High Performance Homes in Saudi Arabia
Revised Passivhaus Principles for Hot and Arid Climates
A Thesis
Presented to the Faculty
of Philadelphia University
in Partial Fulfillment of the Requirement for Degree of
Master of Science in Sustainable Design
By
Mohammad A. Alshenaifi
May 2015
© 2015 Mohammad A. Alshenaifi
ii
ABSTRACT
The aim of the study is to achieve a net-zero energy home in Saudi Arabia in
order to limit the risk associated with the high energy consumption and CO2 emissions.
The Passivhaus concept is taken into consideration to achieve the goal of the study, as
the concept was initially developed to create high-performance homes in cold climates.
However, the Passivhaus did not achieve the same level of performance in hot and arid
climates when compared to what have been achieved in cold climates. The study will
discuss first the potential improvements in energy performance using the Passivhaus
standard in hot and arid climates, and explore the potential to achieve the goal of this
study.
Based on the results of the analysis of the proposed Passivhaus, the Passive
Down-Draft Evaporative Cooling (PDEC) will be implemented into the design with the
goal of increasing the energy efficiency of the building. PDEC is a passive evaporative
cooling strategy that cools the warm fresh air by the evaporation of water. The strategy
will not make the building airtight, which would be counter to one of the Passivhaus
principles. Based upon the success of the PDEC performance, this study suggests that
the Passivhaus principles should be revised for hot and arid climates.
This study provides a proposal of a potential net-zero energy house in Saudi
Arabia. Upon the success of the study, the Passivhaus design for hot and dry climates
would be an ideal means to significantly reduce the high energy consumption in Saudi
Arabia.
iii
ACKNOWLEDGEMENTS
My parents, even when I am very far from you, I always feel you near me, and
your prayers for me. I attribute the success in everything in my life to you. Thank you for
supporting me through thick and thin.
My wife, in every step during my study, I have been inspired by you, and I am
sure you will continue to inspire me in everything I will do in the future. Thank you for
being such a positive force in my life, for everything you have provided me since the first
day we met, and for your patience.
Professor Fleming, thank you so much for being such a wonderful leader,
teacher, and great supporter since our first meeting. The knowledge and experience I
have gained from you are so valuable to me.
Professor Fryer, thank you for helping me with every step in this project, and for
listening to me generously. This study will not have been accomplished without your
support, help, and valuable knowledge.
To all my teachers past and present, thank you for providing the path to achieve
my goals.
Thanks also to all my classmates in the Sustainable Design Program. Every
great moment I have spent at Philadelphia University was great because of you.
iv
TABLE OF CONTENTS
ABSTRACT ............................................................................................... iii
ACKNOWLEDGEMENTS ......................................................................... iv
LIST OF TABLES ..................................................................................... vii
LIST OF FIGURES ................................................................................... viii
LIST OF ABBREVIATIONS....................................................................... xi
CHAPTER 1: INTRODUCTION .................................................................. 1
The Need for Net-Zero Energy Homes in Saudi Arabia......................................................... 1
Building Consumption in Saudi Arabia .......................................................................................... 2
The Case of the Passivhaus for Hot and Dry Climates ......................................................... 4
CHAPTER 2: THE PROBLEM ................................................................... 6
The Passivhaus as a Solution .............................................................................................................. 6
The First Passivhaus in the Middle East: Qatar ........................................................................ 7
The Desert Passive House, Hereford, AZ ................................................................................... 10
LeBois House, Lafayette, LA .............................................................................................................. 11
CHAPTER 3: THE PROBLEM EVALUATION ......................................... 14
CHAPTER 4: THE ANALYSIS AND DESIGN PROPOSAL ..................... 17
The Site............................................................................................................................................................ 18
The Orientation and Form Analysis ............................................................................................... 21
The Baseline Design................................................................................................................................ 25
The Case of the Passivhaus ............................................................................................................... 33
Optimized Building Envelope ............................................................................................................ 33
Daylighting and High Efficiency Lighting and Appliances .............................................. 37
v
High Efficiency Air Conditioning System ................................................................................... 40
Onsite Solar Photovoltaic .................................................................................................................... 41
Passive House Energy Performance ............................................................................................. 41
Evaporative Cooling ................................................................................................................................ 43
Energy Performance................................................................................................................................ 54
Supply Temperature ................................................................................................................................ 59
Case Studies ................................................................................................................................................ 63
The New Stock Exchange in Malta ............................................................................................. 63
Zion National Park Visitor Center ............................................................................................... 66
Passive Down-Draft Evaporative Cooling in Saudi Arabia ......................................... 69
Case Studies Summary .................................................................................................................... 71
CHAPTER 5: CONCLUSION ................................................................... 72
BIBLIOGRAPHY ...................................................................................... 76
vi
LIST OF TABLES
TABLE 4-1: Building Spaces and Their Areas……………………………………………...25
TABLE 4-2: First Floor Spaces and Their Total Areas…………………………………….26
TABLE 4-3: Second Floor Spaces and Their Total Areas………………………………...27
TABLE 4-4: Potential Air Supply Temperature from the PDEC System…………………61
vii
LIST OF FIGURES
FIGURE 1-1: SA Oil Consumption since 1980………….……………………………………1
FIGURE 1-2: Energy Consumption by Sector in Saudi Arabia…………………………….2
FIGURE 1-3: Picture shows the lack of thermal insulation in typical residential
buildings construction in Saudi Arabia……………...………………………...3
FIGURE 1-4: The Passivhaus Concept developed in 1996 by Dr. Feist………………….5
FIGURE 2-1: Perspective of the two buildings, Passivhaus villa and baseline villa……..9
FIGURE 2-2: 3D floor plan for the designs and PV panels covering the
Passivhaus roof………………………………………………………………….9
FIGURE 2-3: The Desert Passive House in Hereford, AZ ......................................…...10
FIGURE 2-4: The LeBois House in Lafayette, LA………………………….………..…….12
FIGURE 2-5: 3D drawing showing the compact design of the house with
the mechanical system………………………………………………………..12
FIGURE 3-1: CO2 emissions have been increasing since 1980…………………………15
FIGURE 3-2: the expected energy generation from non-fossil fuel sources
until 2032…………………………………………………………………….....15
FIGURE 4-1: Hail is located in the north Region of Saudi Arabia………………………..18
FIGURE 1-2: The Site is Located in a Farming Area 15 Mi. North of the
City of Hail……………………………………………………………………...18
FIGURE 4-3: The site is located inside a farm and some pictures of the site ...….…...19
FIGURE 4-4: Weather history in 2014………………………………………………………20
FIGURE 4-5: Weather history in 2013………………………………………………………20
FIGURE 4-6: Prevailing wind directions over the entire year……………………….……21
FIGURE 4-7: Fraction of time spent with…………………………………………….……..21
FIGURE 4-8: The weather tool in Ecotect suggest the best orientation
to be south………………………………………………………………...….22
FIGURE 4-9: Forms and solar radiation analysis for five different forms………….……23
FIGURE 4-10: The annual shadow range in the courtyard and a graph
from the National Renewable Energy Laboratory………………………..24
FIGURE 4-11: the First Floor of the baseline design...…………………..….…….……... 26
FIGURE 4-12: the Second floor of the baseline design………………………….….…….27
FIGURE 4-13: Section A of the baseline design…………………………………….…….28
viii
FIGURE 4-14: Section B of the baseline design……………………………….………….28
FIGURE 4-15: Section C of the baseline design………………………………….……….28
FIGURE 6-16: South Elevation of the baseline design………………………….………..29
FIGURE 4-17: North Elevation of the baseline design…………………………………….29
FIGURE 4-18: East Elevation of the baseline design……………………………………..29
FIGURE 4-19: West Elevation of the baseline design………………………………….....30
FIGURE 4-20: Detail plan of a typical wall and column structure in Saudi Arabia……30
FIGURE 4-21: Detail section of a typical envelope in Saudi Arabia…………………..…31
FIGURE 4-22: Percentage of energy use per use type………………………………..….32
FIGURE 4-23: Detail plan of the optimized wall based on the PHI recommendations..34
FIGURE 4-24: Section detail shows a typical Passivhaus wall……………………..……35
FIGURE 4-25: 3D detail shows the building envelope with the different materials
applied to it……………………………………………………………...…….36
FIGURE 4-26: The family space in the first floor…………………………………...……...38
FIGURE 4-27: The family space in the Second floor………………………………..…….38
FIGURE 4-28: The North West room………………………………………………….…….39
FIGURE 4-29: Energy consumption of lighting and appliances………………………….39
FIGURE 4-30: Potential energy savings in cooling loads from High Efficient AC
System………….……… …………………………………………………….40
FIGURE 4-31: Annual EUI……………………………………………………………………42
FIGURE 4-32: Annual CO2 Emitted…………………………………………………………42
FIGURE 4-33: Potential Energy Consumption for Each Use Type between Baselines
Case and Passive House………………
………………………….…….42
FIGURE 4-34: PDEC Concept……………………………………………………………….44
FIGURE 4-35: Roof Plan and the Cooling Towers Locations…………………………….45
FIGURE 4-36: Cooling Towers in the First Floor……………………………………….….46
FIGURE 4-37: Cooling Towers in the Second Floor…………………………………….…46
FIGURE 4-38: Cooling Towers at the Top………………………………………………….47
FIGURE 4-39: Section A……………………………………………………………………...47
FIGURE 4-40: Section D………………………………………………………………….…..48
FIGURE 4-41: Section C………………………………………………………………….…..48
FIGURE 4-42: South Elevation……………………………………………………………....48
FIGURE 4-43: North Elevation……………………………………………………………….49
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FIGURE 4-44: East Elevation………………………………………………………………..49
FIGURE 4-45: West Elevation……………………………………………………………….49
FIGURE 4-46: South Perspective…………………………………………………….……..50
FIGURE 4-47: North East Perspective……………………………………………….……..50
FIGURE 4-48: South East Perspective……………………………………………….……..51
FIGURE 4-49: 3D Detail Shows the Structure and System of the Cooling Towers.…...52
FIGURE 4-50: 3D Section Shows the PDEC through the Living Room and
Bedrooms……………………………………………………………………..53
FIGURE 4-51: 3D Section Shows the PDEC through the Family Spaces…..……….....53
FIGURE 4-52: Air Flow (CFM) – South East……………………………………………….56
FIGURE 4-53: Air Flow (CFM) – South West…………………………………...………….56
FIGURE 4-54: Air Flow (CFM) – North East………………………………………………..57
FIGURE 4-55: Air Flow (CFM) – North West……………………………………………….57
FIGURE 4-56: Air Velocity – Through East Cooling Tower and Living Room…………..58
FIGURE 4-57: Air Velocity – Through Cooling Towers and Family Area………………..58
FIGURE 4-58: Air Velocity – Through Cooling Towers and Operable Windows…….....59
FIGURE 4-59: Dry-Bulb Temperature……………………………………………………….60
FIGURE 4-60: Wet- Bulb Temperature……………………………………………………...61
FIGURE 4-61: Comparison between Dry-Bulb Temperature and Potential
Air Supply Temperature……………………………………………………..62
FIGURE 4-62: Passive Cooling Strategies in The New Stock Exchange……………….64
FIGURE 4-63: Floor Plan of One of the Buildings in The Torrent Research
Center…………………………………………………………………………65
FIGURE 4-64: Section through the PDEC System in the Torrent Center………………65
FIGURE 4-65: Natural Ventilation Concept in the Zion National Park
Visitor Center…………………………………………………………………66
FIGURE 4-66: Comparison between a Baseline Model and the Developed
Case Using PDEC System in Zion Center………………………………...67
FIGURE 4-67: Section through the PDEC in the Riyadh Case Study…………………...69
FIGURE 4-68: The Location of the PDEC in the Floor Plan of the Case Study………..70
FIGURE 5-1: The Potential to Reach Net-Zero Passive House………………………….74
x
LIST OF ABBREVIATIONS
AIA: The American Institute of Architecture
ASHRAE: American Society of Heating, Refrigerating & Air-Conditioning Engineers Inc.
