Energy Efficient Design for a Connecticut Home
by
Michael J. Gasper
An Engineering Project Submitted to the Graduate Faculty of Rensselaer Polytechnic
Institute in Fulfillment of the Requirements of the degree of
MASTER OF ENGINEERING IN MECHANICAL ENGINEERING
Approved:
_
Ernesto Gutierrez-Miravete, Project Adviser
Rensselaer Polytechnic Institute
Hartford, Connecticut
December, 2014
ABSTRACT
Designing an energy efficient house is very complex. It can be designing electricity
sources, heating systems, cooling systems, and/or the compilation of building materials
and thicknesses used to build the house. This study did an analysis of the compilation of
building materials and thicknesses used to build the house since they significantly
impact wasted energy on heating and cooling in the summer and winter months
respectively. The base house used in this study is the 2011 Connecticut Home Builders
Association house of the year located in Griswold, Connecticut. More specifically the
type and thickness of insulation and walls, type of windows, and doors are analyzed to
determine what the best combination is. From the materials analyzed below for the walls
it was determined that log walls are the best external material and foam two part
urethane mixture is the best insulating material. Two common interior materials of
plaster and gypsum board make a negligible difference to the heat transfer rate so either
could be chosen. For each of these materials common thicknesses were chosen but
thicker walls and or materials would further decrease the heat transfer rate. For the
windows it was determined that a double pane krypton filled window is the most
efficient for heat transfer rate. The triple pane windows also have a good heat transfer
rate but would be better than the double pane in windy areas. It was determined that the
doors with the best heat transfer rate had a polyurethane core with either an aluminum,
fiberglass, or steel sheet on the exterior. The whole house analysis shows how efficient
the BAEC 2011 House of the Year really is. In some cases better materials for heat
transfer could have been used but they were most likely not cost effective at the time.
ii
CONTENTS
ABSTRACT ...................................................................................................................... ii
CONTENTS ..................................................................................................................... iii
LIST OF TABLES ............................................................................................................ iv
LIST OF FIGURES ........................................................................................................... v
SYMBOLS/ABBREVIATIONS LIST ............................................................................. vi
KEYWORDS .................................................................................................................... iv
1. - INTRODUCTION ..................................................................................................... 1
2. - METHODOLOGY .................................................................................................... 2
2.1-Walls ...................................................................................................................... 2
2.2-Roof ....................................................................................................................... 9
2.4-Windows ................................................................................................................ 9
2.5-Doors ................................................................................................................... 12
2.6-Whole House Analysis ........................................................................................ 15
3. - RESULTS AND DISCUSSION ............................................................................. 16
4. - CONCLUSION ....................................................................................................... 17
REFERENCES ................................................................................................................ 18
APPENDIX A .................................................................................................................. 19
APPENDIX B .................................................................................................................. 23
iii
LIST OF TABLES
Table 1: Heat Transfer Rate of Various Single Wall or Floor Materials........................... 2
Table 2: Heat Transfer Rate of Various Multi-Material Walls.......................................... 4
Table 3: Heat Transfer Rate of Various Single Pane Window Materials ........................ 10
Table 4: Heat Transfer Rate of Various Multi-Material Window Materials ................... 11
Table 5: Heat Transfer Rate of Various Single Door Materials ...................................... 13
Table 6: Heat Transfer Rate of Various Multi-Material Door Materials......................... 14
Table 8: Excel Equations-Heat Transfer Rate of Various Multi-Material Walls ............ 23
Table 9: Excel Equations-Heat Transfer Rate of Various Single Pane Window Materials
......................................................................................................................................... 26
Table 10: Excel Equations-Heat Transfer Rate of Various Multi-Material Window
Materials .......................................................................................................................... 26
Table 11: Excel Equations-Heat Transfer Rate of Various Single Door Materials ......... 27
Table 12: Excel Equations-Heat Transfer Rate of Various Multi-Material Door Materials
......................................................................................................................................... 27
iv
LIST OF FIGURES
Figure 1: Page 1 of BAEC 2011 House of the Year Brochure ........................................ 19
Figure 2: Page 2 of BAEC 2011 House of the Year Brochure ........................................ 20
Figure 3: Page 3 of BAEC 2011 House of the Year Brochure ........................................ 21
Figure 4: Page 4 of BAEC 2011 House of the Year Brochure ........................................ 22
v
SYMBOLS/ABBREVIATIONS LIST
Symbol/Abbreviation
Meaning
Units
T
Temperature
°F, °C, or K
A
Area
in2, ft2, mm2, or m2
L
Length
in, ft, mm, or m
k or h
Thermal Conductivity
W/mK
q
Heat Transfer Rate
W
vi
KEYWORDS
Word
Definition
Reference for
Definition
Heat Transfer
“Heat transfer describes the exchange of thermal energy,
(i)
between physical systems depending on
thetemperature and pressure, by dissipating heat. The
fundamental modes of heat transfer
are conduction ordiffusion, convection and radiation.”
Thermal
Conductivity
“In physics, thermal conductivity (often denoted k, λ, or κ)
(j)
is the property of a material to conduct heat. It is
evaluated primarily in terms of Fourier's Law for heat
conduction.
