3D BIM? 4D BIM? 5D BIM? 6D, 7D and 8D BIM? Junk the lot of them and focus on the only BIM dimension that matters. Henry Fenby-Taylor welcomes you to the data dimension.
There is a problem with the dimensions of BIM. They are used to communicate the value that clients can get from a BIM process with value-added services. However, they’ve always sat to the side of information management and data-rich 3D modelling.
What exactly these dimensions are and how they’re implemented is still, years after their first definition, hotly contested. The number of dimensions vary from six to double digits. This makes teaching people about BIM difficult and standardisation impossible. While the processes of information management are clear and purposeful, and data-rich 3D modelling finds a multitude of purposes, the dimensions are bolt-ons, along for the BIM ride.
Five years ago on BIMplus, Richard Saxon called for greater rigour surrounding the dimensions of BIM. I completely agree, and the way to get that rigour is to delete them all and start again.
“The number of dimensions vary from six to double digits. This makes teaching people about BIM difficult and standardisation impossible.”
Higher orders of the universe
Let’s begin by examining a few of these BIM dimensions. Cost is the fifth dimension of BIM. I find the idea that cost is a fundamental dimension of the universe disheartening at best, but I don’t doubt its usefulness in making construction projects better. The other dimensions are broadly linear, with interesting and subtle changes at very large masses and speeds thanks to the laws of special relativity. Cost is close to a dimension at first glance, you can add costs together and create a total cost in the same way that you can take lengths, add them together and create a total length.
If you think of fool’s gold and its complex geometric patterns, we can see that it is three dimensional, it has complex shapes that have their own length, breadth and depth. So cost starts to fall down if it is just one dimension, because cost isn’t just a simple number that gets bigger: there are hourly rates, inflation, scarcity, insurance, penalty clauses, interest and different liabilities. All of these costs and conditions do, however, add up to a specific amount, so they could be said to be a dimension. So, cost can be specific and it can be measured.
Dimensions carry on
However, there is more to a BIM dimension than our ability to measure it: a dimension is ongoing, it carries on. Time, the fourth dimension, is definitely a dimension. The process of combining 3D models with time- and schedule-related information is highly beneficial, but does time end once the asset is built?
What about facilities management, the sixth dimension? Different stakeholders need to make different decisions about how to operate a facility than those who built it, but the decisions are still about time, how long something will take. So even here, in this well-established dimension, the BIM dimensions are unreliable.
Richard Saxon is completely correct to call the BIM dimensions vague, although I am going further than to call the BIM dimensions above the fifth vague: I think they are all vague.
“The one thing BIM dimensions do is hold data that is intended to convey meaning, and by conveying meaning, lead to action.”
The merits of new dimensions
However, adding dimensions to the universe isn’t just the stamping ground of plucky innovators from the construction sector. It is an area rife with invention. Scientists are still looking for the fifth dimension, some think it might solve the problem of dark matter, that large unmeasured part of the universe.
The accepted dimensions were initially only spatial. It took a lot of debate and argument to agree that Einstein’s discovery of the space-time continuum made time the fourth dimension. There is merit to adding new dimensions to the universe, but they must add something fundamental to our understanding of it. I would argue that they must be specific, measurable and they must be ongoing.
The BIM dimensions all hold values about specific and measurable things that are ongoing. Whether cost, sustainability, security or facilities management, the one thing they do is hold data that is intended to convey meaning, and by conveying meaning, lead to action. This chain is important to our sector, because everything must be purposeful, otherwise it is just a waste of time and money.
Throwing good dimensions after bad
All of the BIM dimensions have a factor in common, whether we’re calculating material costs, preparing for handover or assessing security plans. That factor also connects human society, the economy, politics and our everyday lives.
That factor is data, and data is a useful dimension that requires more attention than ever.
New dimensions, so hot right now
Creating new dimensions, or removing some and replacing them with one, has to have a purpose. While there are only four universally recognised dimensions, there are in fact hundreds of others. Those in physics and mathematics who wish to have their dimensions taken seriously rarely start from the fourth and add on from there. All of these dimensions have a specific purpose and task that is well recognised, and can be clearly explained and implemented. The Hausdorff dimension helps calculate fractals, or justify string theory. These dimensions all exist to define the exact arrangement of something in a way that is measurable.
“You cannot build in two dimensions, you cannot build in stasis, and you cannot build without creating data.”
While reading the paper, Information dimension, it occurred to me that data is the dimension that we need in our sector. The reason for collecting and modelling the cost of a construction project is to manage the cost, so cost is the use case and we need data to understand the cost. The use case for collecting and modelling sustainability information is to manage sustainability: without recording and measuring data this is impossible.
Facilities management? How could you manage a facility without knowing what systems are operational within it? That needs data. No one is creating a use case when they design or build a building. “Don’t forget to build in the third dimension”: that is not a use case, that is a universal requirement, that is a fundamental dimension, you cannot build in two dimensions, you cannot build in stasis, and you cannot build without creating data. The question isn’t do we use these dimensions: the question is how?
That is why we should remove all of the dimensions of BIM and put those uses where they have been the entire time, in the Penn State BIM uses web page. We should replace them with the data dimension. If we gave data the amount of thought and care that we gave the shape of a building and how to build it, then we could achieve the important ambitions that we are striving to achieve: increased productivity and net zero.
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