Building Information Modeling-Embedded Building Energy Efficiency Protocol for a Sustainable Built Environment and Society

Abstract

In order to accurately analyze the building energy consumption and identify the problem of building energy consumption in advance, this study carries out the energy consumption analysis based on BIM (Building Information Modeling). The research object is a four-story college student dormitory in Beijing, and this set of BIM-based energy consumption simulation data was obtained using standard operating procedures (SOP). This operating procedure can start energy consumption analysis in the conceptual design stage, and developers can participate in real-time through the use of a three-dimensional information model, without additional design required. Then, comparing this study with the traditional energy consumption analysis, we see that the SOP of this research result has the following advantages: SOP function analysis is more professional, and the visual display method is more popular and intuitive; due to the flexible file format of the SOP, when data exchange is required between different software, the SOP can realize more convenient operation, and users can identify problems in the early stage of design through the SOP, correcting the scheme according to the simulation results, which is conducive to the development of the construction process. Finally, this study puts forward the analysis and estimation of energy consumption in different stages of the building life cycle, so as to provide researchers with ideas for improvement.

1. Introduction

Sustainable development looks into the rational use of natural resources, linking the environment to technology, not only meeting the needs of the current generation, but also taking into account that future generations could also benefit [1]. The building sector is at the forefront that must achieve sustainable development for cities and society, which is the main driving force of building energy efficiency (BEE) and the sustainable building movement [2]. From the perspective of environmental, economic, and social sustainability and a building’s life cycle, sustainable building advocates argue that sustainable buildings trump traditional ones, aiming to reduce energy, water consumption, and maintenance costs [3]. For example, the proper selection of ceiling, window, wall, roof, and floor components could greatly improve energy efficiency [4]. The economic benefits of improved health and productivity are much higher than the additional construction costs in meeting green design standards [5]. Sustainable buildings use only about 30 to 70 percent of the energy used by conventional buildings [6]. However, building owners and developers remain reluctant to stick with green solutions. In addition to the concern associated with high construction costs, the low popularity of sustainable building education also constitutes a development barrier for sustainability [7].

With the development of urbanization, more attention has been paid to building energy efficiency in modern architecture [8]. Throughout the entire life cycle of a building, including conceptualization, design, construction, operation, maintenance, renovation, and deconstruction, environmentally friendly measures and resource-efficient processes are used, which broadens and complements the classical architectural design concerns regarding economy, practicality, durability, and comfort [9]. Sustainable building also covers maximizing resource saving over the whole life cycle, as well as protecting the environment and reducing pollution [9]. Sustainable building is expected to provide people with healthy, efficient, and energy-saving spaces, which in turn puts forward additional requirements for the implementation of sustainable buildings. The increase in building energy consumption in the United States, Europe, and Japan has been modest over the past two decades [2]. Since 1990, energy consumption in the industrial sectors of these countries has decreased, as the economy focus has shifted from manufacturing to services. On the other hand, the BRICS nations show significant increases in energy consumption across the sectors; for example, in China, building energy consumption has risen by nearly 45% in two decades [7]. Sustainable buildings in China can be traced back to the year 1986, and since that time, China has promulgated more than 100 building energy efficiency standards and regulations [10]. In May 2006, China formulated a medium- and long-term development strategy for sustainable buildings. In 2013, the Ministry of Housing and Urban-Rural Development and the National Development and Reform Commission of China formulated the sustainable building action plan, which aimed to have 20 percent of all new buildings meeting the sustainable building standards [11].

The sustainable building development in China is still in its infancy, and the government and other policy makers have taken many steps to promote sustainable buildings in China [6]. For example, the sustainable building action plan, a mandatory sustainable building promotion policy, was jointly issued by the Ministry of Housing and Urban-Rural Development, the General Office of the State Council, and the National Development and Reform Commission [12]. In March 2014, the 2014–2020 China Plan further clarified the medium-term goal of sustainable building development, stating that sustainable buildings should account for at least 50% of new construction by the end of 2020. As the world’s largest developing country and carbon emitter, China has also made great efforts to produce near-zero energy buildings in recent decades [12]. Building projects are increasingly complex and difficult to manage, so Building Information Modeling has been introduced. The term “building information modeling” will be replaced by BIM, referring to a set of interacting policies, processes, and technologies that provide a way to manage basic architectural design and project data in a digital format throughout a building’s life cycle [13]), which is an interactive process that serves the entire life cycle of buildings from the architectural design to facility management, demolition and renovation. Some BIM applications focus on architectural design, while others focus on sustainability analysis. Parameterized information about the creation and use of coordinated computable information for building projects could be used throughout the building life cycle [14]. The current application of BIM is still intertwined with technical problems, such as weak interoperability between different BIM software products and across organizational boundaries. In addition, psychological problems may lead to a discouraging attitude towards BIM-based sustainable building cooperation [15].

