Optimal renovation strategies for education buildings-A novel BIM-BPM-BEM framework

Abstract

The aim of this paper is to propose a novel building information model (BIM)–building performance model (BPM)–building environmental model (BEM) framework to identify the most energy-efficient and cost-effective strategies for the renovation of existing education buildings to achieve the nearly zero-energy goal while minimizing the environmental impact. A case building, the University of Maryland’s Architecture Building, was used to demonstrate the validity of the framework and a set of building performance indicators—including energy performance, environmental impacts, and occupant satisfaction—were used to evaluate renovation strategies. Additionally, this novel framework further demonstrated the interoperability among different digital tools and platforms. Lastly, following a detailed analysis and measurements, the case study results highlighted a particular energy profile as well as the retrofit needs of education buildings. Eight different renovation packages were analyzed with the top-ranking package indicating an energy saving of 62%, carbon emissions reduction of 84%, and long-term cost savings of 53%, albeit with a relatively high initial cost. The most preferable package ranked second in all categories, with a moderate initial cost.

Full text

sustainability
Article
Optimal Renovation Strategies for Education
Buildings—A Novel BIM–BPM–BEM Framework
Ming Hu
School of Architecture, Planning and Preservation, University of Maryland, College Park, MD 20742, USA;
mhu2008@umd.edu; Tel.: +1-301-405-4386
Received: 18 August 2018; Accepted: 11 September 2018; Published: 14 September 2018


Abstract:
The aim of this paper is to propose a novel building information model (BIM)–building
performance model (BPM)–building environmental model (BEM) framework to identify the most
energy-efficient and cost-effective strategies for the renovation of existing education buildings
to achieve the nearly zero-energy goal while minimizing the environmental impact. A case
building, the University of Maryland’s Architecture Building, was used to demonstrate the validity
of the framework and a set of building performance indicators—including energy performance,
environmental impacts, and occupant satisfaction—were used to evaluate renovation strategies.
Additionally, this novel framework further demonstrated the interoperability among different
digital tools and platforms. Lastly, following a detailed analysis and measurements, the case study
results highlighted a particular energy profile as well as the retrofit needs of education buildings.
Eight different renovation packages were analyzed with the top-ranking package indicating an energy
saving of 62%, carbon emissions reduction of 84%, and long-term cost savings of 53%, albeit with
a relatively high initial cost. The most preferable package ranked second in all categories, with a
moderate initial cost.
Keywords:
renovation; education buildings; building information model; building environmental
model; building performance model; nearly zero energy
1. Introduction
1.1. Existing Energy Performance of Education Buildings
Education buildings have a unique energy profile that differs from that of a typical nonresidential
building (refer to Figures 1and 2). Based on the 2012 Commercial Building Energy Consumption
Survey (CBECS) data, in education buildings, space heating accounts for 36% of the overall energy
consumption (higher than in typical nonresidential buildings, at 25%), followed by cooling (11%) and
computers (9%). The three major differences between a typical nonresidential building and education
building are space heating, computing, and cooking. An education building has significantly less
space heating and cooking energy demand, but it has a higher computing energy demand than that of
nonresidential buildings. On average, the number of computers per floor area in education buildings
increased by approximately 71% between 1999 and 2012, and education buildings have nearly twice as
many computers per floor area than any commercial buildings [
1
]. Cooking in education buildings
accounts for 7%, while in a typical commercial office building, the energy spent on cooking is close
to 0%. The differences between education buildings and typical non-commercial buildings may be
attributed to the former’s unique operation schedule and varied user groups.
Sustainability 2018,10, 3287; doi:10.3390/su10093287 www.mdpi.com/journal/sustainability

Sustainability 2018,10, 3287 2 of 22
Sustainability 2018, 10, x FOR PEER REVIEW 2 of 22
Education buildings have longer operation hours than typical nonresidential buildings. Higher-
ed buildings normally host evening classes, and K–12 schools often provide their facilities for the use
of local community activities and meetings. Education buildings also have many varied user groups
(of different ages and behaviors) since most classrooms are shared by different schools and
departments and student levels. Within education buildings, higher-ed facilities differentiate
themselves from K–12 buildings as well: K–12 buildings are normally closed during the summer and
winter breaks while higher education facilities operate on a year-round schedule. Understanding the
different operational characteristics of education buildings helped us to recognize the challenge of
considerable uncertainty in employing a dynamic operational schedule to reduce energy
consumption. Therefore, our renovation strategies shifted toward tightly controlling the categories
and factors that would not be affected by an unpredictable schedule and user groups, such as the
building envelope and systems.
Figure 1. Energy consumption profile of an education building (by author based on CBECS 2012 data
[1]).
Figure 2. Energy consumption profile comparison (created by author based on CBECS 2012 data [1]
and RECS 2015 data [2]).
Space Heating
25%
Cooling
10%
Ventilation
10%
Water heating
7%
Lighting
10%
Cooking
7%
Refrigertation
10%
Office
equipment
3%
Computer
6%
Other
12%
Education building energy profile (trillion BTU)
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
180.0
200.0
All non-
residential
buildings
Office Health care Education All residential
Energy Consumption Intensity (KBTU)
Energy Consumption Profile of Commercial Buildings
Space heating Cooling Ventilation Water heating Lighting
Cooking Refrigeration Office equipment Computing Other
Figure 1. Energy consumption profile of an education building (by author based on CBECS 2012 data [1]).
Sustainability 2018, 10, x FOR PEER REVIEW 2 of 22
Education buildings have longer operation hours than typical nonresidential buildings. Higher-
ed buildings normally host evening classes, and K–12 schools often provide their facilities for the use
of local community activities and meetings. Education buildings also have many varied user groups
(of different ages and behaviors) since most classrooms are shared by different schools and
departments and student levels. Within education buildings, higher-ed facilities differentiate
themselves from K–12 buildings as well: K–12 buildings are normally closed during the summer and
winter breaks while higher education facilities operate on a year-round schedule. Understanding the
different operational characteristics of education buildings helped us to recognize the challenge of
considerable uncertainty in employing a dynamic operational schedule to reduce energy
consumption. Therefore, our renovation strategies shifted toward tightly controlling the categories
and factors that would not be affected by an unpredictable schedule and user groups, such as the
building envelope and systems.
Figure 1. Energy consumption profile of an education building (by author based on CBECS 2012 data
[1]).
Figure 2. Energy consumption profile comparison (created by author based on CBECS 2012 data [1]
and RECS 2015 data [2]).
Space Heating
25%
Cooling
10%
Ventilation
10%
Water heating
7%
Lighting
10%
Cooking
7%
Refrigertation
10%
Office
equipment
3%
Computer
6%
Other
12%
Education building energy profile (trillion BTU)
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
180.0
200.0
All non-
residential
buildings
Office Health care Education All residential
Energy Consumption Intensity (KBTU)
Energy Consumption Profile of Commercial Buildings
Space heating Cooling Ventilation Water heating Lighting
Cooking Refrigeration Office equipment Computing Other
Figure 2.
Energy consumption profile comparison (created by author based on CBECS 2012 data [
1
]
and RECS 2015 data [2]).
Education buildings have longer operation hours than typical nonresidential buildings. Higher-ed
buildings normally host evening classes, and K–12 schools often provide their facilities for the use of
local community activities and meetings. Education buildings also have many varied user groups
(of different ages and behaviors) since most classrooms are shared by different schools and departments
and student levels. Within education buildings, higher-ed facilities differentiate themselves from K–12
buildings as well: K–12 buildings are normally closed during the summer and winter breaks while
higher education facilities operate on a year-round schedule. Understanding the different operational
characteristics of education buildings helped us to recognize the challenge of considerable uncertainty
in employing a dynamic operational schedule to reduce energy consumption. Therefore, our renovation
strategies shifted toward tightly controlling the categories and factors that would not be affected by an
unpredictable schedule and user groups, such as the building envelope and systems.