Heat transfer occurs at a higher rate across materials of
high thermal conductivity than across materials of low
thermal conductivity. Correspondingly materials of high
thermal conductivity are widely used in heat
sink applications and materials of low thermal
conductivity are used as thermal insulation. Thermal
conductivity of materials is temperature dependent.”
Conduction
“On a microscopic scale, heat conduction occurs as hot,
rapidly moving or vibrating atoms and molecules interact
with neighboring atoms and molecules, transferring some
of their energy (heat) to these neighboring particles. In
other words, heat is transferred by conduction when
adjacent atoms vibrate against one another, or as
electrons move from one atom to another. Conduction is
the most significant means of heat transfer within a solid
or between solid objects in thermal contact. Fluids—
especially gases—are less conductive.Thermal contact
conductance is the study of heat conduction” between
solid bodies in contact.[9]
iv
(i)
1. - INTRODUCTION
Designing an energy efficient house is very complex. It can be designing electricity
sources, heating systems, cooling systems, and/or the compilation of building materials
and thicknesses used to build the house. This study did an analysis of the compilation of
building materials and thicknesses used to build the house since they significantly
impact wasted energy on heating and cooling in the summer and winter months
respectively. From this study the materials with the best thermal properties can be
selected. Although the materials with the lowest heat transfer rate may not always be the
best cost effective materials for building. To determine the cost/benefit this analysis
should be coupled with the cost these materials in the area that you are building at that
time and the electricity rates and projections for the next few years ahead. Since we are
located in Connecticut the temperatures and base house used in this study is the 2011
Connecticut Home Builders Association house of the year located in Griswold,
Connecticut. This house was designed to be an energy efficient house. Extreme summer
outside temperatures differ only approximately 40 degrees from a normal inside
temperature whereas extreme winter outside temperatures are approximately 77 degrees
from a normal inside temperature. The materials below were analyzed in extreme winter
temperatures since that will create the largest temperature gradient and therefore the
largest heat transfer rate. There are many different styles of buildings which would also
greatly affect the heat transfer rate for the entire house on top of what is being used for
materials. For instance a conditioned attic will act differently than an unconditioned attic
especially if there are heat and or cooling ducts located in them spaces since they tend to
be a large loss.
1
2. - METHODOLOGY
2.1-Walls
Since the house analyzed in section 2.6 is located in Connecticut the lowest
temperature seen in Hartford in the 2013-2014 winter season was -9˚F on January 4,
2014 per Reference (b). For an energy saving house a good temperature to keep your
thermostat at in the winter is 68˚F per Reference (c). Therefore, assume all of the
following equations are done with an external temperature of -9˚F (250.37K) and an
internal temperature of 68˚F (293.15K). We will assume the heat transfer through a
single 25x8 foot wall (A=18.6m2) with no windows. Thickness is based on material and
construction and will vary. To determine which materials are the best to use for
construction, the one-dimensional steady-state conduction equation 3.4 from Reference
(a) can be applied to each material to obtain the heat transfer rate.
For example of a single material wall with standard brick:
𝑞𝑥 =
𝑊
k=0.72
𝑚×𝐾
𝑘𝐴
𝐿
(𝑇𝑠,1 − 𝑇𝑠,2 )
Equation 3.4 Reference (a)
from Table A.3 of Reference (a)
L=3.625 inches (0.092m) per Reference (d)
𝑞𝑥 =
𝑊
0.72 [𝑚 × 𝐾 ] × 18.6[𝑚2 ]
0.092[𝑚]
(293.15[𝐾] − 250.37[𝐾])
𝑞𝑥 = 6227𝑊
All thermal conductivity values in Table 1 are at approximately 300K.
Table 1: Heat Transfer Rate of Various Single Wall or Floor Materials
Material
Thermal
Reference for
Conductivity
Thermal
(k) [W/mK]
Conductivity
2
Thickness
of
Material
(L) [m]
Reference
for
Thickness
Heat
Transfer
Rate (q)
[W]
Standard Brick
0.72
(a)
0.092
(d)
6227
Doubled-up Brick
0.72
(a)
0.184
(d)
3114
Block 1.1
(a)
0.2
(a)
4376
Block 0.6
(a)
0.2
(a)
2387
Concrete
(Hallow)
Concrete
(Filled)
Cement (4 inch)
0.72
(a)
0.1016
(e)
5639
Cement (8 inch)
0.72
(a)
0.2032
(e)
2819
Cement (10 inch)
0.72
(a)
0.254
(e)
2256
Cement (12 inch)
0.72
(a)
0.3048
(e)
1880
Log (28mm)
0.12
(a)
0.028
(g)
3410
Log (34mm)
0.12
(a)
0.034
(g)
2808
Log (44mm)
0.12
(a)
0.044
(g)
2170
Log (70mm)
0.12
(a)
0.070
(g)
1364
Log (90mm)
0.12
(a)
0.090
(g)
1061
Similar to above with the same temperature difference and wall area the heat
