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Green BIM-based Study on the Green Performance of
University Buildings in Northern China
Qibo LIU1,2 *, Zixin Wang1
1.Department of Architecture, Chang’an University, Xi’an 710061, China
2. Engineering Research Center of Highway Infrastructure Digitalization, Ministry of Education,
Xi’an, 710064, China
* Corresponding author: linka_0@163.com
Abstract
Background: Green BIM emphasizing the contribution of BIM technology to the design and
construction of green buildings. It attaching importance to the impact of climate and regional
environment, using benchmarking and target setting, using BIM architecture for building
performance analysis and realizing performance optimization through scheme comparison and
modification. A university campus is a community that has a certain geographical scope and spatial
scale and involves a variety of functions, such as teaching, scientific research, and living space.
Hence, a campus possesses urban characteristics and diverse building types, and the construction of
green university campuses will play a leading role in green urban construction in China under the
increasing ecological and energy pressure of cities.
Methods: Based on the Green BIM decision cycle model, the study employs BIM architecture to
analyses building performance. By using the <Evaluation Standard for Green Building> as the
evaluation benchmark values and project objectives and taking the most representative teaching
buildings, libraries, and dormitory buildings in universities in northern China as examples, the study
selects appropriate BIM software, establishes models in steps, and conducts targeted visual analysis.
The purpose is to find out the commonness and difference through the analysis, and then realize that
the diversity of building types in campus determines that the green performance research of different
types of buildings should comprehensively consider various design factors.
Results and conclusions: Taking a university library in northern China as an example, the study
optimized it from four aspects: base environment, function layout, envelope performance and
system transformation, and management measures improvement. The results show that the total
annual cumulative energy consumption load of the scheme is reduced obviously. The conclusions
are that the improvement of university buildings' green performance must be comprehensively
carried out from the aspects of planning, building design, system design, energy management, and
energy conservation planning. In the future, we also need to carry out energy consumption data
mining, continue the energy-saving transformation of existing buildings and energy consumption
systems, achieve the goal of green and low-carbon campus.
Keywords: Green BIM, Northern China, University Building, Green Performance, Design Strategy
1. Introduction
A university campus is a community that has a certain geographical scope and spatial scale and
involves a variety of functions, such as teaching, scientific research, and living space. Hence, a
campus possesses urban characteristics and diverse building types, and the construction of green
university campuses will play a leading role in green urban construction in China under the
increasing ecological and energy pressure of cities [1]. Additionally, due to its talent cultivation
effect via environmental education, students are influenced by the green and low carbon concepts
that they constantly see and hear, resulting in a radiation effect of green campus concepts to the
whole society when they enter society [2]. Finally, as a better component of the natural environment
in cities, university campuses will effectively regulate the microclimate and ecological function of
cities by maintaining natural ecology on a considerable scale [3].
By searching the general situation of research on green campuses in the English literature,
discussion and research on green campuses emerged in succession in the mid-1990s, and the
relevant research literature has been increasing year by year since 2000. For instance, in the EI
database, retrievals with English terms "green campus", "ecological campus", and "sustainable
campus" show that the earliest relevant literature appeared in the 1970s, and the number of studies
was very limited during the period from 1970 to 1990; the number of relevant studies increased
gradually from the mid-1990s, and there has been a surge in the number of relevant published studies
since 2000. Especially in recent years, this has become a hot topic in academic research, and
American scholars have in particular paid more attention to green campus topics in the past 20 years
[4]. Based on the research focus, these studies can be divided into three aspects: first, discussion
of the overall characteristics and contents of green campuses; second, research on green campus
evaluation systems; and third, research on multiple aspects of green campuses, such as green
buildings, the ecological landscape, green energy, green materials, green food, green education,
healthy environment, green procurement, etc.
A green building has high requirements for its full lifecycle, especially in the design phase. However,
traditional architectural design lacks systematic design methods and tools, and the currently
prevailing design mode of traditional design + green building consultation has difficulty ensuring
that the actual effect can be in accord with a green design [5]. The design methods that are based
on AutoCAD, SketchUp, etc. split the interactive relationship between plan-view function
streamlining and spatial form design, and various disciplines are loosely connected and exhibit poor
synergy. Two-dimensional drawings cannot fully display and convey information, and bottlenecks,
such as poor communication, a good deal of repeated modelling, and low information integration,
occur between all stages of the building's lifecycle, making it difficult to guarantee the green
performance of the building.
