This document discusses the principles and types of heat transfer relevant to buildings, including conduction, convection, and radiation. It examines how heat transfer occurs in various building components such as walls, windows, and roofs, along with the calculations necessary for effective thermal management. The final conclusion emphasizes the significance of understanding these mechanisms for optimizing energy efficiency in buildings.

1. Environmental Heat Transfer
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Koya University Faculty of Engineering
Chemical Engineering Department
Third stage
Heat Transfer
Heat Transfer in Buildings
2023-2024
supervisor:
Mr. Ahmed Abdulsalam Maroof
Prepared by:
Dima Jawhar
Ara Fakher
Report date: 30/Nov./2023 submission date: Dec./7/2023

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Table of Contents
Abstract: .................................................................................................................................... 3
Introduction:.............................................................................................................................. 4
Methodology: ............................................................................................................................ 6
Types of heat transfer in buildings:....................................................................................... 6
Conduction: ....................................................................................................................... 6
Convection: ....................................................................................................................... 6
Radiation: .......................................................................................................................... 6
Heat transfer in buildings ...................................................................................................... 7
Heat transfer in walls......................................................................................................... 7
Heat transfer in building windows: ................................................................................... 7
Heat transfer through buildings rooms and roofs:............................................................. 9
Conclusion............................................................................................................................... 11
References:.............................................................................................................................. 12

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Abstract:
Introduction: The several ways that thermal energy is transferred from one place to
another are referred to as the principle of heat transfer.
This process is known as radiation heat transfer.
The transfer of energy by thermal radiation, or electromagnetic waves, is known as
radiant heat transfer.
A convection current is created when heated air rises and is replaced by colder air,
transferring heat from the inner pane to the outside pane(s).
Heat is carried via the window frame in triple-glazing units; convection is minor in
double-glazing units up to 20 mm, especially when argon gas is used, which is denser
than air.
Heat transfer through buildings rooms and roofs: Even while convection often involves
more variables than conduction, we are nevertheless able to characterize it and do some
simple, accurate calculations to determine its effects.
Figure 7 illustrates each of the three heat transmission techniques in this portion of the
attic.
This natural convection heating system, when correctly built, may be quite effective in
heating a home evenly.

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Introduction:
The several ways that thermal energy is transferred from one place to another are
referred to as the principle of heat transfer. There are three main
ways that heat travels through building assemblies: radiation, convection, and conduct
ion. One or more of these mechanisms may be involved in a specific thermal energy
transfer.
Phase transitions also release or absorb heat through three processes: conduction, radi
ation, and convection. Examples of this include heat transfer from walls to rooms, fro
m fluids to each other, between pipes, and from outside heat to dwellings.
The types of heat transport are described in Figure 1. a (concept group LLC, 2023)
Figure 1: types of transferring heat. (energy saver, 2023)
Temperature and heat are not the same thing. Temperature is a measurement of the
intensity of kinetic energy, which is what heat is. Consider two water containers, one
holding 10 gallons and the other one holding 1 gallon, to demonstrate this. Both
containers hold 50°F water. The bigger container retains ten times more heat than the
smaller one, even if they are of the same temperature. Because it has a greater capacity,
the larger container can hold more heat. (Clayton DeKorne, 2023)
Building heat transfer calculations are performed for different applications such as:
(Kusuda T., 1977)
• heat transmission via the outer envelope, the basement walls, the slab-on-grade
floor (to a semi-infinite zone),
• transmission, absorption, and reflection of short wavelengths (or solar heat) for
openings.
• thermal storage in the external masses of structures.

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• air leakage via outside envelopes as well as the interior partition walls, ceilings,
and floors.
Interior environmental analyses-:
• radiant heat transfer between heat sinks or sources and interior surfaces,
• the transfer of heat convectively between interior surfaces and room air
• convectional motion within and between rooms, or room air convection
• the interior heat sources, such as heaters, coolers, and occupants, convective and
radiative heat transfer
• internal masses' thermal storage.
Material or building element-related problems:
• convection inside porous insulation,
• the cold-bridge effect,
• moisture condensation brought on by the simultaneous movement of heat,
moisture, and air.
Figure 2: fundamentals of heat transfer in buildings. (Let's Talk Science, 2021)