transfer rate through multiple materials can be calculated. For example of a multimaterial wall with gypsum board, hardboard siding, and cellulose:
𝑊
𝑘𝑔𝑦𝑝𝑠𝑢𝑚 =0.17𝑚×𝐾 from Table A.3 of Reference (a)
𝑊
𝑘ℎ𝑎𝑟𝑑𝑏𝑜𝑎𝑟𝑑 𝑠𝑖𝑑𝑖𝑛𝑔 =0.094𝑚×𝐾 from Table A.3 of Reference (a)
𝑊
𝑘𝑐𝑒𝑙𝑙𝑢𝑜𝑠𝑒 =0.23𝑚×𝐾 from Reference (f)
𝐿1/2′′ 𝑔𝑦𝑝𝑠𝑢𝑚 =0.0127m
𝐿1/2′′ ℎ𝑎𝑟𝑑𝑏𝑜𝑎𝑟𝑑 𝑠𝑖𝑑𝑖𝑛𝑔 =0.0127m
𝐿8′′ 𝑐𝑒𝑙𝑙𝑢𝑜𝑠𝑒 =0.2032m
Using a modified equation 3.15 from Reference (a):
𝑞𝑥 =
(𝑇∞,1 − 𝑇∞,3 )
𝐿
𝐿
𝐿
[( 𝐴 ) + ( 𝐵 ) + ( 𝐶 )]
𝑘𝐴 𝐴
𝑘𝐵 𝐴
𝑘𝐶 𝐴
3
𝑞𝑥
(293.15[𝐾] − 250.37[𝐾])
=
0.0127𝑚
0.0127𝑚
0.2032
[(
)+(
)+(
)]
𝑊
𝑊
𝑊
0.17 [𝑚 × 𝐾 ] × 18.6[𝑚2 ]
0.094 [𝑚 × 𝐾 ] × 18.6[𝑚2 ]
0.23 [𝑚 × 𝐾 ] × 18.6[𝑚2 ]
𝑞𝑥 = 728𝑊
All thermal conductivity values in Table 2 are at approximately 300K.
Table 2: Heat Transfer Rate of Various Multi-Material Walls
Material
Thermal
Reference for
Conductivity
Thermal
(k) [W/mK]
Conductivity
Thickness
of
Material
(L) [m]
Reference
for
Thickness
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
8’’Celluose
0.23
(f)
0.2032
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
4’’Celluose
0.23
(f)
0.1016
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
6’’Celluose
0.23
(f)
0.1524
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
3-1/2’’Fiberglass-
0.046
(a)
0.0889
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
3-1/2’’Fiberglass-
0.038
(a)
0.0889
(-)
Heat
Transfer
Rate (q)
[W]
748
1279
944
377
16kg/m^3
4
316
28kg/m^3
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
3-1/2’’Fiberglass-
0.035
(a)
0.0889
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
6-1/2’’Fiberglass-
0.046
(a)
0.1651
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
6-1/2’’Fiberglass-
0.038
(a)
0.1651
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
6-1/2’’Fiberglass-
0.035
(a)
0.1651
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
8-1/2’’Fiberglass-
0.046
(a)
0.2159
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
8-1/2’’Fiberglass-
0.038
(a)
0.2159
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
8-1/2’’Fiberglass-
0.035
(a)
0.2159
(-)
0.17
(a)
0.0127
(-)
292
40kg/m^3
211
16kg/m^3
176
28kg/m^3
162
40kg/m^3
163
16kg/m^3
136
28kg/m^3
125
40kg/m^3
½’’Gypsum
5
313
½’’Plywood
0.12
(a)
0.0127
(-)
4’’Fiberglass/blown-
0.043
(a)
0.1016
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
6’’Fiberglass/blown-
0.043
(a)
0.1524
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
8’’Fiberglass/blown-
0.043
(a)
0.2032
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
(a)
0.1016
(-)
16kg/m^3
214
16kg/m^3
162
16kg/m^3
4’’Urethane Two Part 0.026
195
Foam
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
(a)
0.1524
(-)
6’’Urethane Two Part 0.026
132
Foam
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
(a)
0.2032
(-)
8’’Urethane Two Part 0.026
100
Foam
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
(a)
0.1016
(-)
4’’Vermiculite Flakes 0.068
475
80kg/m^3
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
(a)
0.1524
(-)
6’’Vermiculite Flakes 0.068
6
329
80kg/m^3
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
(a)
0.2032
(-)
8’’Vermiculite Flakes 0.068
251
80kg/m^3
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
(a)
0.1016
(-)
4’’Vermiculite Flakes 0.063
444
160kg/m^3
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
(a)
0.1524
(-)
6’’Vermiculite Flakes 0.063
306
160kg/m^3
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
(a)
0.2032
(-)
8’’Vermiculite Flakes 0.063
234
160kg/m^3
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
4’’Mineral Wool
0.046
(a)
0.1016
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
6’’Mineral Wool
0.046
(a)
0.1524
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
½’’Plywood
0.12
(a)
0.0127
(-)
8’’Mineral Wool
0.046
(a)
0.2032
(-)
333
Granules with
Asbestos
228
Granules with
Asbestos
7
173
Granules with
Asbestos
1’’Gypsum Plaster,
0.22
(a)
0.0254
(n)
½’’Plywood
0.12
(a)
0.0127
(-)
8’’Celluose
0.23
(a)
0.2032
(-)
1’’Gypsum Plaster,
0.22
(a)
0.0254
(n)
½’’Plywood
0.12
(a)
0.0127
(-)
8’’Celluose
0.23
(a)
0.2032
(-)
1’’Gypsum Plaster,
0.22
(a)
0.0254
(n)
½’’Plywood
0.12
(a)
0.0127
(-)
8’’Celluose
0.23
(a)
0.2032
(-)
11mm Hardboard
0.094
(a)
0.011
(-)
0.22
(a)
0.0254
(n)
90mm Log
0.12
(a)
0.09
(-)
8’’Urethane Two Part
0.026
(a)
0.2032
(-)
½’’Gypsum
0.17
(a)
0.0127
(-)
90mm Log
0.12
(a)
0.09
(-)
8’’Urethane Two Part
0.026
(a)
0.2032
(-)
720
Sand Aggregate
729
Vermiculite
Aggregate
651
Sand Aggregate
Siding
1’’Gypsum Plaster,
92
Sand Aggregate
Foam
8
92
Foam
1/4’’Gypsum
0.17
(a)
0.0127
(-)
90mm Log
0.12
(a)
0.09
(-)
8’’Urethane Two Part
0.026
(a)
0.2032
(-)
92
Foam
For additional information on heat transfer of different wood materials Reference (l)
goes in depth. The 4 of the 5 most common insulating material per Reference (m) are
shown in the table above as options. The 5th material is polystyrene which is a foam
board. This can be added to any wall for additional heat transfer and moisture barrier
properties.
