Optimal Design and Retrofit of Energy Efficient Buildings, Communities, and Urban Centers

628 Pages·2018·12.225 MB·English

by  Moncef Krarti

Optimal Design and
Retrofit of Energy
Efficient Buildings,
Communities, and
Urban Centers
Moncef Krarti
Professor and Coordinator, Building Systems Program,
University of Colorado, Boulder, CO, USA
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About the Authors
Moncef Krarti, Professor and Coordinator, Building Systems Program, Civil,
Environmental, and Architectural Engineering Department at the University of
Colorado, has a vast experience in designing, testing, and assessing innovative
energy efficiency and renewable energy technologies applied to buildings. He
also directed several projects in designing energy efficient buildings with inte-
grated renewable energy systems. Prof. Krarti has published over 250 technical
journals and handbook chapters in various fields related to energy efficiency,
distribution generation, and demand side management for the built environ-
ment. Moreover, he has published several books on building energy efficient
systems. He taught courses related to building energy systems for over 20 years
in the US and abroad. As part of his activities as a professor at the University of
Colorado, he has been managing the research activities of an energy manage-
ment center at the University of Colorado with an emphasis of testing and evalu-
ating the performance of mechanical and electrical systems for residential and
commercial buildings. He has also helped the development of similar energy
efficiency centers in other countries including Brazil, Mexico, and Tunisia.
Dr. Krarti has an extensive experience in promoting building energy efficiency
technologies and policies overseas, including the development of building energy
codes and energy efficiency training programs in several countries, including
Tunisia, Sri Lanka, Egypt and collaborative research with over ten countries in
Europe, Africa, Asia, and South America.
Moncef Krarti, PhD PE LEED®AP
Professor and Coordinator, Building Systems Program,
University of Colorado, Boulder, CO, USA
xiii
Preface
Worldwide, buildings are responsible for over 40% of the total primary energy
use and related greenhouse emissions. Through standards and energy effi-
ciency programs, several countries have succeeded in improving the energy
performance of new and existing buildings. Designing and retrofitting electri-
cal power systems to be energy efficient have been the primary components of
the efforts to reduce energy use consumption by the built environment. Indeed,
most energy end-use systems for both residential and commercial buildings
such as lighting, air conditioning equipment, and appliances require electrical
power to operate. In particular, electricity has to be readily available throughout
the building to ensure people can live comfortably and work productively. How-
ever, if not designed safely, electrical distribution systems can cause serious
injury and even death. Therefore, the main objective when designing and retro-
fitting electrical distribution systems within buildings is safety for both humans
and equipment.
This book outlines the fundamental principles and methods to design safe,
flexible, reliable, accessible, and energy efficient electrical power systems for
both residential and commercial buildings. In particular, this book presents
simplified but effective calculation and analysis methods to design and
evaluate safe and energy efficient distribution electrical systems suitable for
residential and commercial buildings. These simplified methods are based on
well-established engineering principles. In addition, several innovative yet
proven energy efficiency technologies and strategies are presented to improve
the energy performance of existing electrical systems. The book is designed
to be a self-contained textbook aimed at seniors and/or first-year graduate
students interested in designing energy efficient distribution electrical systems
for buildings. The contents of this book can be covered in a one-semester
course for building electrical systems. However, the book can be used as a
reference for practitioners and as a text for continuing education short courses.
The users of this book are assumed to have a basic understanding of basic
electrical circuits including single-phase and three-phase power systems.
Basic knowledge of general concepts of engineering economics, and building
mechanical systems are also recommended.
The book is organized in 14 self-contained chapters with several worked-out
examples, and design case studies. Moreover, several problems are provided at
the end of most chapters to serve as review or homework assignment problems
for the users of the book. As instructor of a course on building electrical
xv
xvi Preface
systems at the University of Colorado, I found that the best approach for the
students to understand and apply the various design and analysis methods and
tools discussed in this book is through group projects. These projects include
(1) the design of electrical systems of new residential and commercial buildings
and (2) audit and redesign of distribution power systems for existing buildings.