ACH50: Air Changes per Hour at 50 Pascal
CHGC: Solar Heat Gain Coefficient.
EIA: U.S. Energy Information Administration.
EPA: US Environmental Protection Agency.
OPEC: Organization of the Petroleum Exporting Countries
SEEC: Saudi Energy Efficiency Center.
K.A.CARE: King Abdullah City of Atomic and Renewable Energy.
PHIUS: Passive House Institute in the United States.
PDEC: Passive Down-Draft Evaporative Cooling
NREL: National Renewable Energy Laboratory
xi
CHAPTER 1: INTRODUCTION
The Need for Net-Zero Energy Homes in Saudi Arabia
In April 2010, King Abdullah bin Abdul-Aziz Al Saud established an initiative
entitled King Abdullah City for Atomic and Renewable Energy (K●A●CARE). The aim of
creating this city is to build a sustainable future for Saudi Arabia and to face the
challenges associated with the significant demand for fossil fuel and increasing CO2
emissions.
In 2014, Saudi Arabia was ranked the number one oil consuming nation in the
Middle East, and 12th in the world with total consumption of approximately 3 million
barrels per day (bbl/d) (EIA, 2015). This is almost double the nation’s consumption in
2000, because of its strong economic and industrial growth. The nation’s oil
consumption, as shown in figure 1-1, has been increasing since 1980. Furthermore, the
fossil fuel demand is expected to increase from 3 million bbl/d in 2010 to 8.3 million
bbl/d by 2028 (K.A.CARE, 2015). The direct burning of crude oil for power generation
contributes significantly to this increase, with an average consumption of 0.7 million
bbl/d in the last few years during the summer alone.
FIGURE 2-1
SA Oil Consumption Since 1980
Source: EIA, 2015
1
Along with its high energy consumption, Saudi Arabia also produced the 10th
largest volume of CO2 emissions in the world in 2014 (EIA, 2015), which represents 57
percent of world’s greenhouse gas emissions which are a known cause of global
warming which could further exacerbate the energy problem for the nation in the future
(EPA: BODEN, MARLAND, & ANDRES, 2010).
Building Consumption in Saudi Arabia
Buildings are major contributor in energy use with more than 50% of the total
energy consumed in Saudi Arabia, according to the Saudi Energy Efficiency Center
(SEEC, 2013). In 2011, buildings consumed approximately 80% of the total electricity
generated, of which 51.2% is used by residential buildings, and air conditioning
represents 70% of the total national electrical demand (SEEC, 2013)
FIGURE 1-2
Energy Consumption by Sector in Saudi Arabia
Commercial
12.2%
Governmental
15.1%
Agricultural
2.6%
Industrial
17.9%
Residential
51.2%
Building
78.5%
Source: SEEC & K.A.CARE, 2013
Based on the information and data mentioned earlier, it is apparent that buildings
in Saudi Arabia are designed and constructed without regard to how they will respond to
their environment when the energy source they rely on is depleted. The currently low
2
cost of electricity bills, the lack of thermal insulation, and the absence of sustainable
standards in the construction industry has led to an assortment of low quality buildings
in the nation’s existing built environment. At the present time, there is no standard
criteria for buildings to raise the level of quality and efficiency. Almost 70% of buildings
in SA are not thermally insulated (SEEC, 2013). Figure 1-3 shows a typical home
structure in Saudi Arabia.
FIGURE 1-3:
Picture Shows the Lack of Thermal Insulation in
Typical Residential Buildings Construction in SA
Source: www.alriyadh.com, 2015
The rapid increase in energy consumption needs an immediate and serious
strategy in order to reduce building consumption until sustainable sources for energy
generation are found. This study recommends that the strategy take into consideration
and focus on the residential sector since it represents the majority of energy consumed
in the nation. Creating more high-performance homes in Saudi Arabia will significantly
reduce the risks associated with the increasing consumption of fossil fuel and related
CO2 emissions. This approach could be achieved through two major steps. First,
3
creating buildings that are more responsive to their environment in order to minimize the
energy consumed. Second, relying on sustainable sources of energy in order to achieve
self-sustained homes.
The Case of the Passivhaus for Hot and Dry Climates
Since the study will focus on developing High-Performance homes for hot and
arid climates, the case of the Passivhaus will be taken into consideration as it was
initially developed for homes in Germany. The Passivhaus concept traces its roots back
to 1988 by Dr. Wolfgang Feist and Bo Adamson (Trubiano, 2013). The first approval of
the concept was in 1990 through their first project, the Kranichstein Passive House, in
Darmstadt, Germany (Passive House Institute, 2015). In 1996, the Passivhaus Institut
was founded as a research group led by Dr. Feist with an interdisciplinary group of
architects, engineers, and construction professionals who work together to develop
energy-free architectural design principles (Trubiano, 2013). Figure 1-4 gives an
overview of what a typical Passivhaus looks like.
A typical Passivhaus, as described in the Passivhaus Institut (figure 1-4), must
be designed and built based on the developed five principles which are as follows:
1. The building should be super-insulated with continuous insulation through its
entire envelope.
2. The building should be designed with minimal thermal bridging.
3. The building envelope is extremely airtight.
4. It employs high-performance windows (typically triple-paned).
5. The building is operated with a heat recovery ventilator and uses a minimal
space conditioning systems.
4
FIGURE 1-4
The Passivhaus Concept Developed in 1996 by Dr. Feist
Source: Passivhaus Institut, 2015
The Passivhaus concept could be an ideal solution to create sustainable homes
in Saudi Arabia. However, since the Passivhaus concept was initially developed for cold
climates, it will not have the ability to be directly implemented in hot and arid climates,
and revising Passivhaus principles adapted to hot and arid climates would therefore be
the ideal approach to achieving net-zero energy homes in Saudi Arabia.
5
CHAPTER 2: THE PROBLEM
The Passivhaus as a Solution
Passivhaus standards were initially developed in Germany to increase buildings’
efficiency in cold climates. Hundreds of Passivhaus homes have been successfully built
around the world (Trubiano, 2013) since the Kranichstein Passive House. This 1990
project is a multi-family house designed and built based on the principles mentioned
earlier. The house was oriented to maximize the desired solar gain for its climate. The
roof, walls, and floor were insulated using polystyrene. A heat recovery system was
incorporated with 80% efficiency. Using these passive strategies a higher level of
efficiency was achieved.
Although the Passivhaus Institute states that these principles work effectively in
hot climates, it is apparent how these principles cannot be directly mapped to hot
climates. Several passive cooling strategies are not taken into consideration when
applying these principles in hot climates. To illustrate that, evaporative cooling is a
passive cooling strategy and requires direct or indirect natural ventilation. The passive
cooling with the direct natural ventilation cannot be implemented when one of the
principles is the building being airtight. Airtightness is an effective strategy to keep the
desired temperature as long as possible in a building. Instead, an evaporative cooling
strategy such as cooling towers could achieve higher level of effectiveness in hot and
arid climates. This strategy uses much less energy than mechanical cooling, with
energy savings ranging between 30% and 90% (Lechner, 2009). As a result, expanding
the Passivhaus principles for their use in hot and dry climates could achieve a higher
level of performance.