2.2-Roof
There are 2 main designs for ceilings/roofs for insulating. The two options are
conditioned and unconditioned attics as described in Reference (o). Both of these behave
similar for heat transfer. For the purposes of this paper and general house building the
ceiling would consist of gypsum board, insulation, and a plywood layer similarly to the
walls above.
2.3-Ground
The ground/foundation can be considered to be cement. We are assuming no
raised structure and that it is below ground such as a basement. Since this is below
ground the exterior will be approximately a constant temperature below the frost line. A
minimal heat transfer can be assumed through the ground/foundation similarly to the
single cement wall above.
2.4-Windows
Using the same methodology and equations as Chapter 1 for walls the heat
transfer rate through various windows can be calculated. For the purposes of showing
which windows are the most efficient we will assume the window size is 58 x 36 inches
9
(A=1.34709m2). Windows come in many various sizes and if a whole house analysis is
performed the specific sizes of each window should be used for accuracy.
For example of a single material window with glass:
𝑞𝑥 =
𝑘𝐴
𝐿
(𝑇𝑠,1 − 𝑇𝑠,2 )
Equation 3.4 Reference (a)
𝑊
k=0.9𝑚×𝐾 from Table I of Reference (h)
L=0.003m per Reference (h)
𝑞𝑥 =
𝑊
0.9 [𝑚 × 𝐾 ] × 1.34709[𝑚2 ]
0.003[𝑚]
(293.15[𝐾] − 250.37[𝐾])
𝑞𝑥 = 17,289𝑊
Table 3: Heat Transfer Rate of Various Single Pane Window Materials
Material
Thermal
Reference for
Conductivity
Thermal
(k) [W/mK]
Conductivity
Thickness
of
Material
(L) [m]
Reference
for
Thickness
Heat
Transfer
Rate (q)
[W]
Glass
0.9
(h)
0.003
(h)
17289
Polyester film
0.14
(h)
0.0001
(h)
80680
Acrylic or
0.19
(h)
0.006
(h)
1825
polycarbonate sheet
Glass is the material that is usually used for most window applications. Acrylic or
polycarbonate are used for applications such as storm windows. Most windows in newer
houses are a composite of double or triple pane with gas separating the panes. For ease
of calculation we are going to assume each composite window has a total thickness of
one inch (0.0254m) and each glass pane has a thickness of 3mm (0.003m). These are the
average window and glass thicknesses but glass and windows can be thicker or thinner
than these in specific applications.
