Study on BIPV Application Based on BIM Technology

Li Shengyi Wang Jia

（Institute of electrical and information engineering Beijing University of Civil Engineering and Architecture Beijing 100044 China）

1 Introduction

With the rapid development of society,the energy consumption is increasing sharply.The conventional energy such as the fossil energy are increasing depletion,and,the results these emissions caused serious environmental pollution,not only destroyed the ecological balance,but also pose a serious threat to human life and health security.So now the use of solar energy resources has become a trend.Photovoltaic power generation technology has a rapid development,and perfects a renewable energy technology in such challenges and opportunities.Among them,BIPV as the core in the field of photovoltaic power generation has been widely concerned and applied.BIPV has the following advantages:photovoltaic arrays can replace the conventional building materials,saving the material cost;the building can provide sufficient area for photovoltaic system,and does not need other space;it can save a support structure of photovoltaic system,saving the transmission cost;it makes installation combined with construction,saving installation cost;it can realize the distributed generation,transmission and distribution of electricity to avoid loss(5%～10%),reduce the transmission and power investment and repair cost;The appearance of buildings will be more attractive[1].

In addition,BIM technology is a profound impact on the construction industry now,especially the revolutionary changes to the mode of architectural design.BIM can greatly improve the whole efficiency of the architectural design industry,and optimize the design to ensure the final quality of the building,and it also can full lifecycle information management in construction.

As a new cross subject,BIPV,in between the participating professionals,such as photovoltaic manufacturers,architects,electrical engineer,the division structure and so on,often appears to link with the cooperation of the fault.This will emerge as the times require,combined application of BIM technology and BIPV technology,make it become an organic whole,not only to better and faster implementation and promotion of photovoltaic building provides effective theoretical guidance,but also triggered the construction industry to the overall cognitive BIPV design.

2 Building Information Modeling

2.1 The origin and development of BIM

BIM is the abbreviation of building information modeling.

Although the industry generally agreed that the article“Comparing Pommes and Naranjas”the industry analyst Jerry Laiserin published in December 16,2002,is as the beginning that BIM was widely used in engineering construction industry as a technical,but the study in fact on similar technology can be traced back to twentieth Century 70 years,and BIM,the term itself,appeared with continuous discussion and collision between peers,not belonging to the creation of a man.

In 1975,American Chuck Eastman proposed building description system (BDS);in 1980s,Finland scholars put forward the "product information model"(PIM);in 1986,America scholar Robert Aish proposed“building modeling”theory;in 2002,the world's largest software supplier Autodesk company pioneered Revit and Civil 3D software based on the building information modeling (BIM).Initially,this software is considered not practical.However,the next few years,several other famous software developers also put forward the concept of information model in the name of different.Hungary Graphisoft proposed Virtual Building (VB) concept,and put it into application in the architectural design software Arch CAD;Bentley pioneered Micro Station Architecture based on Single Building Model (SBM).BIM in the beginning USA,then Europe,Japan,Singapore and other countries have been actively promoted[2].

At present,there are more than 62% American architectural design unit using BIM,and many countries have formed a more mature BIM standard.America draft the domestic application of the BIM standard-NBIMS (National Building Information Model Standard) according to international IFC standards.NBIMS is a complete BIM guidance and normative standard,providing the information of building information model of IFC data format can realize interaction requirements in different industries,and it can realize the informatization to promote commercialization process objective.The establishment of BIM standard not only enhances the competitiveness of the industry,but also has brought significant economic benefits.

In view of the importance of BIM technology,Chinese“fifteen”key science and technology program began related research on BIM technology,focusing on the research of BIM standard-IFC and application software.Through this research,the platform part of the IFC standard is adopted as the industry standard and the design &construction software,so as to accumulate the knowledge of BIM technology,and laid the foundation in order to further open the study.

At the same time,China government also enacted the BIM related documents and regulations to give a high degree of concern and attention.Shanghai government present a notice that clearly pointed out the importance of promoting the application of BIM technology and put forward some suggestions.

2.2 The Basic Connotation and Significance

What’s the BIM?

Autodesk defined BIM as:BIM is an intelligent model-based process that provides insight to help you plan,design,construct,and manage buildings and infrastructure[3].

The key to any successful project is clear,concise understanding between architects,engineers,construction professionals,facility managers,and owners.Today,building information modeling (BIM)is breaking down barriers and bridging communication between extended design and construction teams,providing consistent and reliable information across the scope of a project.BIM is an integrated process that vastly improves project understanding and allows for predictable outcomes.This visibility enables all project team members to stay coordinated,improve accuracy,reduce waste,and make informed decisions earlier in the process-helping to ensure the project’s success.