Sustainability 2018,10, 3287 3 of 22
1.2. Existing Research Condition of Education Buildings
Educational buildings in the United States account for approximately 14% of overall nonresidential
floor areas. When major building systems and equipment reach the end of their service lifespan,
among education buildings, 76.61% are 20 years or older and 38.30% are 50 years or older, with the
latter group representing the approximate expected serviceable lifespan of buildings in general [
1
]
(refer to Figure 3). Based on the 2012 Commercial Building Energy Consumption Survey data,
education buildings are the second largest building type, with an average of approximately 2879 m
2
(31,000 ft
2
) per building. The median energy performance of an education building is 0.41 kWh/m
2
/yr
(130.7 kBtu/sf/yr), and building owners spend an average $1.40 per m
2
($1400 per ft
2
) annually
on utility bills. Moreover, 75% of education buildings have a performance of 0.57 kWh/m
2
/yr
(181.1 kBtu/ft
2
/yr) or higher [
1
], which considerably exceeds the median level of a normal office
building. The majority of education buildings require immediate renovation actions due to the
buildings’ age.
Sustainability 2018, 10, x FOR PEER REVIEW 3 of 22
1.2. Existing Research Condition of Education Buildings
Educational buildings in the United States account for approximately 14% of overall
nonresidential floor areas. When major building systems and equipment reach the end of their service
lifespan, among education buildings, 76.61% are 20 years or older and 38.30% are 50 years or older,
with the latter group representing the approximate expected serviceable lifespan of buildings in
general [1] (refer to Figure 3). Based on the 2012 Commercial Building Energy Consumption Survey
data, education buildings are the second largest building type, with an average of approximately
2879 m2 (31,000 ft2) per building. The median energy performance of an education building is 0.41
kWh/m2/yr (130.7 kBtu/sf/yr), and building owners spend an average $1.40 per m2 ($1400 per ft2)
annually on utility bills. Moreover, 75% of education buildings have a performance of 0.57 kWh/m2/yr
(181.1 kBtu/ft2/yr) or higher [1], which considerably exceeds the median level of a normal office
building. The majority of education buildings require immediate renovation actions due to the
buildings’ age.
Figure 3. Age of education buildings (created by author based on CBECS 2012 data [1]).
In this section, several studies with a focus on education building energy renovation and retrofit
are briefly reviewed. Favrizio et al. [3] proposed a method to diagnose energy performance, aimed at
the integrated design of energy refurbishment of existing buildings. The research team used a method
that combined heat flow measurement, infrared thermography, energy simulation, and situ
investigation. A variety of renovation strategies were tested—such as the reduction of infiltration,
replacement of windows, and increase of thermal insulation in the building façade—with results
indicating the possibility to achieve high levels of energy saving, albeit with cost and construction
constraints. Conversely, De Angelis et al. [4] evaluated the energy reduction potential through
building envelope renovation and renewable energy production. Their results revealed that a
maximum energy reduction of 37.3% could be achieved by improving thermal properties of the
envelope together with effective natural ventilation. Niemelä et al. [5] demonstrated that the near zero-
energy building target could be cost-effectively achieved in existing education buildings in Finland.
They also found that the energy-saving potential of the HVAC system was significant compared to
the building envelope. Dalla Mora et al. [6] studied an existing school building located in Italy, and
several combinations of retrofit measures were applied to derive cost-effective solutions for
renovation. Fonsca et al. [7] designed a renovation plan for the Department of Electrical and
Computer Engineering building in University of Coimbra, Portugal, with the aim to achieve the
nearly zero-energy goal using two primary technologies: LED lighting and photovoltaic panels. In
contrast, Irulegi et al. [8] studied an education building in Spain; the research team proposed different
renovation strategies for the winter and summer, and proved that the total energy-saving potential
could reach as high as 62%.
0
10
20
30
40
50
60
70
80
Before
1946
1946 to
1959
1960 to
1969
1970 to
1979
1980 to
1989
1990 to
1999
2000 to
2007
2008 to
2012
Education (Years of Construction)
Figure 3. Age of education buildings (created by author based on CBECS 2012 data [1]).
In this section, several studies with a focus on education building energy renovation and retrofit
are briefly reviewed. Favrizio et al. [
3
] proposed a method to diagnose energy performance, aimed at
the integrated design of energy refurbishment of existing buildings. The research team used a
method that combined heat flow measurement, infrared thermography, energy simulation, and situ
investigation. A variety of renovation strategies were tested—such as the reduction of infiltration,
replacement of windows, and increase of thermal insulation in the building façade—with results
indicating the possibility to achieve high levels of energy saving, albeit with cost and construction
constraints. Conversely, De Angelis et al. [
4
] evaluated the energy reduction potential through building
envelope renovation and renewable energy production. Their results revealed that a maximum energy
reduction of 37.3% could be achieved by improving thermal properties of the envelope together with
effective natural ventilation. Niemelä et al. [
5
] demonstrated that the near zero-energy building target
could be cost-effectively achieved in existing education buildings in Finland. They also found that
the energy-saving potential of the HVAC system was significant compared to the building envelope.
Dalla Mora et al. [
6
] studied an existing school building located in Italy, and several combinations
of retrofit measures were applied to derive cost-effective solutions for renovation. Fonsca et al. [
7
]
designed a renovation plan for the Department of Electrical and Computer Engineering building
in University of Coimbra, Portugal, with the aim to achieve the nearly zero-energy goal using two
primary technologies: LED lighting and photovoltaic panels. In contrast, Irulegi et al. [
8
] studied an
education building in Spain; the research team proposed different renovation strategies for the winter
and summer, and proved that the total energy-saving potential could reach as high as 62%.

Sustainability 2018,10, 3287 4 of 22
1.3. The Research Gap in Existing Education Building Renovation Research
Overall, despite numerous studies conducted on education buildings, information on the energy
consumption of this building type is still limited, in comparison to other commercial and residential
buildings [
3
,
9
–
15
]. Furthermore, most reports focus on primary and secondary school buildings,
with very limited studies concentrated on higher education buildings. The author conducted a
literature review using academic research articles found on Web of Science (WOB) from 1970 to 2017,
182 articles were found related to energy retrofitting and renovation. Chen and Ma [
16
] studied the
regulation influence on residential buildings’ energy efficiency. Serraino and Lucchi [
17
] looked into
the effectiveness of energy renovation strategies in public housing projects. Studies have also been
conducted on energy refurbishment on historical building renovations [
18
–
20
]. Among the articles,
43% focus on residential building renovation and 35% on commercial buildings, with only 8% on
education buildings. Furthermore, most reports focus on primary and secondary school buildings,
with very limited studies concentrated on higher education buildings.
The second research gap is between energy efficiency improvement and environmental impact
mitigation. While the majority of research articles focused on energy efficiency [
20
–
23
], there were a few
papers that studied the balance between energy efficiency and environmental impact [
20
] examined
European residential buildings and concluded that heating energy consumption was directly related
to high emissions. Scheuer et al. [
20
] evaluated the life cycle energy and environmental performance
(LCA) of a new building on the University of Michigan campus and concluded that the design of
new buildings that integrate more sustainable technologies is a major step toward environmental
impact reduction. At the same time, they pointed out that modeling challenges put great limitations
on the application of the life cycle analysis since a detailed design evaluation was impossible with the
building LCA data at that time [
13
]. Fifteen years after their research, LCA data experienced great
development, which has enabled us to conduct evaluations not only in new buildings but also in
existing buildings.
There is another trend emerging in the institutional environment that requires attention.
Between 2012 and 2018, the number of net-zero energy (NZE)-verified buildings and NZE emerging
buildings increased by over 700% [
21
]. ZNE-verified buildings are the buildings have achieved ZNE
for at least one full year, with actual monitored performance data. ZNE emerging buildings are those
have publicly stated a goal of reaching ZNE but have not yet demonstrated achievement of that goal.
Education buildings (including K–12 schools) comprise the largest portion of NZE building projects,
accounting for 37% (178) of all NZE buildings in the United States. Higher education (higher-ed)
buildings represent 35% of all NZE education buildings [
21
]. There are four major drivers powering
the rapid increase of general net-zero building development, particularly in the education building
sectors. The first driver is energy-saving incentives and economic return that building owners can gain
through setting high standards at the beginning of project planning. The second is “the recognition of
increased market value through green building practice and attention to a label such as net-zero energy
building” (European Union 2009). The third driver is the educational function, which is particularly
valuable for institutional clients. A growing number of high-performance buildings, NZE buildings,
and positive-energy buildings serve as living laboratories for higher education purposes. The final
reason is that the education building sector offers national and regional forums to facilitate the transfer
of the best designs and operational practices. Together, these four reasons explain why education
buildings represent the largest growing portion of NZE projects and will continue to drive the growth
of NZE in the education category. Despite such interest in NZE in the institutional sector, however,
among the verified and certified NZE buildings worldwide, there is only one higher-ed building
in existence and no renovation projects to date. Verified and tested methods and techniques for
renovating existing buildings to achieve the net-zero goal are extremely limited. Consequently, the gap
between the renovation needs of education buildings and verified strategies and techniques presents
opportunities and challenges.

Sustainability 2018,10, 3287 5 of 22
Energy-efficient building does not automatically translate to a satisfactory indoor environment
and occupant satisfaction. Besides energy performance, other critical areas also need to be improved
in aging education buildings, including thermal comfort, acoustic quality, daylight, and views.
These performance indicators comprise the indoor environmental quality. Research indicates that an
improved indoor quality can improve students’ learning outcomes, and the detrimental effects of aging
facilities can be reversed when schools are renovated [
22
–
25
]. In order to meet the energy target and
occupants’ preferences at the same time, a comprehensive performance matrix and baseline condition
(based on existing building performance) for comparison are needed to evaluate the effectiveness of
renovation strategies.
2. Case Project
2.1. Carbon-Neutral Goal of the University of Maryland
The University of Maryland is the flagship institution of the University System of Maryland
(UMD) and the largest university in the state, with 12 schools and colleges across four campuses
(College Park, Baltimore, Eastern Shore, and University of College). In 2018, the institution has more
than 38,000 students, 9000 faculty and staff members, and more than 300 facilities on the College Park
campus (the main campus, 1250 acres). The main campus is located in College Park, five miles north
of the border of Washington, D.C. In 2007, the University of Maryland joined the Carbon Commitment,
which committed to a carbon emissions reduction of 50% by 2020 and a 60% reduction by 2025,
from 2005 levels [
26
] (From 2005 to 2015, UMD reduced carbon emissions by 27%, with a construction
growth of 11%, and reduced energy consumption by 20% or more in select buildings [
27
]. The campus
has set a goal to reduce the energy consumption of existing buildings by 20% by 2020 [
26
]. The average
energy performance of buildings on the College Park campus was 0.34 kWh/m
2
(108 kBtu/ft
2
) in
2017 [
28
] The general climate in Maryland is mild, with a mean annual temperature of 13
◦
C (56.65
◦
F),
an average annual precipitation of 44.26 inches, and an annual humidity of 64%. Most of the academic
year falls under the months of February through May, with the shoulder months being January and
June through July.
On campus, 65.78% of the buildings are more than 25 years old and were not built to comply
with the current building energy efficiency code; 30.66% of buildings are 55 years or older and
approaching the end of their serviceable lifespan [
29
]. Renovation and retrofitting present a challenge
as well as an opportunity. The energy consumption of the academic building stock varies significantly,
from 0.063 kWh/m
2
(20 kBtu/ft
2
) to 4.151 kWh/m
2
(1316 kBtu/ft
2
). The highest energy use intensity
was recorded in the engineering facility, where there are large laboratories and testing equipment.
Most academic buildings are equipped with air conditioning units for heating and cooling, but some
residential buildings do not have air conditioning systems. The campus has a central heating and
cooling system powered by a power plant on site. Pipes connect multiple satellite central utility
buildings (SCUBs) to campus buildings; a single SCUB can connect up to 17 buildings. These pipes
provide both hot and chilled water for heating and cooling. In each individual building, there are
also separate distributed air systems to provide a building-appropriate temperature and humidity
level [29].
2.2. University of Maryland’s Architecture Building
The general shape of UMD’s Architecture Building consists of two different-sized rectangles
that are located at a latitude of 38
◦
59
0
3.73” N and longitude of 76
◦
56
0
51.57” W. The two-story
building occupies a total floor area of 6517 m
2
(70,150 ft
2
), and the total conditioned area is 4355 m
2
(46,877 ft
2
). The main façade is oriented toward the south and north (refer to Figure 4). The building is
composed of classrooms, an auditorium with approximately 200 seats, offices, a library, conference
rooms, two computer labs, and a gallery space. The building has a large atrium space in the center,
with skylights and classrooms facing south and north. The majority of the offices are arranged on the

