Retrofit and regeneration
by Lee McDougall
Director, Building Consultancy
Many Local Authorities (LAs) have, understandably, been wary of taking on BIM unless absolutely necessary, however BIM can provide enormous cost and time savings in retrofit and regeneration projects.
Clearly, at a time when LAs must watch every penny, the costs involved in terms of both software and training can seem prohibitive, especially when perceptions remain of BIM as a wholesale, all-in-one commitment, and indeed as an investment more relevant to large-scale projects.
Given that LAs are more concerned with smaller-scale retrofits and renovations, the tendency to perceive BIM as an unnecessary or inconvenient burden make sense.
This is a shame, because the flipside is that BIM can provide enormous cost and time savings in retrofit and regeneration projects - two obvious benefits for LAs under pressure to refurbish or regenerate existing against a background of increasingly tight budgetary restraints and minimal funding. It is also a shame because, despite lingering perceptions, BIM adoption need not be a complex or costly endeavour.
While LAs have understandably been wary, some Housing Associations are increasingly utilising BIM, possibly because the task of building new social housing has increasingly fallen to Registered Providers, which may be more familiar with the technology through new build.
Yet they are also increasingly interested in BIM’s benefits in retrofitting and regeneration. Even for those entirely new to BIM - and many still are - what has attracted these Registered Providers to dip their toes into the BIM waters has been an increasing awareness of the opportunities for ‘signing up’ to BIM (and indeed its costs) in incremental steps and on smaller-scale projects.
The benefits have proved manifold. Not only does BIM decrease safety risks, providing peace of mind, it also produces significant efficiencies in both cost and time. In social housing, time is particularly of the essence where disruption to residents needs to be minimised, not least for vulnerable or elderly residents for whom intrusion can be especially unsettling.
Conventional surveying methods are more cumbersome and therefore more time-consuming and intrusive. In contrast, the use of laser scanning eliminates the need for extensive scaffolding and, when combined with drone technology, enables access to high-up or difficult-to-reach areas which would previously have required cherry pickers and all the time and inconvenience these entail.
BIM’s capabilities in accurate digital testing also reduce cost inefficiencies: these data-rich models act as replicas of the buildings themselves, and as such provide highly reliable test results which reduce wastage. As but one example, a project as part of a framework with WDH (Wakefield District Housing) involved alterations to the lift arrangements for a series of residential tower blocks. Given the lift shafts were located at the heart of the buildings, the undertaking was highly sensitive because it related to the buildings’ core strength; any alterations would have had clear structural impacts. This is the case whenever alterations have any structural bearing: without BIM, calculations will err on the side of safety and as such over-compensation can occur, which in turn increases the costs of materials.
With BIM, by contrast, we can build a highly accurate digital model and test the structural scenarios under various pressures. Digital testing facilitates far more accurate predictions and so reduces the required over-compensation, in turn providing further assurance and significantly reducing wastage in materials.
This is just one example of the way in which BIM reduces inefficiencies and therefore costs. In another recent project involving a two-storey block of flats, for which a leading London Housing Association was keen to embrace the benefits of BIM, the issue was the excessive ‘wiggle-room’ that would have been required in sizing when replacing balconies, doors, windows and roof lights.
Again, inaccuracies were highly reduced with the added advantage of allowing the client to click and schedule out how many windows were required, the area of roof tiles and so on.
In another project, laser scanning was undertaken by our in-house team for two 11-storey residential blocks that required refurbishment and re-cladding. This provided the client with accurate data on the deviation of the faces from the vertical, allowing precise engineering of the panel system to take into account any movement that would not have been seen prior to fabrication and which might have caused issues during construction. The method’s speed and accuracy also prevented any potential site revisits; minimising time, cost and inconvenience.
This is all very well but these benefits can still seem difficult to access when BIM adoption is perceived as an enormous undertaking and a prohibitive one-time expense, so it’s useful to remember than this need not be the case.
Our work with Housing Associations has often helped to guide them step-by-step so that they can get to grips with BIM in an incremental, low-risk manner, reaping the benefits not only on individual projects but, since each BIM slots into any other, over time through the cumulative development of a data-rich model of the entire estate.
BIM need not be seen as a burden but rather a beneficial and accessible tool that can help control schedules and budgets in a challenging economic climate.
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