With the modern development of the construction industry becoming more and more global,city,sustainable development,there are 11 dimensional indicators of the BIM:Data Richness,Lifecycle Views,Change Management,Roles or Disciplines,Business Process,Timeliness/Response,Delivery Method,Graphic Information,Spatial Capability,Information Accuracy,Interoperability/IFC Support.Now BIM has been widely used in various industries:BIM and city planning,BIM and cost management,BIM and operation &management,BIM and sustainable architecture,and so on.

Promoting the application of BIM technology and playing its visualization,virtual,collaborative management,cost and schedule control and other advantages,will greatly enhance the project decisionmaking,planning,design,construction and operation management level,and reduce rework waste.It will effectively shorten the construction period and improve project quality and investment efficiency.At the same time,it will further improve the transparency and traceability of the constructional information,and it plays an important role to regulate market order and the prevention of corruption in the construction field.

3 Building Integrated Photovoltaic

3.1 The Origin and Development of BIPV

With the rapid development of society,the energy consumption is increasing sharply.The conventional energy such as the fossil energy are increasing depletion,and,the results these emissions caused serious environmental pollution,not only destroyed the ecological balance,but also pose a serious threat to human life and health security.So now the use of solar energy resources has become a trend.

As early as in 1954,America Baer laboratory developed the first solar.But because of that the photoelectric conversion efficiency is low,and the reason of higher production costs,it had no attention but in special fields such as aerospace applications.

When the time to enter 1 970 s,the developed countries who dependent on petroleum energy began to invest much manpower and tried to find an alternative energy after they were hit extremely by the energy crisis twice.Then photovoltaic technology began rapid development.

After twenty-first Century,solar power generation has a large-scale application.With the leading and supporting of Germany,USA and Europe,solar energy craze is sweeping across the world,contributing to the rapid development of solar photovoltaic industry.Especially in the past few years,photovoltaic industry increased at the average annual growth rate of more than 20%.In twenty-first Century,REN21 pointed it out in its report that the world's photovoltaic power generation capacity will grow to 140 000 MW by 2030 from 1 000 MW in 2000.The European Renewable Energy Council predicts that the electric energy produced by photovoltaic power generation technology will provide a supply of 50% of the total demand for global consumption by 2040,which can satisfy the global basic load[4].

BIPV has become an important research topic in twenty-first century.The construction is a complicated system,and in the preparation of materials,construction and maintenance stage it needs to invest a lot of energy.It is one of the main ways of social energy consumption.If you want the new solar technology combined with the architectural design,while continuing to maintain the cultural characteristics of the building,we should start from the two aspects of technology and aesthetics,which are the organic combination of architectural design and the technology of solar energy.And then the concept of“integrated design”appeared.

The integration design of the building in China has been a good practice nowadays.Chinese Academy of Sciences in 2004 built the China domestic first electrical station which integrated grid connected photovoltaic and building photovoltaic power.In 2010,BIPV had also become a major feature in Shanghai expo.Nowadays,the research of BIPV technology has become an indispensable part of the design and technology research of Chinese buildings.

3.2 The Basic Connotation and Significance

The main form of BIPV in photovoltaic and building integration includes:PV walls,photovoltaic curtain wall,PV skylight,photovoltaic,photovoltaic sunshade,awning,and photovoltaic etc.You should accord to the actual need,while selecting the appropriate installation mode.As shown in Fig.1,it is the building integrated photovoltaic system.The PV module installed on buildings produces DC,and it is connected by a junction box and inverters,which convert alternating current.Then the last power is transported to the load in buildings.

Fig.1 The building integrated photovoltaic system.

In BIPV design,there is generally the grid connected system.In the power peak stage,photovoltaic power system supply the power produced by the system to the workload of the buildings.And it can also transport the residual power to the public power grid.As shown in Fig.2.

Fig.2 Photovoltaic grid connected system.

In the professional field of the building electrical and intelligent,grid connected power generation design in BIPV needs to consider the following factors:

（1）Consider building’s surrounding environment,and try to avoid or away from the shade fabric.

（2）The orientation of the building should be as far as possible for the East-West or north-south.

（3）Determine the tilt angle of the roof according to the local latitude and longitude.The earth is kept turning around the sun,so the influence of the roof tilt angle on the whole solar power generation capacity is not large,generally not more than 5%.

（4）Calculate the number of PV modules on each roof and the arrangement according to the size of the components.