The Evaluation Standard for Green Building (GB/T 50378-2019) implemented in August 2019 first
proposes the concept of green performance, which refers to the performance related to building
safety and durability, health and comfort, living convenience, resource conservation (energy savings,
land savings, water savings, and material savings), and environmental liveability [6]. The concept
of green performance is proposed to improve the original standard that regarded technology as the
core and lacked humanity and perceptibility. The standard in Edition 2014 did not reflect high-
quality buildings in the evaluation, and it was difficult for owners to feel the advantages of green
buildings in terms of health, comfort, convenience, and liveability. A building performance study
based on green performance analysis refers to the energy-saving design that takes into sufficient
consideration the external environment of buildings (climate, landform, and place), building factors
(completion year, building function, building form, and building structure), and factors related to
the energy-using system and equipment system, and it studies the impact on a building's green
performance under the combined action of various factors.
2. Objectives of the Green BIM-based Green Performance Design of University Buildings
2.1 Green BIM and its research framework
In 2008, Eddy Krygiel and Bradley Nies formally put forward the concept of Green BIM (Building
Information Modeling) for the first time, emphasizing the contribution of BIM technology to the
design and construction of Green buildings and discussing the impact of BIM on the reform of
design methods and the influence of BIM on all users and participants in the building industry to
achieve the development goal of Green BIM through sustainable solutions [7]. In their opinion,
Green BIM should have the following characteristics: attaching importance to the impact of climate
and regional environment; using benchmarking and target setting; using BIM architecture for
building performance analysis; and realizing performance optimization through scheme comparison
and modification. According to existing studies, Green BIM can be defined as "the process to
generate and manage the full-lifecycle data information of building based on the building
information model, improving the building performance and promoting and achieving the expected
sustainable goal" (as shown in Fig. 1).
The operation and process of the Green BIM decision cycle are designed to assess different design
contents and objectives: first, to fully understand the local climate and base environment; second,
Fig. 1 Green BIM Architecture
(Source: Eddy Krygiel, Brad Nies, Green BIM: Successful Sustainable Design with Building
Information Modelling)
to reduce demand and load and improve quality; third, to set evaluation benchmark values and
project objectives; and finally, to select appropriate BIM software, establish a model in steps, and
conduct targeted visual analysis [8]. A variety of BIM software programs provide a data exchange
function, input the data in the model into relevant analysis software via exchange formats, such as
IFC and gbXML, and present the results of the calculation and analysis within a short time, thereby
providing a guarantee for quick decision making on the Green building design scheme [9] (as
shown in Fig. 2).
There are various types of buildings in Chinese colleges and universities. Diverse types of buildings,
as well as different design standards and construction technologies, create large differences in the
Green performance of different buildings. This study takes the most representative teaching
buildings, libraries, and dormitory buildings in universities as the research object. The climate of
the study area is that of northern China, where the overall layout of buildings is more compact and
enclosed due to the influence of climate and the energy consumption of buildings needs to consider
the comprehensive effect of thermal insulation in summer and winter. By using the process given
by the Green BIM decision cycle and taking the Evaluation Standard for Green Building (GB/T
50378-2019) as the evaluation benchmark values and project objectives (as shown in Tab. 1), the
study selects appropriate BIM software, establishes models in steps, and conducts targeted visual
analysis in an attempt to determine problems in the green performance of different types of buildings.
This study then determines the improvement objectives and finally creates an optimal scheme.
Fig. 2 Green BIM Decision Cycle Model
(Source: Institute of architecture, Ministry of the interior of Taiwan, Green Building Improvement Case
Collection)
Tab. 1 Evaluation System and Scores of the <Evaluation Standard for Green Building (GB/T
50378-2019)>
Evaluation
Item
Safety
and
Durability
Health
and
Comfort
Living
Convenience
Resource
Conservation
Environmental
Liveability
Improvement
and
Innovation
1
Safety
Indoor air
quality
Trip and
accessibility
Land saving and
utilization
Site ecology and
landscape
Including
reducing the
energy
consumption of
heating and air-
conditioning
systems in
buildings,
incorporating
regional
architectural
culture, adopting
the structural
systems and
building
components in
compliance with
industrial
construction
requirements
and applying
BIM technology
2
Durability
Water
quality
Service
facilities
Energy saving
and utilization
Outdoor physical
environment
3
Acoustic
environment
and light
environment
Intelligent
operation
Water saving
and utilization
4
Indoor
thermal and
humid
environment
Property
management
Material saving
and Green
building
materials
Score
100
100
100
200
100
100
2.2 Analysis of the Green performance of different types of buildings in Chinese colleges and
universities
The modelling software used in this research is Autodesk Revit (version 2018), which is used to
establish the BIM model of a teaching building, a library and a dormitory building. This program
exports “.rvt” (Revit) format files as “.3ds” (3-Dimension Studio), “.gbxML”(Green
Building Extensible Mark-up Language) and “.dxf”(Drawing Exchange Format) files. In the
process of simulation analysis, a “.3ds” format file is imported into Phoenics (Parabolic
Hyperbolic or Elliptic Numerical Integration Code Series) for wind environment simulation analysis.