For example of a multi-material with glass-argon-glass:
10
𝑊
𝑘𝑔𝑙𝑎𝑠𝑠 =0.9𝑚×𝐾 from Table I of Reference (h)
𝑊
ℎ𝑎𝑟𝑔𝑜𝑛 =0.016𝑚×𝐾 from Reference (f)
𝑊
ℎ𝑎𝑖𝑟 =0.024𝑚×𝐾 from Reference (f)
𝑊
ℎ𝑘𝑟𝑦𝑝𝑡𝑜𝑛 =0.0088𝑚×𝐾 from Reference (f)
𝐿𝑔𝑙𝑎𝑠𝑠 =0.003m from Reference (h)
𝐿𝑔𝑎𝑝 𝑓𝑜𝑟 𝑔𝑎𝑠 𝑑𝑜𝑢𝑏𝑙𝑒 𝑝𝑎𝑛𝑒 =0.0194m
𝐿𝑔𝑎𝑝 𝑓𝑜𝑟 𝑔𝑎𝑠 𝑡𝑟𝑖𝑝𝑙𝑒 𝑝𝑎𝑛𝑒 =0.0082m
Using a modified equation 3.15 from Reference (a):
𝑞𝑥 =
(𝑇∞,1 − 𝑇∞,3 )
𝐿
𝐿
𝐿
[( 𝐴 ) + ( 𝐵 ) + ( 𝐶 )]
𝑘𝐴 𝐴
ℎ𝐵 𝐴
𝑘𝐶 𝐴
𝑞𝑥
(293.15[𝐾] − 250.37[𝐾])
=
0.003𝑚
0.0194𝑚
0.003
[(
)+(
)+(
)]
𝑊
𝑊
𝑊
2
2
2
]
]
]
0.9 [
] × 1.35[𝑚
0.016 [
] × 1.35[𝑚
0.9 [
] × 1.35[𝑚
𝑚×𝐾
𝑚×𝐾
𝑚×𝐾
𝑞𝑥 = 653𝑊
Table 4: Heat Transfer Rate of Various Multi-Material Window Materials
Material
Thermal
Reference for
Conductivity
Thermal
(k) [W/mK]
Conductivity
Thickness
of
Material
(L) [m]
Reference
for
Thickness
Glass
0.9
(h)
0.003
(h)
Argon
0.016
(f)
0.0194
(-)
Glass
0.9
(h)
0.003
(h)
Glass
0.9
(h)
0.003
(h)
Argon
0.016
(f)
0.0082
(-)
Glass
0.9
(h)
0.003
(h)
Argon
0.016
(f)
0.0082
(-)
11
Heat
Transfer
Rate (q)
[W]
653
769
Glass
0.9
(h)
0.003
(h)
Glass
0.9
(h)
0.003
(h)
Air
0.024
(f)
0.0194
(-)
Glass
0.9
(h)
0.003
(h)
Glass
0.9
(h)
0.003
(h)
Air
0.024
(f)
0.0082
(-)
Glass
0.9
(h)
0.003
(h)
Air
0.024
(f)
0.0082
(-)
Glass
0.9
(h)
0.003
(h)
Glass
0.9
(h)
0.003
(h)
Krypton
0.0088
(f)
0.0194
(-)
Glass
0.9
(h)
0.003
(h)
Glass
0.9
(h)
0.003
(h)
Krypton
0.0088
(f)
0.0082
(-)
Glass
0.9
(h)
0.003
(h)
Krypton
0.0088
(f)
0.0082
(-)
Glass
0.9
(h)
0.003
(h)
Glass
0.9
(h)
0.003
(h)
Argon
0.016
(f)
0.0082
(-)
Glass
0.9
(h)
0.003
(h)
Krypton
0.0088
(f)
0.0082
(-)
Glass
0.9
(h)
0.003
(h)
976
1148
360
425
547
Windows triple pane windows with krypton as the gas are the most efficient but
depending on budget triple pane windows with argon is close to the efficiency with
much less cost.
2.5-Doors
Using the same methodology and equations as for walls the heat transfer rate
through various doors can be calculated. The door options below are for ones without a
12
glass window. Ones with a glass window will be less efficient. If you are designing a
house and using a door with a window, the window area should be considered in the
calculation. Assume all of the doors below are 1.75 inches or 0.04445 meters thick with
an area of 1.85806m2 (36 x 80 inches).
For example of a single material door with wood (oak or maple):
𝑞𝑥 =
𝑘𝐴
𝐿
(𝑇𝑠,1 − 𝑇𝑠,2 )
Equation 3.4 Reference (a)
𝑊
k=0.16𝑚×𝐾 from Table A.3 of Reference (a)
𝑞𝑥 =
0.16 [
𝑊
] × 1.85806[𝑚2 ]
𝑚×𝐾
(293.15[𝐾] − 250.37[𝐾])
0.04445[𝑚]
𝑞𝑥 = 286𝑊
All thermal conductivity values in Table 5 are at approximately 300K.
Table 5: Heat Transfer Rate of Various Single Door Materials
Material
Thermal
Reference for
Conductivity
Thermal
(k) [W/mK]
Conductivity
Thickness
of
Material
(L) [m]
Reference
for
Thickness
Heat
Transfer
Rate (q)
[W]
Hardwood
0.16
(a)
0.04445
(-)
286
Polyvinyl Chloride
0.19
(f)
0.04445
(-)
340
Fiberglass
0.04
(f)
0.04445
(-)
72
Similar to above with the same temperature difference, door thickness, and door
area the heat transfer rate through multiple materials can be calculated. For example of a
multi-material door with steel, polyurethane, and steel:
𝑊
𝑘𝑠𝑡𝑒𝑒𝑙 =16𝑚×𝐾 from Table A.3 of Reference (a)
𝑘𝑓𝑖𝑏𝑒𝑟𝑔𝑙𝑎𝑠𝑠 =0.04
𝑊
𝑚×𝐾
from Table A.3 of Reference (a)
𝑊
𝑘𝑎𝑙𝑢𝑚𝑖𝑛𝑢𝑚 =205 𝑚×𝐾 from Reference (f)
13
𝑊
𝑘𝑝𝑜𝑙𝑦𝑢𝑟𝑒𝑡ℎ𝑎𝑛𝑒 =0.03𝑚×𝐾 from Reference (f)
𝐿 1 ′′
32
𝑓𝑖𝑏𝑒𝑟𝑔𝑙𝑎𝑠𝑠,𝑎𝑙𝑢𝑚𝑖𝑛𝑢𝑚,𝑜𝑟 𝑠𝑡𝑒𝑒𝑙
=0.00079375m
𝐿𝑝𝑜𝑙𝑦𝑢𝑟𝑒ℎ𝑎𝑛𝑒 =0.042863m
Using a modified equation 3.15 from Reference (a):
𝑞𝑥 =
(𝑇∞,1 − 𝑇∞,3 )
𝐿
𝐿
𝐿
[( 𝐴 ) + ( 𝐵 ) + ( 𝐶 )]
𝑘𝐴 𝐴
𝑘𝐵 𝐴
𝑘𝐶 𝐴
𝑞𝑥
(293.15[𝐾] − 250.37[𝐾])
=
0.00079375𝑚
0.042863𝑚
0.00079375𝑚
[(
)
+
(
)
+
(
)]
𝑊
𝑊
𝑊
16 [𝑚 × 𝐾 ] × 1.858[𝑚2 ]
0.03 [𝑚 × 𝐾 ] × 1.858[𝑚2 ]
16 [𝑚 × 𝐾 ] × 1.858[𝑚2 ]
𝑞𝑥 = 56𝑊
All thermal conductivity values in Table 6 are at approximately 300K.
