After managing to produce my Architectural floor plan drawing last week, this week I have started to look at my Mechanical graphical model.
Around my home, there are several different heating products I need to register and capture within my information model. So, I thought I would try something different and attempt to use some manufacturer’s objects instead of producing my own. Unfortunately finding suitable objects has proved rather difficult, however, I did manage to find a few boilers on the portals of each of the three most popular online object libraries: National Building Library (NBL), BIM Store, and BIM Object. So I thought I would compare each of them to decide which I would use.
Let the Object Library Wars Commence!
I went onto the portal for each of these online object libraries and searched for the term ‘Boiler’ and selected the closest object available to compare against the requirements within my BIM Execution Plan. These objects were judged by the following categories based on the appropriate BIM Execution Plan specified BS 8541 standards:
BS 8541-1 specifies how to name objects. The name should include three fields separated by an _underscore, written using CamelCase:
- Source (The library it was taken from or the manufacturer of the object);
- Type (Appropriate IfcType as included in the appendix of BS 8541-1);
- Subtype (Additional details NOT covered in the object’s attributes).
For an object name to be compliant I would expect to see something similar to:
So, what names have been used? Shown below are the boiler names as they were downloaded. As you can see each object included a source, however, none of them used the IFC Type or its predefined subtype or product/model name. In addition, both the BIM Store and BIM Object boilers include hyphens which are not permitted.
Note: I am aware that each of these libraries has their own object standard. However, my EIR didn’t request these. So my BIM Execution Plan needs to comply with the national standards.
Level of Detail:
BS 8541-2 specifies the need to be able to visually represent an object with three levels of detail: Coarse, Medium, and Fine. These levels of detail allow an object to show only relevant elements as required. For example, the detail needed in an assembly drawing would not need to be visible in a general arrangement. I’m pleased to report that each of these objects did incorporate these levels of detail; resulting in a three-way tie.
|Source||Levels of Detail Provided||Rank|
|NBL||Coarse, Medium, and Fine||1st|
|BIM Store||Coarse, Medium, and Fine||1st|
|BIM Object||Coarse, Medium, and Fine||1st|
Shape and Measure:
BS 8541-3 specifies that product objects (those that represent an actual product) are required to have a coordinating level of detail. This means that the product should be visibly recognizable. However, it also warns about the dangers of excessive geometric detail, which can be seen in these objects. Here are two examples:
- Company logo. Shown here is the Worcester logo included in the BIM Store Boiler. Why? The logo itself is only 25mm high and is only legible at quite low scales. What value does having this logo included bring to this object?
- Complex elements. Many of these families utilize nested objects (objects within objects, think Terry Pratchett and turtles). Some of these nested objects are quite complicated for what are essentially graphical placeholders. For example, take the flue basket also shown below from the same BIM Store boiler which uses a horrendous amount of rules to show that it is perforated.
As you can see below, these additional complexities have negatively affected the file sizes. With NBL again coming out best with the smallest file size by far for their generic boiler.
NOTE: The file size for the flue basket is 668KB, so this nested object alone takes up more memory than the whole of the NBL Boiler.
Level of Information:
BS 8541-4 specifies that product objects, as defined earlier, should have both specification and assessment attributes. In addition, these attributes should be named in CamelCase and indicate the data type expected. Of the three boilers, only the NBL boiler followed BS 8541-4 fully by using CamelCase throughout its attributes. BIM Store are a close second, follow this convention only for attributes required to achieve BS 1192-4. While the BIM Object boiler does not include BS 1192-4 attributes or use CamelCase.
This means that once again the NBL boiler leads with its impressive use of CamelCase, with BIM Store second, and BIM Object third.
|Source||Level of Information||Rank|
|NBL||CamelCase for all attributes||1st|
|BIM Store||CamelCase only for COBie attributes||2nd|
|BIM Object||CamelCase not used||3rd|
The winner, consistently ranking first in each category is the National Building Library!
However to be frank none of these objects are ideal. For future product objects, it will be much easier for me to create my own. This is due to the limitations I have listed above as well as the fact that these objects cannot be easily configured to suit my needs. For example, for the Classification information to exchange into COBie I require it to be written into a field called ‘ClassificationForObjects’. However, this property doesn’t exist in any of the three boiler objects. In addition, there are a number of attributes I don’t need that will have to be deleted such as the reference to other classification systems, as well as modifications to the geometry to lower the file size.
And there you have it, after comparing three different boilers I have now begun to make the necessary changes to create my final boiler object. This means that subject to ensuring that the correct product information is attached and the inclusion of a few extraction fans, I have now populated my mechanical model; therefore Plain Language Question PLQ2.4 is well underway!
Note: This model does not have any pipework connecting my heating system together, and nor will it. The majority of my pipework is not accessible, and as such, I have decided that I will not guess where they are located. Pipework, therefore, has been excluded from the model until such time as its precise location can be determined.
2.1 What existing information is available?
2.2 Is there sufficient information to produce a BEP?
2.3 What is the layout of the house?
2.4 What assets are contained within?
2.5 What asset information can be linked to the graphical model?
Now that I have a pretty strong Architectural & Mechanical model, it’s time to look at some electrical objects…