OPINION OPPORTUNITY COSTS


BIM provides an opportunity for building service engineers to reduce construction time and cut costs, but their earlier involvement in design must be refl ected in higher fees, argues Phil King


The building information modelling (BIM) revolution is


well under way. The UK government has set a target to reach BIM Level 2 on public-sector work by 2016 and private-sector clients are increasingly requesting BIM on their projects. BIM leads to better collaboration, coordination and exchange of information within industry. For the client, it helps to mitigate risk, reduce costs, minimise waste, shorten programme time and smooth handover and facilities management. For mechanical, electrical and plumbing engineers, it means early involvement and more detailed work at the front end, giving us a big opportunity to reduce overall construction time and cost through services design. It also means a higher volume of pre-fabrication and modularisation, with benefi ts in quality, reduced snagging time, speed of installation and economies of scale.


BIM in practice BIM is a shared digital representation of physical and functional characteristics of a built object, on which critical project decisions can be based. When we reach Level 3 BIM, we’ll be using a fully integrated and collaborative process enabled by web services and using 4D construction sequencing, 5D cost information and 6D project lifecycle management information. This means inputting more detail in


the design phases and marks a major shift in the way we look at the costs associated with building projects. Traditionally, these look like this: Design 1 unit of cost Construction 10 units of cost In occupation 100 units of cost Using BIM, they look more like this: Design 1.5 units of cost Construction 8 units of cost In occupation 90 units of cost This supports Paul Morrell’s change programme, achieving both greater


20 CIBSE Journal April 2013 BIM: what we need


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Hilson Moran’s BIM model of 20 Fenchurch Street


Building contracts will need to encourage an open culture and cover the use of BIM


integration and a 20% reduction in building costs – not to mention the savings in operation. More time and effort at the design


stage and less in construction should be refl ected in the fees awarded. However, in reality, to achieve this we’ll need to be able to quantify money saved as a result of early involvement. Changes to contracts will inevitably


follow. Appointments and building contracts will need to encourage an open culture and cover the use of BIM, as well as outputs (2D drawings, specifi cation, 3D model, or all three); responsibilities, including transfer of the model; and liability. There should be a single owner of the


3D model during the design and construction stages, to which all parties contribute. Additional responsibility and liability impacts would need to be refl ected in the owner’s contract. On handover to the client, agreement is needed on how the model will be updated after practical completion. Lastly, there’ll be a change in how we


work together – engineer to engineer. There will be greater coordination between mechanical engineers, electrical engineers, public health engineers and BIM operatives. We’ll need to think in 3D, work in areas not


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A standardised library of parts BIM education


Measurable and coordinated outputs BIM standards and codes Best practice examples


A standard to enable CFD, DTM, EPC and Part L calculations in the model


Calculations for pump/fan sizing


An agreed split between the consultant and contractor


A standard to create the bill of quantities and asset register, covering how all objects in the model are quantifi ed


A process for tracking changes


Standardised schedules/templates linked to specifi cation stage by stage


Standard colours for each service


A method for feeding plant quotes into BIM, taking into account variations in tenders


A process for measuring benefi ts of BIM: cost, risk and programme


systems, and eliminate paper mark-ups, using the software instead. We’ll also use BIM to do much more, including the creation of 3D geometric models for the following:


• Dynamic thermal modelling • Computational fl uid dynamics • Comfort studies


• Pedestrian wind comfort analysis • Natural ventilation studies • Fire and smoke modelling • Acoustics modelling • Part L assessments


• Energy performance certifi cate assessments


BIM is an opportunity, not just for engineers, but for the government, too, in meeting its cost-reduction targets. Its success won’t happen seamlessly and, as with any new technology, we’ll all need to evolve.


● PHIL KING is a director at engineering consultancy, Hilson Moran


www.cibsejournal.com


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