Table 6: Heat Transfer Rate of Various Multi-Material Door Materials
Material
Thermal
Reference for
Conductivity
Thermal
(k) [W/mK]
Conductivity
Thickness
of
Material
(L) [m]
Reference
for
Thickness
Steel
16
(f)
(-)
0.00079375𝑚
Polyurethane
0.03
(f)
0.042863
Steel
16
(f)
(-)
0.00079375𝑚
Fiberglass
0.04
(f)
(-)
0.00079375𝑚
Polyurethane
0.03
(f)
0.042863
Fiberglass
0.04
(f)
(-)
0.00079375𝑚
Aluminum
205
(f)
(-)
0.00079375𝑚
Polyurethane
0.03
(f)
0.042863
14
Heat
Transfer
Rate (q)
[W]
56
(-)
54
(-)
(-)
56
Aluminum
205
(-)
0.00079375𝑚
(f)
2.6-Whole House Analysis
The above information for a single wall, door, and window can be combined to
analyze an entire house as shown in this section. The ceiling has the same thickness
gypsum board, cellulose insulation, and hardboard that the walls have so for calculation
purposes we can assume a box. The length of the house is approximately 50 feet and the
width is approximately 25 feet. This house is a split level with a basement under half and
an attached garage under the other, therefore, we can assume this is 2 stories or
approximately 16 feet high. Both of the shorter sides have no windows and are
approximately 25 feet by 16 feet so the value in section 2.1 can be multiplied by 4 to get
the losses on those walls. The front has 5 windows, a door, and a garage door and the
back has 6 windows and a sliding door which subtract area off of the two 50 foot by 16
foot areas.
15
3. - RESULTS AND DISCUSSION
From the materials analyzed for the walls it was determined that log walls are the best
external material and foam two part urethane mixture is the best insulating material. Two
common interior materials of plaster and gypsum board make a negligible difference to
the heat transfer rate so either could be chosen. For each of these materials common
thicknesses were chosen but thicker walls and or materials would further decrease the
heat transfer rate. For the windows it was determined that a double pane krypton filled
window is the most efficient for heat transfer rate. The triple pane windows also have a
good heat transfer rate but would be better than the double pane in windy areas. It was
determined that the doors with the best heat transfer rate had a polyurethane core with
either an aluminum, fiberglass, or steel sheet on the exterior. The whole house analysis
shows how efficient the BAEC 2011 House of the Year really is. In some cases better
materials for heat transfer could have been used but they were most likely not cost
effective at the time. Since building material cost varies greatly based on location and
year the buyer/builder would have to determine energy efficiency versus cost at the time
they are considering the project.
16
4. - CONCLUSION
Designing an energy efficient house is very complex. It can be designing electricity
sources, heating systems, cooling systems, and/or the compilation of building materials
and thicknesses used to build the house. From the materials analyzed below for the walls
it was determined that log walls are the best external material and foam two part
urethane mixture is the best insulating material. Two common interior materials of
plaster and gypsum board make a negligible difference to the heat transfer rate so either
could be chosen. For each of these materials common thicknesses were chosen but
thicker walls and or materials would further decrease the heat transfer rate. For the
windows it was determined that a double pane krypton filled window is the most
efficient for heat transfer rate. The triple pane windows also have a good heat transfer
rate but would be better than the double pane in windy areas. It was determined that the
doors with the best heat transfer rate had a polyurethane core with either an aluminum,
fiberglass, or steel sheet on the exterior. The whole house analysis shows how efficient
the BAEC 2011 House of the Year really is. It was determined that better materials
could have been used in some cases but would have significantly raised the construction
cost of the building. Since building material cost varies greatly based on location and
year the buyer/builder would have to determine energy efficiency versus cost at the time
they are considering the project.