6
The direct implementation of the Passivhaus principles in hot and arid climates
will not achieve the same level of effectiveness as they have achieved in cold climates.
Many Passivhaus projects were built in cold climates and are either net-zero energy or
net-zero ready buildings. However, to date no net-zero energy Passivhaus projects
have been built in hot climates (PHIUS, 2014).
To better understand the success of the Passivhaus in hot climates, three case
studies are analyzed in this study in order to evaluate its level of effectiveness. These
case studies are the existing Passivhaus projects that were built in hot climates and
include: The first Passivhaus in the Middle East, in Qatar; The Desert Passive House in
Hereford, Arizona, and the LeBois House in Lafayette, Louisiana.
The First Passivhaus in the Middle East: Qatar
The first and the only Passivhaus project in Middle East to date was built in 2013
in Qatar. Qatar is located in the Arabian Peninsula and is known for its very hot and
very humid weather. The average dry-bulb high temperature is 105 °F (40 °C) with dew
point temperature of 80 °F (24.7 °C). Many days throughout the year exceed these
points. The weather conditions are reversed from those in Europe where the
Passivhaus concept was developed.
The main purpose of this project is a demonstration project compared to a
standard Qatar villa, to inspire the creation of more sustainable homes. The project
consists of two single family villas, which were designed to be occupied by two similar
families with two young children. The first villa, the Piassavas villa, has a total area of
2153ft 2 (200m 2) and was designed and built based on the Passivhaus guidelines and
standard. The expected annual energy use intensity (EUI) for the Passivhaus is
7
11.1kWh/ft2/yr. (120 kWh/m2/yr.). The envelope is constructed with 14.5 in. (370 mm) of
polystyrene to ensure a super insulated and airtight envelope. Triple panel glazing was
chosen to minimize solar heat gain through windows. A mechanical ventilation system
with energy recovery is used to provide fresh air and to minimize air infiltration. In
addition to that, 2200 ft 2 (205 m 2) of photovoltaic panels cover the roof and provide
shading for the roof and exterior walls (Bryant, Amato, Law & Al Abdulla, 2013).
The second Villa was built next to it, based on typical Qatar standards. It was
built as a baseline and reference in order to compare it with the Passivhaus standard, to
measure the difference in energy usage between the two homes. It is similar in terms of
the architectural design, building orientation, and total square footage. The villa has a
shading structure which covers only two of its exterior walls including the entrance.
Figure 2-1 and 2-2 show the architectural design of the two villas and the Piassavas
villa is apparent with the photovoltaic covering the roof (Bryant, Amato, Law & Al
Abdulla, 2013).
With all the Passivhaus strategies being applied, the project aims include
achieving 50% annual energy reduction, 50% water reduction, and 50% reduction in
CO2 emissions compared with the baseline villa. The question that is raised here, since
there are many Passivhaus homes in cold climates that achieved net-zero energy, why
the developers of this project did not aim to achieve that? The aim was not even close
to what could have been achieved through the Passivhaus Principles. The success of
the Passivhaus in cold regions around the world could be reflected in the developers’
goals in Qatar. The logical reason that the developers in Qatar set these goals lower is
likely the very hot weather, which requires massive cooling loads
8
FIGURE 2-1
Perspective of the Two Buildings, Passivhaus Villa (Right) and Baseline Villa (Left)
Source: Qatar Foundation, 2013
FIGURE 2-2
3D Floor Plan for the Two Design and PV Panels Covering the Passivhaus Roof (Lower Right)
Source: Qatar Foundation, 2013
9
The Desert Passive House, Hereford, AZ
Hereford, Arizona is located in the southwestern part of the United States. The
city has a hot and semi-arid climate. The hot season lasts from May to September with
an average high temperature of 94°F. The cold season lasts for three months, during
the period from the end of November to the end of February, with an average high
temperature of 66 °F (Weather Spark, 2015).
The Desert Passive House is a single family house. It is certified by the Passive
House Institute in the United States (PHIUS). The house has an airtight envelope with
0.59 ACH50 and meets all the US Passive House requirements. However, according
the Passive House Institute, the project did not reach net-zero energy with the Passive
House strategies and the use of Photovoltaics (PHIUS, 2014). This house provides
another example that Passivhaus principles could not have the ability to achieve the
same level of effectiveness in hot climates. The house consumes much less energy
compared to a standard house in Arizona with an annual EUI of 25.9 kBtu/ft2/yr. Figure
2-3 shows a picture of the house with the solar photovoltaic array on the roof (PHIUS,
2014).
FIGURE 2-3
The Desert Passive House in Hereford, AZ
Source: PHIUS, 2015
10
LeBois House, Lafayette, LA
Lafayette, Louisiana is located in the deep south of the United States. The city
has hot-humid climate. During the hot season, the average high temperature is 85°F.
The cold season lasts approximately less than three months from December 1st to
February 21st with an average high temperature of 66 °F (Weather Spark, 2015).
The LeBois House is a single-family house with total floor area of 2190 ft2. The
house was designed and built employing the Passive House principles developed by
the Passive House Institute in the United States. The envelope is thermally well
insulated with R-28 insulation in the walls and R-55 in the roof. The envelope is
designed to minimize air infiltration with airtightness of 0.55 ACH. Based on PHIUS
recommendations, double panel glazing windows with U-0.18 and solar heat gain
coefficient of 30% were chosen
The Passive House Planning Package (PHPP) is a simulation software
developed by the Passivhaus Institute, and was used to run the energy simulation for
the house. The software predicted the primary energy consumption would not exceed
37.03 kBtu/ft²/yr. (116 kWh/m²/yr.). However, the monitored performance results
revealed a greater number, which was 58 kBtu/ft²/yr. (184 Kwh/m²/yr.). Based on the
actual result, the EUI is approximately 50% greater than the PHPP projections.
For the LeBois House, the results were not only lower than what has been
achieved in cold climates, but also lower than what was expected using the PHPP tool.
It is clear that the Passivhaus strategies when applied in the climate conditions in
Lafayette did not yield the expected energy improvement.
11
FIGURE 2-4
The LeBois House in Lafayette, LA
(Source: PHIUS, 2014)
FIGURE 2-5
3D Drawing Showing the Compact Design of the House with the Mechanical System
(Source: PHIUS, 2014)
12
These three case studies are the existing Passive House projects that have been
built in hot climates. Some of the information was gathered from the Passive House
Institute in the US that is published on their website as well as by contacting them
directly. Information that was noted in the case study of the Qatar Passivhaus was
gathered from previous research conducted by governmental organizations in Qatar.
The analyzed case studies give an overview of the potential energy savings by applying
the Passivhaus principles in hot climates.
Implementing the Passivhaus principles directly in Saudi Arabia will not achieve
the net-zero energy in order to encounter the current energy challenges in Saudi Arabia.
When referring to the success of the Passivhaus in cold climates, it will be an ideal
concept as a starting point with the hope of achieving greater energy savings in the
future. Rethinking about passive cooling strategies could improve building efficiency in
Saudi Arabia. Another project, the Showcase House in Phoenix, Arizona, is a
successful example of house built in hot climates and used passive cooling strategies.
The Showcase House was not built based on the Passivhaus principles; however, the
house achieved better EUI when compared with the previous case studies. The total
EUI of this house went down to 9 kBtu/sf/yr. The designer took into account using
natural ventilation to cool the house (AIA, 2015).
13
CHAPTER 3: THE PROBLEM EVALUATION
Saudi Arabia is a developing country and facing a significant increase in energy
demand. In the short-term, it is not yet a major problem with the wide availability of fossil
fuel, which is the primary energy source in the country. However, fossil fuel is not a
sustainable source to rely on, and at some point in the future oil will reach its breaking
point. Nowadays, while Saudi Arabia has total reserves of approximately 265.8 billion
barrels (OPEC, 2015), if the average daily production in SA continues at the same level
until 2050, the country will use approximately 144.5 billion barrels, which is roughly 54%
of its current total oil reserves. This is not yet considered a major problem as the total
reserves have increased since 1980 with the discovery of new oil fields, however, fossil
fuel is not a sustainable source regardless of how long it may last.
With SA’s growing population, by 2032 the energy increasing energy
consumption is expected to become a significant problem. The government expects the
electricity demand to exceed 120 Gigawatts. The average daily consumption of fossil
fuel in the country is expected to grow from 3.4 million bbl/d to 8.3 bbl/d in 2028
(K.A.CARE, 2013). Unless energy conservation principles and sustainable sources of
energy are implemented, the country will face a shortage in less than 20 years.
The other serious problem is the dangerous increase in CO2 emissions. CO2
represent approximately 57% of greenhouse gases, which contribute to the risks
associated with global warming (EPA, 2010). Figure 3-1 shows the rapid increase of
CO2 emission in Saudi Arabia since 1980 (EIA, 2015).
14
FIGURE 3-1
CO2 Emissions Have Been Increasing Since 1980
Source: EIA, 2015
The government of Saudi Arabia plans to offset the increasing energy
consumption through the King Abdullah City for Atomic and Renewable Energy
(K.A.CARE). The aim of the city is to generate 50% of electricity from non-fossil fuel
sources by 2032. K.A.CARE plans to achieve that gradually as shown in figure 3-2.