The “. gbxML” file is imported for Ecotect (Autodesk Ecotect Analysis) to perform local or
indoor environment simulation analysis, such as thermal analysis, resource consumption analysis,
daylighting and building shading analysis. The “.dxf” format file model has a high precision and
contains a large amount of information, which is mainly used for global analysis, such as lighting
intensity analysis, shadow shading and environmental impact analysis.
Xi'an City, Shaanxi Province, is selected as the simulation site and belongs to the cold area of the
building climate division. The simulation models are in accordance with the actual construction
conditions. The specific methods are as follows:
(1) The wind environment of the teaching building was tested in summer of June in 2019, and the
relevant parameters were tested for 48 hours.
(2) The thermal tests of the library and dormitory buildings were conducted in the typical summer
month of July in 2018 and the typical winter month of January in 2019. Temperature, humidity,
wind speed, CO2 concentration and other related parameters of the building thermal comfort
environment were tested for 48 hours.
(3) According to the construction method of the specific building, the model is adjusted through
comparison with the measured temperature and humidity parameters to make it conform to the
actual working conditions of the building.
(4) The research model was developed and prepared for the analysis.
Due to space limitations, the specific parameters of the teaching building, library and dormitory
building are not specified here.
2.2.1 Ventilation design of teaching buildings for the objective of health and comfort
The health and comfort in the Evaluation Standard for Green Building (GB/T 50378-2019) mainly
covers indicators such as indoor air quality, water quality, acoustic environment, light environment,
and indoor thermal and humid environment. For teaching buildings, as the ones most frequently
used by students in colleges and universities, natural ventilation will have an impact on the indoor
air quality and thermal and humid environment, on the thermal comfort of students during use, and
on the ultimate energy-saving goal. Hence, natural ventilation is selected herein to study the Green
performance of teaching buildings.
(1) Typical forms and ventilation simulation of teaching buildings
Most of the teaching buildings in northern areas are arranged in a north-south orientation. Although
some teaching buildings are arranged in an east-west orientation, their space for teaching is still in
the north-south orientation, and the east-west-facing space is generally arranged as offices and
laboratories [10]. The plan-view layout of teaching buildings was dominated by the form of an
internal corridor in the early and middle stages, whereas that of newly built university teaching
buildings is mainly in the form of an internal corridor and an external corridor encircling an internal
courtyard [11]. The teaching buildings mostly had 3 to 4 floors in the early stage, whereas those in
the middle stage and newly built buildings mainly have 4 to 6 floors, and 5-floor buildings are the
most common (as shown in Fig. 3).
Based on the survey above, the study selects three types of internal corridor forms, namely, belt type,
semi-enclosed type, and cluster type, to conduct the current ventilation test of specific buildings.
On this basis, BIM technology is used for modelling, typical buildings are put into the specific wind
field in northern areas (with northeast as the prevailing wind direction and southwest as the
secondary wind direction), and the models are imported into the ventilation simulation software
Phoenics to carry out the study.
From the perspective of the plan-view layout of a single building, in the case of a 15° angle of a
single belt-type building, the wind shadow is relatively small on the leeward side of the building,
the area of flow around the building is not large but the wind speed is high, and the angle between
the wind direction and the north and south facades is too small to be utilized for indoor ventilation.
At an angle of 45°, the wind shadow is relatively large on the leeward side of the building, and the
flow around the building affects a relatively large area, but the angle between the facades and the
wind direction is large, which is conducive to indoor natural ventilation. In the case of a 30° angle,
the wind shadow of the wake flow of the building is the smallest, but the speed is the lowest; the
surrounding wind environment is relatively uniform, and there is a certain angle between the facades
and the wind direction. Therefore, an angle of 30° -- 45° is the most appropriate orientation, among
which 30° is better (as shown in Fig. 4).
Fig. 3 Typical Forms of Teaching Buildings in Northern Areas
(Source: Self-drawn)
Northeast 15°
Northeast 30°
Northeast 45°
When the courtyard opening of a single building of the semi-enclosed typefaces the north easterly
wind at an angle of 15°, the wind speed is relatively high in most of the courtyard and lower at the
corners, the vortex area is relatively small, and the vortex area of the wake flow is comparatively
large. At an angle of 30°, the vortex area at the corners is larger than that at the angle of 15°, and the
vortex area of the wake flow is smaller. At an angle of 45°, there is an increase in the wind speed at
the corners inside the courtyard, but the total low-wind-speed area is the largest, and the vortex area
of wake flow is the smallest. When the opening faces the south westerly wind, along with the
increase in the angle, the vortex area on the windward side decreases gradually, and the vortex area
in the leeward courtyard corner increases gradually. The wind shadow of the wake flow of the
building is the largest at 45°. With two wind conditions taken into consideration, the appropriate
orientation for this type of single building is 30° -- 45° (as shown in Fig. 5).