17
REFERENCES
a) Fundamentals of Heat and Mass Transfer 6th Edition; Incorpera, DeWirr, Bergman,
Lavine, 2007
b) http://www.weatherworksinc.com/winter-statistics-2013-2014
c) http://energy.gov/energysaver/articles/thermostats
d) http://www.archtoolbox.com/materials-systems/masonry/bricksizes.html
e) http://extension.missouri.edu/p/g1700
f) http://www.engineeringtoolbox.com/thermal-conductivity-d_429.html
g) http://www.northwestlogcabins.co.uk/department/the_top_10_tips_on_choosing_a_c
abin/
h) Calculating Heat Transfer Through Windows; Energy Research, Vol 6, 341-349
(1982); Michael Rubin; Lawrence Berkeley Laboratory, University of California,
Berkeley, California 94720, U.S.A.
i) http://en.wikipedia.org/wiki/Heat_transfer
j) http://en.wikipedia.org/wiki/Thermal_conductivity
k) http://www.jm.com/content/dam/jm/global/en/buildinginsulation/Files/BI%20Data%20Sheets/Resi%20and%20Commercial/BID0016%20Kraft-Faced%20Fiber%20Glass%20Data%20Sheet-Acrylic%20Binder.pdf
l) http://www.fpl.fs.fed.us/documnts/pdf1988/tenwo88a.pdf
m) http://www.thermaxxjackets.com/5-most-common-thermal-insulation-materials/
n) http://thecraftsmanblog.com/5-worst-mistakes-of-historic-homeowners-part-4plaster/
o) http://www.greenbuildingadvisor.com/blogs/dept/qa-spotlight/determining-bestattic-option
18
APPENDIX A
This appendix is a brochure from the Builders Association of Eastern Connecticut on
their green 2011 house of the year. This brochure gives details about the construction
and dimensions of the house that are in section 2.6 of this paper.
Figure 1: Page 1 of BAEC 2011 House of the Year Brochure
19
Figure 2: Page 2 of BAEC 2011 House of the Year Brochure
20
Figure 3: Page 3 of BAEC 2011 House of the Year Brochure
21
Figure 4: Page 4 of BAEC 2011 House of the Year Brochure
22
APPENDIX B
The tables below are from excel and show the equations behind the numbers in the
paper above.
Table 7: Excel Equations-Heat Transfer Rate of Various Single Wall or Floor Materials
Single
Material
Walls
Item
brick
doubled brick
block hallow
block filled
cement-4
cement-8
cement-10
cement-12
log -28
log -34
log -44
log -70
log -90
k
0.72
0.72
1.1
0.6
0.72
0.72
0.72
0.72
0.12
0.12
0.12
0.12
0.12
L
0.092
=D4*2
0.2
0.2
0.1016
0.2032
0.254
0.3048
0.028
0.034
0.044
0.07
0.09
q
=C4*18.6*(293.15-250.37)/D4
=C5*18.6*(293.15-250.37)/D5
=C6*18.6*(293.15-250.37)/D6
=C7*18.6*(293.15-250.37)/D7
=C8*18.6*(293.15-250.37)/D8
=C9*18.6*(293.15-250.37)/D9
=C10*18.6*(293.15-250.37)/D10
=C11*18.6*(293.15-250.37)/D11
=C12*18.6*(293.15-250.37)/D12
=C13*18.6*(293.15-250.37)/D13
=C14*18.6*(293.15-250.37)/D14
=C15*18.6*(293.15-250.37)/D15
=C16*18.6*(293.15-250.37)/D16
Table 8: Excel Equations-Heat Transfer Rate of Various Multi-Material Walls
Multi-Material
Walls
Item
3-1/2-fiberglass-28
1/2-gypsum
1/2-plywood
3-1/2-fiberglass-40
1/2-gypsum
1/2-plywood
6-1/2-fiberglass-16
1/2-gypsum
1/2-plywood
6-1/2-fiberglass-28
1/2-gypsum
1/2-plywood
6-1/2-fiberglass-40
1/2-gypsum
1/2-plywood
k
L
0.038
0.17
0.12
0.035
0.17
0.12
0.046
0.17
0.12
0.038
0.17
0.12
0.035
0.17
0.12
23
0.0889
0.0127
0.0127
0.0889
0.0127
0.0127
0.1651
0.0127
0.0127
0.1651
0.0127
0.0127
0.1651
0.0127
0.0127
=(293.
=(293.
=(293.
=(293.
=(293.