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Methodology:
Types of heat transfer in buildings:
Conduction:
The movement of heat from one area of the body at a higher temperature to another
area at a lower temperature is known as conduction. Energy is transferred from
molecules with higher energy levels to those with lower energy levels during the
conduction process, which occurs at the molecular level. This is clearly seen in gases,
where we find that molecules in the higher temperature areas have an average kinetic
energy that is larger than those in the lower temperature regions. (Rohsenow, W.M.,
Hartnett, et al 1998)
Convection:
Heat is transferred between two bodies by convective heat transfer, which is caused by
moving gas or fluid currents. Free convection is the process by which warm air or water
rises and is replaced by a cooler parcel of air or water, moving away from the heated
body. Forced convection effectively eliminates heat from the body by forcing air or
water (as in wind or wind-generated water currents) to flow across the surface of the
body. Because convection keeps the temperature differential between the body and the
surrounding air or water steep, it is an extremely effective means of transferring heat.
(Inna Sokolova 2019)
Radiation:
Heat waves are released into the environment, where they might be absorbed, reflected,
or transmitted via a cooler body. This process is known as radiation heat transfer. Earth
is heated by electromagnetic radiation from the Sun. Heat waves are released by hot
bodies.
Conduction, convection, or a mix of the two are used in the majority of upstream
applications for oil and gas processing facilities. Temperatures in fluid-fluid exchangers
are too low for radiation to play a major role. A flare's heat output must be calculated
with consideration for radiation. (Maurice Stewart, 2021)
The transfer of energy by thermal radiation, or electromagnetic waves, is known as
radiant heat transfer. It happens in any transparent media, including gas, liquid, and

7. Environmental Heat Transfer
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solid states. All objects generate thermal radiation at temperatures higher than absolute
zero because matter's atoms and molecules move randomly. Rohsenow, W.M.,
Hartnett, et al 1998)
Heat transfer in buildings
Heat transfer in walls
The effect of the convective heat that the surface at each side of the element is
exchanging with the surrounding air and the radiant heat exchanges with other surfaces
that the surface is exposed to is known as conduction heat transfer through an opaque
building fabric element, such as an external wall as shown in Fig. 3. The absorbance of
solar radiation, including both direct and diffuse radiation, is included in the radiant
heat exchange at the outside side of an external wall or roof. (engineers daily, 2017)
Figure 3: Heat transfer at an external wall. (engineers daily, 2017)
Heat transfer in building windows:
Radiation from the glass of a typical window is often the source of energy loss from it.
In a double-glazed unit, heat is absorbed by the inner pane and transferred to the exterior
by conduction and convection (see Figure 4 for heat exchanges between the outer pane
and its colder surroundings). Units of measurement for a glazing unit's thermal

8. Environmental Heat Transfer
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transmittance are Watts per square meter per degree of temperature difference
(W/m2C), sometimes referred to as the U-value.
Within the glazing cavity, convection loses a tiny quantity of heat. There are situations
where the inner glass warms the air inside the cavity, especially in larger glazing
cavities. A convection current is created when heated air rises and is replaced by colder
air, transferring heat from the inner pane to the outside pane(s). Heat is carried via the
window frame in triple-glazing units; convection is minor in double-glazing units up to
20 mm, especially when argon gas is used, which is denser than air. The substance of
the frame determines the rate of conduction (U-value); generally speaking, wood
frames outperform metal frames in this regard. (Greenspec, 2023)
Figure 4: Windows: Heat loss & Heat gain. (Greenspec, 2023)
A double-glazed window's cutaway schematic is seen in Figure 5. This can be a sealed
double-glazing unit, often with a gap of about 16 mm between the panes, or it can be a
single-glazed window with an additional secondary pane installed separately. But the
fundamental ideas remain the same. (OpenLearn 2020)

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Figure 5: heat transfer double glazing in windows. (OpenLearn 2020)
Heat transfer through buildings rooms and roofs:
Even while convection often involves more variables than conduction, we are
nevertheless able to characterize it and do some simple, accurate calculations to
determine its effects. In constructing rooms, natural convection is caused by buoyant
forces: hot air rises because temperature causes density to decrease. This is how the
residence in Figure 6 is kept warm. (lumen learning 2023)
Figure 7 illustrates each of the three heat transmission techniques in this portion of the
attic. Solar radiation is absorbed by roofing materials. Warm attic air and exposed
framing are caused by the materials' reradiation of heat as they heat up. Conduction of
heat through the ceiling is restricted by insulation; the more the insulation, the greater
the barrier to conductive heat flow. Air is moved by convection through soffit and ridge
vents and by internal air pressure through ceiling apertures to help cool the attic. (Tim
Healey 2023)