Traditional CAD planning methods lack the ability to make historic decisions, so energy and performance analysis can only be performed in preparing building and building design documents [16]. For example, the construction sector in Iraq is considered as the sector with the most energy consumption and the greatest impact on the environment; this is because of the lack of assessment of building energy performance in the early stages of design, and the neglect of the importance of designers and architects in evaluating energy performance during the design stage. There is also a lack of innovative awareness, and designers and architects rely on CAD methods for calculation and design, which is an ineffective method for evaluating energy performance [17]. In fact, this has led to an increase in energy consumption and pollution in recent years. Building Information Modeling (BIM) is an innovative approach that includes many tools to effectively evaluate the energy performance of buildings [18]. BIM technology can simulate a virtual environment similar to the proper work environment, solving all problems in the early stage of the project [19,20,21]. A new approach, called Building Energy Modeling (BEM), is based on BIM [22]. Design teams can leverage BEM when applying it during the design phase, where alternatives in terms of energy consumption and thermal comfort can be found and comparisons can be made between the alternatives [23].

BIM is a powerful collaborative working method that enables the management of construction projects through digital models, making these projects more efficient and sustainable throughout their life cycle. This method can obtain an energy model of the building and its subsequent analysis, which is called the sixth dimension of BIM, or BIM 6D, in which information from previous dimensions is used, mainly the definitions of geometry, building materials, and equipment [24]. Through this energy model, the actual behavior of the building can be simulated, allowing it to help make decisions about the design and operation of the building. Take natural lighting, for example—one of the main factors used to test whether the interior environment and the building meet human requirements is daylight [25]. The role of daylight in everyday life and the fact that it affects the quality of interior spaces makes it very important. Through the simulation of the energy model, the possibility of improving efficiency can be investigated from different perspectives, such as lighting equipment consumption, occupancy control, daylighting, building orientation, and the proportion of glazed areas on the walls. Using BIM and parametric environmental analysis tools, building retrofits can be analyzed for visual comfort improvements. The building model is exported into a computer-aided design software for parametric solar analysis by environmental simulation software [26]. Through energy simulations, and after analyzing the building’s current energy situation, it is used to study alternatives to improve energy efficiency, optimize its sustainability [17,27], and to study the possibility of incorporating renewable energy sources and using natural light.

This study first compared the different evaluation systems on sustainable buildings in three regions and identified the problems that restrict the development of building energy efficiency. A BIM-embedded building energy efficiency protocol for a sustainable built environment and society was developed, and a case study aided by BIM tools was used to validate the developed protocol. This standard operating procedure (SOP) of BIM-based energy simulation provides architects and designers with a better standardized process for natural environment analysis in the design stage, providing a reference for the replacement or modification of the design scheme, rather than relying on traditional CAD methods for calculation and design, reducing model redesign.