Sustainability 2018,10, 3287 6 of 22
second floor, around a shaded courtyard, so the orientation of the offices varies; most of the offices
have a window and view. The original building was constructed in 1972, with several renovations
and revisions performed after the initial construction. The gallery lighting system was replaced and
upgraded in 1992, and the chiller was replaced in 1997. Major renovations occurred in 1998, where the
computer rooms were renovated as well as the large auditorium space. In 2007, additional librarian
offices were added to the library, and later in 2009, a visual resource center was also added to the library.
As estimated by the university, to completely replace the existing building and meet the modern codes
and standard, the total cost (including all soft costs) would be $36,391,731 ($518/ft
2
) while renovating
the existing building would cost approximately $26,565,950 ($379/ft2) [28].
Sustainability 2018, 10, x FOR PEER REVIEW 6 of 22
added to the library, and later in 2009, a visual resource center was also added to the library. As
estimated by the university, to completely replace the existing building and meet the modern codes
and standard, the total cost (including all soft costs) would be $36,391,731 ($518/ft
2
) while renovating
the existing building would cost approximately $26,565,950 ($379/ft
2
) [28].
Figure 4. Existing School of Architecture Building.
3. Methodological Approach and Process
The research methodology was based on the proposed BIM–BEP–BEM framework. As
mentioned earlier, BIM stands for the building information model, BPM represents the building
performance model, and BEM is the building environment model (refer to Figure 5).
Figure 5. Research framework: building information model–building performance model–building
environmental model (BIM–BPM–BEM).
The building information model (BIM) is a process involving the generation and management
of digital representations of physical and functional characteristics of buildings. BIMs are files that
can be extracted, exchanged, or networked to support decision-making regarding a building or other
built asset [30]. BIM also introduces the opportunity to try out solutions in advance before building
the structure on site: with a constructible model, the design solutions can be prototyped virtually
[31,32]. BIM has been recognized as a suitable method for support planning, collaboration, and the
design of new or existing buildings [33]. More practice-oriented publications often advocate the
benefits of BIM as a maximization of efficiency and reduction in time effort [34]. BIM is also
understood as a digital platform that enables interoperability and data exchange [35]. Oftentimes,
Existing Building
Condition
Field
Measurement
(FM)
Post
Occupancy
Survey
(POS)
Infrared
and
Visual
Inspection
(IVI)
Construction
Document Review
(CDR)
Building
Performan ce
Indicators
Form
Energy
Retrofit
Strategies
BIM
Building Information Model
Building Envelope
Building System
Energy Retrofit
Strategy
Building
Renovati on
Packag e
Building Energy Model
BPM BEM
Carbon Emi ssions
Reduction
Acidification
Potential
Smog Potential
Environmental
Impact
Analysis
Building Environment Model
Global Warming
Potential
Revit / Sefaira
Revit /Tally
Identify
Problematic
Areas
Figure 4. Existing School of Architecture Building.
3. Methodological Approach and Process
The research methodology was based on the proposed BIM–BEP–BEM framework. As mentioned
earlier, BIM stands for the building information model, BPM represents the building performance
model, and BEM is the building environment model (refer to Figure 5).
Sustainability 2018, 10, x FOR PEER REVIEW 6 of 22
added to the library, and later in 2009, a visual resource center was also added to the library. As
estimated by the university, to completely replace the existing building and meet the modern codes
and standard, the total cost (including all soft costs) would be $36,391,731 ($518/ft
2
) while renovating
the existing building would cost approximately $26,565,950 ($379/ft
2
) [28].
Figure 4. Existing School of Architecture Building.
3. Methodological Approach and Process
The research methodology was based on the proposed BIM–BEP–BEM framework. As
mentioned earlier, BIM stands for the building information model, BPM represents the building
performance model, and BEM is the building environment model (refer to Figure 5).
Figure 5. Research framework: building information model–building performance model–building
environmental model (BIM–BPM–BEM).
The building information model (BIM) is a process involving the generation and management
of digital representations of physical and functional characteristics of buildings. BIMs are files that
can be extracted, exchanged, or networked to support decision-making regarding a building or other
built asset [30]. BIM also introduces the opportunity to try out solutions in advance before building
the structure on site: with a constructible model, the design solutions can be prototyped virtually
[31,32]. BIM has been recognized as a suitable method for support planning, collaboration, and the
design of new or existing buildings [33]. More practice-oriented publications often advocate the
benefits of BIM as a maximization of efficiency and reduction in time effort [34]. BIM is also
understood as a digital platform that enables interoperability and data exchange [35]. Oftentimes,
Existing Building
Condition
Field
Measurement
(FM)
Post
Occupancy
Survey
(POS)
Infrared
and
Visual
Inspection
(IVI)
Construction
Document Review
(CDR)
Building
Performan ce
Indicators
Form
Energy
Retrofit
Strategies
BIM
Building Information Model
Building Envelope
Building System
Energy Retrofit
Strategy
Building
Renovati on
Packag e
Building Energy Model
BPM BEM
Carbon Emi ssions
Reduction
Acidification
Potential
Smog Potential
Environmental
Impact
Analysis
Building Environment Model
Global Warming
Potential
Revit / Sefaira
Revit /Tally
Identify
Problematic
Areas
Figure 5.
Research framework: building information model–building performance model–building
environmental model (BIM–BPM–BEM).
The building information model (BIM) is a process involving the generation and management of
digital representations of physical and functional characteristics of buildings. BIMs are files that can be
extracted, exchanged, or networked to support decision-making regarding a building or other built

Sustainability 2018,10, 3287 7 of 22
asset [
30
]. BIM also introduces the opportunity to try out solutions in advance before building the
structure on site: with a constructible model, the design solutions can be prototyped virtually [
31
,
32
].
BIM has been recognized as a suitable method for support planning, collaboration, and the design
of new or existing buildings [
33
]. More practice-oriented publications often advocate the benefits of
BIM as a maximization of efficiency and reduction in time effort [
34
]. BIM is also understood as a
digital platform that enables interoperability and data exchange [
35
]. Oftentimes, BPM is described
as a building energy model that focuses on energy performance. The process of expanding BIM
into a building energy model has been extensively studied in the past several years with much
success [
36
–
38
]. A building’s environmental impact is generated through the entire building life
cycle, from raw material extraction, construction, and operation to demolition. There are different
approaches to quantify a building’s impact, and life cycle assessment is one of the most commonly
used and agreed-upon methods. There are a variety of tools that can be employed during the design
and planning stage, such as Talley and the Athena Impact Estimator for buildings. However, the links
between BIM, building energy performance, and environmental impact have not been fully established.
Very recently, Barreca et al. [
39
] studied how to improve building information modeling by applying
advanced 3D survey techniques, such as a 3D point cloud laser scanner and infrared thermos-graphic
camera. Wong and Zhou [
40
] pointed out the limited research efforts regarding the management
of environmental performance at the building renovation stage and the lack of a comprehensive
BIM-based environmental sustainability simulation tool. Chong et al. [
41
] outlined the need for
improved interoperability among BIM software and energy simulation tools, especially in renovation
and refurbishment projects.
In this research project, based on original construction documents and on-site measurement,
firstly, a virtual BIM model was constructed; the software chosen for this project was Autodesk
Revit. Autodesk Revit is a BIM software developed by Autodesk; it also has 4D capability to track
various building life cycle stages. Then, information and data from the BIM model were transferred
to a building performance simulation program called Sefaira. Sefaira is a cloud-based software that
simulates building energy performance and visualizes the daylight quality in spaces. Additionally,
it has a plug-in tool in Autodesk Revit that can translate building information and data—such as the
location, area, building system, materials, geometry, window configuration, and functional use—to an
online platform. Alternative design options or a renovation package can be set up in the cloud and
outputs—such as energy reduction, carbon emissions reduction, and cost—can be compared.
Sefaira uses EnergyPlus as the primary simulation engine. EnergyPlus was developed by the
U.S. Department of Energy (DOE) as an open-source whole-building energy modeling engine [
42
].
EnergyPlus was built on the strength of both BLAST and DOE-w and includes simulation capacities
such as heat balance load calculations; integrated loads, system and plant calculations in the
same time step; and a user-configurable HVAC system description [
43
]. Sefaira’s interface was
developed with support from DOE to allow modelers to model heating, ventilation, cooling, lighting,
water use, renewable energy generation, and other building energy flows using sub-hourly time-steps,
modular systems, and plant integrated with heat balance-based zone simulation [
44
]. Furthermore,
it allows the modeler to simulate thermal comfort and customize the operation schedule. Figure 6
illustrates the dashboard of an energy model for a case building on the Sefaira website.
Sefaira also accounts for occupant behavior in regression forms. For instance, the modeler can
create and define different energy model profiles based on the set temperature (user preference)
and operational schedule. In this research project, multiple BPM models were created in the cloud
and the results compared, which are explained in the following sections. Finally, the material and
building system information was extracted from the BIM model and translated into a BEM model.
The software used for data transfer and to run an environmental impact analysis is Tally. Tally is the
first software that has a direct plug-in in Autodesk Revit that allows the modeler and designers to run
a whole building life cycle assessment of the environmental impact from different design solutions.
The output from the environmental analysis includes acidification potential, eutrophication potential,