Figure 3-2:
The Graph Shows the Expected Energy generation
from non-fossil fuel sources until 2032
Source: K.A.CARE, 2013
15
The establishment of K.A.CARE seems to be a great beginning towards a
sustainable future. Nevertheless, alternative sustainable energy sources are not enough
to offset the total energy demand. Developing energy conservation principles, and
energy-conscious designs and projects will significantly limit the risks associated with
increasing energy demand and CO2 emissions.
16
CHAPTER 4: THE ANALYSIS AND DESIGN PROPOSAL
This chapter discusses a proposal provided to improve the efficiency level of the
Passivhaus in hot and arid climates in order to accomplish the goals of the study. The
goals of this study include:
•
Creating sustainable homes through designing buildings that are more
responsive to the environment
•
Revising the Passivhaus standard for hot and arid climates, to take into
consideration new passive cooling strategies
•
Achieving net-zero homes for hot and arid climates
•
Using solar energy as the main source of energy
•
The proposed house design could be an initial step to move towards an overall
sustainably built environment for the future
The process followed to reach the goals will include a design of a single family
house for a Saudi family, the Passivhaus principles applied to the design, a revised
Passive House design, and finally an energy analysis and comparison between the
Passivhaus case and the developed proposal. The first step will include a site analysis
and a design used as a baseline based on a typical Saudi standard. In the second step,
the Passivhaus principles will be applied to the baseline design. An energy simulation
will be made to estimate the level of performance in the climate of Saudi Arabia. In the
third step, the Passive Downdraft Evaporative cooling strategy will be incorporated into
the Passivhaus design, aiming to achieve a higher level of performance and to reach
net-zero energy. Finally, air movement analysis, air velocity analysis and previous case
studies will be analyzed as well to measure the potential improvement in performance.
17
The Site
The site is located in Hail province, SA as shown in figure 4-1, 4-2 and 4-3. Hail
is located in latitude 27.6° and longitude 41.6°. The location is a farming area located 15
mi. (25 km) north of the city of Hail. This location provides an ideal setting, providing
typical weather conditions that are not affected by surrounding buildings.
FIGURE 4-1
Hail Is Located In the North Region of Saudi Arabia
Source: The Saudi Network, 2015
FIGURE 3-2
The Site is Located in a Farming Area 15 Mi. North of the City of Hail
Source: Google Maps
18
FIGURE 4-3
The site is located inside a farm, with some pictures of the site
Source: Google Maps
The climate of Saudi Arabia is known for its low relative humidity and very high
temperature during the summer. The weather data of the study is based on historical
weather records from 1978 to 2014 (Weather Spark, 2015). The weather observations
in the last two years can be seen in Figure 4-4, 4-5, 4-6, and 4-7. The key climatic data
for the study is as follows:
•
From April to October the temperature is high
•
The average high temperature during the hot season is 103 °F
•
The prevailing winds come from:
o South: 13% of the time
o North: 12% of the time
o South West: 12% of the time
o North East: 11% of the time
•
In 2014:
o The highest average was recorded in April with 9 mi/h
o The lowest average was recorded in September with 6 mi/h
19
FIGURE 4-4
Weather history in 2014
Colored
Temperature
Diagram
Average High
Temperature
Temperature
Range
Average Low
Temperature
Wind
Direction
Source: Weather Spark, 2015
FIGURE 4-5
Weather history in 2013
Colored
Temperature
Diagram
Average High
Temperature
Temperature
Range
Average Low
Temperature
Wind
Direction
Source: Weather Spark, 2015
20
FIGURE 4-6
Prevailing Wind Directions over the Entire Year
Source: Weather Spark, 2015
FIGURE 4-7
Fraction of Time Spent with Various Wind Directions
Source: Weather Spark, 2015
The Orientation and Form Analysis
This study concentrates on the design of a single family house, with orientation
and form being important initial design decisions. Privacy also plays an important role
when designing a home in Saudi Arabia, which will be explained in more detail below.
The simulation software Ecotect was used in order to find out the ideal orientation for
the house. The weather tool in Ecotect suggests that 172.5o (south) is the ideal angle
to orient the house (Figure 4-8).
21
Figure 4-8
The Weather Tool in Ecotect Suggest the Best Orientation to Be South
Source: Weather Tool Ecotect
Source: Weather Tool - Ecotect
After considering the best orientation for the house, several forms were analyzed
using the simulation software Sefaira and Ecotect to find the ideal form with the lowest
solar radiation when designing the house. These forms include a square, rectangle,
square configuration with a courtyard in the middle; a rectangle with courtyard in the
middle; and finally a u-shaped form with a courtyard located in the south. The analysis
reveals that the basic rectangular form has the lowest annual EUI. The square and ushaped forms has almost the same EUI, while the square and rectangular shapes with
courtyards were the worst. When shading devices were applied to the lowest three
forms, the u-shaped form was the most affected form and the EUI decreased by 7.2%.
The rectangular form was the least affected form with only a 3.1% decrease. The
analysis of the five different forms can be seen in figure 4-9.
22
Software: Sefaira & Ecotect
5.9%
3.1%
FIGURE 4-9
Forms and Solar Radiation Analysis for Five Different Forms
NO SHADING
SHADING
% Of
Improvement
23
7.2%
Although the rectangular shape was the most effective shape, the u-shaped form
was chosen for several reasons. The first and most important reason is privacy. Privacy
in Saudi Arabia is very important for religious and traditional purposes. As a result,
courtyards are known in the culture of Saudi Arabia to create homes with more privacy.
The second important reason is minimizing east and west windows. Among all the four
orientations, buildings located in the 27o latitude absorb most of the solar radiations in
the building from the east and west walls (NREL, 1996). The u-shaped design will help
avoid windows in the east and west façades and minimize glare as well. Windows that
would be on the eastern and western sides will be relocated in the courtyard as needed.
In addition, when a courtyard is incorporated into a building design, it connects the
inside and outside environment, and creates an aesthetically pleasing experience.
FIGURE 4-10
The Annual Shadow Range in the Courtyard and a Graph Shows How Much Solar Radiation
Absorbed From the East and West Facades
Source: NREL, 1996 – Software: Ecotect
24
The Baseline Design
The house was designed to fit a large family of 8 occupants. The design is a two
story U-shaped house with a courtyard located in the south. The house has two
separate entrances. The first entrance is the family entrance, located on the north side
of the house. The other entrance is the guest entrance, which is located on the east
side. The building has a total length of 66 feet and width of 43 feet. The total built area
is 3770 ft2 (350 m2). The size of the house considered to be average and fits most of the
residential lots in Saudi Arabia. The first floor is 2 feet higher than the ground level. The
floor-to-floor height is 10 feet while the total height of the building is 25 feet taking into
account the height of the parapet. Several spaces are included in the house which are
normally found in a typical Saudi house. Table 4-1, 4-2, and 4-3 show the different
spaces in the house with their areas while the model drawings can be seen from figure
4-11 to 4-19.
TABLE 4-1
Building Spaces and Their Areas
Level
Room
Area ft2
1st & 2nd
Family Spaces
590
1st
Living Room
190
1st
Winter Room
218
1st
Guest Room
263
1st
Dining Room
121
2nd
Bedrooms
894
1st
Kitchen
222
1st & 2nd
Toilets
300
2nd
Office
80
25
FIGURE 4-11
First Floor
6
1
3
4
A
8
7
2
9
5
B
C
TABLE 4-2
First floor spaces and their total areas
Space Number
Name
Area ft2
1
Guest Room
263
2
Living Room
190
3
Family Space
405
4
Dining Room
121
5
Winter Room
218
6
Kitchen
222
7
Guest Toilet
63
8
Family Toilet
60
9
Courtyard
485
26
FIGURE 4-12
Second Floor
3
4
5
A
6
2
1
B
C
TABLE 4-3
Second Floor Spaces and Their Total Areas
Space Number
Name
Area ft2
1
Master Bedroom + Toilet
372
2
Bedroom + Toilet
282
3
Bedroom + Toilet
225
4
Bedroom+ Toilet
225
5
Family Space
185
6
Office
80
27
FIGURE 4-13
Section A
TABLE 4-14
Section B
FIGURE 4-15
Section C
28
Figure 4-16
South Elevation
Figure 4-17
North Elevation
Figure 4-18
East Elevation
29
FIGURE 4-19
West Elevation
The building model was designed with a more “business as usual” design and
construction in Saudi Arabia, with the envelope and glazing properties based on typical
construction standards in the state. Figure 4-20 and 4-21 show a typical wall and roof
construction in Saudi Arabia.
Figure 4-20
Detail Plan of a Typical Wall and Column Structure in Saudi Arabia
30
FIGURE 4-21
Detail Section of a Typical Envelope in Saudi Arabia
Concrete
Concrete Beam
Source:
www.alriyadh.com
31
The core materials used in the design are concrete for the roof and slabs, and
CMU for the walls. The construction properties of the design are as follows:
•
Total R-values
Floor: R-15 ft2⋅h⋅°F/BTU (U-0.36 W/m2K)
Walls: R-15 ft2⋅h⋅°F/BTU (U-0.36 W/m2K)
Roof: R-15 ft2⋅h⋅°F/BTU (U-0.36 W/m2K)
•
Single panel glazing with:
Total U-value: 0.42 BTU/h⋅ft2⋅°F (2.4 W/m2K)
Solar heat gain coefficient (SHGC): 60%
•
Airtightness: 5 ACH ( about 0.5 cfm/ft2)
•
Thermal Mass: 19 BTU/°F
Using Sefaira, the estimated total energy consumption of the house was 258,890
kBTU with a EUI of 69 kBTU/ft2/yr. (217 kWh/m2/yr.). The potential total carbon emitted
was 97,141 lbs CO2. ooling demand represents 70% of the home’s total energy
consumption (Figure 4-22). This data acts as a reference for the energy performance of
the developed cases, which will be explained in detail in the following sections.