2. Current State of Knowledge

The latest studies on sustainable built environment assessment are comprehensive; for example, a study analyzing the consumption pattern of housing in Saudi Arabia using parametric analysis found that the residential energy consumption was significantly affected, not only by the building type, but also by occupant behavior, meteorological conditions, envelope structure, and air conditioning settings [28]. The relationship between the thermal performance of the envelope and building energy consumption was analyzed in different climates using DeST-C to simulate the annual dynamic energy consumption and to determine the optimal protective layer thickness [29]. Energy Plus was used to develop a multi-object and parameter optimization model through a case study, which can comprehensively optimize multiple design parameters [30]. An ISCOA-LSTM sine-cosine optimization algorithm was proposed, and the experimental results showed stable and accurate functions, which could be used as a tool to solve the problem of energy consumption prediction [31]. A coordinated online multi-object control strategy based on the cooperative game theory was proposed to effectively achieve the goal of zero energy/low energy consumption [32]. A passive energy saving technology system and its evaluation criteria were introduced and validated through real cases [33]. Sustainable building codes in different countries vary in object, content, mechanism, process, index category, method, and weight setting [34]. The United States and China released the latest version of sustainable building assessment standards in 2013 and 2014, respectively. In particular, ESGB2014 contains a significant change from the previous version; thus, it is necessary to compare the latest assessment standards for sustainable buildings in different countries [35]. The latest version of China’s sustainable building evaluation standard, Evaluation Standard for Green Building (ESGB), was compared with the Leadership in Energy and Environmental Buildings (LEED) of the United States and British Research Establishment Environmental Assessment Method (BREEAM) of the United Kingdom [36]. Sustainable buildings represent the response of the building industry to the need for sustainable development, such as improving health and the environment, energy and water efficiency, and reducing natural resource consumption [10]. The ability to import building geometry and building heat data from building information modeling (BIM) has great potential to reduce time and uncertainty in building energy modeling. The complexity of diversified energy sources and a set of general methods to characterize the flexibility of diversified energy systems were proposed using BIM [37]. There was considerable interest in the interoperability of data between complex BIM applications and building energy analysis tools. The Extensible Markup Language (XML) is a set of rules for designing text format specifications that provide a standard way to define data in BIM. The gbXML schema is the most common data format used to exchange building information between BIM and energy simulation tools, such as Energy Plus and Ecotect. Many BIM tools and vendors, such as Autodesk and Bentley, support gbXML for a better exchange of architectural information between BIM and various engineering applications [15]. Time could be saved by importing geometric models from BIM into the energy simulation tool without having to rebuild the building geometry in the simulation interface [38]. The files in gbXML format are space-based models, and the components of the building envelope are simplified in the form of surfaces, without thickness and detail of the components, but can carry richer additional information, such as component materials, thermal performance parameters, etc. The thermal properties of building components, such as thermal conductivity and specific heat, are derived entirely from the gbxml-based BIM and are passed directly to the energy simulation engine. To model an existing building, tools are needed to measure the actual thermal properties of building elements and to update their relevant entries in gbXML [38].

Developed by the United States Sustainable Building Council (USGBC), LEED is one of the most recognized built environment assessment programs in the world. LEED has become a reference for some other countries to develop their own sustainability building assessment standards [39]. There are LEED programs in more than 150 countries and territories, representing all continents, except Antarctica. The United States sustainable building council has published a list of the top 10 LEED countries outside the United States, based on the cumulative total LEED certified square meters (GSM) of each country [40]. China is the second largest LEED user outside the United States, with 22.97 million GSM LEED spaces. Since 1998, LEED has been evolving to more accurately represent and integrate emerging sustainable building technologies [41]. The weights in LEED are listed in

Table 1. Weights in LEED.

S. No 1	New Buildings	Weight
1	Integrated design	1
2	Site selection and transportation	16
3	Sustainable site	10
4	Water-use efficiency (WUE)	11
5	Energy and atmosphere	33
6	Materials and resources	13
7	Indoor environmental quality	16
8	Innovation (bonus points)	6
9	Localization of materials (bonus points)	4
10	Total	110

. In the grading, the satisfaction degree in each indicator table corresponding to the building is scored. The scores were summarized to obtain the scores of each index. According to the total score of the buildings evaluated, the LEED 4th edition has four certification grades, namely: certification grades 40~49, silver grades 50~59, gold grades 60~80, and platinum grades above 80 [41].

BREAAM is the world’s first comprehensive assessment system for sustainable buildings, and it was introduced to the public in 1990 [42]. It is sponsored and operated by the building research establishment (BRE) in the UK for sustainable building design, and has become one of the most comprehensive and widely recognized measures of built environment performance. BREEAM is widely used in Europe and many other parts of the world. BREAAM’s domestic version was replaced by the Code for Sustainable Homes (CSH) in April 2008 [39]. The system, which is mostly used for new and renovated small homes and apartments, aims to ensure that the homes meet people’s needs for a high quality of life, while providing a safe and healthy internal environment. According to the characteristics of residential buildings, it has formulated specific contents and relevant weights. Based on a scientific understanding of the relationships among people, buildings, and the environment, the system is evaluated in 10 categories: energy, management, health and comfort, transportation, water, materials, garbage, land use and ecology, pollution, and innovation, as shown in

Table 2. Weights in CSH.

