Building information modelling mannual

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1. Norwegian Home Builders' BIM Manual Version 1.0 November 2011 Norwegian Home Builders' Association 2. 2 3. 3 Table of Contents…
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  • 1. Norwegian Home Builders' BIM Manual Version 1.0 November 2011 Norwegian Home Builders' Association
  • 2. 2
  • 3. 3 Table of Contents Preface..................................................................................................................................................... 4 1. Introduction to the BIM User Manual............................................................................................ 5 1.1. Background .................................................................................................................................. 5 1.2. Goals............................................................................................................................................. 5 1.3. Target group................................................................................................................................. 5 2. Structure of the BIM manual.......................................................................................................... 6 2.1. Process (Building Information Management).............................................................................. 6 2.2. Product model (Building Information Model).............................................................................. 6 2.3. Modelling (Building Information Modelling) ............................................................................... 6 3. Glossary. Acronyms and definitions. .............................................................................................. 7 4. Fundamental BIM rules for building models.................................................................................. 9 4.1. How to make a good model......................................................................................................... 9 4.2. Fundamental rules for modelling:.............................................................................................. 10 4.3. Modelling practices.................................................................................................................... 12 4.4. Common errors and misunderstandings ................................................................................... 14 4.5. Identification of objects. ID........................................................................................................ 17 4.6. Rooms and naming .................................................................................................................... 17 4.7. Relations between objects......................................................................................................... 18 4.8. Components/building parts that consist of multiple parts........................................................ 18 4.9. Tidying up models...................................................................................................................... 18 5. Fundamental BIM structure for others to be able to utilise the model....................................... 18 6. User manual for the disciplines in the project planning phase.................................................... 19 6.1 The sales representative............................................................................................................. 19 6.2. Project planning manager.......................................................................................................... 20 6.3. The architect .............................................................................................................................. 21 6.4. Electro (RIE)................................................................................................................................ 22 6.5. Sanitation (RIV) .......................................................................................................................... 23 6.6. Heating/ cooling (RIV)................................................................................................................ 25 6.7. Calculations................................................................................................................................ 26 6.8 Ventilation (RIV).......................................................................................................................... 27 6.9. Roof trusses................................................................................................................................ 28 6.10. Energy ...................................................................................................................................... 29 7. Further work................................................................................................................................. 30
  • 4. 4 Preface Making use of information technology to support businesses processes can provide significant and important productivity gains. Through the buildingSMART Project, the Norwegian Homebuilders Association has been involved for many years in the development of open international standards in the field of BIM (Building Information Modelling). We are seeing how new technology and new tools are making it possible to introduce new ways of working. This will contribute to increased value creation and improved abilities to compete. Through the boligBIM Project, we wish to place the members of the Norwegian Homebuilders Association in a position to implement new technology and new tools. The greatest challenges certainly lie, all things being equal, in how each individual member company is able to alter its own business processes. Version 1.0 of the Norwegian Homebuilders Association BIM Manual is intended to be a practical aid for those who perform the project planning for residential dwellings. In conjunction with the user manuals of the software suppliers, we hope that this will be able to provide useful tips and hints that facilitate profitable consequences in the communications of the construction process. We wish to direct a special thank you to Innovasjon Norge, who has contributed valuable financing through the BIT Programme to the work on the on the boligBIM Project. Oslo, 1 November 2011 Norwegian Homebuilders Association Jøns Sjøgren Lars Myhre
  • 5. 5 1. Introduction to the BIM User Manual 1.1. Background The Norwegian Homebuilders Association is working actively to have technology and knowledge developed that will be built up during the use of BIM in the industry. This user manual is a result of the tangible work with the modelling processes out in the companies. Through the manual, the Norwegian Homebuilders Association desires to disseminate practical knowledge to its member companies that will to switching over to a BIM process. The manual summarises general modelling methodology, independently of the software. In addition, the manual describes in more depth the four main areas (calculations, roof trusses, energy calculation and ventilation) in the boligBIM Project and documented “best practices” originating from it. Even though the different homebuilders have different structures in relation to the specific fields which they have centralised and the specific disciplines and phases that they possess internally, most of them will be able to recognise the different roles that contribute to the homebuilders' construction process. Regardless of whether the work is performed externally or internally, a building must for example fulfil customer requirements, have its project planning performed, be approved, constructed and documented. In this manual, we have taken a point of departure in the different roles and tasks, regardless of whether these are external or internal. 1.2. Goals The goal of the user manual is to cover central areas where savings can be achieved by converting to a BIM process. The manual will provide overall assistance in how one ”works BIM” and gives references to other places where specific advice can be obtained in connection with special software programs and tools that go beyond the processes that the homebuilders have in common. 1.3. Target group The target group for this manual is those who are commencing BIM processes in companies that produce residential dwellings. The manual will serve an a aid to working with BIM in practice, both as regards the interaction between the different players and with respect to those who will model the different disciplines in their software.