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Figure 6: The so-called gravity furnace heats the air, which then rises and expands to
create a convective loop that distributes energy throughout the space. The air constricts
as it cools near ceilings and outside walls, finally becoming denser than room air and
dropping to the ground. This natural convection heating system, when correctly built,
may be quite effective in heating a home evenly. (uni central Florida 2023)
Figure 7: heat transfer through roofs. (Tim Healey 2023)

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Conclusion
Concluding everything together about heat transfer in building is that thermal energy
transfer from one place to another and there are 3 main types : conduction, convection,
radiation. Its calculation for application in uses of buildings heat transfer along with
Interior environmental analyses and Material or building element-related problems
In methodology it talks about the three main type of heat transfer in details its
requirements along others. Then the mention of our topic in building Heat transfer in
walls window rooms and roofs.

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References:
1. Energy saver (2023), the principle and types of heat transfer. [online] available
at: https://www.energy.gov/energysaver/principles-heating-and-
cooling#:~:text=Heat%20is%20transferred%20to%20and,conduction%2C%2
0radiation%2C%20and%20convection. [Accessed: Nov./30/2023]
2. Concept Group LLC (2023), What are the different types of heat transfer?
[online] available at: https://conceptgroupllc.com/glossary/what-is-heat-
transfer/#:~:text=Heat%20transfer%20refers%20to%20various,or%20more%2
0of%20these%20processes. [Accessed: Nov./30/2023]
3. Rohsenow, W.M., Hartnett, J.P. and Cho, Y.I., 1998. Handbook of heat transfer
(Vol. 3). New York: McGraw-Hill. Available at:
https://www.academia.edu/download/53726135/handbook_of_HeatTransfer.p
df [Accessed: Nov./30/2023]
4. Inna Sokolova, (2019)Convective heat flow from suddenly heated surfaces
embedded in porous media. [online] Available at:
https://www.sciencedirect.com/topics/earth-and-planetary-
sciences/convectiveheattransfer#:~:text=Convection,parcel%20of%20air%20o
r%20water. [Accessed: Nov./30/2023]
5. Maurice Stewart, (2021), radiation heat transfer. [online] Available at:
https://www.sciencedirect.com/book/9780128037225/surface-production-
operations [Accessed: Nov./30/2023]
6. Clayton DeKorne (2023), Heat Transfer Through Buildings. [online] Available
at: https://www.jlconline.com/training-the-trades/heat-transfer-through-
buildings_o#:~:text=Heat%20moves%20through%20building%20assemblies,in%20th
e%20transfer%20of%20heat. [Accessed: Nov./30/2023]
7. Kusuda, T., 1977. Fundamentals of building heat transfer. JOURNAL OF
RESEARCH of the National Bureau of Standards, 82(2), p.1. Available at:
https://nvlpubs.nist.gov/nistpubs/jres/82/jresv82n2p97_a1b.pdf [Accessed:
Nov./30/2023]
8. Let's Talk Science (2021), Introduction to Heat Transfer. [online images] .
Available at:

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https://letstalkscience.ca/educationalresources/backgrounders/introduction-heat-
transfer [Accessed: Nov./30/2023]
9. engineers daily, (2017), Heat Transfer in Building Elements, article:
26Oct2017. [online] Available at: https://www.engineersdaily.com/2017/10/heat-
transfer-in-building-elements.html [Accessed: Nov./30/2023]
10. Greenspec (2023), Windows: Heat loss & Heat gain. [online] Available at:
https://www.greenspec.co.uk/building-design/windows/ [Accessed:
Nov./30/2023]
11. OpenLearn (2020), Energy in buildings. [online] Available at:
https://www.open.edu/openlearn/nature-environment/energy-buildings/content-
section-2.2.1 [Accessed: Nov./30/2023]
12. Uni central Florida (2023), Mechanisms of Heat Transfer. [online] available at:
https://pressbooks.online.ucf.edu/osuniversityphysics2/chapter/mechanisms-
of-heat-transfer/ [ accessed: Dec./3/2023]
13. Tim Healey (2023), heat transfer through roofs. [online] available at:
https://www.jlconline.com/author/tim-healey [ accessed: Dec./3/2023]