S. No 1	Category	Remark	Weight
1	Management	Commissioning, construction site impact, safety	12
2	Health and comfort	Lighting, thermal comfort, sound, indoor air and water quality, lighting	15
3	Energy	Carbon dioxide emissions, low or zero carbon technologies, energy metering, building energy efficiency systems	19
4	Transportation	Bus connection, non-motor vehicle facilities, convenient municipal facilities, surrounding facilities index	8
5	Water	Water consumption, leak detection, and water recycling	6
6	Materials	Material recycling, reuse, procurement range, high performance materials	12.5
7	Waste	Construction waste, recycled aggregate, recycling facilities	7.5
8	Land use and ecology	Site selection, ecological function protection, mitigation/enhancement of ecological value	10
9	Contamination	Refrigerant use and leakage, flood risk, NOx emissions, river pollution, external light and noise pollution	10
10	Innovation	Excellent management level, BREEAM AP, new technology and new process	10

[40].

CSH has been fully implemented as a national standard in the UK since May 2010, with the goal of reducing carbon emissions while achieving the environmental sustainability of buildings [35]. The recommendations and applications of CSH could point to the direction of future adjustment of the UK residential building code. BREEAM has certified more than 425,000 programs, and 1.9 million registered programs in 60 countries, and it has a profound impact on other sustainable building evaluation systems, promoting the development of sustainable buildings [34]. However, the system does not specify a construction phase to be evaluated, and most buildings focus on the design phase instead of the operational phase [43]. The concept of sustainable building was first introduced in China in the 1990s. During the learning process, the China Ministry of Construction formulated the evaluation standard for the first time in 2006, namely the sustainable building evaluation standard ESGB (GB/t50378-2006) [11]. It was also the first national standard system for evaluating sustainable buildings in China. The standard continued to improve, with LEED as a reference [39]. ESGB version 2006 and version 2014 are compared and contrasted in

Table 3. Comparison between ESGB version 2006 and version 2014.

Items	ESGB 2006	ESGB 2014
Assessment object	Residential buildings, public buildings (office, shopping mall, hotel)	Residential buildings, public buildings (unlimited)
Assessment phase	Design evaluation and operational evaluation (after 2008)	Design evaluation and operational evaluation
Assessment system	Preserving land and outdoor environment; saving energy; saving material; saving water; indoor environmental quality; operations management	Preserving land and outdoor environment; saving energy; saving water; indoor environmental quality; operations management; construction management
Index categories	Energy, resource, and environmental loads and indoor environmental quality; operation management	Energy, resource, and environmental loads and indoor environmental quality; operation management; construction management
Structural system	Control items; general and preference items	Control and score items
Assessment method	Calculate the specified quantity	Total points earned
Additional item	0	Innovation (less than 10)

[11]. Currently, ESGB 2014 (GB/t50378-2014) is in use. Each type of indicator includes control items and scoring items, with a total score of 100. In order to encourage technological innovation and improvement of sustainable buildings, the evaluation index system also uniformly rates innovation projects [5]. It gives a score of one to three, based on its performance using seven criteria. The main evaluation criteria are based on the following indicators: preserving land and the outdoor environment, saving and utilizing energy, saving and utilizing water, saving and utilizing materials, indoor environmental quality, and operation management, using the original standard, while the newly revised standard adds construction management to effectively cover the whole life cycle [34]. The assessment criteria assign the highest weight to energy efficiency. With the improvement of China’s environmental protection awareness, this assessment standard is in line with China’s national conditions [44].

3. Research Methods and Procedures

Through a case study, the evaluation systems of sustainable building in the UK, the US, and China were compared to identify the similarities, differences, advantages, and disadvantages of each evaluation system. The case study was conducted with a four-story dormitory building for college students in Beijing, and the main function of this dormitory building was accommodation. There were reading rooms, reception rooms, fitness areas and other multi-functional entertainment and leisure locations in this building. The total land area was 3344 m², the total construction area was 2370 m², the building density was 21.5%, the greening rate was 38.4%, and the plot ratio was 0.71. The region was in the northern part of the north China plain, backed by Yanshan, and adjacent to Tianjin and Hebei provinces. The typical climate of this area was a semi-humid continental monsoon climate in the north temperate zone, with an average elevation at 43.5 m. The altitude was 20 to 60 m above sea level. The research flowchart is presented in Figure 1. First of all, in the second section of this paper, we compare the sustainable building evaluation systems in the UK, the US, and China, found the similarities and differences, advantages, and disadvantages of each evaluation system, found the problems that restrict the development of building energy efficiency, and put forward suggestions on the related issues for green buildings in China. The third section of this paper clearly illustrates the research methods and steps of this study using the research flow chart. The fourth section shows the experimental data. This paper takes a four-story college student dormitory in Beijing as the research object. After the BIM model is established, we use import energy consumption software for energy consumption analysis (such as sunshine analysis, direction optimization, hygrometer analysis, wind analysis, thermal environment analysis, optical simulation analysis, energy consumption simulation, etc.). The standard operating procedure (SOP) of BIM-based energy consumption simulation is summarized and compared with the traditional energy consumption analysis. The fifth section expounds the research conclusions of this paper, and analyzes and forecasts the energy consumption in different stages of the building life cycle, so as to provide researchers with ideas for improvement.

