibility. It is reviewed and analyzed that, the composite material concrete with Polyurethane foam is better suited for low cost and comfort as durable roof in passive designs of building applications. These composite materials properties are good for comfort in building conditions as compared to other materials.

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International Research Journal of Engineering and Technology (IRJET)

e-ISSN: 2395 -0056

Volume: 02 Issue: 04 | July-2015

p-ISSN: 2395-0072

www.irjet.net

Experimental Thermal Analysis of Composite Roof and Its Effects on
Overall Thermal Resistant in Building Envelope
Mr. Sawankumar E. Patil1, Mr. Abhishek R. Deshmukh2, Mr. N.N.Shinde3, Mr. R A Charate4
1Research

Student, Department of Technology, Shivaji University, Kolhapur, Maharashtra, India
Student, Department of Technology, Shivaji University, Kolhapur, Maharashtra, India
3Professor, Department of Technology, Shivaji University, Kolhapur, Maharashtra, India
4Principal, Lattthe polytechnic, Sangali, Maharashtra, India
---------------------------------------------------------------------***--------------------------------------------------------------------2Research

Abstract – A design and analysis of three types of
composite roof has been evaluated. The adoptive
temperature in the range of 22ºC to 32ºC in moderate
zone is achieved. It is important, that a designer should
be able to calculate the temperatures and heat transfer
rate for any combination of materials exposed to any
climatic conditions. The new innovative and modified
composite roof helps make building envelope cool in
summer and warm in winters and saves energy in
respective seasons.
The composite materials, innovated are
concrete (M20), Expanded Polystyrene (thermocol)
foam insulation plus ferroconcrete; concrete plus
Polyethylene foam insulation plus ferroconcrete and
concrete,
Polyurethane
foam
insulation
plus
ferroconcrete material. This composite material is
sandwiched between water proofing compound layer
and are further analyzed for techno-economical
feasibility.
It is reviewed and analyzed that, the composite
material concrete with Polyurethane foam is better
suited for low cost and comfort as durable roof in
passive designs of building applications. These
composite materials properties are good for comfort in
building conditions as compared to other materials.

Key Words: Composite roof, comfort conditions,
energy saving in building envelope, roof thermal
analysis, roof and comfort analysis, techno-economical
feasibility, roof cooling effect, roof thermal balance.
1.

INTRODUCTION

In building design simple techniques such as orientation,
aspect, prospect, shading of windows, colour, and
vegetation among others create comfortable conditions.
Such techniques pertain to the building envelope. Building
envelopes not only provide the thermal divide between
the indoor and outdoor environment, but also play an
important role in determining how effectively the building
can utilize natural resources like heat, light and wind.
Thus, intelligent configuration and moulding of thebuilt
form and its surroundings can considerably minimize the
level of discomfort inside a building, and reduce the

© 2015, IRJET.NET- All Rights Reserved

consumption of energy required to maintain comfortable
conditions.
The physical manifestation of some of the concepts on
building configuration that can reduce heat gain in arid
and hot climate is depicted by various factors like, Walls,
Windows, Roofs, and Adjacent Walls etc.
In building envelope most of the important part is roof.
Roof of a building receives a significant amount of solar
radiation. Thus, its design and construction play an
important role in modifying the heat flow, day lighting and
ventilation.As per Indian Standard code 3792 (1978), the
heat gain through roofs may be reduced by the following
methods:
 Insulating materials may be applied externally or
internally to the roofs. In case of external
application, the insulating material needs to be
protected by waterproofing to avoid intrusion of
moisture inside the living space.
 For internal application, the insulating material
may be fixed by adhesive or by other means on
the underside of the roofs. A false ceiling of
insulation material may be provided below the
roofs with air gaps in between.
 Shining and reflecting material (e.g. glazed china
mosaic) may be laid on top of the roof.
 Movable covers of suitable heat insulating
material, if practicable, may be considered.
 White washing of the roof can be done before the
onset of each summer.
 Typical heat loads in filtering from various sides
of building envelope in moderate zone in India are
calculated and is represented in graph 1. below.
Almost 17.9% of heat is due to roof.

Graph.1. Pie chart on solar radiation by heat load

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International Research Journal of Engineering and Technology (IRJET)

e-ISSN: 2395 -0056

Volume: 02 Issue: 04 | July-2015

p-ISSN: 2395-0072

www.irjet.net

1.2 Composite Roof:
Composite roof is a mixture of multiple materials that are
compressed and blended together. They possess different
physical or chemical properties, that when combined,
produces a material with characteristics different from the
individual components. In composite roof new material
can be preferred, for many reasons: common examples
include materials which are stronger, lighter and less
expensive when compared to traditional materials. The
composite roof looks like any other roof and can be casted
at site with due care and high tech practices. These
composites are tested for ISO: 9705 for its fire resistance
but are not analyzed for thermal transmittance for passive
design applications.
Typical engineered composite materials include:
 Composite building materials such as cements,
concrete, ferroconcrete.
 Reinforced plastics such as fiber-reinforced
polymer.
 Metal Composites.
 Ceramic Composites (composite ceramic and
metal matrices).
 Polyurethane foam and polystyrene foam and
polyethylene foam insulation material.