Northeast 15°
Northeast 30°
Northeast 45°
Fig. 4 Ventilation Simulation Analysis Graphics of Rectangular Teaching Buildings in Different Orientations
(Source: Self-drawn)
Southwest 15°
Southwest 30°
Southwest 45°
Compared with other layout forms, the layout of the cluster type is more flexible, and the single
buildings are more diverse. As revealed by CFD (Computational Fluid Dynamics） simulation
analysis, the form of single buildings around the central space, the road and opening directions
between single buildings, and the angle between the buildings and the prevailing wind direction all
have an impact on the overall outdoor wind environment. Through the selection of the angle
between single buildings and the prevailing wind direction, the interference of the wind shadow
between the buildings can be reduced so that each single building can obtain relatively good outdoor
wind. This type of layout can also keep out cold winds to a certain extent in winter. Meanwhile, in
the southeast direction where the wind frequency is very low in winter, the reasonable selection of
openings can improve the wind environment during the transition season. However, a small opening
in the combination will give rise to the Venturi effect and will accelerate the airflow, so narrow
openings should be avoided as far as possible in the prevailing wind direction in winter (as shown
in Fig. 6).
Fig. 5 Ventilation Simulation Analysis Graphics of Semi-enclosed Teaching Buildings in Different Orientations
(Source: Self-drawn)
Wind Speed Nephogram of Teaching Buildings of the
Cluster Type (North easterly Wind)
Wind Speed Nephogram of Teaching Buildings of the
Cluster Type (South westerly Wind)
(2) Internal ventilation simulation of teaching buildings in northern areas
Teaching buildings in northern areas mostly adopt the plan-view layout of the internal corridor. With
respect to such teaching buildings, the study sets the corridor width as 2.1 m, 2.4 m, 2.7 m, 3 m, 3.3
m, and 3.6 m for the CFD simulation experiment; the plan-view dimensions of classrooms on both
sides of the corridor are 7,800 mm × 14,500 mm. Additionally, there are 8 evenly distributed 1,400
mm × 700 mm ventilation openings at a height of 0.9 m above the ground in the exterior wall of
each classroom and an 800 mm × 600 mm opening at a height of 2 m above the ground in the interior
wall. Two 1,400 mm × 1,700 mm ventilation openings at a height of 0.9 m above the ground are
centred in the exterior walls at both ends of the corridor, and the area of the two openings does not
increase with the corridor width. These buildings are placed into the specific wind field in northern
areas for simulation. The results are shown in Fig. 7.
Corridor Width 2.1 m
Corridor Width 2.4 m
Corridor Width 2.7 m
Fig. 6 Ventilation Simulation Analysis Graphics of Teaching Buildings of the Cluster Type
(Source: Self-drawn)
Corridor Width 3 m
Corridor Width 3.3 m
Corridor Width 3.6 m
The results show that a corridor width of 2.1 m or 2.4 m will achieve the highest wind speed, while
a corridor width of 2.7 m or 3 m will lead to the lowest; when the width is 3.3 m or 3.6 m, the wind
speed is lower than that when the width is 2.1 m or 2.4 m, but the wind speed above 0.7 m/s is more
evenly distributed, and the area of wind speed above 0.4 m/s in the classroom increases. Along with
the increase in corridor width, the function of the corridor as a horizontal wind corridor is weakened,
and the cross ventilation effect inside the building is enhanced. Since a corridor wider than 3 m will
increase the overall depth of the building, the economic benefits of the building will be reduced to
obtain a better cross ventilation effect; therefore, it is advisable to choose a smaller corridor width
in the layout with a relatively long corridor and use a horizontal wind corridor to control indoor
natural ventilation.
2.2.2 Energy-saving design of library buildings for the objective of resource conservation
The resource conservation in the Evaluation Standard for Green Building (GB/T 50378-2019)
covers four indicators, i.e., land saving and utilization, energy saving and utilization, water saving
and utilization, and material saving and Green building materials. The libraries of colleges and
universities generally have a large volume and many energy use points, and the energy use is
complex, so the factors related to energy conservation are selected here to carry out a Green
performance study on library buildings.
(1) Building form design
The major functions of university library buildings are book collection, borrowing, self-study, and
auxiliary offices. In terms of their functional nature, modern university library buildings mainly
feature functional layouts integrating collection, borrowing, and reading, and the functional plan-
view layouts are primarily divided into the following forms: symmetrical distribution, hollow
Fig. 7 Ventilation Simulation Analysis Graphics of Teaching Buildings with Different Internal Corridor Widths
(Source: Self-drawn)
square-shaped single corridor, U-shaped distribution, and belt-shaped distribution [12]. The
daylighting and ventilation simulations of these basic layout forms are analysed and compared with
Ecotect, and the results are shown in Tab. 2.