Sustainability 2018,10, 3287 8 of 22
global warming potential, ozone depletion potential, and smog formation potential. The following
sections present different parts of the methodology applied in this case project.
Sustainability 2018, 10, x FOR PEER REVIEW 8 of 22
Figure 6. Sefaira online dashboard.
3.1. Building Information Model (BIM)
The BIM stage in this research comprises four components: the construction document review
(CDR), field measurement (FM), infrared and visual inspection (IVI), post-occupancy survey (POS),
and BIM model building. There are three primary purposes of the BIM stage: (1) to generate an overall
assessment of the existing building’s (UMD’s Architecture Building) conditions; (2) identify
problematic areas and potential improvement opportunities according to alignments and
discrepancies within CDR, FM, IVI, and POS; (3) and set up a BIM model based on information from
IVI, POS, FM, and CDR and then prepare for data extraction to the BPM and BEM models.
3.1.1. Construction Document Review (CDR)
Exterior Envelope of the Architecture Building
The original exterior wall is composed of composite brick veneer with two tiers of CMU
(concrete masonry unit) backup and no insulation or air space in between (with an overall dimension
of 305 mm (12 inches), which provides a very limited R-value for the exterior walls, estimated at 10.8
W/m2 K (1.90 Btu/h·ft2·°F). The existing wall construction does not meet the current code requirement:
an R-value of 13 for the exterior wall [45]. The exterior brick units are in fairly good condition; there
are only a few areas in which minor damage to the mortar can be seen. The original roof is made of
concrete with 1-inch insulation board and composition roofing over it (refer to Figure 7). Based on
the original construction of the roofing system, the estimated R-value is 28.3 W/m2 K (5.0 Btu/h·ft2·°F).
There were no recordings indicating that the original roof had been replaced, and the composition
roofing only has a warranty of 20 years. However, we cannot assume that the roofing has not been
replaced sometime between 1972 and 2018. The current campus-wide standard for roof insulation is
R-30 (ASHRAE 2016). The existing windows are the original units composed of single-pane
uninsulated glass with painted steel frames. Most current windows units are not operable, with a U-
value of approximately 7.3 W/m2 K (1.29 Btu/h·ft2·°F). The windows account for around 40% of the
total vertical surface area. The existing doors generally have hollow metal frames. The current R-
value of the window and door units also does not meet current energy efficiency standards. In
general, the existing building exterior requires complete to moderate repair and maintenance,
considering the age of the building. The primary problem is that the existing building envelope
Figure 6. Sefaira online dashboard.
3.1. Building Information Model (BIM)
The BIM stage in this research comprises four components: the construction document review
(CDR), field measurement (FM), infrared and visual inspection (IVI), post-occupancy survey (POS),
and BIM model building. There are three primary purposes of the BIM stage: (1) to generate an
overall assessment of the existing building’s (UMD’s Architecture Building) conditions; (2) identify
problematic areas and potential improvement opportunities according to alignments and discrepancies
within CDR, FM, IVI, and POS; (3) and set up a BIM model based on information from IVI, POS, FM,
and CDR and then prepare for data extraction to the BPM and BEM models.
3.1.1. Construction Document Review (CDR)
Exterior Envelope of the Architecture Building
The original exterior wall is composed of composite brick veneer with two tiers of CMU (concrete
masonry unit) backup and no insulation or air space in between (with an overall dimension of
305 mm (12 inches), which provides a very limited R-value for the exterior walls, estimated at
10.8 W/m
2
K (1.90 Btu/h
·
ft
2·◦
F). The existing wall construction does not meet the current code
requirement: an R-value of 13 for the exterior wall [
45
]. The exterior brick units are in fairly good
condition; there are only a few areas in which minor damage to the mortar can be seen. The original
roof is made of concrete with 1-inch insulation board and composition roofing over it (refer to Figure 7).
Based on the original construction of the roofing system, the estimated R-value is 28.3 W/m
2
K
(5.0 Btu/h
·
ft
2·◦
F). There were no recordingsindicating that the original roof had been replaced, and the
composition roofing only has a warranty of 20 years. However, we cannot assume that the roofing
has not been replaced sometime between 1972 and 2018. The current campus-wide standard for roof
insulation is R-30 (ASHRAE 2016). The existing windows are the original units composed of single-pane
uninsulated glass with painted steel frames. Most current windows units are not operable, with a
U-value of approximately 7.3 W/m
2
K (1.29 Btu/h
·
ft
2·◦
F). The windows account for around 40% of the

Sustainability 2018,10, 3287 9 of 22
total vertical surface area. The existing doors generally have hollow metal frames. The current R-value
of the window and door units also does not meet current energy efficiency standards. In general,
the existing building exterior requires complete to moderate repair and maintenance, considering the
age of the building. The primary problem is that the existing building envelope standard falls quite
below the current building energy code requirements. However, with the appropriate retrofit, there is
large potential for energy reduction with minimal costs.
Sustainability 2018, 10, x FOR PEER REVIEW 9 of 22
standard falls quite below the current building energy code requirements. However, with the
appropriate retrofit, there is large potential for energy reduction with minimal costs.
Figure 7. Original construction documents illustrating the roof assemblies.
Architecture Building System
The heating for the building is supplied by satellite central utility plants: hot water is pumped
into the building, and the centralized climate control system in the building controls the indoor
temperature in the winter by supplying the hot water. In the basement, there are seven air handling
units that supply cool air to 16 different zones within the building. The annual energy consumption
between 2015 and 2017 was, on average, 148 kWh/m2 (47.13 kBtu/ft2). The general lighting is
composed of fluorescent lamps and some LED lighting in one computer room. There is no ventilation
system; air renewal is executed through the opening of windows and doors and natural infiltration.
The existing building, in general, has sufficient daylight due the large skylights on the roof and large
exterior windows.
3.1.2. Infrared and Visual Inspection (IVI)
An infrared thermograph camera, FLIR One, was used to identify the major thermal bridge, heat
loss, and air infiltration in the Architecture Building’s envelopes (walls, roofs). The infrared
inspection around the windows’ frame indicated the potential for air leakage and infiltration.
Outdoor images revealed a maximum of an 8 °C (46 °F) difference between different sides of
buildings, which could be caused by insufficient insulation. Indoor images clearly illustrated that the
thermal leaking happened primarily where the ceilings and walls connected [3] (refer to Figure 8).
Figure 8. Infrared images of interior and exterior conditions.
Figure 7. Original construction documents illustrating the roof assemblies.
Architecture Building System
The heating for the building is supplied by satellite central utility plants: hot water is pumped into
the building, and the centralized climate control system in the building controls the indoor temperature
in the winter by supplying the hot water. In the basement, there are seven air handling units that supply
cool air to 16 different zones within the building. The annual energy consumption between 2015 and
2017 was, on average, 148 kWh/m
2
(47.13 kBtu/ft
2
). The general lighting is composed of fluorescent
lamps and some LED lighting in one computer room. There is no ventilation system; air renewal is
executed through the opening of windows and doors and natural infiltration. The existing building,
in general, has sufficient daylight due the large skylights on the roof and large exterior windows.
3.1.2. Infrared and Visual Inspection (IVI)
An infrared thermograph camera, FLIR One, was used to identify the major thermal bridge,
heat loss, and air infiltration in the Architecture Building’s envelopes (walls, roofs). The infrared
inspection around the windows’ frame indicated the potential for air leakage and infiltration.
Outdoor images revealed a maximum of an 8
◦
C (46
◦
F) difference between different sides of buildings,
which could be caused by insufficient insulation. Indoor images clearly illustrated that the thermal
leaking happened primarily where the ceilings and walls connected [3] (refer to Figure 8).