FIGURE 4-22
Percentage of Energy Use per Use Type
AppliancesHotwater
8%
0.001%
Lighting
16%
Heating
6%
Cooling
70%
32
The Case of the Passivhaus
In this section, the Passivhaus principles will be applied to the design to ascertain
the potential improvements in energy performance when Passivhaus requirements are
implemented. In the first step, the building envelope will be optimized to meet the
Passivhaus requirements. Second, maximizing daylight and selecting high efficient
lighting and appliances will be explored, to minimize energy requirements for the house.
Third, a high-efficiency HVAC system will be incorporated to reduce the energy
consumed for heating and cooling. After that, a photovoltaic system will be installed on
the roof to generate energy for the house. Finally, an energy simulation will be
conducted to measure the potential improvements in the energy performance. The
result will reveal if the Passivhaus requirements are enough to reach net-zero energy
for this house at the designated site. Sefaira, Ecotect, and Radiance design tools will be
used to simulate the energy performance and daylighting analyses.
Optimized Building Envelope
The building envelope was optimized based on the Passivhaus requirements.
The Passive House Institute in the United States has developed climate specific
recommendations for each climate zone. The current Passive House recommendations
for hot and dry climates have been applied to the building envelope. The major
differences in the envelope from the baseline case in the materials used, R-values, and
U-values. When compared with a typical Passivhaus building built in cold climates, walls
with lower R-values are recommended to reach the desired improvement in the building
envelope in hot climates. Windows with higher U-values and lower SHGC are also
recommended in such climate. These recommendations are not only benchmarks, but
33
also cost-effective values. Figures 4-23, 4-24 and 4-25 show a plan, a section, and 3D
detail for the optimized envelope. The envelope properties are as follows:

Total R-value for:
o Floor: R-35 ft2⋅h⋅°F/BTU (U-0.16 W/m2K)
o Walls: R-35 ft2⋅h⋅°F/BTU (U-0.16 W/m2K)
o Roof: R-40 ft2⋅h⋅°F/BTU (U-0.14 W/m2K)
•
Glazing:
o Double panel windows
o Total U-value: 0.27 BTU/h⋅ft2⋅°F (1.55 W/m2K)
o Solar heat gain coefficient (SHGC): 30
•
Shading for south windows & courtyard
•
Thermal Bridge Free Construction
•
Airtightness: 0.6 ACH (0.050 cfm/ft2)
•
Thermal Mass: 19 BTU/°F
FIGURE 4-23
Detail Plan of the Optimized Wall Based On the PHI Recommendations
Stud
34
FIGURE 4-24
Section Detail Shows a Typical Passive
Concrete Beam
Source: Passipedia, 2015
Floor Insulation
35
36
FIGURE 4-25
3D Detail Shows the Building Envelope with the Different Materials Applied
The two layers of insulation, polyurethane and rigid, along with the continuous
concrete structure, minimize the thermal bridging through the envelope and provide the
airtightness of the building. Additionally, the thick layer of concrete masonry unites
creates a high thermal mass envelope. With the optimized envelope, the annual EUI is
reduced from 69 kBTU/ft2/yr to 51 kBTU/ft2/yr. with total energy savings of 26%. The
carbon emissions from this household energy use is reduced by 24.5% from 97,141 lbs
CO2 to 73270 lbs CO2. For the Passive House design, the cooling loads are reduced
by 36% from 158,669 kBTU to 100,183 kBTU and the heating loads are reduced by
53% from 13,923 kBTU to 6,484 kBTU. The higher reduction in heating loads reveals
that Passive House recommendations for the building envelope design are more
effective when it comes to minimizing heating loads.
Daylighting and High Efficiency Lighting and Appliances
Maximizing daylighting was taken into consideration when designing the house.
The u-shaped design maximize sun light and minimizes glare. The daylighting analysis
was conducted on a summer day at 12pm (figure 4-26, 4-27 and 4-28). The results
show that the amount of sunlight in the family room in the first floor is higher than 300
lux, which is enough for reading purposes. Other places in the house receive a
significantly greater amount of daylight. After that, high performance lights and
appliances were chosen for the building during the simulation process. The lighting
power density and plug load power density were set to 0.2 W/ft2. These values are
considered to be high-efficient lighting and appliances (ASHRAE, 2013). Figures 4-29
shows a comparison of the energy consumption between a standard lighting power
density and the improved case.
37
FIGURE 4-26
The Family Space on the First Floor
Source: Ecotect &
Software: Ecotect & Radiance
FIGURE 4-27
The Family Space on the Second Floor
Software: Ecotect & Radiance
38
FIGURE 4-28
The Northwestern Room
Software: Ecotect & Radiance
FIGURE 4-29
Energy Consumption of Lighting and Appliances
40000
35000
30000
kBTU
25000
20000
15000
10000
5000
0
Lighting
Baseline
Appliances
High Efficient Lights and Appliances
Software: Sefaira
39
In conclusion, approximately 70% of the house is naturally well lit during daytime
hours. This amount of light was achieved without placing windows in the west façade,
and only one window for the guest room in the east. Lighting loads are reduced by 66%,
and appliance loads are reduced by 33%. The annual EUI decreased by 13% from 69
kBTU/ft2 To 60 kBTU/ft2 while the carbon emitted reduced by 14% from 97,141 lbs CO2
to 83,277 lbs CO2.
High Efficiency Air Conditioning System
This aspect of the design process relies significantly on mechanical engineers.
Due to the limited personal knowledge about designing an air conditioning and HVAC
system for the house, the simulation software Sefaira was used to find out the potential
energy savings that could be achieved from a high efficiency HVAC system. The
software allows designers to insert the basic data of a mechanical system used in the
house. The inputs were set as a high efficiency mechanical system with ventilation
recovery. Based on the analysis results from Sefaira, a high efficiency HVAC system
could achieve 20% energy savings, a 16.7% CO2 reduction, and the cooling loads
could be reduced by 24%. Figure 4-32 shows a comparison of energy consumption
FIGURE 4-30
Potential Energy Savings in Cooling Loads from High
Efficiency HVAC System
180000
160000
140000
120000
100000
80000
60000
40000
20000
0
Baseline
High Efficient Air
Conditioning system
40
between a standard AC system and a high-efficiency energy recovery ventilation (ERV)
system.
Onsite Solar Photovoltaic
Onsite solar photovoltaic panels are placed on the roof to generate energy. In
this high efficiency design case, almost all of the area that is exposed to the sun in the
roof is covered with PV panels. The total area of the PV panels is 646ft2 (60m2). The
PV’s efficiency is 15%, which considered average. This amount of PV panels could
generate up to 48,264 kBTU. The total energy consumption of the baseline case could
be reduced by 26% when using onsite PV’s alone.
Passive House Energy Performance
After applying all the Passive House strategies, an energy simulation was
conducted to measure the projected performance improvements of the house, and then
to find out the potential of achieving net-zero Passive House in hot climates.
Based on the energy simulation, the Passive House strategies along with with
the PV system have helped to achieve significant reductions in the home’s energy
consumption. The total energy consumption decreased by 71% from 258,890 kBTU to
74,891 kBTU. Without the PV system, the annual EUI of the Passive House dropped
from 69 kBTU/ft2 to 33 kBTU/ft2 with a total projected energy savings of 52%. When the
PV system was added to the house, the annual EUI went down further to 20 kBTU/ft2
(Figure 4-31), and the carbon emissions are reduced by 70% from 97,144 lbs CO2 to
28,958 lbs CO2 (Figure 4-32). The cooling loads are still dominating the total energy
consumption, representing 71% of the total energy consumed. The cooling loads are
reduced by 54% while heating loads are reduced by 72% (Figure 4-33). So it is
41
apparent how the Passive House strategies are more effective when it comes to
reducing heating requirements than cooling requirements.
kBTU/ft2
FIGURE 4-31
Annual EUI
80
69
60
33
40
20
20
0
Baseline
Passive House
Passive House
with PV's
FIGURE 4-32
Annual CO2 Emitted
120,000
lbsCO2
100,000
80,000
60,000
40,000
20,000
0
Baseline
Passive House
Passive House with
PV's
kBTU
FIGURE 4-33
Potential Energy Consumption for Each Use Type between
Baseline Case and Passive House
180000
160000
140000
120000
100000
80000
60000
40000
20000
0
Cooling
Heating
Baseline
Lighting
Appliances
Passive House
42
Hotwater
Although significant improvements have been achieved, the Passive House
principles did not accomplish a net-zero energy house. This analysis confirms the
results and information from the case studies analyzed in Chapter 2, expecting that the
Passive house could achieve a high level of efficiency in Saudi Arabia although the
results were similar to what the Passive House achieves in cold climate regions. As a
result, the developed case that will be discussed in the next section will take into
consideration other cooling strategies with the aim of reaching a net zero energy
Passive House.
