A 3D representation of Abu Dhabi international airport, designed by Arup Associates, which says it uses BIM at early-stage design (see CIBSE Journal, January 2011, page 22)


Although some cynics see BIM as being


driven by commercial software developers, there are tri-partite client-designer-contractor pioneers who already see the long-term benefits of BIM. Large contractors are also increasingly demonstrating capability and influencing the BIM agenda. In some parts of the world, mechanical-


and-electrical (M&E) manufacturers have been quick to produce BIM representations of their products (known as ‘objects’) as a means of gaining a foothold in BIM –


‘Objects’: parametric and non-parametric


Non-parametric objects are components in a drawing or model of limited capability, so they will have no ‘intelligence’. For example, in a traditional computer aided design environment these may come from a library of symbols or graphic representations of components that can be imported, visually resized, rotated and transformed. They may be quick to produce but, with little functionality and as ‘image’ objects, they can consume a large amount of memory, particularly when providing high-resolution visualisations. Any changes to a non-parametric object will require specific action on the shapes and lines that make up the object, and any resulting


36 CIBSE Journal January 2012


variation in its functionality (such as light output from a luminaire) and the varying relationship with other components, would need to be established separately. Parametric objects would typically be based on a set of rules and relationships that define its appearance and performance, allowing a range of unique instances of the object. For example, a simple light fitting could have rules that define the pattern of light output based on varying the shape, reflector colouring/ reflectivity, and light source. And, as these parameters are altered, together with relationships defined by the luminaire position and other room definitions, the profile


of the light output can be used to feed into a lighting visualisation. Parametric modelling maintains relationships between different objects to feed data between themselves, and hence adapt and evolve the design. For example, if the walls in a room are moved (as well as other walls adapting automatically to maintain a consistent room) the number and/or size or luminaires can automatically adapt to maintain appropriate lighting levels. The parametric information can flow through integrated applications (such as energy models) and interoperable systems (such as procurement systems).


although many UK manufacturers have been slow to make their equipment available as BIM objects. This is partly due to the lack of standardisation of the defining framework for the software objects, and an absence of a clear policy direction from government and professions. Many have already built up large resources of simpler ‘non-parametric’ objects for use in existing drawing and fabrication software. And, indeed, some manufacturers have faced criticisms when producing over- complex, resource-hungry BIM objects. Without appropriate standardisation, this is almost inevitable, as their objects are driven by commercial forces rather than the need for functional elegance.


Procurement UK-based building services consultancies are very conscious of competitors in Europe, particularly Scandinavia, Russia, Japan and China moving forward with BIM. National policy is key. Following the publication of the UK government BIM Strategy in July 2011, it is expected that all government-funded projects worth more than £5m will have to adopt BIM by 2016. Such government procurement must


also be accompanied by clear advice on how BIM will affect roles, responsibilities, as well as risk and reward in construction. The industry needs project and business implementation advice so that it can


www.cibsejournal.com


Arup Associates


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