Shining a Light on Building Information Modelling
What is BIM?
Building Information Models (BIM) originated within the building construction industry and have been proven to deliver whole life cost savings. The Government Construction Strategy was published by the Cabinet Office in 2011. This report announced the Government’s intention that all centrally procured contracts should be compliant with BIM Level 2 by 2016. The key objective of this approach is to reduce the capital cost and the carbon burden from the construction and operation of the built environment by a fifth.
Building design, to take one example, has transitioned over the last 30 years or so from one largely undertaken on a drawing board to a highly digital, information rich software based activity. It is now possible for computers to greatly speed up and assist the designer. Design standards, regulations and other rules can be ‘built-in’ to the digital model, for instance, if two windows are too close in a design, the computer can provide a warning that building standards will be breached.
All too often however, at the end of the design process, the output is simply a printed sheet or perhaps a PDF file that lacks any of the ‘intelligence’ of the model, and much of the associated information such as manufacturers’ part numbers, and subsequent value is lost. This value can reduce costs of construction, and more significantly whole life maintenance costs.
BIM has often been said to be 20% technology, 80% process, and the primary focus for industry is to develop joined up thinking throughout the whole life of infrastructure. BIM is not software, it is more about planning and a way of integrating all of the tasks and related information with all stakeholders. It is important to identify the project deliverables, and this may need to be developed in discussions with clients.
Underpinning and defining what BIM means for each project will be a ‘BIM Execution Plan’ (BEP). The BEP is a document that will be agreed at the outset. It should be regularly reviewed and may evolve as design teams, suppliers and manufactures, and perhaps even technology changes throughout the project.
What is BIM for Lighting Engineers?
Whilst the lighting industry looks somewhat different to building construction, there are nevertheless many advantages to building a digital street lighting information model. Traditionally, scheme implementation and contract drawings have provided little value after installation. However, lighting design is highly data driven. Lighting assets are also already maintained, usually by means of a Geographic Information System (GIS) so BIM can provide clear benefits by linking information, defined at design time, such as photometric data, and data captured during the scheme implementation, with the maintenance phase.
Whilst most lighting designers will determine the appropriate selection of luminaires against the backdrop of real, to scale, mapping, this context can provide the opportunity for all aspects of a lighting scheme to be calculated. For example, map based design can assist with power, cabling and ducting design as voltage drops are based on actual physical distances read directly from the map. Cable lengths and other design parameters can then be taken forward along with other aspects of the scheme design to assist with testing and commissioning of lighting schemes.
3D vs Data
Much is made about BIM and what it means. BIM is defined as a graduated process, Level 0 being simple CAD (or paper!) based systems that ‘allows for the exchange of information between all parties’. Level 1 and 2 encourage collaboration through the implementation of standards and protocols and the use of 3D; and Level 3, currently seen as the holy grail, represents a fully integrated and collaborative process that will utilise construction sequencing (4D). Many have been seduced by the attractiveness of 3D particularly when this provides photorealistic visualisations, whilst visualisation is important to communicate design intent before a scheme is built, the real value of BIM is to the whole life asset management. To support this the focus needs to be on data, whether that be meta-data attached to the digital design, such as part numbers, or 3D information embedded in 2D objects, such as column planting depths and foundation dimensions.
The image above shows how data can be captured, viewed and edited within the KeyLIGHTS design environment. This data needs to ‘travel’ with the as-built digital representation of objects for the whole life of the digital model. The transfer of as-built data from system to system provides the greatest value by means of efficient data transfer and standardised data formats, and often 3D representations can be effectively created when needed from the embedded data.
It is crucial to BIM that the ‘as built’ situation is captured. Decisions based on the digital model can only be made with confidence if the model reflects the real world accurately. A common situation with poor data – for example below ground assets whose location has not been accurately captured – can often mean that costs are increased due to the need for hand digging, hasty design revisions or repair to accidentally damaged drains, electrical or fibre optic cables.
The process of BIM is not just one-way, however. The process can be described as maintaining value from design through the life and ultimately to the disposal of assets. But the value in the digital model can also be used to inform the design of future schemes and reduce installation costs.
Lighting design data has value beyond the construction, often however, this information can be lost. The process of BIM enables this value to be available for the whole life of the assets. When the data is collated in systems, designed to unify different types of data, such as services and utilities, a more complete and valuable information model can be built. Comprehensive and rich digital lighting models enable sophisticated and cost effective maintenance and operational decisions to be made, and will enable savings to be made in the capital cost and the carbon burden from the construction and operation of the built environment.