Evaporative Cooling
Passive Down-Draft Evaporative Cooling
Direct evaporative cooling is considered to be more effective in hot and arid
climates as it increases the relative humidity in the air during the cooling process. It
basically provides cooling to the spaces with much less energy when compared to
traditional mechanical systems. This strategy could be achieved by passing the outside
air through a water medium to a building. This strategy cools the air by evaporation, as
well as increasing the moisture in the air.
Cooling Towers
Passive Down-Draft Evaporative Cooling (PDEC), or cooling tower, is one of the
most effective evaporative cooling approaches. The PDEC system is basically designed
to capture winds at the top of the tower, then cools the hot air by water evaporation
before it enters the building (Figure 4-34). The energy consumed in this strategy is only
the energy needed to pump water to the top of the tower. This strategy could achieve
between 30% and 90% energy savings in the cooling loads depending on the design
(Lechner, 2009).
43
FIGURE 4-34
PDEC Concept
Source: The Center for Global Ecology, Stanford, CA
Since cooling loads represent most of the energy consumed, the PDEC will be
implemented in the design in order to decrease the cooling demand and reach a netzero energy Passive House. However, the PDEC relies significantly on natural air to
cool the building, and the mechanism of the PDEC contradicts one of the Passive
House principles, of airtightness. By applying PDEC, the house will be open to external
air and the building will not be airtight. As a result, if this strategy achieves higher
performance, the Passive House principles should be revised for hot and arid climates
in order to better meet the needs of such climate.
The house was designed for a large family with four bedrooms. At least two
cooling towers are needed to deliver cooled air to each space in the house. The cooling
towers are positioned in the east and west side of the house. These locations allow the
cooling towers to supply every space in the house with fresh and cooled air. Each tower
44
is 8x4 ft., and has water sprays at the top. There are four openings with louvres at the
top of each tower to control and capture winds. The cooled air will be delivered to the
different spaces in the house through smaller openings in each room. Fans are optional
and should be located at the top of the towers to control air velocity as needed. On the
roof, a long clerestory is located between the cooling towers to improve the air
circulation in the house. The clerestory location is right above the family space on the
second floor. A part of the 1st floor family area is a double high space. The design of the
cooling towers and clerestory will allow cool air to enter through the cooling towers and
leave through the clerestory after it cools the spaces. Figures 4-35 to 4-48 show plans,
sections, elevation, and 3D views of the house after incorporating the PDEC to the
design.
FIGURE 4-35
Cooling Towers Locations
Two Cooling
Towers 8 x 4ft
Clerestory
2
646ft PV
System
generate
approximately
48264kBTU/yr
45
FIGURE 4-36
Cooling Towers on the First Floor
A
Cooling
towers on the
first floor
C
FIGURE 4-37
Cooling Towers on the Second Floor
Cooling
towers in the
2nd floor
46
D
B
FIGURE 4-38
Cooling Towers at the Top
Source: Zarja, 2015
OR
Fans
(Optional)
Source: Nature Cool
A
FIGURE 4-39
Section A
47
FIGURE 4-40
Section D
FIGURE 4-41
Section C
FIGURE 4-42
South Elevation
48
FIGURE 4-43
North Elevation
FIGURE 4-44
East Elevation
FIGURE 4-45
West Elevation
49
FIGURE 4-46
South Perspective
FIGURE 4-47
North East Perspective
50
FIGURE 4-48
South East Perspective
The structure of the cooling towers is very similar to the rest of the building. The
only added material is the PTFE Teflon. This material covers the internal part of the
cooling towers. PTFE Teflon is a water resistant material, and has exceptional
resistance to high temperatures. These characteristics make this material an ideal
choice for the cooling towers. The top of the towers have louvres with dust and insect
control devices. Water sprays and fans are located in the top to cool the air. Figure 4-49
shows a 3D detail for the structure of the PDEC system.
The design of the house allows fresh cooled air to enter the house through the
cooling towers, and then leave through two different routes. In the living spaces, the
heavy cooled air will push the warmer air to the top, which will then leave through the
clerestories. Small windows placed in each room are enough to circulate the air in the
room. The concept of the PDEC system can be seen in Figures 4-50 and 4-51.
51
52
FIGURE 4-49
3D Detail Shows the Structure and System of the Cooling Towers
Figure 4-50
3D Section Shows the PDEC through the Living Room and Bedrooms
Figure 4-51
3D Section Shows the PDEC through the Family Rooms
53
Energy Performance
Due to the difficulty in running an energy simulation for a PDEC, the energy
performance analysis was conducted in two steps. In the first step, IESVE, an
integrated building analysis software system was used to study the air velocity and air
movement in the building. After that, the potential air temperature supplied by the
cooling towers will be determined by using an equation that has been developed in
previous research (Phillip, T. & Lau, B, 2013). This analysis will reveal if the air is
moving properly through tower to the building, and the supplied temperatures are at a
comfort zone. After ensuring that the air is moving and the cooling tower approach is
working, several case studies will be analyzed to find out the potential energy savings in
cooling loads from the towers. This analysis will not provide an accurate number for the
energy consumption and energy savings, however, it will provide an overview of how
much can be achieved and how much is needed to reach a net zero energy Passive
House.
IESVE Analysis
The whole model with the two cooling towers was drawn in IESVE. First, the
airflows were analyzed through the cooling towers, clerestory, and windows. The results
show that the towers are able to capture winds from the top and move them down
through the different spaces in the house. In the family spaces a significant amount of
air is rising to the top and leaving through the clerestories. The IESVE software does
not take into account water sprays in the top, so the results show air is moving in and
out of the top of the cooling towers. In the clerestories, some amount of air is entering
the building, which will bring hot air to the house, however, at the moment selected for
54
the analysis, the air was coming from south, and all the clerestory windows were open.
The design of the clerestory will allow more flexibility to open the desired windows
based on the wind direction. To illustrate that, the wind directions used forth time of the
analysis were coming mostly from south. In this case, the south windows in the
clerestory will be closed to prevent the hot winds from entering the building while the
north windows will be opened to push the warmer air out of the building. The results can
be seen in Figures 4-52, 4-53, 4-54, and 4-55 which show the airflow for each space in
the house.
The site and climate analysis in Chapter 3 shows the average wind speed in Hail
ranging between 6 and 9 mi/h. This wind speed is advantageous in terms of taking
advantage of natural ventilation. Air velocity analysis was conducted during the highest
typical wind speed, to find out what maximum wind speed could be flowing through the
cooling towers. The minimum speed is recognized to be calm. During a calm day, the
fans could be used to move the air inside the towers. During the maximum wind speed
when there are gusty winds, the analysis indicates that the air velocity inside the cooling
towers could reach above 10 ft/s. The desired air velocity in a building should range
between 1 and 1.6 ft/s. The results show that the wind speed is much higher than what
is needed. During this situation, the louvres in the top of the cooling towers will be
adjusted to allow enough air entering the building in order to meet the desired air
velocity. Figure 4-54 to 4-60 shows the results from IES from the design proposal.
55
FIGURE 4-52
Air Flow (CFM) - South East
st
1 Cooling
tower
Clerestory
Master
Bedroom
SW bedroom
Winter
Room
Living
Space
Software: IESVE
FIGURE 4-53
Air Flow (CFM) - South West
st
1 Cooling
tower
Clerestory
Master
Bedroom
Living
Space
nd
2 floor
st
1 floor Family space
SW bedroom
Winter
Software: IESVE
56
FIGURE 4-54
Air Flow (CFM) – North East
nd
2 Cooling
tower
NW
bedroom
Kitchen
nd
2 floor
st
1 floor Family space
NE bedroom
Guest Room
Software: IESVE
FIGURE 4-55
Air Flow (CFM) – North West
nd
2 Cooling
tower
NW
bedroom
Guest Room
NE bedroom
Kitchen
st
1 floor
Family space
Software: IESVE
57
FIGURE 4-56
Air Velocity (ft/s) – Through East Cooling Tower and Living
Software: IESVE
FIGURE 4-57
Air Velocity (ft/s) – Through Family Areas
Software: IESVE
58
FIGURE 4-58
Air Velocity (ft/s)
Software: IESVE
Supply Temperature
Studies have revealed that a significant reduction in the air supply temperature of
a cooling tower could be achieved. Phillip, T. & Lau, B, 2013 state that “the cooling
potential of a PDEC system is such that a temperature reduction of up to 80% of the
difference between the Dry-bulb and Wet-bulb temperatures is achievable”.
This relationship can be seen in the equation below:
TT=TDB-0.8(TDB-TWB)
Where:
TT = Tower supply air temperature
TDB = Dry-bulb temperature
TWB = Wet-bulb temperature
59
The high potential reduction in air temperature is achievable in a location with
high dry-bulb temperature and low relative humidity, and the climate conditions of the
Hail site meet this criteria. IESVE provides the dry-bulb and wet-bulb temperatures of
the site for the entire year. Figures 4-59 and 4-60 show the difference between the drybulb and the wet-bulb temperatures at the site. The significant reduction of the wet-bulb
temperatures suggest that a comfortable air supply temperature from the PDEC system
is highly achievable. By using the equation mentioned earlier, six cases through the
year were calculated. These days include the average dry-bulb and wet-bulb
temperatures of the hottest three months. The other three cases represent some of the
hottest days of the year. Table 4-4 and Figure 4-61 show the potential air supply
temperature of the six different cases compared with the dry-bulb temperature.