Parameterized components, as an important part of drawing models in Revit, provided a complete system of graphical forms to combine settings, as well as design and draw images precisely and reasonably. Data interoperability issues between complex BIM applications and building energy analysis tools were well solved in this study. Extensible markup language (XML) as a set of rules for designing a text format specification provided a standard way to define information in this case study. The extensible markup language (gbXML) for sustainable buildings supported the architectural modeling. Figure 2, Figure 3, Figure 4 and Figure 5 present the Autodesk Revit drawing of this case study, and Figure 6, Figure 7 and Figure 8 detail the beds, tables, and chairs inside the dormitory, as well as the sofas, cabinets, and other components in the reception room. Figure 9 shows the rendered model of this case study in Revit. Ecotect Analysis was used in this study to analyze the detailed energy performance by providing an interactive analysis method with a step-by-step scheme. Local and climatic data were imported to conduct a comprehensive technical analysis of the model in six aspects: thermal environment, optical environment, acoustic environment, sunshine, economy and environmental impact, and visibility. Optical environment is the influence of natural light and artificial light on the building, and visibility is the human visibility in the optical environment. This article analyzes the optical environment before construction, so artificial light is not added in the process of optical environment analysis, but is added through the software analysis to maximize the use of natural light, so as to reduce energy use. Ecotect used the data exchanged from Revit in the XML format to analyze air conditioning load, sound environment, light environment, and other kinds of information analysis through factors such as sunshine hours in the building, and the building ventilation condition.

4. Data Analysis and Results

The data analysis included sunlight analysis, orientation optimization, psychrometric chart analysis, wind analysis, thermal environment analysis, optical simulation analysis, and energy consumption simulation. The analysis started with exporting the model to gbXML format in Revit for saving, and transferring this file to Ecotect to set the geographical location and meteorological data of the region, as shown in Figure 10.

4.1. Sunlight Analysis

Sunlight analysis started with selecting the building and the surrounding area, then selecting Display Shadows. We set the time range of shadow display at 9 a.m. to 17 p.m., dragging the timeline to observe the shadow changes. Figure 11 shows the solar orbit orthography of the planned area using the Cartesian coordinate system, and Figure 12 shows the sphere shadow diagram, where the x-coordinate is the height angle of the sun, and the y-coordinate is the azimuth angle of the sun, which could quickly denote the position of the sun anytime and anywhere, analyze the shading relationship between adjacent buildings, and obtain the shadow map of buildings at any time.

Figure 13 animated the annual shadow changes of the building, enabling a comprehensive analysis to avoid potential mistakes. According to the annual shadow map, light-loving plants were cultivated in areas with more solar radiation throughout the year. Large areas of evergreen trees were planted to provide shading where the sunshine accumulated in intensity. In places where the sunshine accumulation was less, deciduous trees were planted, leaving people to enjoy the sunshine in winter. The shadow shielding analysis on multiple buildings was carried out by setting a bench in the shade to create a more comfortable and livable atmosphere, and then the height, position, and window area were adjusted to provide the rooms with sufficient light and ventilation.

4.2. Orientation Optimization

According to the annual incident solar radiation data plotted in Figure 14 and Figure 15, June to August represents the period of overheating, December to February represents the period of undercooling, and the curve represents the average direct solar radiation throughout the year.