Tab. 2 Analysis of the Daylighting and Wind Field Conditions in the Basic Plan-view Layouts
(Source: Qibo Liu, Juan Ren. Research on the Building Energy Efficiency Design Strategy
of Chinese Universities Based on Green Performance Analysis)
Layout Form
Diagram
Daylighting Analysis
Wind Field Analysis
Symmetrical
distribution
Hollow square-
shaped single
corridor
U-shaped
distribution
Belt-shaped
distribution
Through analysis of the daylighting and wind field conditions of buildings, it can be found that the
four layout forms have their own advantages and disadvantages. In the symmetrical distribution
form, the indoor daylighting is comparatively uniform, but the long and narrow plan-view layout is
relatively simple, and it easy to subject the building to a large wind load. In the hollow square-
shaped single corridor form, the indoor daylighting is sufficient, the form utilization rate is high,
and the indoor and outdoor wind pressure ventilation effect is good, but the volume coefficient of
the building itself is large, and the problems of solar radiation heat and heat loss are prominent. The
building in the form of U-shaped distribution has a high daylighting rate and good indoor ventilation.
The building in the form of belt-shaped distribution has many windows that open to the outside, but
it is hard to produce wind pressure ventilation because of the open space of a single building, and
the natural daylighting in the middle rooms is poor [13].
(2) Outer-building envelope energy saving design and material selection
Northern China has distinct conditions in summer and winter. It is cold in winter, so a high
requirement is imposed for the thermal insulation of buildings to maintain the indoor temperature
balance; the high-temperature weather in summer also has a high requirement for the thermal
insulation performance of the building envelope to reduce the impact of outdoor high temperatures
on indoor environment comfort [14]. The service time of university library buildings is usually
from 09:00 a.m. to 22:00 p.m. In the design of the outer envelope wall of library building, the better
the thermal insulation performance of the exterior wall is, the less heat transmitted indoors and
outdoors through the envelope will be, and the less the operating load of the indoor full air-
conditioning mechanical equipment will be. The thermal insulation technologies of exterior walls
are mainly classified into three types: external thermal insulation of exterior walls, internal thermal
insulation of exterior walls, and self-thermal insulation of exterior walls [15]. The internal thermal
insulation technology of the exterior wall has a lower insulation efficiency than the external thermal
insulation, and there are problems in heat bridge treatment. This design is widely used in renovation
projects in hot-summer/cold-winter and hot-summer/warm-winter regions [16]. Due to its strong
climate adaptability, the practice of the external thermal insulation of exterior walls is widely used
in newly built buildings. Based on the different climatic characteristics of different regions, the
selection of insulation materials and the practice of constructional thermal control are also different
[17]. According to the actual requirements of public construction projects, the selection of external
insulation materials and the construction practices of exterior walls can be adjusted in line with the
exterior wall's system type, construction technology level, climatic environment, and fireproof
performance requirements, as shown in Tab. 3.
Tab. 3 Characteristics of Exterior Wall's System Types and Selection of Thermal Insulation
Materials (Source: Self-drawn by the Author)
System Type of
Exterior Wall
Characteristics
Material Selection
Curtain wall dry-
hanging system
There are many embedded components, so
materials with high strength and high
ductile deformation should be selected;
A ventilation layer can be set to take away
the heat in air layer by air flow and reduce
the impact of solar radiation;
The fireproof performance is somewhat
poor.
Rock wool, mineral
wool, ceramic
insulating plate, foamed
concrete slab
Thin-plaster finish
system
Has good waterproof performance and wind
pressure-resistant performance and solves
the problems of wall cracking and seepage;
Meets the requirements of energy-saving
design standard in cold and severe cold
regions.
Polystyrene foam
plastic board, inorganic
light-aggregate
insulating mortar
Insulation-
decoration
integrated board
system
The insulating and decorative system is
extended to the wall surface and has an
outstanding thermal insulation effect and
little heat bridge effect;
Prevents deformation resulting from the
negative pressure generated by the
exchange between high and low
temperature of internal accumulated water;
The board has a light weight, high strength,
and relatively long service life.
Fluorocarbon metallic
paint finish, PU metallic
paint finish, faux stone
or faux granite finish
A glass curtain wall is a common facade form and window opening form of modern public buildings
and is usually used as the outer-building envelope and decorative structure of a single facade or
multi-oriented facade. The window-wall ratio can be as high as 0.8 -- 0.9, so the requirement for its
thermal performance is higher than that for other window types, and the designs of wind pressure
resistance, watertightness, airtightness, plan-view deformation, and thermal insulation are all
extremely important. Regarding the selection of wall glass, the study mainly summarizes the types
and application scopes of building energy-saving glass materials whose heat transfer coefficient is
below 3.0 in the thermal indicators of glasses as specified in the Design Standard for Energy
Efficiency of Public Buildings (GB 50189-2015) [18], as shown in Tab. 4.
