Explaining the Basics of BIM Analysis
How Building Information Modelling Helps You to Create More Accurate Models
Most architects and engineers will have come across the concept of building information modelling (BIM). It’s a methodology that can reap enormous benefits for your firm. Building information modelling allows you to centralise your project's information. Instead of dealing with lots of documents, you can pool all the relevant data into a single database.
The benefits of this are immediately apparent. As your projects become more complex, they generate a lot more paperwork. Your firm has to spend hours ploughing through all this information. Designers need to compare lots of different drawings to ensure everything matches up. Even the smallest of inconsistencies can damage the project. One missed piece of information may not show up at the design stage. However, it will certainly have an effect when you come to build your structure.
Building information modelling does away with all that manual work. You can feel sure that your calculations and information are both correct. After all, the methodology ensures it. For example, the Revit BIM software will store every bit of data anybody on the team enters into a central database. You work from one model, which everyone on the team can access. Revit notes any changes and applies them instantly.
This allows you to pick up on issues in the early stages of the project. Your firm creates more accurate prototypes, which leads to better models. When you begin building, you can trust your model to offer all the data you need. Best of all, you can access that information any time.
The downside is that adopting building information modelling isn’t simple. In some cases, it requires your firm to undergo an entire culture change. That’s why you need as much information as possible before you make the switch. Let’s look at the basics of BIM models, and how you can use BIM for structural analysis.
The Basics of BIM Models
You’ll need to consider your model type before you can begin a building information modelling analysis. The model you use will differ depending on the type of information that you’re looking to extract.
Here are two basic types of BIM model:
- Energy Models: These building information modelling models deal with all the big questions. You’ll often use an energy model at the earliest stages of your analysis. The energy model helps you to interpret the basic information. You’ll figure out what you need to know about your structure’s form and orientation at this stage. Often, you’ll only use basic geometry to build your models. More realistic and defined specifications come with later energy models.
- Lighting Models: These are all about the presentation because the lighting model handles the visual aspect. They tend to contain much more detail than energy models. You’ll touch up your geometry, and use this model to define the properties of your materials. This is the model that helps you to figure out exactly what you need, as well as how everything should fit together. Generally, your finished lighting model is similar to the one you’ll present to clients.
There are other model types. However, most BIM practitioners agree that the energy model is the most important.
A Word on BIM Energy Models
Lighting models are certainly important. However, your energy model is crucial to the success of your project. Let’s look at energy models in more detail.
As mentioned, the energy model will help you to pull together the basic geometry of your structure. However, it serves a much more important purpose than that. Building information modelling is all about sustainability. It is through your energy model that you’ll be able to determine the effects your structure will have on the environment.
For example, analysis of your energy model allows you to figure out the structure's energy consumption. From there, you can work out how much it will cost to power the structure. You can also calculate the carbon footprint it generates.
As a result, your energy model runs throughout the design process. It forms the basis of everything you build into your models. It will also prove useful in the post-construction phase. Further analysis of your energy model may show future areas of improvement. Or, it may highlight current issues with the structure that affect its performance.
Think of it as a holistic building model. It brings every element of the model together. Thus, it creates a cohesive whole. As the design stages advance, you’ll build even more information into your energy model. You’ll also be able to figure out how the different design elements combine.
You could think of your energy model as your design playground. Constant experimentation, coupled with parametric analysis, will lead to optimisation of the model. You’ll develop a greater understanding of your structure’s energy efficiency. As importantly, you’ll figure out how different components change things. This leads to quick analysis because you can track the most important parameters.
As such, energy models are much more than what was stated above. While your initial energy model will deal with the basics of building form, you’ll build detail into this model as time goes on. Eventually, it will answer even more questions. For example, you’ll be able to figure out how the air conditioning system needs to work. Or, you can check to see that the lighting system is optimised.
As a result, your energy model is key to successful building information modelling.
Do I Need Multiple Models?
Building information modelling focuses on offering a centralised source of information. However, this doesn’t always mean that you only need one model.
For example, you could build several models, each of which analyses something different. One may examine energy usage, while another offers visual clarity. Sometimes, you may even use several models to analyse one goal at different stages.
However, building information modelling doesn’t lose its centralised nature when you use multiple models. In fact, it helps you to build several models. Remember that all the models are linked. A change in one gets reflected in the others. The Revit BIM software shows this in action.
