Last reviewed 1 October 2014
Building Information Modelling (BIM) is a hot topic in construction at the moment; although it has been around as a concept for some time, the advent of new technology, together with the lure of projected 15–20% savings, means there is a real impetus from Government to make it work. Roland Finch explores the ways in which BIM can help with the planning process.
Models are not new. Over the centuries, many landmark buildings would not have existed were it not for the use of models. Sir Christopher Wren’s “Great Model” of St. Paul’s Cathedral is now on display in the cathedral’s Trophy Room. Containing geometric information about the proposed construction, it is an early example of a BIM.
The National Building Specification (NBS) has been carrying out surveys of the use and adoption of BIM since 2010.
During that period, there has been a five-fold increase in people saying they are using BIM, while there is now 95% awareness, compared with almost half of respondents who declared themselves “unaware” only four years ago.
An interesting finding from the most recent survey was that 61% of users believed that BIM brought cost efficiencies, 52% said it increased the speed of delivery and 45% felt that it increased profitability.
But surely BIM is only about construction; it has nothing to do with planning? A simple question will resolve this: do drawings and specification information have a role in the planning process? Then so does BIM.
Historically, the way to convey information about a project (and this is not just restricted to construction) was to provide a written description of what is required. If the written description was going to be difficult to interpret, this was supplemented by drawings. As time has progressed, the preferred method has been to supply a drawing, accompanied by some written notes.
With BIM, however, all this information is contained within a computer model; it is all collected in what is called a “Common Data Environment”. The resulting drawings and specification documents can therefore be extracted from the model, without the need for double-handling. The advantage of this is that there is therefore less opportunity for mistakes in the process.
Of course, there are many other advantages of holding information in this way. Possibly the most frequently quoted benefit is the ability of the model to simulate the construction process without having to go to site. Simulation is one thing that computers do particularly well. Given a set of rules, the computer can imitate a range of different situations, with the result that the optimum solution can be reached, whether this represents the best construction sequence, or the most efficient use of materials.
Unlike the traditional two dimensions of drawn information, models work in “3D”, which means they may be used to show that a particular building component can be placed in a particular position. Consequently, they are very popular when it comes to “clash detection”, not only in the sense that for example the location of building services will correspond with the designed openings through the structure and fabric, but if we add a time dimension to the package, it means that the methods and sequences of construction can be prototyped. If we go a further step and add cost — what some people have termed “5D” — then it means that a series of financial scenarios can be considered.
In fact, the possibilities are vast. If there is a property of the model that someone needs a “report” for, from health and safety to operation and maintenance, then it is possible that a BIM will make it easier.
BIM and the planning process
It can be demonstrated that there are many opportunities for BIM use during the construction process. So with what aspects of the planning process can a BIM assist?
There are some obvious candidates: at its basic level the model, like the drawing, is concerned with geometry — dimensions, shapes and sizes. However, because it is computerised, it is relatively easy to automate the calculation of things like floor areas and the footprint of the building. It may be argued that some of this can be replicated in computer aided design (CAD) packages.
To an extent, this is true, but a fully constructed BIM will contain much more information concerning the properties of individual components within the model. While this may be useful during the construction phase for the automation of measurement of quantities of materials, it can also be very useful during the conceptual stage.
As an example, something as fundamental as how space is enclosed to form a building can be simulated using a model. Because the representation is in three dimensions, it can be done vertically as well as horizontally. From a planning perspective, this could be very important when height is a consideration, or proximity to other structures. Other planning-related considerations like the effect on trees, or loss of view or sunlight can also be modelled, and the best solution agreed.
The model can also be used to calculate the effect of the building on infrastructure. It is possible to simulate likely loading requirements from utilities such as electricity or gas, as well as the consequences for the public drainage system, or local traffic.
The real winner for BIM, however, and possibly its biggest selling point, is the fact that many of these processes can be automated. Already, satisfaction of the energy performance of buildings requirement from Part L of the Building Regulations is demonstrated through the use of a software tool, and this can be applied to a number of different planning and development control requirements.
With a properly constructed BIM, the characteristics of individual components, referred to as the “object properties”, are not simply restricted to physical dimensions. Doors can be modelled by fire rating, for instance, and walls can be modelled using thermal performance, allowing automatic calculation of K and U values. In addition, the individual properties of materials can be included, on a project-wide scale, allowing things like COSHH or manual handling assessment to be carried out.
In fact, almost anything that requires compliance with a set of rules can be dealt with using BIM. This all serves to illustrate why it has such great potential.
BIMs have been tried before. In previous existences, the “M” has represented “management”, “movement” and “monitoring”. This time, however, technology is most definitely driving the BIM process, and the possibilities are there for all to see.
A word of caution, however: BIMs are not a solution; they are only a tool. A BIM can carry out the automated “policeman” role — such as checking for building regulation compliance, as well as the “postman” compliance role, such as confirming that everyone has the relevant software, hardware and latest versions of data. When combined with other applications such as Geographical Information Systems, (GIS), it represents a very powerful tool indeed.
Making best use of a BIM depends on a number of other conditions. First, the model relies on the use of common formats, which in turn necessitate a common classification and terminology. In an industry renowned for its use of vernacular, there will need to be a steep learning curve for practitioners and users alike. It will require close collaboration between all concerned; again something that is not always fully embraced in the design team. Questions have already been asked about intellectual property and liability for errors, so it is not an instant panacea. Like all good things, it has to be worked at to make it a success.
Moreover, the quality of the information within the BIM is only as good as the ability and knowledge of the people generating it. However, it also means there will always be a need for competent and experienced professionals who can assess that information, and ensure the significant project hazards and risks can be identified, discussed, actioned, reported and recorded in a consistent and collaborative way.