Tab. 4 Energy-saving Designs, Characteristics, and Application Scopes of Wall Glass Types
(Source: Self-drawn by the Author)
Type
Practice
Characteristics
Application Scope
Low-E glass
Solar-radiant Low-E film-coated
glass
It changes the thermal emissivity of
glass by changing the physical and
optical properties of building glass,
thereby realizing the selective shielding
of solar radiation energy, preventing
glare from entering the room, and
meeting the demand for energy
conservation and consumption
reduction.
It is used at high
northern latitudes for
glare control and
thermal insulation and
heating by exploiting
solar radiation.
Hollow glass
Vacuum thermal-insulating glass
Light-transmitting Low-E + air +
transparent glass
Light-transmitting Low-E + argon
+ transparent glass
Two (or three) sheets of glass are
bound with a kind of composite binder
having high strength and airtightness to
reduce the heat transfer coefficient of
glass and lighten the mechanical load
of indoor air conditioning. High-
performance hollow glass can
guarantee the indoor constant
temperature and humidity performance.
Hollow glass is mainly
used in buildings that
need heating, air
conditioning, noise or
condensation
prevention, and no
direct sunlight and
special light.
Ultra-white
solar glass
Applying a coating that can absorb
solar energy to ordinary glass
Solar glass has a high requirement for
production technology; it can achieve
the absorption of solar energy, thereby
improving the effect of energy
conservation and environmental
protection and being used for
constructing solar eco-building and
making solar radiator.
Northern areas with
strong solar radiation.
Double-layer
respirable
curtain wall
glass
Double-structure glass curtain wall
of external circulation type
Double-structure glass curtain wall
of internal circulation type
It is composed of inner and outer
curtain walls; an air layer is added
between the curtain walls, where the
air is always in a flowing state to
realize the effect of thermal insulation
and energy conservation.
Buildings taking curtain
wall as the outer-
building envelope for
main facade in most
regions.
(3) System design
The air-conditioning and ventilation system of university library buildings generally has the
problems of poor design effect, old unit, and low energy efficiency; the major problem of heating
system is the unsound regulation mechanism, which is unable to regulate the system dynamically
according to meteorological conditions and energy use rules, thus causing excess heat supply in
some periods of time and wasting energy. In regard to metering, zone metering is commonly not
available, so it is impossible to compare and analyse various energy use areas of buildings and
difficult to identify the weak points of energy use.
For the energy-saving design of library buildings with complex volumes and functions, it is difficult
to achieve the main purpose of controlling building energy consumption and improving indoor space
comfort by relying only upon passive energy-saving technologies, and the energy-saving control
engineering of building equipment is also an important link in the energy-saving design.
2.2.3 Planning and layout of dormitory buildings for the objective of environmental liveability
The environmental liveability in the Evaluation Standard for Green Building (GB/T 50378-2019)
mainly includes two indicators, namely, the ecology and landscape and the outdoor physical
environment. Dormitory buildings in Chinese colleges and universities generally form an
architectural complex [19]. For buildings in northern areas, good sunshine conditions both indoors
and outdoors will influence the indoor heat gain of the building on the one hand and the outdoor
walking and activity comfort of students on the other hand. As a result, the Green performance study
is carried out here based on the overall layout forms of dormitory buildings. The layout designs of
table 5 coincides with one of a paper published by the author [13], but with the addition of diagonal
layout and optimized integrated layout of long and short staged, the overall layout types are more
diverse, which can fully explain which layout form is more suitable for the objective of
environmental liveability.
Tab. 5 Ecotect Simulation Analysis of Typical Layout Designs of Dormitory Buildings
(Source: Self-drawn by the Author)
Layout Form
Courtyard layout
Blocking
Percentage
Analysis
In the enclosed layout, the impact of building blocking is great, and the sunshine condition is also
the worst of all; the sunshine duration is 4 hours at the maximum and even less than 1 hour in
some parts on the first floor of south-facing building.
Evaluation
Poor
Layout Form
Row layout
Blocking
Percentage
Analysis
The N-S blocking of buildings ranges between 50% and 60%, and the E-W blocking of middle
dormitory buildings almost reaches 90% -- 100%.
Approximately 90% of dormitory buildings have a sunshine duration of 4 -- 3 hours on the lower
floors, and 10% of them have a sunshine duration of 1 -- 2 hours, which does not meet the sunshine
requirement.
Evaluation
Moderate
Layout Form
Diagonal layout
Blocking
Percentage
Analysis
The N-S blocking of buildings is 40% -- 50%, and the E-W blocking is 90% -- 70%.
The sunshine condition is moderate, and the diagonal layout does not solve the effect of E-W
blocking.