  • 6. 6 2. Structure of the BIM manual The manual delves into the different parts of “working BIM”. It seeks to give practical advice associated with the processes, modelling and utilisation of the model itself. Even the BIM concept itself is often used somewhat imprecisely, since it can contain the process, the model and the modelling itself. 2.1. Process (Building Information Management) The primary focus in a BIM process is the transfer of information between the phases. These phases may either be within one discipline, or they can be interfaces between the disciplines. What is important in the BIM process is the reuse and reusability of data. The responsibility lies both with those who produce information as well as with those who have received available information. Those who produce information must place the information in a location that allows others to find it, and those who have obtained the information must see to it that it is used and not “reinvent the wheel”. This is main essence of an effective BIM process. If one can be effective in this process, it will open new possibilities for better interaction and more iterative processes converging on a better result, without consuming additional time or resources. 2.2. Product model (Building Information Model) BIM in the form of a digital product model of the house that is to be built is the most widely used form of the BIM concept. In this case, BIM is the building information model itself and contains all the data that is produced in the different process steps. This is often a geometric 3D model, however just as important is all the information it can contain beyond the three first dimensions (the geometric x, y and z directions). Other properties are associated with time, cost, energy consumption and material properties, and are at least of equal importance for building good houses with an effective process. 2.3. Modelling (Building Information Modelling) Modelling is the process of creating the digital building information model. Modelling replaces both drawings and documentation of what previously had been drawn. The first version of the Norwegian Homebuilders Association BIM Manual deals primarily with how one should model building information. Software is available on the market that supports all three of the BIM purposes. It thus is important to use the software for the BIM purpose it has been created for. In practice, this is to say that those who wish to model need to have modelling tools and those who have responsibility for co-ordination and construction processes need to have tools for these purposes.
  • 7. 7 3. Glossary. Acronyms and definitions. Abbreviations: Definition: BIM (Model) Information-enhanced geometric model of one or more objects having relations to each other. The objects may be information-enhanced with different properties and functions, as well as 4D and 5D. BIM (Modelling) The process of constructing a BIM (model). (Digital modelling) BIM (Process) Information and resource management of a project process based on BIM technology and methodology. BIM Co-ordinator A person who has the responsibility for following up on whether the BIM plan is being followed. The BIM Co-ordinator often has the responsibility for checking the level of information and the quality of the BIMs (the models) from the different disciplines, as well as checking the usability of composite interdisciplinary models. The BIM Co-ordinator will often be organised as a support function to the project planning manager, or the role itself may be possessed by the project planning manger. BIM plan Also called BIM Execution Planning. A plan that describes how the BIM project is envisioned being executed, including with respect to information management, exchanges of information, the disposition of resources and competencies, dependency relationships between different participants, etc. Georeferencing The act of placing the project geographically. GUID Globally Unique Identifier, which is a unique code for each individual IFC object (in the world). IFC (Industrial Foundation Classes) An open file format for the exchange of information-enhanced models. The IFC format has broad support as an interchange format between the most significant players in the building and construction sector. The BuildingSMART organisation is working for the development of better and less expensive buildings, including via the use of IFC as an open interchange format. IFC classification The IFC classification of an object encompasses the three parameters of IFC Type, IFC Position and IFC Structural Function IFC object Encompasses all physical objects in one IFC model such as walls, joists, etc. In addition, room objects and conceptual objects such as grids and building lines, etc., are also encompassed. IFC Position This parameter describes the IFC object's placement in relation to the ”climate shell”. If an object is classified as interior, all of its sides face towards the inside of the building, or towards an exterior wall. If an object is classified as exterior, all of its sides face towards the ”outside” of the shell of the building. This classification of elements is especially important for energy simulations in the model.