（5）Determine the total number of each series according to the DC voltage inverter input[5].Generally,a house faces of an inverter in order to improve the inverter efficiency

Photovoltaic system is mainly composed of the following important components:

（1）Photovoltaic cell.It is composed by the semiconductor materials which can produce voltage and current in the sunlight.

（2）Photovoltaic module.It is composed of the photovoltaic cells,plating into a sheet placed between two encapsulation layers.

（3）Panels.They are fixed together by one or more modules.

（4）Photovoltaic phalanx.It consists of one or more panels connected together by wires,and it provides a certain voltage value,fixed on the bracket structure.

Fig.3 Schematic diagram of photovoltaic phalanx.

（5）Charge controller.The equipment regulates the cell voltage,used to prevent the battery from excessive charge or discharge in order to reduce the performance and service life.

（6）Storage battery.It can storage DC in chemical means.

（7）Inverter.An electrical apparatus converts the direct current to the alternating current.

（8）The DC load：equipment,motor and DC power device.

（9）The AC load：equipment,motor and AC power equipment.

From the view of construction,or the technical and economic considerations,building integrated photovoltaic has a lot of advantages:

BIPV can solve the problem of energy consumption of the building well,and will not cause pollution to the surrounding environment.The excess electricity generated by the grid connected photovoltaic power generation system can be fed into the grid,and it need not occupy extra land and excessive transmission line.BIPV is not only an effective environmental protection of the construction design,but also embodies the people now living a new life attitude and life style.BIPV will become the main form of the future architectural design.

4 BIM-BIPV

4.1 BIM-BIPV

The current research on BIPV is a typical interdisciplinary.Its participants lack a" whole" field of vision.This obviously hinders the development and popularization of BIPV now.So the BIM technology and BIPV design are combined that will effectively alleviate this problem.Based on BIM,we can integrate the various stakeholders of the building photovoltaic industry,so that they can get the information support and a full range of services,and ultimately improve the quality of BIPV design and management[6].Based on BIM,we can optimize the performance of the system better,such as the operation structure,lighting function,power function,aesthetic properties,thermal properties and other aspects of the photovoltaic system,and finally the overall performance of the project will have a great improvement.

BIPV design based on BIM is the process of simulation and optimization design of photovoltaic system by using the storage information in the building information model.When creating the BIM model on BIPV,the flow of information is the clue,and related software is the platform,such as REVIT,CAD,weather tool,pvsyst and ecotect analysis.At the same time,we look the management and operation mechanism,indicators and evaluation system as the criterion,and thus we can make overall consideration on the BIPV project life cycle.

In order to construct the model of BIM system for BIPV,we should integrate the overall performance and database,and complete the modeling and simulation of the platform construction,and supervise the operation management during the BIPV design and optimization,and construct the platform of the climate &product and the instance database &management information,then we can provide the services,such as detection,management,inspection,scientific research and engineering design for the government,scientific research institution and the design institute.

With the establishment of BIM model,the BIPV design develops into the accurately detailed quantitative analysis from the rough qualitative analysis.Here the framework of this model system is mainly divided into:management information platform,BIPV modeling and simulation platform,data platform and BIPV energy detection and analysis platform[7].

1）Management information platform.Its unction mainly includes the energy regulation,energy optimization,power forecasting and decision support.Management information platform is a group of the application systems for different owners in the framework of unified design,and it is an open and sustainable system,and it can continue to expand the platform to provide these functions according to the actual requirements.And then you can also perform simulation and optimization according to the operation data on these buildings,providing the basis of the construction and improvement for the property owners and the construction units.

2）Data platform.Database is an important part of building model and the basis of the upper modeling and simulation platform,and it is also the core part of processing business of the management information platform.Data platform has the very important status in the whole BIM system.As shown in Tab.I,the BIM model database on the BIPV design is divided into:the basic database of the building,monitoring database,business database,service database,model database and case database.

Tab.1 Database Classification

4.2 The Design Process

Now most architectural designs of the Design Institute in Chia are designed after out of construction drawing,so they are just to meet the relevant standards.If you change a small angle during the design,there may be a serious affection on the generation efficiency of the photovoltaic system.The combination of BIM and BIPV design can effectively solve this problem.

（1）Data collection and analysis.We must first investigate the local environment to ensure that the photovoltaic can be sheltered as less as possible from 7:00 am to afternoon 17:00 pm to generate enough electricity,and we can collect the information,such as climate data,the load modeling data and environmental information.After the analysis,the various data will be input into the databases,including that the basic information database of the building,business database,service database,model database,case database.Usually we can use ecotect software,PV*Sol expert to analysis the data of sunshine and shadow of BIPV project.