As a result, you can build several models for different types of analysis. However, all these models draw from the same, centralised pool of data.
What Model Inputs Do I Need?
So what inputs do you need for your analysis? It all depends on what you’re using the model to analyse. You could be looking for anything, from energy usage through to lighting arrangements. The inputs you use will be specific to the analyses that you run.
As a result, the structure’s geometry isn’t enough. You may also need to input thermal qualities of the materials you use. Or, you may have to consider how well those materials match your energy usage goals.
Let’s return to the energy model that is so critical to building information modelling. Here is a list of the inputs you’ll need to use to get the desired outputs:
- Information about the structure’s geometry. This includes the basic information, such as the structure’s shape and its layout.
- The technologies that you’ll build into the structure to meet the building’s energy needs. For example, you’ll need to input information about the lighting system, ventilation system, and air conditioning units.
- Thermal performance information for each material used in the structure’s geometry. For example, you will need to account for the type of windows you use. A single pane window would not offer the same energy performance as a double-paned window.
- The surrounding climate, and how it will affect the building's energy performance. For example, you’ll need to know about sunlight if the building uses solar panels.
- The number of people who will need to use the building. As a general rule, more people leads to higher energy demands.
- Which energy sources you have available for the structure. This includes information about the costs of each source, and whether you could mix several sources to obtain better results.
So where does all of this information go? In many cases, you’ll send it to the model’s simulation engine. However, you may also use a simulation tool, such as Green Building Studio. In any case, this information will lead to a more complete energy model. You’ll receive more accurate outputs. Furthermore, you can use this information for other models.
You’ll also find that your inputs improve as the project moves forward. Early inputs are often little better than estimates. As you keep tinkering, you’ll figure out how everything fits together. The fact that building information modelling keeps all of the information in a central database will also ensure you can make these tweaks faster.
What about the Outputs?
As with the inputs, the outputs you return will depend on your goals for the model. This means you need to think about your aims before deciding on inputs. Furthermore, you need to have metrics in mind that will allow you to analyse the output.
You can then use these metrics to compare different designs. Whichever fulfils your goals the best becomes the superior model.
Here are some examples of the sorts of outputs you might expect from your models:
- An early energy model may help you to figure out how much energy the structure will use per year.
- A lighting model may show you how natural light casts shadows on the structure at different times of the day.
These are just two examples of the outputs you can generate using building information modelling. There are many more. Which ones are most important to you will depend on the project.
Geometry and Building Information Modelling
Now let’s look at the issue of geometry.
The key thing to remember here is that building information modelling allows you to analyse the structure. As a result, geometry is secondary to accurate measurements. In fact, most architects and engineers will use simple geometry in the models, which allows them to get actionable outputs quickly.
Furthermore, detailed geometry slows down your simulation times. If you’re using the model to retrieve data, you can’t afford to spend a long time waiting for your software to create the simulation.
Instead, you will use the material parameters to define things like the thickness of walls and surface properties.
Of course, this may not suit your needs when presenting to clients. However, it’s crucial in the early stages of business information modelling. Focus on the data when you’re in the initial design stages. This will help you to design accurate prototypes that make use of all the information at your disposal. You’ll also run faster simulations, which move the project along.
More complex geometry can wait until you’re satisfied with your business information modelling analysis.
As you can see, building information modelling isn’t a simple subject. In fact, it will require you to change how you do things. This is especially the case for architects. Many architects focus primarily on how attractive their models look, rather than how efficient they are. BIM allows you to work with more information. It’s a holistic methodology. You can still create attractive models, only now they have much more reliable information behind them.
Your building information modelling analyses benefit the project at every stage. You’ll create better prototypes quickly. The information that collects in your database will help you to figure out important metrics. These include energy consumption, material needs, and many other things. As the design advances, you’ll be able to prepare your construction teams. Furthermore, the collaborative nature of BIM means every project member can contribute.
So what should you do if you want to explore business information modelling further? For one, ArchiStar Academy’s blog contains a lot more information about the subject. Additionally, ArchiStar Academy also provides courses in several digital design software packages. These include a Revit BIM course. This will show you how to use Revit to create great models. You will also learn more about building information modelling.
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Posted on 10 Dec 2018