Sustainability 2018,10, 3287 10 of 22
Sustainability 2018, 10, x FOR PEER REVIEW 9 of 22
standard falls quite below the current building energy code requirements. However, with the
appropriate retrofit, there is large potential for energy reduction with minimal costs.
Figure 7. Original construction documents illustrating the roof assemblies.
Architecture Building System
The heating for the building is supplied by satellite central utility plants: hot water is pumped
into the building, and the centralized climate control system in the building controls the indoor
temperature in the winter by supplying the hot water. In the basement, there are seven air handling
units that supply cool air to 16 different zones within the building. The annual energy consumption
between 2015 and 2017 was, on average, 148 kWh/m2 (47.13 kBtu/ft2). The general lighting is
composed of fluorescent lamps and some LED lighting in one computer room. There is no ventilation
system; air renewal is executed through the opening of windows and doors and natural infiltration.
The existing building, in general, has sufficient daylight due the large skylights on the roof and large
exterior windows.
3.1.2. Infrared and Visual Inspection (IVI)
An infrared thermograph camera, FLIR One, was used to identify the major thermal bridge, heat
loss, and air infiltration in the Architecture Building’s envelopes (walls, roofs). The infrared
inspection around the windows’ frame indicated the potential for air leakage and infiltration.
Outdoor images revealed a maximum of an 8 °C (46 °F) difference between different sides of
buildings, which could be caused by insufficient insulation. Indoor images clearly illustrated that the
thermal leaking happened primarily where the ceilings and walls connected [3] (refer to Figure 8).
Figure 8. Infrared images of interior and exterior conditions.
Figure 8. Infrared images of interior and exterior conditions.
3.1.3. Field measurement (FM)—Indoor Environmental Quality
One of the major obstacles to an affordable energy retrofit is the fact that most older,
existing buildings are not metered, making it difficult to identify which categories could gain the most
from an energy retrofit. Under such conditions, different renovation strategy indicators, other than
energy consumption, could be beneficial for the design team to identify problematic areas. In this study,
the combination of a field auditing index and post-occupancy satisfaction index were used as building
performance indicators. The energy retrofit packages not only measured an energy consumption
reduction but also the users’ preferences. Since summer 2017, four filed measurements have been
conducted to measure every room in the Architecture Building: 6 July and 4 September 2017 and
23 January and 4 June 2018. The temperature, humidity, CO
2
levels, acoustic levels, and lighting
levels were recorded. The five sets of data were normalized; Section 4.1 illustrates the results of the
datasets. Overall, thermal comfort and acoustic level (speech privacy) were the top two problematic
areas based on field auditing. The equipment used for this project included the Supco IAQ55 indoor
air quality/temperature/humidity CO
2
tester, Graniger light meter, and RISEPRO digital sound
level meter.
3.1.4. Post-Occupancy Survey (POS)
In order to further understand the overall space quality and problematic areas in the existing
building, as well as common dissatisfaction points of the indoor environmental quality, a post-occupancy
survey, the Indoor Environmental Quality Survey, was conducted online between September 2017
and March 2018. The online survey was sent out to all UMD School of Architecture students, faculty,
and staff. A total of 85 responses were received, equaling a total response rate of approximately
24%, which is consistent with the response rates of 10% to 50% for online surveys. The only personal
information asked for was the participants’ age. Among those who responded, 40% were between the
ages 16–22, 37.1% were between 23–36, and 8.6% were 56 and above (refer to Table 1).
Table 1. The demographics of survey participants.
Age Range Participation Percentage
16–22 years old 40%
23–36 years old 37.1%
37–45 years old 5.7%
46–55 years old 8.6%
56 years and above 8.6%
The survey comprised thirteen questions based on the users’ time spent in the Architecture
Building during February 2018. Eleven of these questions asked the participants to rank their
satisfaction level for light, noise, temperature, and acoustics, from very dissatisfied (1) to very satisfied
(7), seen below in Table 2. The analysis was done based on these numerical responses, and it omitted
the two questions that did not ask for any rankings.

Sustainability 2018,10, 3287 11 of 22
Table 2. Rating system for the Indoor Environmental Quality Survey.
Very Dissatisfied
1 2 3 4 5 6 7 Very Satisfied
3.1.5. BIM Model Building and Identification of Problematic Areas
The BIM model was constructed based on original construction documents from the Architecture
Building’s library as well as documents recording different versions of renovations from the facility
management archive library; the research team also conducted field measurements to verify critical
dimensions and several unidentified areas that were not indicated in the architectural drawings.
The author constructed a three-dimensional virtual model (refer to Figure 9) using Autodesk Revit and
manually input all related material properties that were not part of the default Revit template [
46
].
All information related to physical characters and conditions of the existing buildings were embedded
in the three-dimensional objects. The Revit model was then prepared and set up to simulate the energy
performance of different renovation techniques and packages, which are explained in the next BPM
stage in the following Section 3.2.
Sustainability 2018, 10, x FOR PEER REVIEW 11 of 22
Autodesk Revit and manually input all related material properties that were not part of the default
Revit template [46]. All information related to physical characters and conditions of the existing
buildings were embedded in the three-dimensional objects. The Revit model was then prepared and
set up to simulate the energy performance of different renovation techniques and packages, which
are explained in the next BPM stage in the following Section 3.2.
Figure 9. BIM model of the Architecture Building.
From the results of FM, POS, IVI, and CDR, two primary problematics areas were identified (a
detailed explanation is included in Section 4, findings): sound transmission and overheating. These
two problematic areas were then used as a guiding principle, together with the energy reduction goal,
to evaluate the effectiveness of varied renovation strategies.
3.2. Building Performance Model (BPM)
In this research project, there was limited control regarding the building’s embodied energy
since a large portion of it was already spent in the initial construction of the existing building.
Accordingly, the author focused on the existing and future operational energy performance of the
building. The BPM is composed of three steps: (1) identify and simulate building envelope retrofit
techniques; (2) identify and simulate building system retrofit techniques; and (3) identify and
simulate the building retrofit package based on results from 1 and 2. The metric used to measure and
compare the techniques and packages were total energy reduction (%), total CO2 emissions reduction
related to energy (%), cost saving per year (%), initial construction cost (low to high), and construction
feasibility (low to high). The primary purposes during the BPM stage were to create a ranking of the
proposed renovation packages from energy-saving and cost-optimized perspectives. The Sefaira
system was used to carry out the simulation. The construction and maintenance cost information was
provided by the Facility Management Office of the University of Maryland.
3.2.1. Energy retrofit Techniques—Envelope and Lighting System
To tackle the two primary problematic areas, a focus on retrofit techniques resulted in exterior
envelope upgrades and an interior partition retrofit. In the existing building, the exterior wall and
partition walls were either made of CMU block or cast-in-place concrete without thermal and acoustic
insulation. Renovation techniques identified for the building envelope and lighting system were:
(1) T1: Substitution of present window with low-emissive units (with U-value of 0.25 w/m2 k)
(2) T2: Application of additional thermal insulation to the roof slab (R-50)
(3) T3: Application of additional thermal insulation for the exterior walls (add additional 3-inch
panels of expanded polystyrene insulation, R-38)
(4) T4: Application of additional thermal insulation and acoustic insulation for the interior walls
(add additional 2-inch panels of expanded polystyrene insulation, R-10)
(5) T5: Replace all existing windows with double glazing window units
(6) T6: Reduce air infiltration by using air-tight windows (air infiltration rate, 0.3 L/s·m2, 0.06 cfm/ft2)
(7) T7: Replace all existing lights with LED lighting
Figure 9. BIM model of the Architecture Building.
From the results of FM, POS, IVI, and CDR, two primary problematics areas were identified
(a detailed explanation is included in Section 4, findings): sound transmission and overheating.
These two problematic areas were then used as a guiding principle, together with the energy reduction
goal, to evaluate the effectiveness of varied renovation strategies.
3.2. Building Performance Model (BPM)
In this research project, there was limited control regarding the building’s embodied energy since
a large portion of it was already spent in the initial construction of the existing building. Accordingly,
the author focused on the existing and future operational energy performance of the building. The BPM
is composed of three steps: (1) identify and simulate building envelope retrofit techniques; (2) identify
and simulate building system retrofit techniques; and (3) identify and simulate the building retrofit
package based on results from 1 and 2. The metric used to measure and compare the techniques
and packages were total energy reduction (%), total CO
2
emissions reduction related to energy (%),
cost saving per year (%), initial construction cost (low to high), and construction feasibility (low to
high). The primary purposes during the BPM stage were to create a ranking of the proposed renovation
packages from energy-saving and cost-optimized perspectives. The Sefaira system was used to carry
out the simulation. The construction and maintenance cost information was provided by the Facility
Management Office of the University of Maryland.
3.2.1. Energy retrofit Techniques—Envelope and Lighting System
To tackle the two primary problematic areas, a focus on retrofit techniques resulted in exterior
envelope upgrades and an interior partition retrofit. In the existing building, the exterior wall and