FIGURE 4-59
Dry-Bulb Temperature
Software: IESVE
60
FIGURE 4-60
Wet-Bulb Temperature
Software: IESVE
TABLE 4-4
Potential Air Supply Temperature from the PDEC
Time or Month
Dry-Bulb
Temperature - ºF
Wet-Bulb
Temperature - ºF
Potential
Temperature from
Cooling Towers - ºF
June 21st at 2:00pm
105
63
71.4
Aug 6th at 3:00pm
115
66
75.8
June 15th at 3:00pm
106
71
78
Average in June
111
63
72.6
Average in July
113
64
73.8
Average in August
113
66
75.4
Source: Alshenaifi, 2015
61
FIGURE 4-61
Comparison between Dry-Bulb Temperatures and Potential Air Supply Temperature
140
120
100
80
60
40
20
0
June 21st at
2:00pm
Aug 6th at
3:00pm
Dry-Bulb Temperature
June 15th at
3:00pm
Wet-Bulb Temperature
Average in June
Average in July Average in August
Potential Temperature from Cooling Towers
Source: Alshenaifi, 2015
Tithe results of the IESVE analysis show that the air supply temperatures range
between 71oF and 78oF during the worst cases throughout year when the outside
temperature exceeds 100oF. During cooler days or at night, temperatures supplied by
the cooling towers will be even below comfortable zones.
The results of the airflow and air velocity reveal that the two cooling towers were
designed and located properly at the site. The average wind speed at the site is
advantageous, and in some cases, the louvers will work to minimize the air velocity to
the desired speed. During calm winds situations, the fans will work as needed to move
the air inside the cooling towers, and then to the house. The potential air temperature
reduction from cooling towers will lead to a significant reduction in cooling demands. As
a result, achieving the net-zero energy Passive House is highly achievable. After
ensuring that the cooling towers are working properly, several case studies will be
analyzed in the next section to ascertain out the potential energy improvements.
62
Case Studies
In this section, several case studies that used PDEC system are analyzed in
order to find out the potential energy reduction in cooling loads. The case studies will
provide the potential minimum and maximum energy reduction using PDEC. Based on
that, the results would be used to estimate the energy saving needed to reach net-zero
energy Passive House. These case studies are analyzed briefly in the following
sections.
The New Stock Exchange in Malta
The New Stock Exchange is located in Valletta, Malta. Malta has a mild winter
with an average temperature of 49oF and warm summers with an average of 86oF. The
cooling loads represent a large volume of the total energy consumption. The New Stock
Exchange is an office building with a huge atrium on the middle. The atrium requires
huge mechanical units with large ducts in order to be cooled. The PDEC system was
taken into consideration to cool the atrium along with a cooling coil system for the rest of
the building. The energy consumption for cooling the whole building was approximately
103,924 kWh. By incorporating the PDEC system in the atrium, the cooling loads were
reduced to 54,139 kWh by 48%. Figure 4-62 shows the passive cooling strategy in the
building (WSP Environmental Ltd, 2002).
63
4-63
FIGURE 4-62
Passive Cooling Strategy in the building using PDEC System
Source: WSP Environmental Ltd, 2002
1. The Torrent Research Center
The Torrent Research center is located in Ahmadabad, India. The center is a
large pharmaceutical laboratory with office space as well, and providing natural
ventilation in the building is extremely important. The center consists of 6 buildings, and
the PDEC system is incorporated in only four of them. In each building, the PDEC
system is located above a central corridor separating the offices from the laboratories.
On the long sides of each building, several shafts are built to maximize air circulation
and push the warmer air out of the building. When the outside temperature reaches its
maximum, the PDEC drops the interior temperature between 10 and 14ºC. With the
PDEC, The total savings in cooling demands for the center reached 64% (KANG, D.
2011). Figures 4-63 and 4-64 are plan and section showing how the PDEC system is
working at the center.
64
FIGURE 4-63
Floor Plan of One of the Buildings in the Center
Source: Thomas, L. & Baird, G., 2005
FIGURE 4-64
Section through the PDEC system in the Center
Source: Thomas, L. & Baird, G., 2005
65
Zion National Park Visitor Center
The visitor center at the Zion National Park is located in southwestern Utah. The
summer daytime temperatures range between 95º - 100ºF while overnight lows are
comfortable (65º–70ºF). The total area of the building is 8475-ft2 (787-m2). The building
envelope is well insulated to minimize heating and cooling loads. Two cooling towers
are incorporated in the building. Natural air is cooled by an evaporation process using
four wet pads in the top of the towers. Clerestories are designed in the roof to maximize
daylighting and improve the air movement with the cooling towers (Figure 4-65). Most of
the cooling requirements are met by natural ventilation (P. Torcellini, S. Pless, N. Long,
and R. Judkoff, 2004).
FIGURE 4-65
Natural Ventilation Concept in the Zion National Park Visitor Center
Source: Source: NREL, 2004
66
An energy performance evaluation was conducted over a 2 year period. The
annual EUI for the building was 26.9 kBTU/ft2/yr (8.5 kWh/m2/yr). The building
consumes 65% less energy when compared with a building that meets U.S. federal
codes. Passive cooling towers combined with the clerestories were the most effective
strategies to reduce cooling loads. All the cooling demands were met naturally with 93%
energy savings. The remaining 7% was consumed to pump the water to the top of the
towers. Figure 4-66 shows a comparison between a baseline case and the case with
the cooling towers (P. Torcellini, S. Pless, N. Long, and R. Judkoff, 2004).
FIGURE 4-66
Comparison between a Baseline Model and the Developed Case using PDEC
Source: P. Torcellini, S. Pless, N. Long, and R. Judkoff, 2004
67
Primary School Reference Building by the U.S. Department Of Energy
This case study provides an energy performance study of the PDEC by Kang, D
in 2011. The study was a dissertation for a PhD in Architecture at the University of
Illinois at Urbana-Champaign. The building chosen for the study was a one story Eshaped school provided by the US Department of Energy. The building consists of one
main corridor. The spaces in the building include classrooms, an office, corridors, an
auditorium, a gymnasium, a cafeteria, a kitchen, and a library. The total square footage
of the building is 6,871 ft2.
Two different geographic locations were chosen to run energy simulations using
the PDEC system. The first location is Yuma, Arizona, which has a hot and dry climate.
The second location is Sacramento, California, which has a warm moderate climate. In
the baseline case, the total electricity consumption for cooling was 7100.78 mega joules
in Yuma. In Sacramento, the cooling consumption was lower, as the average
temperature is cooler then Yuma (Kang, D, 2011).
By applying the PDEC to the design, the estimated cooling consumption was
reduced in Yuma by 96.3% to 258.72MJ. In Sacramento, the cooling loads reduced by a
similar percentage, approximately 95.5%.however, the PDEC was more effective in the
Yuma case as it requires much more energy for cooling. Moreover, the increase in
relative humidity in the Yuma case had a positive impact on the energy performance
and reduced all of the cooling loads. The remaining energy consumption in both cases
was only needed used to pump the water to the top of the towers. The expected total
energy consumption in the building with the PDEC system was only 57.3% in Yuma and
44.9% in Sacramento (Kang, D, 2011).
68
Passive Down-Draft Evaporative Cooling in Saudi Arabia
A study has been conducted measuring the performance of PDEC in residential
buildings in Saudi Arabia. The location selected was Riyadh, the capital city. Riyadh is
an ideal location to find out how the PDEC will work since it has similar weather
conditions to Hail. A single family house design was proposed for this purpose. The total
floor area of the house is 1657ft2 (154m2). The house includes three bedrooms, a guest
room, 2 lounges, a kitchen, and a dining room (Toyin Phillip & Benson Lau 2013).
One 1 x 1.5m cooling tower was placed in the middle of the house. The PDEC
was designed to cool most of the spaces, which include the bedrooms, two lounges,
and dining room (Figures 4-67, 4-68). Water mists were placed in the cooling tower to
cool the air. The falling cool air is distributed within the building via windows and doors
between the spaces (Toyin Phillip & Benson Lau 2013).
FIGURE 4-67
Section through the PDEC in the House
Source: Phillip, T. & Lau, B., 2013
69
FIGURE 4-68
The Location of the PDEC in the Floor plan
Source: Phillip, T. & Lau, B., 2013
The study did not analyze the overall energy performance of the house, but
rather focused on the home’s cooling needs. The study was conducted during the
period between April and October (the summer season), and. the proposed PDEC met
the cooling requirements for more than 75% of the required periods. This reveals that
PDEC system is highly effective in Saudi Arabia’s climate.
70
Case Studies Summary
Based upon the potential savings in cooling loads from the PDEC, the Passive
House principles should be revised for hot-dry climates in order to increase the energy
efficiency in those locations. The previous analysis of the case studies, as explained
above, suggests that there is a significant potential to reduce cooling loads by using the
PDEC system. The potential savings in cooling consumptions in the previous case
studies range between 48% to more than 90%. In the case of the Passive House
design, this reduction in the cooling demand greatly contributes to the home’s overall
level of energy performance, and could reach net zero energy Passive House in a hotdry climate.
71
CHAPTER 5: CONCLUSION
Saudi Arabia is a top oil consumer in the Middle East, with approximately 3
million bbl/d. This high consumption is expected to increase to 8.3 million bbl/d by 2028
and Saudi Arabia was ranked the 10th largest CO2 producer in the world in 2014.
Buildings represent approximately 51.2% of total energy consumed in Saudi Arabia, and
70% of the total building consumption goes to cooling loads.
Unless immediate sustainable solutions are implemented, the country will face a
serious problem by 2032 with the increasing consumption. The proposed solutions
should take into account energy reduction strategies before looking to alternative,
sustainable energy sources.