Figure 16 and Figure 17 present the optimal orientation diagram, where the arrow pointing to 157.5 represents the best orientation, and the arrow pointing to 67.5 represents the worst orientation. The blue circle represents the amount of solar radiation in the coldest three months, the red circle represents the amount of solar radiation in the hottest three months, and the green circle represents the average radiation dose throughout the year. Good positioning could provide thermal comfort and energy efficiency. In the north temperate zone, the southward direction allowed the building to take full advantage of the sun and blocked the main wind direction in winter, providing the best thermal conditions for the southern facade. The green line represents the direction in which the buildings obtain the most solar radiation in winter, the thin red line represents the direction in which buildings obtain the most solar radiation in summer, and the yellow line represents the optimal orientation after comprehensive consideration.

4.3. Psychrometric Chart Analysis

Figure 18 and Figure 19 present the psychrometric chart analysis showing the relationship between different parameters in humid air, where enthalpy is a physical quantity of energy inside a substance with the units of kJ. In the modeling process, the psychrometric chart intuitively obtained the cold, hot, dry, and wet indoor and outdoor conditions of the building, and the deviation was analyzed by comparing the optimal comfort zones and were adjusted for time. The comfort zone was determined by air temperature, relative humidity, air velocity, and ambient radiation temperature. As shown in Figure 18 and Figure 19, each point represents the temperature and humidity state, where the horizontal axis represents the temperature, the vertical axis represents the absolute humidity, the dotted line represents the relative humidity, the straight line represents the wet-bulb temperature, and the area surrounded by the yellow line is the comfort zone. The blue line shows the monthly data. The region was sultry in summer and cold in winter; thus, most of the data fell outside the optimal region, so that more ventilation and insulation measures were considered in summer, and more moisturizing measures were considered in winter.

Figure 20 presents the thermal comfort percentage used as reference for passive strategies of different climates, which could not only reduce the adverse impact of buildings on the environment, but also reduce the high cost caused by inappropriate schematics. The combination of different passive strategies, thermal mass effect, exposure quality, night ventilation, and natural ventilation could improve human comfort, while direct and indirect evaporative cooling strategies had no significant impact on high humidity. The effects of technical measures, such as enhancing the thermal storage capacity of the envelope, night ventilation, passive solar energy, natural ventilation, direct evaporation, and indirect evaporation cooling on the thermal comfort of the building were included. The white column represents the percentage of thermal comfort without the relevant technology, and the dark column represents the percentage of thermal comfort after the technology is adopted. The passive strategies were more effective in spring and autumn than in summer, because high temperature and high humidity did not improve human comfort; thus, one way to improve human comfort in summer is to consider proper natural ventilation and to take measures of sunshade and radiation protection. Due to the low temperature in winter, one way to improve the comfort level is to adopt active heating to enhance the building’s heat storage capacity. The rational use of the enthalpy diagram could not only determine the optimal comfort zones of the building, controlling the early design cost, but also put forward improvement measures regarding the passive design for the comfort of the housing.

4.4. Wind Analysis

Natural ventilation as an effective energy saving measure uses various construction techniques, such as temperature control and expelling moisture, to guide and optimize airflow to improve the indoor air quality. Natural ventilation considerations covered construction materials, natural lighting, underground cold and heat storage, and automatic control. The building layout had a great effect on natural ventilation. Figure 21 and Figure 22 present the wind frequency, wind direction, and wind speed distribution throughout the year, indicating that the main wind direction is southeast in summer and northeast in winter. Smart use of natural ventilation for cooling could be aided by the wind frequency chart. For example, the main roads in the scheme area were aligned with the prevailing wind direction to allow smooth passage. For the building itself, the main wind direction in summer is southeast; thus, the height of the north window was raised to make the air outlet higher than the air inlet. Meanwhile, movable vertical shutters were set up on the south façade so that adjusting the vertical shutter according to the wind direction and sun height angle could increase the air intake and effectively reduce the indoor temperature.

4.5. Thermal Environment Analysis

A temperature and humidity analysis was conducted based on the meteorological data, which is presented in the three-dimensional diagram in Figure 23, Figure 24, Figure 25 and Figure 26. Beijing has distinct seasons, in which the winter is long, dry, and cold, the summer is hot and rainy, and the autumn is comfortable.