The first chapter provides a basic overview of the basic components of
electrical distribution systems specific to both residential and commercial
buildings. In addition, the general approach as well as the main objectives
of designing building power distribution systems are outlined. In Chapters 2
through 4, a basic review is presented for electric circuits, transformers, and
motors. Chapter 5 provides the basic operation of protection devices while
Chapter 6 summarizes the design criteria for wiring systems including branch
circuits and feeders. Chapters 7 and 8 present the detailed design require-
ments as well as specific case studies for residential and commercial buildings,
respectively. Then, Chapters 9 through 11 outline sequentially the principles of
economic analysis, typical energy efficiency measures for electrical systems,
and general power quality issues and means to avoid or eliminate them. Chapters
12 and 13 present the components as well typical design procedures for
photovoltaic (PV) systems and electrical generation systems. Finally, Chapter 14
introduces optimization-based design methods to integrate renewable electricity
generation technologies in designing electrical systems for buildings.
When using this book as a textbook, the instructor should start from Chap-
ter 1 and proceed through Chapter 14 in order. However, some of the chapters
can be skipped or covered lightly depending on the time constraints and the
background of the students. First, basic design approaches of all components
of electrical distribution systems are outlined (Chapter 1). Some of the funda-
mental principles of electrical power systems are then reviewed (Chapter 2).
The characteristics and the basic features of single-phase and three-phase
transformers are discussed in details (Chapter 3). Similarly, the operation fea-
tures and characteristics of single-phase and three-phase electrical motors are
summarized (Chapter 4). Then, some of the major components of building
electrical distribution systems are presented including protection devices as
well as grounding (Chapter 5), and conductors for branch circuits and feeders
(Chapter 6). Specific design approaches for specific building types are then
outlined with specific applications to well-defined case studies for residen-
tial buildings (Chapter 7), and commercial buildings (Chapter 8). To assist
in designing energy efficient electrical systems, some economic analysis
methods are overviewed (Chapter 9). Then, a wide range of energy efficiency
strategies and technologies are discussed to reduce energy use from electri-
cal power systems including transformers, wires, lighting fixtures, motors,
and appliances (Chapter 10). Measures and methods to improve the power
quality of electricity delivered to building energy systems are also discussed
(Chapter 11). Approaches to design systems to generate electricity within
buildings are presented including solar PV systems (Chapter 12) and fuel-based
Preface xvii
generation systems (Chapter 13). Finally, optimization-based analysis approach
is introduced and applied to design net zero energy buildings (Chapter 14).
A special effort has been made to use metric (SI) units throughout the book.
However, in several instances English (IP) units are also used as they are still
the standard set of units used in the United States. A conversion table between
the two unit systems (from English to metric and metric to English units) is
provided as part of back materials for the book.
I wish to acknowledge the assistance of several people in the conception
and the preparation of this book. Special thanks to the input of several of my
students at the University of Colorado at Boulder. Finally, I am greatly indebted
to my wife Hajer and my three children for their continued patience and support
throughout the preparation of this book.
Moncef Krarti
Conversion Factors
(Metric to English)
Area 1 m2 = 1550.0 in2