Sustainability 2018,10, 3287 12 of 22
partition walls were either made of CMU block or cast-in-place concrete without thermal and acoustic
insulation. Renovation techniques identified for the building envelope and lighting system were:
(1)
T1: Substitution of present window with low-emissive units (with U-value of 0.25 w/m2k)
(2)
T2: Application of additional thermal insulation to the roof slab (R-50)
(3)
T3: Application of additional thermal insulation for the exterior walls (add additional 3-inch
panels of expanded polystyrene insulation, R-38)
(4)
T4: Application of additional thermal insulation and acoustic insulation for the interior walls
(add additional 2-inch panels of expanded polystyrene insulation, R-10)
(5)
T5: Replace all existing windows with double glazing window units
(6)
T6: Reduce air infiltration by using air-tight windows (air infiltration rate, 0.3 L/s
·
m
2
, 0.06 cfm/ft
2
)
(7)
T7: Replace all existing lights with LED lighting
(8)
T8: Application of phase-change material (PCM) wall board on the inside face of exterior wall
Based on the available records, there were no major upgrades/renovations done to the building
envelope; therefore, improving the exterior wall and roof insulation were considered first as well
as enhancing the window energy performance. Roof insulation can be increased to R-50 by adding
additional panels of expanded polystyrene [
3
] (10-inch thickness). The overall achievable annual saving
is around 250,671 kWh, and it implies avoided CO
2
equivalent emissions of about 22%, compared to
the existing building. The cost of this renovation technique, including demolition and roof surface
repair, is around $33,230 to $64,839, based on a unit cost of $10.25/ft
2
to $20/ft
2
[
47
]. In the first year of
installation, a saving can be realized. The existing building has a minimal R-value for the exterior wall;
adding additional insulation board on the inner face of the exterior wall could increase the R-value
to R-38. The retrofit of the exterior wall alone could produce an energy saving of approximately
290,635 kWh and a CO
2
emissions reduction of roughly 21%. Insulation could also be applied to the
surface of the interior wall with insulating plaster, which could provide acoustic insulation. With 2-inch
thermal plaster, it potentially adds an additional R-10 insulation, which represents a considerable
reduction of heat transmittance through the rooms and prevents sound transmission. Meanwhile,
thermal insulation also provides extra sound protection. For instance, acoustic batts insulation and
other composite materials can absorb the sound transmission through vibrations within the wall
cavity [
48
,
49
]. The total energy saving is around 3%, with the CO
2
emissions reduction around 8%.
Another practical envelope retrofit technique includes replacing the existing glass with low emissivity
(Low-E) glazing or replacing all single-pane glass with double-pane glass. The latter results in a 19%
CO2emissions reduction and 11% energy consumption reduction.
Most buildings on campus were built in the late 1960s and early 1970s, and the air infiltration rate
varied from 3.0
×
10
−4
to 3.0
×
10
−4
m
3
/s
·
m
2
(pa)
0.65
(2.1 to 4.9 cfm/ft
2
(inches of water). Additionally,
15% to 45% of the overall air leakage could be attributed to flow through the intake and exhaust system
openings [
50
–
52
]. Based on ANSI/ASHRAE standard 62.1-2016, the minimal requirement for an office
space and auditorium seating area is 0.06 cfm/ft
2
and 0.12 cfm/ft
2
for a library [
46
]. A reduction in air
infiltration through the façade presents the most obvious gain in heat-related energy consumption,
with a reduction of approximately 27%. As heating accounts for 44% of the overall energy consumption,
reducing the air infiltration by tightening the building envelope may be the most efficient energy-saving
technique, equivalent to a saving of $29,643. However, other impacts of this solution should be further
studied such as indoor air quality.
Two other techniques that were compared include replacing existing T4 and T8 lighting fixtures
with LED lights and adding phase-change materials in the exterior wall. Lighting accounts for 9%
of the overall energy consumption; installing LED lights could save approximately 282,375 kWh,
12% compared to the baseline. Additionally, phase-change materials (PCM) could be added into the
wallboard to increase insulation [
53
]. Below, Figure 9and Table 3presents a comparison of different
techniques. Overall, T6 and T8 generate the largest energy consumption reduction and CO
2
emissions
reduction, with T4 following as the third most effective technique.

Sustainability 2018,10, 3287 13 of 22
Table 3.
Building envelope retrofit techniques: a comparison of energy saving, cost saving, and CO
2
emissions reductions.
Technique
(Envelope)
Overall
Energy
Reduction (%)
CO2
Reduction
(%)
Cost Saving
(Per Year %)
Peak Cooling
Reduction
(%)
Peak Heating
Reduction
(%)
Initial Cost Construction
Feasibility
NPV in
5 Years
T1 11% 19% 7% 4% 5% High ($40–55/ft2)High Neutral
T2 13% 22% 9% 7% 7% Moderate
($0.6–1.2/ft2)High +
T3 12% 21% 7% 4% 5% Moderate
($0.6–1.2/ft2)Moderate Neutral
T4 13% 23% 8% 5% 5% Moderate
($0.6–1.2/ft2)Moderate Neutral
T5 11% 19% 7% 4% 5% High
($400–1500/window)
High -
T6 16% 27% 10% 6% 6% Low ($0.2/ft2)Moderate +
T7 12% 16% 10% 7% 7% Moderate
($70–250/fixture) High +
T8 15% 28% 9% 5% 5% - Low -
In terms of cost, T6 is the most cost-effective (saving) in comparison to other techniques, with T8
following in second (refer to Table 3). T2 and T7 are the most effective in reducing the peak heating and
cooling loads (refer to Figure 10). In terms of the initial construction cost, T6 has the lowest cost while
T5 has the highest cost; T8 is difficult to predict due to the lack of enough data, and the remaining
techniques share similar per-unit costs. When observing the construction feasibility, T7 represents
the most practical strategy whereas T8 is the least feasible, due to the accessibility of phase-change
materials (refer to Table 3).
Sustainability 2018, 10, x FOR PEER REVIEW 13 of 22
Figure 10. Envelope and lighting retrofit comparison.
Table 3. Building envelope retrofit techniques: a comparison of energy saving, cost saving, and CO2
emissions reductions.
Technique
(Envelope)
Overall
Energy
Reduction
(%)
CO2
Reduction
(%)
Cost
Saving
(Per
Year %)
Peak
Cooling
Reduction
(%)
Peak
Heating
Reduction
(%)
Initial Cost Construction
Feasibility
NPV in
5 Years
T1 11% 19% 7% 4% 5%
High ($40–
55/ft2) High Neutral
T2 13% 22% 9% 7% 7%
Moderate
($0.6–1.2/ft2) High +
T3 12% 21% 7% 4% 5%
Moderate
($0.6–1.2/ft2) Moderate Neutral
T4 13% 23% 8% 5% 5%
Moderate
($0.6–1.2/ft2) Moderate Neutral
T5 11% 19% 7% 4% 5%
High ($400–
1500/window) High -
T6 16% 27% 10% 6% 6% Low ($0.2/ft2) Moderate +
T7 12% 16% 10% 7% 7%
Moderate
($70–
250/fixture)
High +
T8 15% 28% 9% 5% 5% - Low -
3.2.2. Energy Retrofit Techniques—Building System
Renovation techniques identified for the building system included the following:
(1) HVAC1: VAV with rooftop package unit
(2) HVAC 2: VAV with central plant
(3) HVAC 3: DOAS System (Package Terminal AC)
(4) HVAC 4: DOAS System (Split System)
(5) HVAC 5: DOAS System (Fan Coil Units and Central Plant)
(6) HVAC 6: DOAS System (Water Source Heat Pump Fan Coils)
(7) HVAC 7: DOAS System (Active Chill Beams)
(8) HVAC 8: DOAS System (Passive Chill Beams)
Table 4 below presents a comparison of the different techniques. Compared to a conventional
variable air volume VAV system, a dedicated outdoor air system (DOAS) can provide better
11%
13% 12% 13%
11%
16%
12%
15%
19%
22% 21%
23%
19%
27%
16%
28%
7%
9%
7% 8% 7%
10% 10% 9%
12% 13% 12% 13% 12%
16%
12%
16%
4% 7% 4% 5% 4% 6% 7% 5%
5%
7%
5% 5% 5% 6% 7%
5%
0%
5%
10%
15%
20%
25%
30%
T1 T2 T3 T4 T5 T6 T7 T8
Percentage of Saving Compared to Existing
Building
Envelope and Lighting Retrofit Comparison
Overall Energy Reduction (%) CO2 Reduction (%)
Cost Saving (per year %) EUI Reduction (%)
Peak Cooling Reduction (%) Peak Heating Reduction (%)
Figure 10. Envelope and lighting retrofit comparison.
3.2.2. Energy Retrofit Techniques—Building System
Renovation techniques identified for the building system included the following:
(1)
HVAC1: VAV with rooftop package unit
(2)
HVAC 2: VAV with central plant
(3)
HVAC 3: DOAS System (Package Terminal AC)
(4)
HVAC 4: DOAS System (Split System)

Sustainability 2018,10, 3287 14 of 22
(5)
HVAC 5: DOAS System (Fan Coil Units and Central Plant)
(6)
HVAC 6: DOAS System (Water Source Heat Pump Fan Coils)
(7)
HVAC 7: DOAS System (Active Chill Beams)
(8)
HVAC 8: DOAS System (Passive Chill Beams)
Table 4below presents a comparison of the different techniques. Compared to a conventional
variable air volume VAV system, a dedicated outdoor air system (DOAS) can provide better ventilation
and humidity control, thus creating enhanced indoor air quality. However, because the DOAS system
requires a separate system for outside air, the VAV system is more cost-effective and offers lower
maintenance requirements. Among the eight different options, HVAC 1 and 2 produce the highest
energy-saving and CO2emissions reduction potential, with a relatively low cost (refer to Table 4).
Table 4. Comparison of building system retrofit techniques.
Retrofit Techniques
(HVAC)
Total Energy
Reduction (%)
CO2Emissions
Reduction (%)
Cost Saving
(Per Year %) Initial Cost
HVAC1 (VAV) 53% 70% 45% low
HVAC2 (VAV) 57% 86% 44% low
HVAC3 (DOAS) 18% 44% 6% moderate
HVAC4 (DOAS) 18% 44% 6% moderate
HVAC5 (DOAS) 35% 97% 6% moderate to high
HVAC6 (DOAS) 26% 79% 1% moderate to high
HVAC7 (DOAS) 5% 12% 2% moderate to high
HVAC8 (DOAS) 26% 49% 15% moderate to high
3.2.3. Retrofit Strategy Package Setup
Based on the results from the building envelope and building system retrofit techniques, six
different packages were proposed according to their energy-saving potential, carbon emissions
reduction potential, construction feasibility, and initial cost (refer to Table 5). A simulated final
site energy use intensity was also provided.
Table 5. Comparison of building retrofit packages for achieving the nearly zero-energy goal.
Building Envelope Techniques HAVC Initial
Construction Cost
Final Energy Use
Intensity (EUI) kWh/m2
Retrofit
Package T1 T2 T3 T4 T5 T6 T7 T8 With PV Panel Installed
on Roof
P1 x x x x HVAC 2 Low 0.082 kWh/m2
P2 x x x x x HVAC 2 Moderate 0.088 kWh/m2
P3 x x x x x HVAC 2 Moderate 0.082 kWh/m2
P4 x x x x x x HVAC 2 High 0.088 kWh/m2
P5 x x x x x x x HVAC 2 High 0.078 kWh/m2
P6 x x x HVAC 2 Low 0.088 kWh/m2
P7 x x x x HVAC 5 Moderate 0.196 kWh/m2
P8 x x x x x x x x HVAC 8 High 0.23 kWh/m2
3.3. Building Environment Model (BEM)
In stage three, different retrofit packages were investigated and compared to further understand
their environmental impact. Life-cycle assessment (LCA) is a process whereby the material and
energy flows of a system are quantified and evaluated. Given the complexities of the interactions
between the built and natural environments, LCA represents a comprehensive approach to examining
the environmental impacts of an entire building [
46
]. The five environmental impact indicators
selected for this study were global warming potential, ozone depletion potential, acidification potential,
eutrophication potential, and smog formation potential. The LCA conducted in this project is based on