The system type, number of internal occupants, calorific value, and activity schedule were key in the building model, which was a student dormitory building with four-person rooms. Weekdays were from Monday to Friday, leaving the room empty from 8:00 to 12:00, and from 14:00 to 17:00. Figure 24 presents the hourly temperature distribution. The daily heat gain and loss situation was obtained through measurements such as the proportion of the heat generated by the comprehensive temperature, the heat from direct solar radiation, the heat from cold air infiltration, the heat from internal personnel and equipment, and the heat from interregional heat and loss. The actual heat gain of the scheme and various proportional indexes were simulated. For rooms with relatively extreme temperature distributions, corresponding active and passive coping strategies were adopted to analyze the temperature change of non-air-conditioned rooms, facilitating the rationalization of functional partitioning and the optimization of the design scheme.

The simulation results of all the visible thermal regions are shown in Figure 25. The heat conduction of the envelope constituted 32.2%, the heat generated by direct solar radiation and the comprehensive temperature constituted 27.1%, the heat gained or lost by air penetration constituted 59.3%, which is directly related to the air tightness of the doors and windows. The heat loss over the entire year was mainly caused by the building envelope, accounting for about 60% of the total proportion. The natural heat gain throughout the year came mainly from solar radiation, which accounted for about 30%.

The thermogram of the adaptability index is presented in Figure 26, where the abscissa was outdoor temperature, the ordinate was indoor thermal condition, and the middle line represented the ideal state of the housing interior area. The dots represented the trend of the discrete points for the heat gains and losses of the housing area. The heat loss of the rooms was serious, and attention should be paid to the insulation effect of doors, windows, balconies, and other enclosures in the building in winter to save energy consumption and to improve indoor thermal comfort.

4.6. Daylighting Analysis

Figure 27 presents the daylighting analysis, where the axis offset of the grid was 600 mm above the ground, and the number of cells represented the density of the grid. Due to the irregular envelop of the building, the lighting condition of the northern rooms was not sufficient, and the lighting distribution of some rooms facing west was not even. As a solution, the proportion of windows in the enclosure system was increased, and the function of the rooms was adjusted according to the lighting condition. The duration of sunshine was calculated based on the number of hours of sunshine the rooms received in a specified day. In terms of the sunshine time for residential buildings, the current regulations in China required that the effective sunshine time of sheltered residential buildings should not be less than 2 h on the coldest day of the year, and a bedroom or living room should have at least 2 h of sunlight from 8 am to 4 pm. Sunshine quality referred to the cumulative utility of ultraviolet rays in the sunshine per hour. Figure 27 indicates that the room met the basic sunshine requirements, including building orientation, solar radiation, and sunshine distribution.

4.7. Application of Analysis Results

Through the comprehensive analysis of ECOTECT, the designer has a certain understanding of the building orientation, solar radiation, sunshine distribution, natural ventilation, etc., and conducts comprehensive analysis in the early planning phase to avoid potential errors. For example: (1) Daylight analysis helps determine the location and scale of daytime entry into a building, helping designers and architects improve the daylight performance of a building’s interior; (2) The daylight ratio obtained by daylight analysis helps to reduce the number of lamps, reducing energy consumption and reducing the cost of lamps; (3) Thermal environment, wind environment, temperature, and humidity analyses help to determine the design of heating, ventilation, and refrigeration systems, identifying the best alternatives to improve energy efficiency in the early stages of design and maximizing the use of the natural environment to save energy.

4.8. Standard Operating Procedures (SOP) for Energy Consumption Simulation Based on BIM

The standard operating procedures (SOP) for energy consumption simulation based on BIM are developed in Figure 28, and the comparison and contrast between traditional and BIM-based energy consumption analysis is presented in

Table 4. Comparison between traditional and BIM-based energy consumption analyses.

Items	Traditional Energy Consumption Analysis	BIM-Based Energy Consumption Analysis
Participants	Professionals specializing in energy analysis	Developers, designers
Software	PKPM, DeST, Designbuilder, DOE2D	Ecotect, Sustainable Building Studio
Analysis process	Most energy consumption analysis starts after the construction drawing is completed, when the construction project design scheme is generally finished. PKPM software is based on the energy-saving design standard, and the calculated results can only meet the design standard limit. The modified model should be designed separately.	At the beginning of the conceptual design stage, developers participate in real-time through a 3D information model. No additional design is required.
Display of analytical results	The analysis results are mainly expressed in figures.	Besides chart and figures, animation is also exported.
Model follow-up usability	The model is only used to simulate the energy consumption of the project.	With the progress of the construction project, the model is constantly refined in real-time, which could, in turn, guide the on-site construction.