= 10.764 ft2
Energy 1 J = 9.4787 × 10−4 Btu
1 GJ = 0.023884 TOE
1 GJ = 9.48043 Therm
1 GJ = 0.163456 BOE
1 XJ = 0.9478 Quad
1 kWh = 3412 Btu
1 GWh = 85.9845 TOE
1 TWh = 0.0034 Quad
Heat transfer rate 1 W = 3.4123 Btu/h
Heat flux 1 W/m2 = 0.3171 Btu/h·ft2
Heat generation rate 1 W/m3 = 0.09665 Btu/h·ft3
Heat transfer coefficient 1 W/m2·K = 0.17612 Btu/h·ft2·°F
Latent heat 1 J/kg = 4.2995 × 10−4 Btu/lb
m
Length 1 m = 3.2808 ft
1 km = 0.62137 mile
Mass 1 kg = 2.2046 lb
m
1 ton = 2204.62 lb
m
Mass density 1 kg/m3 = 0.062428 lb /ft3
m
Mass flow rate 1 kg/s = 7936.6 lb /h
m
Mass transfer coefficient 1 m/s = 1.1811 × 104 ft/h
Pressure 1 Pa = 1 N/m2 = 0.020886 lb/ft2
f
= 1.4504 × 10−4 lb/in.2
f
= 4.015 × 10−3 in. water
1 atm = 100 kPa = 14.69595 psi
= 1 bar
Power 1 kW = 1 kJ/s = 1.340 HP
= 3,412 Btu/h
1 × 105 N/m2 = 1 bar
xix
xx Conversion Factors (Metric to English)
Refrigeration capacity 1 kJ/h = 94,782 Btu/h
= 7.898 × 10−5 ton
1 kW = 0.2844 ton
Specific heat 1 J/kg·K = 2.3886 × 10−4 Btu/lb ·°F
m
Temperature 1 K = (5/9) °R
= (5/9)(°F + 459.67)
= °C + 273.15
Temperature difference 1 K = 1°C
= (9/5) °R = (9/5) °F
Thermal conductivity 1 W/m·K = 0.57782 Btu/h·ft·°F
Thermal diffusivity 1 m2/s = 38750.0775 ft2/ h
= 645.835 ft2/min
=10.7639 ft2/s
Thermal resistance 1 C.m2/W = 5.7683 °F.ft2.h/Btu
U-value 1 W/°C.m2 = 0.17611 Btu/h.°F.ft2
Volume 1 m3 = 6.1023 × 104 in3
= 35.314 ft3
= 264.17 gal
Volume flow rate 1 m3/s = 1.2713 × 105 ft3/h
1 L/s = 127.13 ft3/h
= 2.119 ft3/min
Chapter 1
Introduction
Chapter Outline
1.1 Global trends in energy 1.2.6 Beyond BEEC
consumption 1 Requirements 29
1.1.1 Primary Energy 1.2.7 Holistic Design
Supply 2 Approach 30
1.1.2 Final Energy 1.3 Strategies for large scale
Consumption 6 EE program implementation 33
1.1.3 Energy Consumption 1.3.1 Foundational Strategies
by the Building Sector 10 for Large-Scale
1.1.4 Energy Productivity Energy Efficiency
Trends 14 Program 33
1.2 Energy efficiency policies 19 1.3.2 Voluntary Strategies
1.2.1 Benefits for Improving for Large-Scale
Energy Efficiency Energy Efficiency
of Buildings 20 Program 35
1.2.2 Barriers for Energy 1.3.3 Mandatory Strategies
Efficiency 22 for Large-Scale
1.2.3 Energy Efficiency Energy Efficiency
Programs for New Program 36
Buildings 24 1.3.4 Approaches
1.2.4 Types of Building for Energy Intensive
Energy Codes 25 Buildings 36
1.2.5 Overview of BEEC 1.4 Summary 40
Establishment 27 References 42
1.1 GLOBAL TRENDS IN ENERGY CONSUMPTION
In this section, historical energy consumption in the world and select countries
as well as regions is first discussed based on reported data for primary energy
supply and final energy consumption. Specific trends in current and future en-
ergy consumption and energy mix of the building sector are also outlined using
available data and analyses. In addition, the economic output per unit energy
consumed is evaluated to assess the macroeconomic energy efficiency of select
countries and regions in the world.
Optimal Design and Retrofit of Energy Efficient Buildings, Communities, and Urban Centers.
http://dx.doi.org/10.1016/B978-0-12-849869-9.00001-6 1
Copyright © 2018 Elsevier Inc. All rights reserved.
2 Optimal Design and Retrofit
FIGURE 1.1 Annual variation of total primary energy supply (TPES) for the world from
1990 to 2015. (Source: IEA, 2017).
1.1.1 Primary Energy Supply
From 1990 to 2015, the total primary energy supply (TPES) in the world in-
creased by 60% while the energy mix remained almost unchanged as noted in
Fig. 1.1. Indeed, fossil fuels provided over 80% of the primary energy supply
of the world during the last two decades. The specific composition of the world
primary energy mix for 2015 is detailed in Fig. 1.2 (IEA, 2017). Specifically,
the world relied mainly on oil (32%), coal (28%), and natural gas (22%) to meet
its energy needs. Biofuels and waste (10%), nuclear (5%), hydro (2%), and
FIGURE 1.2 Resource composition for the world TPES during 2015. (Source, IEA, 2017).