Sustainability 2018,10, 3287 15 of 22
ISO standards for life cycle assessment 14040 (principles and framework) and ISO 14044 (requirements
and guidelines) in accordance with EPA, SETAC guidelines [54,55].
The tool used for analysis was Tally. Tally is the only application to conduct a lifecycle assessment
that is fully integrated in the Autodesk Revit model. It analyzes environmental impact during the whole
building life cycle, from raw material extraction to demolition. Tally uses the GabB Life Cycle Inventory
(LCI) database, which is one of the leading databases used by life cycle analysis practitioners [
56
,
57
].
First, the renovation packages were constructed in Revit as design options. The model created in
BIM included all necessary data of building assemblies and systems, such as windows, doors, walls,
columns and floors, and the HVAC system, among others. Afterward, the materials and constructed
data were translated from the Revit model through Tally to be mapped with LCI data. The plug-in
tool Tally allows researchers to map BIM objects with the GaBi LCI database to run an analysis of
the environmental impact of different renovation packages. Detailed results and an explanation are
presented in Section 4below.
4. Findings
4.1. Existing Condition and Problematic Areas
Based on field measurement (FM) results, several problematic areas were identified. (1) The
acoustic quality represented the largest problematic area. The preferable noise level is 30 dBA for an
open-plan class and 44–48 dBA for a closed office. On the ground floor, 67% of rooms had a noise level
above 55 dBA, and 40% of rooms in the entire building had a noise level above the recommended level.
(2) The second problematic area was thermal comfort—particularly temperature—where 30% of the
spaces had a temperature outside of the acceptable range, based on ASHRAE 90.1 (20
◦
C to 23.6
◦
C).
Moreover, those spaces became overheated in the winter, spring, and summer. None of the spaces had
a humidity level outside of the recommended range. (3) The third problematic area was the lighting
level, which was unevenly distributed across the building. Less than 8% of the rooms fell below the
recommended light level range, of 300–500 lux. Furthermore, 18% of the rooms were overlit, with a
median lux level of 500 lux (refer to Figure 11).
Sustainability 2018, 10, x FOR PEER REVIEW 15 of 22
practitioners [56,57]. First, the renovation packages were constructed in Revit as design options. The
model created in BIM included all necessary data of building assemblies and systems, such as
windows, doors, walls, columns and floors, and the HVAC system, among others. Afterward, the
materials and constructed data were translated from the Revit model through Tally to be mapped
with LCI data. The plug-in tool Tally allows researchers to map BIM objects with the GaBi LCI
database to run an analysis of the environmental impact of different renovation packages. Detailed
results and an explanation are presented in Section 4 below.
4. Findings
4.1. Existing Condition and Problematic Areas
Based on field measurement (FM) results, several problematic areas were identified. (1) The
acoustic quality represented the largest problematic area. The preferable noise level is 30 dBA for an
open-plan class and 44–48 dBA for a closed office. On the ground floor, 67% of rooms had a noise
level above 55 dBA, and 40% of rooms in the entire building had a noise level above the recommended
level. (2) The second problematic area was thermal comfort—particularly temperature—where 30%
of the spaces had a temperature outside of the acceptable range, based on ASHRAE 90.1 (20 °C to 23.6
°C). Moreover, those spaces became overheated in the winter, spring, and summer. None of the
spaces had a humidity level outside of the recommended range. (3) The third problematic area was
the lighting level, which was unevenly distributed across the building. Less than 8% of the rooms fell
below the recommended light level range, of 300–500 lux. Furthermore, 18% of the rooms were
overlit, with a median lux level of 500 lux (refer to Figure 11).
Figure 11. Field measurement results.
The POS results indicate that people were least satisfied with the speech privacy, thermal
comfort, and window view, and they were most satisfied with the cleanliness and maintenance,
amount of light, air quality, and visual comfort. Furthermore, 55% of the occupants were dissatisfied
with the speech privacy in their workspace, 38% were unhappy with their access to a window view,
and 37% were displeased with the thermal comfort (refer to Figure 12).
Figure 11. Field measurement results.
The POS results indicate that people were least satisfied with the speech privacy, thermal comfort,
and window view, and they were most satisfied with the cleanliness and maintenance, amount of light,
air quality, and visual comfort. Furthermore, 55% of the occupants were dissatisfied with the speech

Sustainability 2018,10, 3287 16 of 22
privacy in their workspace, 38% were unhappy with their access to a window view, and 37% were
displeased with the thermal comfort (refer to Figure 12).
Sustainability 2018, 10, x FOR PEER REVIEW 16 of 22
Figure 12. Post-occupancy survey (POS) results.
In general, the POS results indicate high-level alignment with FM data. Acoustic quality
improvement and overheating mitigation were identified as the top two primary focuses to improve the
indoor environmental quality and user satisfaction. There were certain areas that revealed large
discrepancies between POS and FM (refer to Figure 13): air quality, window view, and visual comfort.
Although FM indicates that the air quality and window view meet the design criteria, many users
expressed their dissatisfaction through the survey. Further in-depth individual interviews could help
to identify the causes of these discrepancies.
Figure 13. Problematic areas in existing building.
4.2. Building Energy Saving due to Retrofit Packages
Among eight different packages, P4 and P5 produce large energy-saving benefits with a
relatively high initial construction cost. Alternatively, P1 and P6 produce considerably high energy-
saving benefits with a relatively low cost. P2 and P3 produce the same results as P1 and P6 but with
0.00
1.00
2.00
3.00
4.00
5.00
6.00
Overall Score
Overall Comparison
Figure 12. Post-occupancy survey (POS) results.
In general, the POS results indicate high-level alignment with FM data. Acoustic quality improvement
and overheating mitigation were identified as the top two primary focuses to improve the indoor
environmental quality and user satisfaction. There were certain areas that revealed large discrepancies
between POS and FM (refer to Figure 13): air quality, window view, and visual comfort. Although FM
indicates that the air quality and window view meet the design criteria, many users expressed their
dissatisfaction through the survey. Further in-depth individual interviews could help to identify the
causes of these discrepancies.
Sustainability 2018, 10, x FOR PEER REVIEW 16 of 22
Figure 12. Post-occupancy survey (POS) results.
In general, the POS results indicate high-level alignment with FM data. Acoustic quality
improvement and overheating mitigation were identified as the top two primary focuses to improve the
indoor environmental quality and user satisfaction. There were certain areas that revealed large
discrepancies between POS and FM (refer to Figure 13): air quality, window view, and visual comfort.
Although FM indicates that the air quality and window view meet the design criteria, many users
expressed their dissatisfaction through the survey. Further in-depth individual interviews could help
to identify the causes of these discrepancies.
Figure 13. Problematic areas in existing building.
4.2. Building Energy Saving due to Retrofit Packages
Among eight different packages, P4 and P5 produce large energy-saving benefits with a
relatively high initial construction cost. Alternatively, P1 and P6 produce considerably high energy-
saving benefits with a relatively low cost. P2 and P3 produce the same results as P1 and P6 but with
0.00
1.00
2.00
3.00
4.00
5.00
6.00
Overall Score
Overall Comparison
Figure 13. Problematic areas in existing building.
4.2. Building Energy Saving due to Retrofit Packages
Among eight different packages, P4 and P5 produce large energy-saving benefits with a relatively
high initial construction cost. Alternatively, P1 and P6 produce considerably high energy-saving