The Passivhaus concept could be an ideal solution to face the challenges
associated with increasing building energy consumption. By applying the Passivhaus
principles to a typical Saudi house, a 71% energy reduction was achieved including the
use of photovoltaics. As the Passivhaus principles are able to achieve a higher level of
energy performance in cold climates, revising the Passivhaus principles for hot and dry
climates by applying other passive cooling strategies will achieve a higher level of
performance.
The PDEC system was taken into consideration as a passive cooling strategy to
improve residential energy performance and reach net zero energy in Saudi Arabia.
This strategy relies significantly on natural ventilation by evaporation. However, the
application of this strategy contradicts with the Passivhaus principles, as the building will
not be airtight.
72
Air velocity, air movement, and case study analysis revealed that significant
potential energy savings can be achieved through the PDEC system. The air movement
analysis in IES shows that the PDEC design in the house work effectively, and the
amount of natural air entering the house meets the desired rates. Additional case
studies have shown a significant reduction in cooling loads can be achieved through the
PDEC system.
The total energy consumption of the baseline case was 258,890 kBTU with
annual EUI of 69 kBTU/ft2. Using US Passive House principles for hot and arid climates,
this total energy consumption was reduced to 100,405 kBTU without the use of
photovoltaics. With the use of photovoltaics, the Passive House total EUI went down to
20 kBTU/ft2, resulting in total energy reduction of 71%. Cooling loads in the Passive
House case represent 71% of the total consumption with 71,993kBTU and the
estimated total photovoltaic production is 48,264 kBTU. In order to reach net-zero
energy Passive House, the total energy consumption needs to be reduced by
52,141kBTU, which represents 72% of total cooling demands Based on an analysis of
the case studies, this amount of reduction is highly possible using properly designed
cooling towers (Figure 5-1). When compared with the case studies, the size and design
of the cooling towers in the house could provide enough cooled air to cool the house
most of the time. If the cooling loads are reduced by 90%, which is the typical result in
the case studies, the project could be net-positive energy and even produce
approximately 12,652 kBTU/yr.
73
74
Source: Alshenaifi, 2015
FIGURE 5-1
Diagram shows the Potential to Reach Net-Zero Energy Passive House based on the Case Studies Analysis
The results from the study have shown that using passive cooling strategies, a
higher level of efficiency is very possible. Based on the results of this study, PDEC is a
valuable strategy for hot-dry climates. Revising the Passive House principles for each
climate zone would be effective and provide alternative choices to meet the needs of
each climate zone.
Due to the limit of available data from energy simulations for mechanical and
dynamic systems, further energy simulations for the PDEC are needed to provide more
accurate results. This could be achieved through the development of more advanced
simulation software, and would lead to more research opportunities on this subject. One
of the areas needing further investigation is the water consumption of the cooling
towers. The PDEC uses water as its main source to cool natural air by evaporation,
which requires a significant use of water. Conducting a study in this matter could
provide solutions or water saving strategies supply the PDEC system. Another area for
further research in this subject is passive evaporative cooling for residential
communities. The strategy of the PDEC could also be applied to cool open or semiopen spaces in residential communities, which l would also have a positive effect in the
energy performance if the outside environment of a community becomes cooler.
75
BIBLIOGRAPHY
AIA, (2015). Environmental Showcase Home. Retrieved 30 April 2015, from
http://www.aiatopten.org/node/225
ASHRAE Standard. (2015). Retrieved 4 May 2015, from
https://ashrae.iwrapper.com/ViewOnline/Standard_90.1-2013_I-P
Bryant, J., Amato, A., Law, S., & Al Abdulla, A. (2013). Integrated Project and Metering
Design for the First Passivhaus in Qatar. ASHRAE.
BODEN, T., MARLAND, G., & ANDRES,, R. (2010). GLOBAL, REGIONAL, AND
NATIONAL FOSSIL-FUEL CO2 EMISSIONS. Carbon Dioxide Information Analysis
Center (CDIAC) Datasets. doi:10.3334/cdiac/00001_v2010
Colorado Energy. (2015). R-Value Table. Retrieved 22 May 2015, from
http://www.coloradoenergy.org/procorner/stuff/r-values.htmInsulated CMU R-Value
http://ncma-br.org/pdfs/66/TEK%2006-02C1.pdf
Cbe.berkeley.edu, (2015). The Center for Global Ecology - Cool tower. Retrieved 5 May
2015, from
http://www.cbe.berkeley.edu/mixedmode/images/carnegie/Carnegie_cool_tower.html
Dupont. (2015). PTFE Coating, Extrusion, Molding | DuPont™ Teflon ® PTFE.
Retrieved 30 April 2015, from
http://www2.dupont.com/Teflon_Industrial/en_US/products/product_by_name/teflon_ptfe/
Eia.gov,. (2015). Saudi Arabia - U.S. Energy Information Administration (EIA). Retrieved
21 April 2015, from http://www.eia.gov/countries/country-data.cfm?fips=SA#cde
EPA. (September 9th, 2013), Global Greenhouse Gas Emissions Data. Retrieved from
http://www.epa.gov/climatechange/ghgemissions/global.html
Fennell, H., & Haehnel, J. (2015). Setting Airtightness Standards (1st ed., pp. 26-30).
North Thetford, Vt: ASHRAE.
Global Greenhouse Gas Emissions Data. (September 9th, 2013). EPA, Retrieved from
http://www.epa.gov/climatechange/ghgemissions/global.html
How much of the world’s energy is consumed by buildings? (2015). IEA. Retrieved from
http://www.iea.org/aboutus/faqs/energyefficiency/
76
IEA. (2015). How much of the world’s energy is consumed by buildings? Retrieved from
http://www.iea.org/aboutus/faqs/energyefficiency/
KANG, D. (2011). ADVANCES IN THE APPLICATION OF PASSIVE DOWN-DRAFT
EVAPORATIVE COOLING TECHNOLOGY IN THE COOLING OF BUILDINGS (PhD of
Architecture). Graduate College of the University of Illinois at Urbana-Champaign.
Kang D. and Strand R., (2009). SIMULATION OF PASSIVE DOWN-DRAUGHT
EVAPORATIVE COOLING (PDEC) SYSTEMS IN ENERGYPLUS (pp. 369 - 376).
Glasgow, Scotland: Building Simulation.
K.A.CARE. (2013). The Vision | King Abdullah City for Atomic and Renewable Energy.
Retrieved 23 April 2015, from http://www.kacare.gov.sa/en/?page_id=84
K.A.CARE. (2012). Building the Renewable Energy Sector in Saudi Arabia. Internation
Renewable Energy Agency. Retrieved 21 April 2015, from
http://www.irena.org/documentdownloads/events/maltaseptember2012/5_ibrahim_babel
li.pdf
Lechner, Norbert. (2009). Heating, Cooling, Lightning Sustainable Design Methods for
Architecture (p.2)
Nature-cool.com. (2015). Nature Cool Evaporative Cooling Pads. Retrieved 5 May
2015, from http://www.nature-cool.com/
OPEC. (2015). OPEC Share of World Crude Oil Reserves. Retrieved from
http://www.opec.org/opec_web/en/data_graphs/330.htm
PHILLIP, T. & Lau, B. (2013). PASSIVE DOWNDRAUGHT EVAPORATIVE COOLING:
In 29th Conference, Sustainable Architecture for a Renewable Future. London, UK:
University of Nottingham, UK.
Institute, P. (2015). Passivhaus Institut. Passiv.de. Retrieved 19 May 2015, from
http://www.passiv.de/en/02_informations/02_passive-house-requirements/02_passivehouse-requirements.htm
PHIUS. (2015). PHIUS Certified Projects: The Desert Passive House. Retrieved from
http://www.phius.org/projects/1154
Passive House Institute US. (2015). The Desert Passive House. Retrieved from
http://phius.westhostsite.com/project_detail.php?id=1154
77
Passipedia. (2015). Passivehaus Wall System. Retrieved 22 May 2015, from
http://passipedia.org/_media/picopen/ph_suitable_ext_wall_systems.jpg?cache
Qatar Foundation,. (2013). Boost to Green Living as New Figures For Passivhaus Add
Up. Retrieved 23 April 2015, from http://www.qf.org.qa/news/299
SEEC. (2013). Saudi Energy Efficiency Center. Retrieved from
http://www.seec.gov.sa/2013/03/27/‫م بان ي‬/?lang=en
The Rise of the Green Buildings, (Dec 2nd, 2004). The Economist.
http://www.economist.com/node/3422965\
Thomas, L. & Baird, G. (2005). Post-occupancy evaluation of passive downdraft
evaporative cooling and air conditioned buildings at Torrent Research Center Sydney:
University of Technology.
WSP Environmental Ltd. (2002). Passive Downdraught Evaporative Cooling (PDEC)
applied to the central atrium space within the New Stock Exchange in Malta. London,
UK.
Weatherspark.com,. (2015). Historical Weather For The Last Twelve Months in Ha'il,
Saudi Arabia - WeatherSpark. Retrieved 23 April 2015, from
https://weatherspark.com/history/32765/2015/Ha-il-Hail-Saudi-Arabia
Zion National Park Visitor Center: Performance of a Low-Energy Building in a Hot, Dry
Climate. (2004). the World Renewable Energy Congress VIII and Expo. Denver,
Colorado.
Zarja Elektronika,. (2015). Water mist | Zarja Elektronika. Retrieved 5 May 2015, from
http://www.zarja.com/en/systems/extinguishing-systems/water-mist/
78