2.0 The research criteria
2.1 Selection of roof composite materials
2.2 Heat balance and its thermal Analysis
2.3 Analysis
2.1. Selection of roof composite materials

Figure-1: General composite roof design

x1, x2, x3 are the thickness of ferroconcrete, insulation ,
and concrete(M20), respectively.
k1, k2, k3 are the thermal conductivity of ferroconcrete,
insulation, and concrete(M20), respectively.
The rate of heat conduction (Q conduction) through any
element such as roof, wall or floor under steady state can
be written as [1]
Q, conduction = A U ΔT
Where,
A = surface area (m2)
U = thermal transmittance (W/ m2- K)
ΔT = temperature difference between inside and
outside air (K).
It may be noted that the steady state method does not
account for the effect of heat capacity of building
materials.
U is given by[1]
U=1/Rt
Where Rt is the total thermal resistance and is given by [1]

hi and ho are the inside and outside heat transfer
coefficients respectively. Lj is the thickness of the jth layer
and kj is the thermal conductivity of its material.
U indicates the total amount of heat transmitted
from outdoor air to indoor air through a given wall or roof
per unit area per unit time. The lower the value of U, the
higher is the insulating value of the element. Thus, the Uvalue can be used for comparing the insulating values of
various building elements.
Equation is solved for every external constituent
element of the building i.e., each wall, window, door, roof
and the floor, and the results are summed up. The heat
flow rate through the building envelope by conduction is
the sum of the area and the U-value products of all the
elements of the building multiplied by the temperature
difference. It is expressed as:

2.2 Heat Balance and its thermal Analysis
Heat transfer by roof conduction and convection equations
Abbreviation:Q= rate of heat conduction (w)
A = surface area (m2)
U = thermal transmittance (W/ m2- K)
ΔT = temperature difference
Rt = total thermal resistance
hi =inside heat transfer coefficients
ho= outside heat transfer coefficients
L j =thickness of the jth layer.
K j =thermal conductivity of its material.
i = building element.
Nc = number of components.
© 2015, IRJET.NET- All Rights Reserved

where,
i = building element.
Nc = number of components.

Page 1392

International Research Journal of Engineering and Technology (IRJET)

e-ISSN: 2395 -0056

Volume: 02 Issue: 04 | July-2015

p-ISSN: 2395-0072

www.irjet.net

2.3 Analysis
Case 1

Figures - 2: Composite roof structure with
polystyrenefoam as an insulation material.
Where
A= Water Proofing ferroconcrete material,
B= Polystyrene Foam,
C= Concrete (M20),
K1= Thermal Conductivity of Water Proofing
ferroconcrete material,
K2= Thermal Conductivity of Polystyrene Foam
K3= Thermal Conductivity of concrete (M20),
X1= Thickness of first layer offerroconcrete material,
X2= Thickness of Polystyrene Foam
X3= Thickness Concrete (M20),
A= A1= A2= A3= Heat Transfer area.

Graph-2: All temperature in case 1 (Polystyrene foam
insulation) Vs Time in minute

Case 2 Figures No 3: Composite roof structure with
polyethylene foam as an insulation material.

© 2015, IRJET.NET- All Rights Reserved

Where
A= Water Proofing ferroconcrete material,
B= Polyethylene Foam,
C= Concrete (M20),
K1= Thermal Conductivity of water proofing ferroconcrete
material,
K2= Thermal Conductivity of Polyethylene Foam,
K3= Thermal Conductivity of concrete (M20),
X1= Thickness of layer first ferroconcrete material,
X2= Thickness of Polyethylene Foam,
X3= Thickness Concrete (M20),
A= A1= A2= A3= Heat Transfer area.

Graph.3: All temperature in case 2 (Polyethylene foam
insulation) Vs Time in minute
Case 3 Figures-4: Composite roof structure with
polyurethane foam as an insulation material.

Where
A= Water Proofing ferroconcrete material,
B= Polyurethane Foam,
C= Concrete (M20),
K1= Thermal Conductivity of water proofing ferroconcrete
material,
K2= Thermal Conductivity of Polyurethane foam,
K3= Thermal Conductivity of concrete (M20),
X1= Thickness of layer first ferroconcrete material,
X2= Thickness of Polyurethane Foam,

Page 1393

International Research Journal of Engineering and Technology (IRJET)

e-ISSN: 2395 -0056

Volume: 02 Issue: 04 | July-2015

p-ISSN: 2395-0072

www.irjet.net

X3= Thickness Concrete (M20),
A= A1= A2= A3= Heat Transfer area.

Graph-4: All temperature in case 3 (Polyurethane foam
insulation) Vs Time in minute

2.3 Techno comfort analysis

Graph- 5: Thermal Transmittance (U)Vs Materials in all
case

3. CONCLUSIONS
The following results were obtained from the analysis of
the composite roof structures.
In case of composite roof with insulation of polystyrene
foam, it is observed that the increase inthe inside room
temperature is less with respect to time. If outside average
temperature is 53.13°C then inside room temperature is
32.60 °C.
In case of composite roof with insulation of polyethylene
foam, it is observed that the increase in the inside room
temperature is less with respect to time. If outside average
temperature is 60.7 °C then inside room temperature is
32.28 °C
In case of composite roof with insulation of polyurethane
foam, it is observed that the increase in the inside room
temperature is less with respect to time. If outside average
temperature is 66.84 °C then inside room temperature is
32.10 °C.
Finally it is concluded that the inside room temperature
value of composite roof with polyurethane foam using
material is effective in transfer of less heat inside the room
and hence itis recommended that the practice of PUF in
composite roof will result in energy saving and energy
conservation in building envelope.
© 2015, IRJET.NET- All Rights Reserved

REFERENCES
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[2] B.I. Hoglund, G.P.Matalas and D.G.Stephenson;
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Page 1394

International Research Journal of Engineering and Technology (IRJET)

e-ISSN: 2395 -0056

Volume: 02 Issue: 04 | July-2015

p-ISSN: 2395-0072

www.irjet.net

[12] Mohamed Krem; “Effect of Building Morphology on
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© 2015, IRJET.NET- All Rights Reserved

[16] 15. ASHRAE handbook: fundamentals, American
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Page 1395

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