Sustainability 2018,10, 3287 17 of 22
benefits with a relatively low cost. P2 and P3 produce the same results as P1 and P6 but with a
moderate initial cost. Lastly, P7 and P8 produce less energy and cost saving compared to the other
packages (refer to Figure 14).
Sustainability 2018, 10, x FOR PEER REVIEW 17 of 22
a moderate initial cost. Lastly, P7 and P8 produce less energy and cost saving compared to the other
packages (refer to Figure 14).
Figure 14. Renovation packages: comparison of energy, CO2 emissions reduction, and cost saving.
4.3. Building Environmental Impact from Retrofit Packages
Among the eight retrofit packages, the best-performing package with the least environmental
impact is P3 and P5. P4 has the highest environmental impact potential in all categories, thus also
having the potential to create the most damage in the long term. P1 represents the second most
negative package, with a higher potential impact in all environmental categories than the rest of the
options. The third least favorable package is P6, which has much higher ozone depletion potential
and slightly higher eutrophication potential (refer to Figure 15).
Figure 15. Renovation package environmental impact comparison.
Below, Table 6 ranks the different renovation packages based on their potential to achieve the
nearly NZE goal while minimizing the environmental impact and considering the initial cost and
construction feasibility. P3 presents the optimal solution, considering all performance indicators; P5
offers an alternative solution if the budget is sufficient. Conversely, P1 could potentially achieve the
62% 62% 64% 62% 64% 62%
35%
40%
85% 85% 84% 86% 86% 84%
61%
68%
50% 51% 53% 50% 53% 51%
22% 26%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
P1 P2 P3 P4 P5 P6 P7 P8
Percentage of Saving
Retrofit Package Comparision
Energy Saving (%) CO2 Emissions Reduction (%) Cost Saving (annual)
0.00E+00
5.00E+02
1.00E+03
1.50E+03
2.00E+03
2.50E+03
3.00E+03
3.50E+03
4.00E+03
P1 P2 P3 P4 P5 P6 P7 P8
Renovation package environmental impact coamprison
Sum of Acidification Potential
(kgSO2eq)/10
Sum of Eutrophication
Potential (kgNeq)
Sum of Global Warming
Potential(kgCO2eq)/1000
Sum of Ozone Depletion
Potential (CFC-11eq) x 100000
Sum of Smog Formation
Potential (kgO3eq)/100
Figure 14. Renovation packages: comparison of energy, CO2emissions reduction, and cost saving.
4.3. Building Environmental Impact from Retrofit Packages
Among the eight retrofit packages, the best-performing package with the least environmental
impact is P3 and P5. P4 has the highest environmental impact potential in all categories, thus also
having the potential to create the most damage in the long term. P1 represents the second most
negative package, with a higher potential impact in all environmental categories than the rest of the
options. The third least favorable package is P6, which has much higher ozone depletion potential and
slightly higher eutrophication potential (refer to Figure 15).
Sustainability 2018, 10, x FOR PEER REVIEW 17 of 22
a moderate initial cost. Lastly, P7 and P8 produce less energy and cost saving compared to the other
packages (refer to Figure 14).
Figure 14. Renovation packages: comparison of energy, CO2 emissions reduction, and cost saving.
4.3. Building Environmental Impact from Retrofit Packages
Among the eight retrofit packages, the best-performing package with the least environmental
impact is P3 and P5. P4 has the highest environmental impact potential in all categories, thus also
having the potential to create the most damage in the long term. P1 represents the second most
negative package, with a higher potential impact in all environmental categories than the rest of the
options. The third least favorable package is P6, which has much higher ozone depletion potential
and slightly higher eutrophication potential (refer to Figure 15).
Figure 15. Renovation package environmental impact comparison.
Below, Table 6 ranks the different renovation packages based on their potential to achieve the
nearly NZE goal while minimizing the environmental impact and considering the initial cost and
construction feasibility. P3 presents the optimal solution, considering all performance indicators; P5
offers an alternative solution if the budget is sufficient. Conversely, P1 could potentially achieve the
62% 62% 64% 62% 64% 62%
35%
40%
85% 85% 84% 86% 86% 84%
61%
68%
50% 51% 53% 50% 53% 51%
22% 26%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
P1 P2 P3 P4 P5 P6 P7 P8
Percentage of Saving
Retrofit Package Comparision
Energy Saving (%) CO2 Emissions Reduction (%) Cost Saving (annual)
0.00E+00
5.00E+02
1.00E+03
1.50E+03
2.00E+03
2.50E+03
3.00E+03
3.50E+03
4.00E+03
P1 P2 P3 P4 P5 P6 P7 P8
Renovation package environmental impact coamprison
Sum of Acidification Potential
(kgSO2eq)/10
Sum of Eutrophication
Potential (kgNeq)
Sum of Global Warming
Potential(kgCO2eq)/1000
Sum of Ozone Depletion
Potential (CFC-11eq) x 100000
Sum of Smog Formation
Potential (kgO3eq)/100
Figure 15. Renovation package environmental impact comparison.

Sustainability 2018,10, 3287 18 of 22
Below, Table 6ranks the different renovation packages based on their potential to achieve the
nearly NZE goal while minimizing the environmental impact and considering the initial cost and
construction feasibility. P3 presents the optimal solution, considering all performance indicators; P5
offers an alternative solution if the budget is sufficient. Conversely, P1 could potentially achieve
the nearly NZE goal with a low cost and high construction feasibility; however, the long-term
environmental impact would be of great concern.
Table 6. Overall renovation package comparison.
Retrofit
Package
Energy
Saving
(%)
CO2
Reduction
(%)
Cost
Saving
(yr)
Initial
Cost
Construction
Feasibility
Ranking of
Achieving Nearly
NZE (Refer to
Table 5)
Ranking of Lowest
Environmental
Impact (Refer to
Figure 14)
Improvement
in Speech
Privacy
Improvement in
Thermal
Comfort
P1 62% 85% 50% Low High 2 7 Yes Yes
P2 62% 85% 51%
Moderate
High 3 5 Yes Yes
P3 64% 84% 53%
Moderate
Moderate 2 2 Yes Yes
P4 62% 86% 50% High Moderate 3 8 Yes Yes
P5 64% 86% 53% High Moderate 1 1 Yes Yes
P6 62% 84% 51% Low High 4 6 Yes Yes
P7 35% 61% 22%
Moderate
High 5 3 Yes Yes
P8 40% 68% 26% High Low 6 4 Yes Yes
5. Conclusions
This paper presented a novel BIM–BPM–BEM framework tailored toward education building
renovation. It aimed to select suitable renovation strategies that take into account all performance
indicators: an energy consumption reduction, CO
2
emissions reduction, environmental impact
reduction, and indoor quality improvement. A variety of renovation techniques were identified,
and multiple retrofit packages were compiled with four primary goals: (1) to optimize the energy
demand reduction to contribute to UMD’s overall carbon neutrality goal; (2) improve speech privacy
by adding additional acoustic insulation; (3) improve thermal comfort by mitigating overheating
problems, and; (4) minimize the long-term environmental impact. Firstly, the data derived from field
measurements was cross-referenced with a post-occupancy survey and infrared thermography scan
to create an accurate building profile and BIM model. Then, the BIM model was clearly defined
in order to be translated to the BPM stage, where it simulated the energy performance of different
renovation packages. The environmental impacts of eight proposed renovation packages were then
compared in the BEM stage. Finally, the BPM and BEM results and cost indicators were analyzed
together to determine the optimal renovation solution for the existing building. The data used for the
environmental impact analysis and energy simulation was derived directly from the BIM model to
ensure the data interoperability.
This research fills the current gap between energy efficiency improvement and environmental
impact mitigation. The results from the BPM and BEM analyses revealed that the energy and
cost-saving benefits do not always align with the environmental impact reduction potential.
For instance, renovation packages 2 and 4 produced high cost savings as well as energy and CO
2
reductions; however, they also produced the largest environmental impact potential in all five
indicators studied. Awareness of the asymmetrical benefits between energy saving and environmental
impact could encourage design teams and decision-makers to examine balanced solutions for building
renovations. Energy, indoor environmental quality, and long-term environmental impacts should be
integrated and used together in a building performance evaluation matrix. To this extend, package 3
presents the optimal solution, considering all performance indicators.
The proposed framework could potentially be applied to large-scale projects, such as campus
district renovation or neighborhood renovation. Studying the energy consumption reduction on a
large scale is a relatively new focus area: the first published study on energy retrofit on the district
level was found in 2008 by [
58
]. Since then, several large-scale studies have been published, such as
Moscow’s residential district renovation impact on energy and emissions [
59
]. Easy-to-use evaluation

Sustainability 2018,10, 3287 19 of 22
and analysis frameworks and tools help to promote the adoption of large-scale energy renovation
planning and implementation.
Another important insight resulting from this study was the importance of interoperability among
different software in facilitating data translation and transformation. Advanced digital technologies
and platforms—such as BIM (Autodesk Revit), BPM (Sefaira), and BEM (Tally)—make it possible
for decision-makers to examine all performance indicators within the same framework and form
decisions with a holistic understanding of all the advantages and disadvantages of the proposed
renovation strategies.
Funding: This research was supported by University of Maryland, Sustainability Fund.
Acknowledgments:
I thank all faculty, staff and students in School of Architecture, Planning and Preservation at
University of Maryland, for their contribution to the survey and other supports. Particular, I thank Architecture
students, Samantha Zuber, Michael Delash and Andrew Koenings for their assistance with collecting data,
documents and filed measurements. I would also like to show my gratitude to Mark Stewart, Sustainability
Manger, Office of Sustainability, University of Maryland Martha Shrader, Sustainability Manger, University of
Maryland for their help to review my original research proposal and continuous feedback and input during the
entire research process. Lastly, I want to thank Ralph Bennett, Professor Emeritus, for sharing his wisdom with
me during the course of this research, and I thank 3 “anonymous reviewers for their comments and suggestions
that helped me to improve this paper.
Conflicts of Interest: The author declares no conflicts of interest.
Nomenclature
BIM Building Information Model
BPM Building Performance Model
BEM Building Environment Model
DOE Department of Energy
CDR Construction Document Review
IVI Infrared and Visual Inspection
POS Post-Occupancy Survey
FM Field Measurement
LCI Life Cycle Inventory
NZE Net-Zero Energy
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