（2）Create a basic model.At the beginning of the design,choose the reasonable installation method of the photovoltaic modules according to the sunlight conditions,the surrounding environment and architectural function condition,and establish in turn the whole model and the sub models which have the support of real data to provide a data basis for the next step of the analysis[8].

Fig.4 Ecotect software interface

Fig.5 Arrangement for PV modules in PV*Sol software

First,determine the binding means of photovoltaic system and buildings.According to the demand for power generation,photovoltaic module ventilation and the shape of the building requirements,the means combined with the PV system and structure can be roughly divided into eight types,as shown in Fig.5.

Fig.6 The means combined with the statistical photovoltaic system and buildings

Then choose the configuration of the photovoltaic system.That is to say,we should calculate the average daily power consumption and the system voltage according to the load situation,weather conditions and shielding factors.Then determine the various correction factors and system margin with the load conditions,the loss of the system,the efficiency of the system and the selection of equipment.Finally,we should get some information,such as the cable section area,model and the number.Now this part is specified in many books about photovoltaic power plant.

（3）Analysis the energy consumption of the building.With the idea of BIM model,building model can be directly into ecotect by REVIT.After the analysis of natural lighting in ecotect,the designer can adjust the light transmission rate according to the results of photovoltaic epidermis.After the analysis of outdoor wind field,designers can adjust the ventilation strategy of the photovoltaic epidermis.If the shadow analysis found that the photovoltaic component may be blocked,designers could adjust the arrangement and installation of the photovoltaic component.

The energy consumption analysis software,Energy Plus,will be used when you want to analysis the energy consumption of the buildings.Energy Plus can be used to simulate the load and energy consumption of the building and air conditioning system in the whole year hourly,contributing to considering how to save energy for the architects and engineers from the architectural design process.As shown in Fig.7,take the house coming from Tianjin University,named sunny inside,which participated in the Europe ten Solar Decathlon competition as an example.It is well known as a zero energy house.

According to the analysis of the annual energy consumption data,generating capacity is slightly lower than the electricity only in January,but the rest of a year is the realization of the negative consumption,and the annual generating capacity of the photovoltaic power generation system was 17 202 kW·h,and the annual electricity consumption of the building was 10 875 kW h,so the surplus was 6 327 kW·h,meeting the design requirements of zero energy consumption.

Fig.7 Sunny Inside

5 Conclusion

From the planning stage to the final feedback of the owners and the property,the implementation of the BIPV system is a very complicated process.It needs not only the personal ability of the architects,engineers,contractors,construction workers and owners,and the communication association between personnel who involved in,but also needs a good platform for work and communication.The introduction of BIM concept has responded to these needs in a certain extent.

BIM-BIPV design must be combined with a holistic view.In order to meet the technical requirements of the photovoltaic system,and the function and aesthetics requirements of the structure,the designers should coordinate comprehensively the various technical parameters of the photovoltaic epidermal,such as lighting,power generation,heat insulation and the ventilation.At the same time,designers must consider the full-life cycle of the photovoltaic system,and make the overall positioning and detailed deployment on the various stages of the project to improve the environment around the buildings and economic benefits.

With the new development of the BIM technology,BIM-BIPV is now a further extension in the construction area,which is a new BIPV solution based on the“overall perspective”.However,there is a big problem.Now in China the BIM standard is not unified,which will be one of the serious obstacles for the BIM’s promotion and application.

Reference

[1]Zhiyong Jiang,“The application of BIPV”.BuildingElectricity,2008.

[2]Ying Shi,“Solar building design based on BIM”,Tianjin University,2012.

[3]Autodesk,“What is BIM”,Autodesk:http://www.autodesk.com/solutions/building-information-modeling/overview.

[4]Yang Chao,“Buildings generate energy-BIPV”,Architecture &Culture,2011.

[5]Cui Shao,“Inverter research suitable for the small power BIPV system”,Harbin Institute of Technology,2010.

[6]Sumei Yang,“Research on the BIM &BIPV”,Tianjin University,2011.

[7]Nam-Hyuk Ham,Kyung-Min Min,Ju-Hyung Kim,Yoon-Sun Lee,Jae-Jun Kim,“A Study on Application of BIM (Building Information Modeling) to Predesign in Construction Project”,Third 2008 International Conference on Convergence and Hybrid Information Technology,2008.

[8]USA International Solar Energy Society,Photovoltaic Design and Installation Manual (Book Style).Hunan science and Technology Press,2014,ch.9.