Evaluation
Moderate
Layout Form
Staggered layout
Blocking
Percentage
Analysis
The N-S blocking of buildings is 40% -- 50%, and the E-W blocking is 90% -- 70%.
Approximately 90% of dormitory buildings have a sunshine duration of 4 -- 5 hours on the lower
floors.
Most buildings have a sunshine duration of 5 -- 7 hours. Different from the sunshine condition of
row layout, there are few 1--2 hour sunshine areas in the staggered layout and little impact of
building blocking on east and west sides.
Evaluation
Fairly good
Layout Form
Optimized integrated layout of long and short staggered
Blocking
Percentage
Evaluation
Good
It can be seen from Tab. 5 that:
(1) Dormitory buildings should be arranged at a reasonable sunshine spacing between buildings. As
an extensively used form in northern areas, row layouts have better sunshine conditions than
courtyard layouts.
(2) To satisfy the basic sunshine requirement, the staggered layout is less blocked than the row
layout at a reasonable sunshine spacing between buildings.
(3) From the perspective of a single building form, a long-corridor layout is more reasonable than a
short-corridor layout in terms of land use, whereas a short corridor is better than a long corridor in
terms of sunshine conditions; therefore, the two should be combined to arrange long-corridor
dormitory buildings on the northern side and short-corridor buildings on the southern side to reduce
blocking.
3. Results --Green BIM-based Optimized Design of Green performance of a University
Library in Northern China
Taking a university library in North China as an example, this study uses BIM software to establish
the basic model, according to the operation and process of Green BIM decision cycle, carries out
the optimization design and simulation of the retrofit scheme from the perspective of Green
performance, which is described as follows:
(1) Optimization of the base environment based on environmental liveability: In combination with
the regional prevailing wind direction, wind environment simulation software is used to analyse the
wind environment of the site selected for the building under the influence of other buildings. The
year-round natural daylighting demand of the lower-floor south-facing rooms of the building
affected by the shade of trees is improved by tree transplantation. The inadequate sun-shading
condition in summer is improved by the planting of deciduous trees more than 20 m away from the
building on the southern side (as shown in Fig. 8).
Fig. 9 Schematic Diagram of Thermal
Pressure Ventilation in the Atrium
(Source: Self-drawn)
Fig. 8 Schematic Diagram of the Wind Environment and Flow Field of the Architectural
Complex at the Base of a Library (Source: Self-drawn)
Fig. 10 Accordion Lighting Roof of the
Atrium (Source: Self-drawn)
(2) Optimization of the functional layout based on health and comfort: The problem of insufficient
daylighting in the reading area is improved through the change in furniture arrangement. A light-
pipe lighting system is added, and pipes are set outdoors to collect natural light so that sunlight can
be scattered by the light guide plate to supplement indoor natural lighting and reduce the power
consumption by indoor artificial lighting. High windows are added in the partition walls on both
sides of corridor, and the high windows and the window sashes in the exterior facade are opened at
specific time to meet the requirement for normal natural ventilation inside and outside the building.
The lighting roof of the atrium is transformed into an accordion structure, with raised inclined planes
facing the east and the west for lighting to fully absorb incident light from different directions. An
electric sun-shading curtain is installed indoors to timely block the sunlight from the west, obtain
relatively soft diffused light, and ensure comfort in the atrium space (as shown in Fig 9, Fig 10).
(3) Building envelope performance transformation based on resource conservation: The building
was completed only approximately 17 years ago. To transform the external thermal insulation of the
exterior wall, it is necessary to transform the exterior facade, which is uneconomical and unfeasible,
so the transformation of the internal thermal insulation of the exterior wall is adopted. In this project,
in consideration of the economic efficiency, aesthetics, and feasibility of energy-saving design, 50-
thick PU hard foamed plastic is used as the insulating material to replace the 20-thick rare-earth
thermal insulation material for the composite wall, and the average heat transfer coefficient of the
wall is 0.50 W/(m2·k). For the glass curtain wall, a double-layer respirable glass curtain wall system
of external circulation type is selected, and the heat generated by solar radiation can be discharged
to the outside by means of natural ventilation instead of mechanical equipment, thus reducing the
energy consumption of mechanical equipment inside the building. Integrated sun-shading measures
for the glass curtain wall are employed to prevent indoor overheating.
After the optimization and improvement of the passive energy-saving design of the university
library in North China, the data of the BIM analysis model are updated and adjusted according to
the modified content, and the energy consumption simulation analysis of Ecotect air conditioning,
heating and ventilation energy consumption is carried out again after the transformation design. The
total annual cumulative energy consumption load of the scheme after transformation has decreased,
the annual heat load has decreased by 59.1%, and the total annual cooling load has decreased by
21.5%. After calculation, the total annual accumulated load decreased by approximately 47.4% after
the transformation. The results are shown in Figure 11.
