LIGHTING BIM
such as windows, wall thickness, shading and so on, says Bissell. ‘However, to feed into the BIM, you need to have completed your strategy by hand, and already have completed some check calculations with a separate model. So again, we still need to design ahead of putting information into the BIM.’ Tulla also raised the issue of the size of files involved. ‘The complete files are massive. There is a basic level showing where all the building services go, but this doesn’t tell you much – you don’t know what the space looks like and you can’t do renderings because there is no photometric data attached to the luminaire. ‘Once you get to the second level – where all
the technical characteristics of the equipment are included – you get weighed down with data. There are ways around it by only using selected layers, but this nullifies the whole point of a totally integrated BIM file.’ Shaw foresees that BIM could have repercussions at the installation stage. ‘Another concern I have is that the whole coordination piece only works if the workmen physically installing on site actually install stuff as shown in the model. Are we really expecting the guys on the tools to look at the model to know where to take their fixings, how tight to soffits to hang ducts, and have the ceiling grids hung exactly where they are drawn? ‘More often than not, the existing paper drawings are not consulted; neither are
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manufacturer’s instructions – hence the problems we experience at present. How do we see this part of the BIM process working?’ Perhaps one of the most fundamental reservations concerns the actual definition of the lighting design function itself, says Bissell. ‘The people who are Revit-proficient may believe they can do the lighting design. This has been a problem for daylight design – daylight factors – for a good few years now with some engineers thinking design is just about pressing buttons. It seems to be heading that way with climate-based daylight modelling (CBDM) with some just wanting a process and a series of buttons to press. ‘BIM is likely to introduce a whole new
group of people to lighting through a simple button-press process. Software can be, and indeed should be, a very positive and productive tool, but it has to be used by people educated in that subject – and, more importantly, by people who care passionately about that subject.’ CJ
BIM by demand
‘The Government Construction Strategy (GCS) requires that: government will require fully collaborative 3D BIM (with all project and asset information, documentation and data being electronic) as a minimum by 2016 [BIM
Level 2]. This refers to all centrally procured government projects as outlined in the GCS, including new build and retained estate, vertical and linear.’ BIM Task Group (
www.bimtaskgroup.org/)
March 2014 CIBSE Journal 43
Image (top) created in Photoshop and Dialux. The room was created using CAD and Radiance by Cundall Light4
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