. The use of this standard operating procedure (SOP) of BIM-based energy simulation provides architects and designers with a better standardized process for natural environment analysis in the design stage, providing a reference for the replacement or modification of the design scheme, rather than relying on traditional CAD methods for calculation and design, reducing model redesign. Compared with traditional methods, the BIM-based approach could conduct more functional analyses, such as sunlight analysis, orientation optimization, psychrometric chart analysis, wind analysis, thermal environment analysis, optical simulation analysis, and energy consumption simulation, which could also be demonstrated in a simple and visualized way. In traditional energy consumption analysis, most of the energy consumption analysis begins after the construction drawing is completed, and the construction project design scheme has been roughly completed. Data exchange could be conducted directly using Revit in different file formats to reduce modeling time. Meanwhile, the exported data could also be used for subsequent analysis by other applications. The calculation function becomes more powerful in the BIM-based approach, making the climatic information of geographical location more complete and accurate. Compared to traditional approaches, the BIM-based approach could identify problems earlier in the design stage.

Table 5. BIM-based simulation focusing on various design stages.

Conceptual Design Stage	Detailed Design Stage	Final Design Stage
Climate analysis	Solar energy utilization	Optimized design of building details
Resource and material analysis The best direction	Natural ventilation	Air-conditioning load calculation
Master plan	Energy saving analysis	Lighting optimization design
Passive strategy selection	Daylighting analysis	Optimal design of water supply and drainage
Comparison of building structure system	Acoustic environment analysis	Structural optimization design

lists the BIM-based simulation focus at various design stages, such as the conceptual design stage, detailed design stage, and the final design stage. The application of BIM simulation technology at different stages will have a certain impact on the design and selection of architectural plans, through the analysis of climate, resources and materials, and on the overall planning in the conceptual design stage. Thus, technical changes after the start of construction can be reduced. In the detailed design stage of construction, the best solution or alternative is selected through the analysis of solar energy utilization, natural ventilation, daytime lighting, and the acoustic environment. In the final design stage, other facilities of the building, such as the lighting system, water supply, and drainage system, can be reasonably analyzed, imported, and exported.

5. Conclusions

Most traditional energy consumption analyses start after the construction drawing is completed, when the construction project design scheme is generally completed, and the modified model is to be designed separately. The standard operating procedures (SOP) for energy consumption simulation based on BIM developed in this study could start the energy analysis at the beginning of conceptual design stage, allowing developers to participate in real-time through a 3D information model, and no additional design is required. BIM-based approaches could export animations, in addition to charts and figures. With the progress of the construction project, the model is constantly refined in real-time, which could, in turn, guide the on-site construction. Compared with traditional methods, the BIM-based approach could conduct more functional analyses, such as sunlight analysis, orientation optimization, psychrometric chart analysis, wind analysis, thermal environment analysis, optical simulation analysis, and energy consumption simulation, and all of these could be demonstrated in a simple and visualized way. Data exchange could be conducted directly with Revit in different file formats to reduce modeling time. Meanwhile, the exported data could also be used for subsequent analysis by other applications. The calculation function becomes more powerful in the BIM-based approach, making the climatic information of geographical location more complete and accurate. Compared to traditional approaches, the BIM-based approach could identify problems earlier in the design stage. Limited market demand restricts the development of sustainable buildings and the BIM-based R&D efforts in achieving it. The transparency of market information and a healthy market competition mechanism are important guarantees for sustainable building development, which are recommended in future research.

Environmental assessments in the early stages maximize opportunities for environmental improvement and reduce the costs and other challenges of realizing these opportunities. As a result, the industry can access the most comprehensive and reliable information by applying advanced simulation tools to help support decision making during the design phase and the earliest stages of the decision-making process. Design professionals face immense and complex regulatory and professional responsibility horizons, and having professionally trained practitioners and consultants is critical, regardless of the environmental factors that must be considered in the design process, which places higher demands on the professionals’ limited time and resources. Architects, builders, and managers should work with life cycle assessment (LCA) professionals to assess the environmental impact and utilization of various design solutions through the application of BIM technology to maximize the energy efficiency potential of buildings and minimize the unnecessary affects that may be further produced in the design process. The joint efforts of LCA practitioners and scholars are more conducive to the public’s recognition of the financial, environmental, and risk-reducing benefits that LCA assessment provides to the industry and to independent organizations.