8-1/2-fiberglass-16
1/2-gypsum
1/2-plywood
8-1/2-fiberglass-28
1/2-gypsum
1/2-plywood
8-1/2-fiberglass-40
1/2-gypsum
1/2-plywood
4-fiberglass blown-16
1/2-gypsum
1/2-plywood
6-fiberglass blown-16
1/2-gypsum
1/2-plywood
8-fiberglass blown-16
1/2-gypsum
1/2-plywood
4-urethane 2 part mixture foam
1/2-gypsum
1/2-plywood
6-urethane 2 part mixture foam
1/2-gypsum
1/2-plywood
8-urethane 2 part mixture foam
1/2-gypsum
1/2-plywood
4-vermiculite flakes - 80
1/2-gypsum
1/2-plywood
6-vermiculite flakes - 80
1/2-gypsum
1/2-plywood
8-vermiculite flakes - 80
1/2-gypsum
1/2-plywood
4-vermiculite flakes - 160
1/2-gypsum
1/2-plywood
6-vermiculite flakes - 160
1/2-gypsum
24
0.046
0.17
0.12
0.038
0.17
0.12
0.035
0.17
0.12
0.043
0.17
0.12
0.043
0.17
0.12
0.043
0.17
0.12
0.026
0.17
0.12
0.026
0.17
0.12
0.026
0.17
0.12
0.068
0.17
0.12
0.068
0.17
0.12
0.068
0.17
0.12
0.063
0.17
0.12
0.063
0.17
0.2159
0.0127
0.0127
0.2159
0.0127
0.0127
0.2159
0.0127
0.0127
0.1016
0.0127
0.0127
0.1524
0.0127
0.0127
0.2032
0.0127
0.0127
0.1016
0.0127
0.0127
0.1524
0.0127
0.0127
0.2032
0.0127
0.0127
0.1016
0.0127
0.0127
0.1524
0.0127
0.0127
0.2032
0.0127
0.0127
0.1016
0.0127
0.0127
0.1524
0.0127
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
1/2-plywood
8-vermiculite flakes - 160
1/2-gypsum
1/2-plywood
4-Mineral wool granules with
asbestos
1/2-gypsum
1/2-plywood
6-Mineral wool granules with
asbestos
1/2-gypsum
1/2-plywood
8-Mineral wool granules with
asbestos
0.12
0.063
0.17
0.12
0.0127
0.2032
0.0127
0.0127
0.046
0.1016
0.17
0.12
0.0127
0.0127
0.046
0.1524
0.17
0.12
0.0127
0.0127
0.046
0.2032
1-gypsum plaster, sand aggregate
1/2-plywood
8-celluose
0.22
0.12
0.23
0.0254
0.0127
0.2032
0.25
0.0254
0.12
0.23
0.0127
0.2032
1-gypsum plaster, sand aggregate
1/2-plywood
8-celluose
11-hardboard siding
0.22
0.12
0.23
0.094
0.0254
0.0127
0.2032
0.011
1-gypsum plaster, sand aggregate
log -90
8-urethane 2 part mixture foam
0.22
0.12
0.026
0.0254
0.09
0.2032
=(293.
1/2-gypsum
log -90
8-urethane 2 part mixture foam
0.17
0.12
0.026
0.0127
0.09
0.2032
=(293.
1/4-gypsum
log -90
8-urethane 2 part mixture foam
0.17
0.12
0.026
0.00635
0.09
0.2032
1-gypsum plaster, vermiculite
aggregate
1/2-plywood
8-celluose
25
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
=(293.
250.37
Table 9: Excel Equations-Heat Transfer Rate of Various Single Pane Window Materials
Single
Material
Windows
Item
glass
polyester film
acrylic or polycarbonate
sheet
k
0.9
0.14
L
0.003
0.0001
q
=C126*1.34709*
=C127*1.34709*
0.19
0.006
=C128*1.34709*
Table 10: Excel Equations-Heat Transfer Rate of Various Multi-Material Window
Materials
Multi-Material
Windows
Item
0.003 glass
0.0194 argon
0.003 glass
0.003 glass
0.0082 argon
0.003 glass
0.0082 argon
0.003 glass
0.003 glass
0.0194 air
0.003 glass
0.003 glass
0.0082 air
0.003 glass
0.0082 air
k
0.9
0.016
0.9
0.9
0.016
0.9
0.016
0.9
0.9
0.024
0.9
0.9
0.024
0.9
0.024
26
L
0.003
0.0194
0.003
0.003
0.0082
0.003
0.0082
0.003
0.003
0.0194
0.003
0.003
0.0082
0.003
0.0082
q
=(293.15-250.37)/((D
=(293.15250.37)/((D133/(C13
=(293.15-250.37)/((D
=(293.15250.37)/((D141/(C14
0.003 glass
0.003 glass
0.0194 krypton
0.003 glass
0.003 glass
0.0082 krypton
0.003 glass
0.0082 krypton
0.003 glass
0.003 glass
0.0082argon
0.003 glass
0.0082 krypton
0.003 glass
0.9
0.9
0.0088
0.9
0.9
0.0088
0.9
0.0088
0.9
0.9
0.016
0.9
0.0088
0.9
0.003
0.003
0.0194
0.003
0.003
0.0082
0.003
0.0082
0.003
0.003
0.0082
0.003
0.0082
0.003
=(293.15-250.37)/((D
=(293.15250.37)/((D149/(C14
=(293.15250.37)/((D154/(C15
Table 11: Excel Equations-Heat Transfer Rate of Various Single Door Materials
Single
Material
Doors
Item
hardwood door
PVC
fiberglass
k
0.16
0.19
0.04
L
0.04445
0.04445
0.04445
q
=C160*1.85806*(293
=C161*1.85806*(293
=C162*1.85806*(293
Table 12: Excel Equations-Heat Transfer Rate of Various Multi-Material Door Materials
Multi-Material
Doors
Item
steel
polyurethane
steel
fiberglass
polyurethane
fiberglass
aluminum
polyurethane
aluminum
k
16
0.03
16
0.04
0.03
0.04
205
0.03
205
27
L
0.00079375
0.042863
0.00079375
0.00079375
0.042863
0.00079375
0.00079375
0.042863
0.00079375
q
=(293.15-250.37)/((D
=(293.15-250.37)/((D
=(293.15-250.37)/((D