  • 8. 8 IFC Structural Function The parameter indicates whether the IFC object has a load-bearing function or not in the structural model. IFC Type This parameter describes what type of object is represented in the IFC model. This can for example be a wall, a deck, a window or a flight of stairs. Object A model is as a rule built up from several different objects having relations with respect to each other. For example, a room will preferably consist of four interconnected walls. These walls may in turn contain, for example, doors and windows. The walls, windows and doors represent different objects with different properties and functions. Object ID The different objects are marked with a ”label” which serves as identification to ease its recognition in lists in connection with calculations, etc. The object can be labelled with an easily understandable code such as EW-01 (exterior wall type 1) or another code that corresponds to a labelling system or a product database. Origin The project's ”0 point” (zero point) often marked as a small cross in the modelling programs. The geometric models in the different disciplines must be oriented and related equally in relation to the Origin. Property Set (P sets) Property Sets encompasses all the dynamic information (properties and functions) that are included in the ”translation” of an object to an IFC object. Proprietary file formats The file format that a program has as its unique storage language. Project hotel A central database for secure distribution and sharing of models, documents and information in the project group. The project hotel ensures that all participants, at all times, have the same and the most recently updated information available. Room object If one imagines that one or more rooms in a building will be filled with an object that corresponds to the extent of the room in all three directions, then we have an object that corresponds to the volume of the room. This is called a room object. Open file formats Open file formats have been drafted in order for it to be possible to share information in a simple manner between different programs and software producers. 3D Geometry with an extent and orientation in the x, y and z directions. 4D A geometric model associated with a timeline in a project. 5D A geometric model associated with a timeline and a cash flow.
  • 9. 9 4. Fundamental BIM rules for building models 4.1. How to make a good model The purpose of the model must be clearly and unambiguously defined before construction of a model is commenced. What is to be extracted from the model during the different phases? Who will use the model? How should the information in the model be communicated to others? If the purpose is only to make a good visualisation or simple building permit application drawings, it would hardly be appropriate to model a BIM at a detailed level, with a substantial emphasis on correct technical construction and the level of information in the model. If the purpose of the BIM is however to make good working drawings, prepare a cost calculation or execute an energy simulation, then the need for a precise and ”correctly” modelled BIM is crucial for a simple work process and a good result. Figure 4.1. Purpose of a BIM model. The point of departure for this BIM manual is a need for a model that goes beyond simple drawings, visualisations, etc. It is also a prerequisite that the information must be able to be exchanged using the open file format IFC. In order to develop a model that will, for example, be used for quantity call- offs/calculations, it is a requirement that the model be modelled approximately as the building ”will actually be built”. Good modelling practices thus involves the technical solutions that will be used in the building also being used in the model. This means, for example, that an exterior wall on a storey will as a primary rule be modelled from the upper edge of the deck on the storey to which it belongs to the lower edge of the deck on the storey above. Furthermore, there will be a need to model a deck front edge between the exterior wall elements if the exterior wall elements are to be prefabricated. Figure 4.2. Modelling of elements in an exterior wall/facade
  • 10. 10 4.2. Fundamental rules for modelling:  The common origin (0 point) ought to be placed such that the entire model has positive x and y co-ordinates. The origin ought to lie on the bottom side and to the left of the project/model. Figure 4.3. Placement of the origin (0 point)  Any possible georeferencing of the project should not be done in the model, but externally when the model will possibly be used by surveyors (staking). If there is a need for map data in the model, then map data should be imported as an underlay.  Common storey heights that bear similar relations to the defined 0 point in the model (z co- ordinate). It is also important that everyone agrees on common naming for the storeys in the project. The naming of the storeys and the relations to the model's level function (Entrance, Above Ground, etc.) should be inserted as P Sets in IfcBuildingStorey. Figure 4.4. Example of common naming of storeys  Correct object type. The correct tool must be used in the modelling program, and there must be a conscious relation to the specific IFC type that the objects will be classified as. In the example below, the IFC Element Type is set to ”Automatic”. This is ok if one is sure that the correct tool has been used in the modelling of the object. Figure 4.5. Classification of IFC objects (IFC Type, IFC Position, IFC Structural Function)
  • 11. 11  Objects must have an affiliation to the correct storey, i.e. the storey on which they occur. A column or a staircase that goes from the basement to the attic must in other words be modelled as individual columns or staircases belonging to each storey.  ID setting for objects must be consistent in the model and ought to correspond to an agreed information manual.  Avoid collisions between objects. A collision will rarely be buildable, and in addition may lead to erroneous quantity call-offs, etc.  The different disciplines ought to each be modelled in models for thei
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