(4) Management measures based on improvement and innovation: An automatic control device is
added indoors to realize the automatic control of room temperature at different personnel densities
and to avoid overcooling indoors; meanwhile, the air-conditioning system is timely replaced and
cleaned to improve energy use. A university-level energy management platform and single-building
metering devices are added to boost energy conservation at management and awareness levels.
4. Conclusion and Discussion
China started the work of improving energy conservation and the formulation of relevant standards
and regulations in the 1980s. It has been more than 40 years since then, but it is still commonly
considered that energy-saving buildings do not save energy [20]. With the gradual advancement of
design ideas, methods, and technologies of Green buildings, Green performance has been put on the
agenda. The energy-saving design based on the Green performance of buildings places stress on the
safety and durability, health and comfort, living convenience, resource conservation, and
environmental liveability of buildings, which complies with the people-oriented ecological and
Green development philosophy.
(1) There are diverse types of university buildings whose planning and layout are subject to the
overall planning of campus, and the light, wind, temperature, and humidity of the built environment
will all have an impact on individual buildings. The reasonable layout of various types of university
buildings on campuses can reduce traffic energy consumption and raise the energy use efficiency of
various functional facilities. The selection of building orientation is an important link in passive
0
200000
400000
600000
800000
1000000
1200000
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Monthly Energy Consumption Comparison Chart of HVAC Before and After
Energy-saving Transformation
节能改造前 (KWh) 节能改造后 (KWh)
Before
After
Fig. 11 Monthly Energy Consumption Comparison Chart of HVAC Before and
After Energy-saving Transformation (Source: Self-drawn)
energy-saving design. The best orientation can be selected through simulation analysis of solar
radiation, the trajectory of the sun, current daylighting illumination, and the wind environment of
the base.
(2) University buildings have complex functions, so Green building design and energy-saving
transformation should be carried out according to the characteristics of different types of buildings.
An efficient plan-view layout adapted to functions can not only improve the energy use efficiency
of buildings but also meet the requirements of buildings for sound, light, and heat to the greatest
extent and reduce energy consumption. China's Green buildings with conservation at the core
especially emphasize the importance of natural ventilation and lighting for energy conservation
[21], and the spatial layout design of buildings will influence natural ventilation and lighting, which
is one of the key issues of energy conservation.
(3) The design of thermal insulation and heat storage performance of the outer-building envelope is
an important link in the passive energy-saving design of architectural details, so reasonable
improvement of the thermal performance of the outer-building envelope can decrease the energy
consumption of cooling in summer and heating in winter, avoid the heat bridge effect, reduce the
impact of the outdoor climate on the inner environment of the building during the service time, and
achieve the goal of an energy-saving building design.
(4) For large buildings in colleges and universities, such as libraries and sports/event venues, it is
difficult to achieve the goal of controlling building energy consumption and improving indoor space
comfort by relying only upon passive energy-saving technologies. For this reason, the energy
conservation of the water supply and drainage system and HVAC system is particularly important.
To date, the energy management platforms of more than 40 colleges and universities in China have
passed the review of the Ministry of Housing and Urban-rural Development [22]. Such platforms
are helpful for discovering weak links in energy use, effectively preventing unreasonable utilization
of energy, and enhancing the energy-saving awareness of personnel to some extent.
Abbreviation
BIM: Building Information Modeling
rvt :Revit
3ds: 3-Dimension Studio
gbxML: Green Building Extensible Mark-up Language
dxf: Drawing Exchange Format
Phoenics: Parabolic Hyperbolic or Elliptic Numerical Integration Code Series
Ecotect: Autodesk Ecotect Analysis
CFD: Computational Fluid Dynamics
Fig. Figure
Tab. Table
Ethics approval and consent to participate
Not applicable
Consent for publication
All the authors agree to publish the article.
Availability of data and materials
All data and materials can be obtained free from the author, and the authenticity of the data is
guaranteed.
Competing interests
The authors declare that they have no competing interests.
Funding
The authors are grateful for the funding support provided by 2019 Shaanxi Natural Science Research
Program(2019JM-488)：Research on the construction of digital platform of Green campus building
based on the life cycle; Also, special fund project of basic scientific research business expenses of
Central University: Research on the construction of economical campus of Chang'an University.
Authors’ contributions
All authors made the same contributions to the article. Both authors read and approved the final
manuscript.
Acknowledgements
Thank my students Chang Li, Shuang Wu and Liang Cao's contributions to the research
investigation and data analysis.
Authors' information
1. Corresponding author Qibo Liu is doctor of engineering. Associate professor of school of
architecture, master tutor of architecture, international master tutor. Vice dean of the school of
architecture of Chang'an University. Deputy director of traffic BIM research center, Chang'an
University. Research area is Green building design method and technical system, Green human
living environment.
2. Zixin Wang is a second-year master. Research area is Green building design method.
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